chrysiptera parasema , also known as yellowtail damselfish , yellowtail blue damsel , goldtail demoiselle , and other variations , is a popular saltwater aquarium fish from the indo-pacific .

it was described by fowler in 1918 .

chrysiptera parasema

chrysiptera parasema has not been evaluated for the iucn red list of threatened species .
light - emitting diode spectral sensitivity relationship with reproductive parameters and ovarian maturation in yellowtail damselfish , chrysiptera parasema .
chrysiptera parasema , also known as yellowtail damselfish or goldtail demoiselle is a popular saltwater aquarium fish from the indo - pacific .
) because they do look very similar . the chrysiptera hemicyanea , however , has more yellow on its body than the chrysiptera parasema , which just has the yellow on its tail .
specificationsmpnf91 0007 0076manufacturerthat fish placecommon nameyellowtail damsel scientific namechrysiptera parasema difficultyeasy reef safeyes . . .
azure demoiselle ( chrysiptera hemicyanea ) spawning in the branches of an sps coral .
the yellowtail damsel ( chrysiptera parasema ) has a bright electric blue body and a yellow caudal fin . they should not be confused with c . arnazae , whi . . .
varies - chrysiptera species occur singly , in pairs , or in small loose groups .
the fish chrysiptera parasema is known under several different common names in english , such as yellowtail damsel , yellow - tail blue damselfish , blue yellowtail damselfish , goldtail demoiselle , and yellowtail demoiselle .
less attitude and a brilliant blue body with bright yellow tail make c . parasema quite an appealing little damselfish !
when it comes to the genus chrysiptera , there are several good choices , and i’ve had very good success with them .
sand - chrysiptera species like to burrow under rubble , coral ( they will not harm the coral ) , and dead coral .
chrysiptera parasema is a hardy member of a saltwater aquarium . because of this and its usually low price it is often recommended as a way for novice marine aquarium keepers to gain experience . thirty gallons is typically quoted as the minimum tank size required to permanently house this fish .
citation :
goldtail demoiselles , chrysiptera parasema ~ marinebio . org .
marinebio conservation society . web . accessed monday , july 9 , 2018 . < urltoken > . last update : 1 / 14 / 2013 2 : 22 : 00 pm ~ contributor ( s ) : marinebio
light - emitting diode spectral sensitivity relationship with reproductive parameters and ovarian maturation in yellowtail damselfish , chrysiptera pa . . . - pubmed - ncbi
the yellowtail blue damselfish is sometimes confused with the azure damselfish ( chrysiptera hemicyanea ) because they do look very similar . the chrysiptera hemicyanea has more yellow on its body than the chrysiptera parasema , which just has the yellow on its tail . this damsel is usually better kept in groups of 3 or more because they can become very territorial if kept singly . this is probably one of the least aggressive of all the damsels , but can still be aggressive nonetheless . try putting your arm in the tank to perform tank maintenance and you ' ll see what we ' re talking about .
video shows a goldtail damsel ( chrysiptera parasema ) specimen from the philippines or indonesia locations . these have only yellow on the back tail and a little into the body . they are small , mellow for a damsel , and easy to take care of . they do spawn in captivity easily , though rearing the young can be quite difficult .
the blue devil damsel ( chrysiptera cyanea ) is a hardy , brilliant blue fish . the only significant marking is one small black spot by the rear of their . . .
this species is a member of the very large pomacentridae family of damselfish and anemonefish . it belongs to the subfamily pomacentrinae in the large chrysiptera genus . there are currently 34 recognized species in this genus .
with respect to conspecifics , c . parasema is one of the few damsels that can be kept in groups . however , i would recommend attempting this only in larger systems with lots of rockwork to provide ample hiding places and disrupt the damsels’ line of sight .
while the usual conundrum when choosing tankmates for a damsel is finding species that won’t be tormented by the damsel , that problem is sort of turned on its head with c . parasema —you have be more wary of introducing aggressive tankmates that will pick on the yellowtail .
research chrysiptera parasema » barcode of life ~ bioone ~ biodiversity heritage library ~ cites ~ cornell macaulay library [ audio / video ] ~ encyclopedia of life ( eol ) ~ esa online journals ~ fishbase ~ florida museum of natural history ichthyology department ~ gbif ~ google scholar ~ itis ~ iucn redlist ( threatened status ) ~ marine species identification portal ~ ncbi ( pubmed , genbank , etc . ) ~ ocean biogeographic information system ~ plos ~ siris ~ tree of life web project ~ unep - wcmc species database ~ worms
not only is c . parasema a perfect choice for beginners , but it’s also an ideal candidate for reef systems . this diminutive gem of a damsel is completely inoffensive to corals and other sessile invertebrates and will have a minimal impact on the system’s bioload . photo credit : moto @ club4ag
not all damsels are such brutes , however . while not exactly angelic , the yellow tail and azure damsels , chrysiptera parasema and c . hemicyanea respectively , are , on the whole , much better behaved and a better choice for the newcomer . in terms of clownfish , common clowns , amphiprion ocellaris , are generally quite docile , and at a push , i’d recommend the timid orange skunk clownfish , a . sandaracinos , providing optimal water quality and a host anemone are provided . quarantine all clowns upon purchase , and buy captive bred specimens whenever possible .
now , that doesn’t mean that c . parasema is a complete caspar milquetoast . it’s a damsel , after all , and the rules of appropriate order of introduction still apply . extremely shy , retiring species—especially those that are very similar in size and color , should be introduced before the yellowtail .
a little humbug or domino damsel ( various dascyllus species ) or aptly - named blue devil damsel , chrysiptera cyanea , might look like butter wouldn’t melt , but allow one to establish its territory and further additions of stock could be in a whole world of hurt .
damsels are placed in the genera ; abudefduf , amblyglyphidodon , amblypomacentrus , cheiloprion , chrysiptera , dischistodus , hemiglyphidodon , hypsypops , lepidozygus , mecaenichthys , microspathodon , neoglyphidodon , neopomacentrus , nexilosus , parma , plectroglyphidodon , pomacentrus , pomachromis , pristotis , similiparma , stegastes and teixeirichthys .
the yellowtail blue damsel , also known as the yellowtail damselfish , yellowtail demoiselle , or azure damselfish , is bright blue , with a tail of energizing yellow . ( some call c . parasema the azure damselfish , however , in the aquarium trade , the azure damselfish is considered to be c . hemicyanea . )
. . . angelfishes , damselfishes , clownfishes ) , which lay their adhesive eggs on solid materials , different spawning substrates for breeding have been tested . for example , olivotto et al . successfully spawned lemonpeel angelfish , centropyge flavissimus , and the yellowtailed damselfish , chrysiptera parasema , using natural live substrates , i . e . live rocks [ 7 , 9 ] . however , the use of live rock as substrate is not ideal because its removal is harmful to the marine environment and it is likely to carry a range of nuisance and pathogenic organisms that could severely affect broodstock health . . . .
the yellowtail blue damsel , chrysiptera parasema , also known as the yellow tail blue damsel , features a bright blue body with a neon yellow tail that turns into translucent at the edges of the fins . they are a prime community reef fish that live best in small groups of at least three or more , or else they can become territorial . they are best introduced last into the tank as well . the yellowtail blue damsel is very hardy and eats almost anything contributing to its lifespan of up to five years . the yellowtail blue damsel is a versatile fish that will thrive in almost any home aquarium .
allen , g . r . , m . v . erdmann and p . h . barber0 a new species of damselfish ( chrysiptera : pomacentridae ) from papua new guinea and eastern indonesia . aqua , intnl . j . ichthyol . 16 ( 2 ) : 61 - 70 . ( ref . 84037 )
this genus of damsels , the chrysiptera , has a wide array of temperaments with the yellowtail blue damselfish being one of the less aggressive . like all damsels , however , they can become territorial and aggressive when kept as a pair and as they get older . still they are not anywhere near as aggressive as their cousin the
their small size along with the less pugnacious nature of many of the chrysiptera makes them suitable for the aquarium . some of the more passive species can even be kept in groups and may get along with more peaceful tankmates . there are exceptions , however , as some species become highly aggressive in the confines of an aquarium as they mature .
c . parasema is omnivorous , and , therefore , its captive menu should include a good variety of both meaty and algae - based foods . mysid shrimp , brine shrimp , finely chopped seafood , pellets , flakes , and various frozen formulations for omnivores and herbivores are just a sampling of the foods it will accept . again , feeding is a snap and hunger strikes are rare with this species .
i’ve also kept two other quite peaceful damsels in the genus chrysiptera , e . g . , c . hemicyanea ( azure demoiselle ) , and more recently , c . starcki ( starck’s demoiselle ) . they both made good reef aquarium additions , and were added at various times during the history of those aquariums . both did well on the foods mentioned above .
some chrysiptera species occur at rather deep reef zones , but the majority are found in the shallower waters of lagoons , sheltered bays , and coastal fringing reefs . they live near coral growth and may hover close to the substrate . they occur singly , in pairs , or in small loose groups . they are omnivores , feeding on plankton , algae , and small benthic crustaceans .
few species are better suited to beginners than the yellowtail blue damsel . c . parasema is remarkably hardy , so it can usually weather the occasional water - quality missteps that beginner’s are prone to , and it will readily accept standard aquarium fare . owing to its diminutive size and the fact that it doesn’t demand a great deal of open swimming space , it’s also a great choice for smaller aquariums ( down to about 20 gallons ) .
the yellowtail damsel is a bright blue fish with a yellow tail that fades into clear at the edges . it is sometimes confused with its close relative the azure damsel ( chrysiptera hemicyanea ) , but the azure damsel has more yellow on its body than the yellowtail damsel . in an azur damselfish , the yellow colour is primarily found in the pectoral and anal fins and not in the tail .
the yellowtail damsel is also known as the yellowtail blue damselfish , the yellowtail demoiselle and the goldtail demoiselle . it is confused in naming with the azure damselfish ( chrysiptera hemicyanea ) , which is yellow in the pectoral and anal fins , but not in the tail . the yellowtail comes from the central and western pacific , including the red sea . it is bright blue , with a yellow tail that fades to clear at the edges .
c . parasema is truly a gem of a fish . its body is a lustrous blue overall . depending on the lighting over the aquarium , this coloration can take on brighter or deeper hues or even appear purple or almost black . as the common name suggests , the tail and caudal peduncle are bright yellow . in some specimens , yellow may also appear on the anal fin and the trailing edge of the dorsal fin . the maximum length for this species is not quite 3 inches .
adults are typically found by themselves or in pairs , while juveniles are found in small groups . this is one of the more peaceful of the chrysiptera genus , yet it is just as sturdy as its conspecifics . it is similar in temperament to a less aggressive clownfish . the yellowtail blue damselfish will swim up to 20” above the substrate to feed on zooplankton , and will also consume other planktonic foods and algae that are near the bottom .
these beautifully marked , smaller damsels are very easy to keep . they are very durable and will readily eat any aquarium food offered . provide rock work or corals in and around all areas of the tank which offer lots of nooks and crannies for them to hide in . they prefer to hang out at the middle to bottom of the tank . like all the damsels in the chrysiptera genus they also like to burrow . they will make areas under rocks to retreat at night , so a sandy bottom is preferred .
one of the most commonly available species is the yellow - tail blue damselfish c . parasema . it comes from the central indo - pacific where it inhabits , in large numbers , areas around dense coral growths . it gets to about 3 inches in length . it’s another readily available species in the trade and is always inexpensive , especially considering its beautiful electric - blue body and yellow tail . as with most damselfish it thrives on meaty foods , e . g . , mysis shrimp , brine shrimp , shredded marine - fish or crustacean flesh , cyclops , and enriched flake foods .
these nests can have almost 10 , 000 eggs from several different females ! males have been known to abandon their small eggs clutch to take over larger abandoned egg clutches of another male . they know that the more eggs they have in their nest , the better the chance the female will spawn with them . the male will stay and protect his eggs until they have hatched , which can take up 4 days in the wild , depending on water temperature . the larval stage for chrysiptera species can last between 10 to 50 days .
demoiselles of the chrysiptera genus are very durable damsels once acclimated . the most dangerous time in their lives is the shipping stress they deal with . overall they are tough and do not often fall ill , but it has been documented that there seems to be an unexplained “sudden death” that damselfish can fall victim to . there are no signs , the fish is just dead one day . they can contract any normal disease that other saltwater fish are susceptible to . but it is pretty rare unless they are captured with an illness already in motion , so a quarantine period is a good idea .
these are one of the less aggressive damselfish . they swim in mid to lower areas of the tank , but as they are often preyed upon in nature , they need many places to hide to feel secure . they will appreciate little crevices , nooks and crannies created within rock work ( preferably live rock ) , corals , or other decor . they appreciate branching stony corals to retreat into , be it live or artificial , which helps simulate their natural environment . in the wild , the chrysiptera genus are found in areas of rubble , and like to dig their nests underneath dead corals , a 1 / 2 clam shell , or rubble . a substrate of sand will make it easier for them to burrow in . you can also add a larger shell for them to lay their eggs in .
mini reef aquarium guide . reef aquarium setup for large reef tanks , nano reef tanks , pico reef or micro reef aquariums with reef tank lighting , filtration , choosing coral reef animals , and problem solving !
setting up a saltwater aquarium . guide to marine supplies , putting the aquarium together , cycling the aquarium water and adding fish !
throughout the ages people of been fascinated , thrilled , frightened , and horrified by these creatures . they have been the subject of myths , novels , movies . . .
observations and insights of a marine enthusiast . an in - depth explanation of what it takes to be a successful marine aquarist
enter your freshwater aquarium enter parameters for your freshwater aquarium to get compatibility information while browsing .
enter your saltwater aquarium enter parameters for your saltwater aquarium to get compatibility information while browsing .
fish finder search our database for compatible pets ! enter characteristics of what you are looking for and find them instantly .
dr . jungle ' s pets and animal speak - newsletter featured pet of the week and more . . .
we would like to import some live zebra shark . contact me please . best regard , liu wei chung . email : s89186 @ urltoken
i have a green moray eel that is just too big now , does anyone have a huge tank . . . . 400 + gallons ?
last month i lurched 3 to cycle my tank . they lived peacefully for around 4 days then the smallest and another one pecked a hole in the biggest one . then once he . . . ( more ) andrew
is a beautiful small fish . its coloring is very dramatic with a bright blue body and a yellow tailfin , but it will only reach about 2 3 / 4 inches ( 7 cm ) in length . depending on their location of origin they can also have a yellow pelvic fin and some may have yellow pectoral fins . another damselfish it can sometimes be confused with is the
, which is similar in coloring . the azure also has the yellow fins but is distinguished from the yellowtail damselfish because the yellow also extends along the bottom part of the body .
this fish is considered by many aquarists to be the ultimate damselfish . it ' s an aquarium favorite because it ' s very active and a great eater . it is also extremely hardy and very is inexpensive to boot . it makes a great choice for beginners , yet is enjoyed by all aquarists . other common names it is known by are yellowtail damselfish , yellowtail damsel , and goldtail demoiselle .
this is a damsel that will not reign terror in your tank when given plenty of room . they are a great addition to any peaceful community tank , be it a reef or fish only tank . they need a minimum tank size of 20 gallons for one , or a male and female pair if they are the only fish in the tank . groups can be kept in medium sized tanks of at least 40 gallons , where they will readily get along with other peaceful fish . while they can be kept in a nano tank , they are less likely to cause trouble in larger tanks with other less aggressive tank mates . they are the ones that tend to get picked on by larger , more aggressive fish , so proper tank mates are essential to keep them from being stressed out .
real nice video showcasing this wonderful beginner saltwater fish . this pretty little fish is also known as the blue yellowtail damselfish and the goldtail demoiselle .
. this species is also known by the common names yellowtail damselfish , yellowtail damsel , goldtail demoiselle , yellowtail demoiselle and yellowtail blue damsel , all of which aptly describe their coloring .
they are found in the western pacific , in the solomon islands , northern papua new guinea , philippines and ryukyu islands . this species is not listed on the iucn red list of threatened species .
this genus contains some of the most beautiful and brightly colored damselfish , as well as some of the smallest . on average the species range from about 2 . 8 inches ( 7 cm ) in length to a few centimeters longer . they may be territorial towards conspecifics , but many are not as aggressive as other pomacentrids towards other types of fish .
the goldtail demoiselles prefer densely populated coral groupings in sheltered lagoons and inshore reefs . they are found at depths between 3 . 3 to 52 feet ( 1 to 16 m ) . small groups , especially juveniles , are found over acropora colonies .
the yellowtail blue damselfish is a deep bodied fish . these damselfish are small , reaching only up to 2 3 / 4 inches ( 7 cm ) in length . similar to other damselfish , their life span in the wild is likely 2 to 6 years and they probably live the typical 15 years in captivity .
this damsels body is an intense medium blue color with a yellow tail fin . some only have a yellow tail fin , while others may also have the yellow extending onto the body up to the back of the anal and dorsal fin . they can have a yellow pelvic fin as well , and some may have yellow pectoral fins . although these damsels have a rather distinct look , a couple other fish may be confused with them :
this fish has yellow on the belly , whereas the yellowtail damselfish does not .
certain specimens have yellow on the nose and chin , whereas the yellowtail damselfish does not . some blue devils have a yellow to orange tail , and their blue is less intense . these fish also grow larger , reaching up to 3 . 1 inches , and are much more aggressive .
the yellowtail blue damselfish have various quantities of yellow on their tail fins , depending on their location of origination , but yellow is never found on the back or belly . those that have a yellow tail fin with just a little yellow extending into the body are generally specimens from the philippines and indonesia . specimens from papua new guinea may have yellow on their tail fin that extends onto the body to the back of the dorsal and anal fins . species from this area may have yellow pectoral and / or pelvic fins as well .
15 years - damselfish generally live up to 6 years in the wild and up to 15 years in captivity .
the yellowtail blue damselfish are durable and very easy to care for . they make a great addition for the beginning saltwater hobbyist or any other marine aquarist . these attractive “demoiselles” are hardy little fish and great eaters . they will help with algae control and appreciate meaty foods as well . they tolerate a wide range of non - fluctuating temperatures , but even though they are quite durable , they can still fall ill if exposed to poor water conditions for too long .
the tank needs to be at least 20 gallons for one damsel or for a mated pair , so make sure water changes are frequent in such small tanks . they will be quite happy in a reef or a fish only community tank , but as they are often preyed upon in nature , they need peaceful companions and a lot of places to hide in rock work or corals to feel safe . doing normal water changes , feeding them a variety of foods several times a day , and having proper tank mates will keep this damselfish happy and healthy .
beginner - they are suitable for the beginner , but being a more peaceful damselfish , tankmates must be selected with care .
the yellowtail blue damselfish are omnivores . in the wild they feed on zooplankton , and will also consume other planktonic foods and algae . in the aquarium provide variety in their diet that includes plenty of proteins as well as some vegetable foods .
offer meaty foods like mysis shrimp , vitamin - enriched brine shrimp , cyclops , finely shredded frozen seafoods , and preparations for omnivores . these foods can be given as freeze dried , frozen , sinking pellets , flake or fresh . you can also offer some flakes and other preparations for herbivores . color enhancing foods can help maintain their bright coloring .
it is best to feed small amounts of food several times a day . feeding them more often helps to dissipate any possible aggression within a tank , since food is the biggest reason for protecting their little patch of the reef or tank . sinking pellets work great because these fish tend to feed near the bottom of the tank . if feeding pellets , make sure they are wet before adding them to the tank so air will not enter into their digestive tract , which can cause issues .
yes - make sure to soak pellets for a few seconds to dispel any air . use sinking pellets since they stick close to the bottom , and preferably those designed for carnivores .
some of diet - only needed if you want to offer a treat or condition them to spawn .
several feedings per day - feed several times a day , this also helps to counter any possible aggression .
these damselfish are hardy and easy to keep with a well maintained tank . minimum tank size is 20 gallons , so make sure water changes are frequent in such a small tank . regular water changes performed bi - weekly will help replace the trace elements that the fish and corals use up . guidelines for water changes with different types and sizes of aquariums are :
nano / small tanks up to 40 gallons , perform 5 % water changes bi - weekly .
medium sized tanks up to 90 gallons , perform 15 % bi - weekly .
large tanks 100 gallons and over , once water is aged and stable , can be changed 10 % bi - weekly to 20 % monthly , depending on bioload .
nano / small tanks up to 40 gallons , perform 15 % water changes bi - weekly .
medium sized tanks up to 90 gallons , perform 20 % to 30 % monthly depending on bioload .
large tanks 100 gallons and over , once water is aged and stable , can be changed 20 % to 30 % every 6 weeks depending on bioload .
for more information on maintaining a saltwater aquarium see : saltwater aquarium basics : maintenance . a reef tank will require specialized filtration and lighting equipment . learn more about reef keeping see : mini reef aquarium basics .
bi - weekly - do bi - weekly water changes of 15 % in a reef setting or 20 % monthly in a fish only tank .
the yellowtail blue damselfish can be happily kept in a reef setting as well as in a fish only peaceful community tank . they typically only grow to 2 3 / 4 inches , so the minimum tank size is 20 gallons for one , or for a mated pair . in that small size of an aquarium , however , be very careful when adding other fish since they are territorial , especially if you have a mated pair . they can also be kept in a nano tank if they are the only fish in the tank .
a larger tank will be needed to keep them with other fish . housing them in tanks over 40 gallons will allow plenty of territory for them to occupy and they shouldn’t bother the other peaceful fish you want to add . if keeping other peaceful damsels , including less aggressive clownfish , add them at a rate of 1 fish per 15 gallons . if you are going to have larger fish like a large surgeonfish / tangs , the tank size should fit the larger fish’s needs .
there are no special requirements for water movement or lighting , unless housed with corals , in which case the coral requirements will need to be considered . water temperatures between 74°f to 84°f ( 23° - 29°c ) , with ph from 8 . 2 to 8 . 4 will keep them happy and healthy . breeding temperature should be similar to clownfish , with optimal spawning production occurring between 79°f to 83°f ( 26°c to 28°c ) .
20 gal ( 76 l ) - a 20 gallon tank is suggested for one fish or a male and female . a larger tank , of 40 gallons or more is suggest when keeping with other peaceful fish .
yes - this fish should be alone or as a mated pair in this size tank .
typical plus hiding places - provide places for them to hide within rockwork or coral .
any - it has no special lighting requirements , though if kept with live coral the coral may need strong lighting .
79 . 0° f - the optimal temperature for good quality eggs and larvae occurs with temperatures of 79° f to 82° f ( 26° - 28°c ) .
these are one of the less aggressive of the damselfish , with a temperament that is closer to a less aggressive clownfish . the minimum tank size is 20 gallons when kept alone or as a mated pair . . you may keep them in small groups by “crowding” with other peaceful damselfish at a rate of 1 fish per 15 gallons . with a spawning pair the male will viciously guard his eggs , at which point , a separate tank may be needed if he starts attacking tank mates . larger tanks of at least 60 gallons should make this situation less volatile .
they will get along with peaceful , passive fish in these larger tanks though you should allow the peaceful tank mates to become established first . they do not seem to be bothered by most other peaceful and semi - aggressive fish , except the more aggressive damsels or clownfish such as the
. tanks over 55 - 60 gallons should allow both to get along without any trouble , as long as their territories are at least two feet apart .
keep an eye on semi - aggressive fish to be sure they are not harassing your yellowtail blue damselfish . very aggressive dwarf or pygmy angelfish and very aggressive roaming clownfish may attack the this damsel . do not house them with larger semi - aggressive fish who are also planktivores , like anthias , or any sized aggressive fish . they will not do well with aggressive fish at all , and tend to be the ones picked on by fish that are larger and more aggressive than they are . predatory fish are also out of the question , since they may eventually eat your damsel !
in a reef setting the yellowtail blue damselfish thrive . they make a great addition to a reef because they pose no threat to corals . in fact branching stony corals benefit from the flutter of their fins between their branches , helping to dislodge detritus . bottlebrush acropora seem to be a favored coral . they will also happily pick off any algae growing at the base of a hard coral . they won ' t bother any large or small invertebrates , though they may eat a copepod or two .
semi - aggressive - although they are considered semi - aggressive , they are one of the less aggressive of their genus .
yes - adults can be kept singly or housed as a male / female pair , and as juveniles in small groups .
monitor - only safe in tanks of 55 gallons or more . avoid very aggressive clowns such as clarks and aggressive anthias unless tank is at least 100 gallons .
monitor - dottybacks will be too aggressive . other small damsels with a similar mild temperament can be kept if the tank is at least 60 gallons . six - and eight - line wrasses may harass your talbot’s in smaller tanks .
monitor - these damsels may picked on by aggressive large angelfish . add first and provide multiple hiding places and allow them to acclimate before adding this type of fish .
threat - do not house with fish large enough to swallow them . even a smaller predatory fish that cannot swallow them whole would make these damselfish too afraid to come out and feed .
monitor - these damsels will out compete them for food in smaller tanks . larger tanks over 100 gallons should provide enough food for all .
all damsel species are similar to clownfish and follow the general breeding pattern of clownfish . successful breeding requires perfect water parameters and a large , non - predatory aquarium system . if breeding in captivity , note that brittle stars , serpent stars , wrasses and crabs will eat the eggs of damselfish . the eggs and larvae are much smaller than clownfish , and are difficult to rear .
the yellowtail blue damselfish readily spawns in captivity . they need the water temperature to be between 79°f to 83°f ( 26°c to 28°c ) . similar to others in their genus , in the wild , males have their own territory , which is near a nesting site . this site has rubble or a half of a shell from a clam as the roof and a burrow underneath . the day before the spawning ritual begins , a female will visit the males in her colony . when she chooses a fit and healthy partner she will stop swimming , and facing upward , will flash a light ring around each eye .
after she sends the signal the male whose nest she wants to inspect responds by acting out displays . these displays are also evaluated ! the female will then follow the male to his nest after his display to see how many eggs he has . she will stay up to 20 minutes inspecting his “crib” and then move on to the next male . she is not ready to lay her eggs during this evaluation and she is very picky . she will review many of the potential mates , even traveling up to 325 feet ( 100 m ) in distance from nest site to nest site .
at dawn of the next day , the female will then spawn with the male that she decided would be the best candidate . this male that is chosen is typically the largest and the male with the most eggs . if there is another female at the nest who wants to spawn with the same male , she will wait her turn at the entrance of the nest . up to 4 females have been seen at one nest site spawning one at a time , one after the other , with the same male .
the yellowtail blue damselfish have been known to spawn easily in captivity , with the one female depositing around 300 eggs . the eggs will hatch within 96 hours when the temperature is 84˚f ( 28˚c ) . they hatch a couple of hours after the lights are turned off . once they are are all hatched , olivotto , 2003 , suggests feeding the larvae pufa as their first food and keeping the light on 24 hours a day for the larvae to survive . this produces “green water” which helps to maintain better water quality due to the decreasing of waste by the larvae . water changes of 10 - 30 % per day , cleaning the bottom of the bare tank is essential . see general breeding techniques under clownfish on the marine fish breeding page .
moderate - the eggs and larvae of damselfish are quite small and the fry are difficult to rear .
the most easily cured of these is crypt ( salt water ich ) , but they are all treatable if caught in a timely manner . marine velvet is a parasitic skin flagellate and one of the most common maladies experienced in the marine aquarium . it is fast moving and primarily infects the gills . uronema disease , which is typically a secondary infection , is very deadly and will attack your damsel quickly and lethally . the first symptom is lack of appetite . it is most often contracted when the aquarist lowers the salinity to treat another type of illness , but doesn ' t lower it far enough . this parasite thrives in mid - level brackish water salinity , which is a specific gravity of around 1 . 013 to 1 . 020 .
treat your new damselfish as gingerly as you would any other saltwater fish , and they will respond well . anything you add to your tank that has not been properly cleaned or quarantined , including live rock , corals and fish can introduce disease . the best prevention is to properly clean or quarantine anything you want to add to the tank . for information about saltwater fish diseases and illnesses , see aquarium fish diseases and treatments .
the yellowtail blue damselfish are readily available and are inexpensive . they can obtain from stores and online
h . debelius and r . h . kuiter , world atlas of marine fishes , ( in german ) hollywood import & export , inc . , 2006
burgess , axelrod , hunziker iii , dr . burgess ' s atlas of marine aquarium fishes , t . f . h publications inc . , 1990
rob van woesik , environment editor prof . , interactive effects of interspecific competition and microhabitat on early post - settlement survival in a coral reef fish , springer link , 2009
last month i lurched 3 to cycle my tank . they lived peacefully for around 4 days then the smallest and another one pecked a hole in the biggest one . then once he was dead the smallest started going after the other one . so i gave it to my uncle and now am left with the mean killer one .
my husband and i are new at the saltwater . after we got our tank set and waited till all was right w / the salt and such , we bought two of these lovely fish . however , after we put them in , we can ' t seem to find them anymore , we are confused as there are no other fish in the tank . hope to see them soon .
um the last time i had one of these fish it jumped right out of the tank and we found it dried out on the floor = ( but they could just be hiding too .
if they are small and you have an over flow on your thank they might have fallen into the overflow so you might have to fish them out if they are still alive . if the tank is new and rocks were not set up sturdy enough a rock might have fallen on one of them . both of these have happened to me . my experience with damsels is that they usually don ' t hide . especially if they are the only fish in the tank ! most of them are fearless . every time i have ever gotten more than one damsel , they have killed their conspecifics until there was only one left . but those are the blue devil damsels . if one is chasing the other it would be possible that one just jumps out of the tank too , so i would look around the tank also
may have jump , got sucked into filter , check sump . maybe try sifting the sand a bit .
damsels are good fish for the cycle process and are cute while they are young or juvenile . when they age , like people , they lose their vibrance and become a little more cranky . i house 2 of them now , a yellowtail and a velvet in a 55 gallon reef tank . i was going to trade or sell the damsels after the cycle process was completed but i noticed them eating algae off the rocks in between the zoas and the paly ' s that the turbo snails can ' t get at so i am thinking now that i may keep them around . typically they hate anything new in their space but mine seem oddly docile . . . they don ' t attack other fish , even new tank mates . they do go after the snails and my hermit crabs but i can ' t tell if it is an aggressive lunge or if they are eating off the shells . it appears as though they are just picking stuff off the shells .
i ' ve had my yellow tail damsel for almost a year now , it was the first fish in my tank . i ' ve had fish come and go in my tank due to various reasons , but my yellow tail has held on thick and thin and is by far the hardiest fish i ' ve ever had . however , he is aggressive with new fish , though only shortly after he
tells them he ' s boss
. my damsel is cautious and loves swimming in and out of my rock . he is getting
lighter
in color as he gets older . this is a great fish starting out and isn ' t that aggressive .
copyright © [ animal - world ] 1998 - 2015 . all rights reserved .
html public
- / / w3c / / dtd xhtml 1 . 0 transitional / / en
urltoken
comparative biochemistry and physiology . toxicology & pharmacology : cbp . ( journal , magazine , 2000 ) [ worldcat . org ]
your web browser is not enabled for javascript . some features of worldcat will not be available .
your list has reached the maximum number of items . please create a new list with a new name ; move some items to a new or existing list ; or delete some items .
note : citations are based on reference standards . however , formatting rules can vary widely between applications and fields of interest or study . the specific requirements or preferences of your reviewing publisher , classroom teacher , institution or organization should be applied .
the e - mail address ( es ) field is required . please enter recipient e - mail address ( es ) .
the e - mail address ( es ) you entered is ( are ) not in a valid format . please re - enter recipient e - mail address ( es ) .
i thought you might be interested in this item at urltoken title : comparative biochemistry and physiology . toxicology & pharmacology : cbp . publisher : new york , ny : elsevier science , ©2000 - isbn / issn : 1532 - 0456 oclc : 43977002
please choose whether or not you want other users to be able to see on your profile that this library is a favorite of yours .
comparative biochemistry and physiology . part c , pharmacology , toxicology and endocrinology ( dlc ) 2003233211 ( ocolc ) 38840872 comparative biochemistry and physiology . part c , toxicology & pharmacology ( dlc ) 2003233210 ( ocolc ) 53256156 comparative biochemistry and physiology . toxicology & pharmacology ( ocolc ) 680321345
comparative biochemistry and physiology . toxicology & pharmacology toxicology & pharmacology toxicology and pharmacology cbp . comparative biochemistry and physiology . comparative biochemistry and physiology .
add tags for
comparative biochemistry and physiology . toxicology & pharmacology : cbp .
.
you may have already requested this item . please select ok if you would like to proceed with this request anyway .
comparative biochemistry and physiology . toxicology & pharmacology : cbp . / ; new york , ny : elsevier science , ©2000 -
worldcat is the world ' s largest library catalog , helping you find library materials online . learn more ››
don ' t have an account ? you can easily create a free account .
control of chromatophore movements in dermal chromatic units of blue damselfish - - ii . the motile iridophore . - pubmed - ncbi
warning : the ncbi web site requires javascript to function . more . . .
comp biochem physiol c . 1986 ; 83 ( 1 ) : 1 - 7 .
control of chromatophore movements in dermal chromatic units of blue damselfish - - ii . the motile iridophore .
the mechanism regulating the movements of the unique motile iridophores of the blue damselfish , chyrsiptera cyanea , was studied . the reaction in which the cells become reflective to light rays of longer wavelength , i . e . from the near u . v . region to the green region , was designated as the
coloring response
, while the reverse process was labeled the
clearing response
. both nervous stimuli and adrenergic agonists gave rise to the coloring response , which could be antagonized by alpha adrenolytic agents . the clearing response was accelerated by adenosine and inhibited by theophylline . none of the hormonal substances tested had any effect on the motile response of the cells . it was concluded that the motile iridophores are solely under the control of the sympathetic adrenergic system , and that the co - transmitter , adenosine , may function to antagonize quickly the true transmitter - induced colored state of the cells .
the yellowtail damselfish is particularly hardy and many hobbyists will use them to cycle a new tank . using them to cycle your tank is not recommended because it is very cruel to the fish . a better , more humane way to cycle your saltwater tank would be to use live rock . as always , do not keep them with fish large enough to view them as a nice snack .
yellowtail blue damselfish will go after most fish food including vitamin enriched flake food , frozen , freeze dried and live foods .
much like other damsels , this one can be moderately aggressive . aggression can be lessened or spread out if you have 3 to 7 in your aquarium .
they shouldn ' t bother the corals and / or anemones but can sometimes be little jerks to the other fish in a reef aquarium setup .
omnivore - try to give them a variety of foods . they will take vitamin enriched flake foods , frozen and definitely live foods .
© urltoken - providing tropical fish tank and aquarium information for freshwater fish and saltwater fish keepers . sitemap | aquarium fish sitemap | aquarium fish dictionary | privacy policy | contact us
please select from the available marine fish species below . you may also click here to browse the category .
please select from the available invertebrate species below . you may also click here to browse the category .
please select from the available coral species below . you may also click here to browse the category .
please select from the available aquarium supplies below . you may also click here to browse the category .
with 79 or more in marine life . use coupon code : freeshipping more details
contrary to popular belief i had had no problems with this damsel . . i have heard that they are the meanest lil jerks and can be such pains . . . but this guy ai have had since start of my tank he has never attacked another fish he is never mean . hes healthy hardy and been a great community addition !
these are so cute , , a great addition for any tank . the color is so vibrant , they arrive healthy . just a little acclamation time and you can enjoy them for years .
great fish if you ' re looking for a splash of blue . very peaceful damselfish . he gets along with all his tank mates , including the kupang damselfish i added at the same time . oftentimes he will swim with my two clowns .
all images , pictures and descriptions are generalizations and cannot be exact representations . copyright 2018 saltwaterfish . com . all rights reserved .
receive free shipping on qualifying order when you sign up to receive our email . open your email for complete details .
greek , chrysos = golden + greek , pteron = fin , wing ( ref . 45335 )
marine ; reef - associated ; non - migratory ; depth range 1 - 16 m ( ref . 7247 ) . tropical ; 30°n - 13°s
western pacific : including solomon islands , northern papua new guinea , philippines , and ryukyu islands . there is a doubtful record from the great barrier reef off cairns , australia .
maturity : l m ? range ? - ? cm max length : 7 . 0 cm tl male / unsexed ; ( ref . 9710 )
dorsal spines ( total ) : 13 ; dorsal soft rays ( total ) : 10 - 12 ; anal spines : 2 ; anal soft rays : 11 - 12 .
adults inhabit coral - rich areas of sheltered lagoon and inshore coral reefs ( ref . 9710 ) . they occur in small groups on acropora patches ( ref . 48636 ) . oviparous , distinct pairing during breeding ( ref . 205 ) . eggs are demersal and adhere to the substrate ( ref . 205 ) . males guard and aerate the eggs ( ref . 205 ) .


the abc islands bears ( ursus arctos sitkensis ) is a subspecies of brown bear that resides in southeast alaska and is found on admiralty island , baranof island , and chichagof island of alaska .

these islands have the colloquial name of the abc islands ( alaska ) and are a part of the alexander archipelago .

this brown bear population has a unique genetic structure , which not only relates them to brown bears but to polar bears as well .

ursus arctos sitkensis habitat exists within the tongass national forest , which is part of the perhumid rainforest zone .

abc islands bears

- statistic measurements of polar bear ancestry on the x chromosome vs . autosomes reveal a striking difference between abc islands bears and non - abc islands bears . the pattern of
note , however , that brown bears do not live on pow island today and the abc islands sit several islands to the north .
within the abc islands , the brown bears from baranof and chichagof islands have more polar bear ancestry than the brown bears from admiralty island ( fig .
abc bears from chichagof island . a sow and cubs . courtesy jim baichtal ( more “real” abc bears )
this observation led some researchers to conclude that the abc islands brown bears gave rise to modern day polar bears .
abc islands brown bears are more closely related to female polar bears than to male polar bears . ( photo by michael dobson )
abc bears from chichagof island . a boar and a sow . courtesy jim baichtal ( more “real” abc bears )
they concluded that the abc islands bears descended from polar bears that were gradually converted into brown bears through interbreeding with male brown bears from the alaskan mainland .
the first genetic studies of abc islands brown bears looked at their mitochondrial dna , which is separate from the chromosomes and is inherited only through the female lineage . the mitochondrial dna of abc islands brown bears matches that of polar bears more closely than that of other brown bears , which led some scientists to think that the abc islands brown bears gave rise to modern polar bears .
the team compared the x chromosomes of the abc islands brown bears to the x chromosome of brown bears from the alaskan mainland .
, table s2 , supporting information ) . consistent with previous observations using only a single mainland brown bear , comparison between any abc islands bear and any non - abc islands brown bear showed an excess of polar bear ancestry in the abc islands bear . also as before , the excess of polar bear ancestry in abc islands bears was greater on the x chromosomes than on the autosomes ( fig .
previous research had traced the earliest female brown bear ancestor for modern polar bears back 14 , 000 years to the alaskan abc islands .
mitochondrial phylogeny for polar bears , abc island brown bears and extinct irish brown bears . adapted from edwards et al .
the genetic debate stems from a population of brown bears that live on alaska ' s admiralty , baranof , and chicagof islands , known as the abc islands . these bears that are clearly brown bears in appearance and behavior have genetic similarities closer to polar bears .
a key finding is that the polar bear ancestry of abc islands brown bears is conspicuously enriched in the maternally inherited x chromosome . about 6 . 5 percent of the x chromosomes of the abc islands bears came recently from polar bears , compared to about 1 percent of the rest of their genome . this means that the abc islands brown bears share more dna with polar bear females than they do with polar bear males , shapiro said .
ak coastal guiding offers both brown and black bear guided hunts on the abc islands and mainland coast of southeast alaska .
knowing that abc bear populations could survive glacial conditions on pow adds to the importance of understanding the relationship of abc brown bears to modern and ancient polar bears .
at the center of the confusion is a population of brown bears that live on alaska ' s admiralty , baranof , and chicagof islands , known as the abc islands . these bears - - clearly brown bears in appearance and behavior - - have striking genetic similarities to polar bears .
for each of the non - abc islands alaskan brown bears we analysed , excess polar bear ancestry is observed on the autosomes over the x chromosome when compared to the swedish brown bear . the opposite is observed in the abc islands brown bears . this x chromosome depletion is more pronounced than the x chromosome enrichment on the abc islands . there are multiple plausible hypotheses that could explain this result , both demographic and selective .
) . the strongest evidence is found with brown bears from the abc islands and the weakest with brown bear populations from north america and fennoscandia , suggesting gene flow continued between polar bears and abc brown bears also after the brown bear populations diverged . in addition , we find evidence of recent migration between brown bear populations . our data included six brown bear samples from the abc islands (
at the center of the controversy : a group of brown bears that live on the admiralty , baranof and chichagof ( abc ) islands of southeastern alaska .
we observe a geographic signal wherein bears from the islands less accessible from the mainland – baranof and chichagof islands – have more polar bear ancestry than the bears of admiralty island ( fig .
these results have several important implications for understanding the admixture event on the abc islands . most importantly , we now estimate a much greater amount of polar bear ancestry in each abc islands brown bear than previously reported . recalculating the absolute amount of polar bear ancestry for the five abc islands bears using the swedish bear as the nonadmixed standard results in higher estimated proportions of polar bear ancestry than when using the denali bear ( table
) . the brown bear mitochondrial lineage that is most closely related to those of polar bears is found today only on alaska ' s abc islands ( fig .
the scientists analysis featured blood and tissue samples from 79 greenlandic polar bears and 10 brown bears from sweden , finland , as well as alaska ' s glacier national park and abc islands .
while attending a conference this summer , beth shaprio spoke about the unique phylogeography of brown bears on the abc islands of alaska ; specifically that abc brown bears have polar bear mitochondrial genomes . after her talk , i was frequently asked if black bears from the alexander archipelago ( which includes the abc islands ) have a similar story . they don’t ! but they have their own interesting story i want to tell you about .
shapiro and her colleagues analyzed genome - wide dna sequence data from seven polar bears , an abc islands brown bear , a mainland alaskan brown bear , and a black bear . shapiro ' s team found that polar bears are a remarkably homogeneous species with no evidence of brown bear ancestry , whereas the abc islands brown bears show clear evidence of polar bear ancestry .
here , we test the extent of polar bear ancestry within and beyond the abc islands population by analysing genomewide data from a more diverse panel of brown bears ( fig .
model of continuous migration of mainland male brown bears to abc islands initially populated with polar bears . migration starts at time t gf . the migration rate per generation is constant and equal to m .
what they found is that abc bears are genetically close to polar bears because that ' s what they used to be .
but there is one group of brown bears that has shown signs of mixed heritage — the so - called abc bears on the admiralty , baranof and chichagof islands off the coast of alaska . previous studies of some of their dna have shown the abc bears are more closely related to polar bears than they are to other browns .
but research shows that it was the other way around , with the abc polar bears interbreeding with brown bears in the past .
notably , baranof and chichagof islands brown bears’ polar bear ancestry is less x chromosome biased than admiralty island bears’ polar bear ancestry ( fig .
abc island brown bears share genes with polar bears , which led scientists to think they were similar to the bears that would have been the ancestors of the polar bear . but scientists at uc santa cruz now think the story of the abc bears goes the other way around — that they are the descendants of female polar bears who were the original inhabitants of the islands .
our previous observations about polar bear ancestry within abc islands bears relied on comparison to a single mainland brown bear from denali national park , alaska . while the comparisons were consistently and strongly in the direction of excess polar bear ancestry in abc islands bears , use of a single comparison genome is limiting in an important way . quantifying the absolute amount of polar bear ancestry requires making an assumption about the amount of polar bear ancestry in the comparison brown bear . for our previous work , we made the assumption that the denali bear was free of polar bear ancestry . following this assumption , the excess polar bear ancestry in abc islands brown bears was interpreted as a measure of the absolute amount of polar bear ancestry in the abc islands brown bears .
sitka is a community of about 9 , 000 on baranof island . admiralty , baranof , and chichagof islands together are known as the
abc islands .
they ' re sparsely populated with humans but heavily populated with bears that alaska researchers have found are genetically more closely related to polar bears than to other brown bears .
these genetic observations and the natural history of the abc islands are consistent with a model wherein abc islands brown bears are the descendants of an original population of polar bears . immigration of primarily or exclusively male brown bears gradually converted the phenotype and genotype of the abc islands bears into those of brown bears . this male - biased gene flow did not convert the strictly maternal mitochondrial dna and was less pronounced in converting x chromosome loci , but completely converted the paternal y chromosome . this result overturns the previous hypothesis that polar bears received their mitochondrial haplotype via introgression from a population of brown bears closely related to the abc island brown bears or ancient irish brown bears ( edwards et al . 2011 ) . rather , the mitochondrial haplotype found in polar bears is of polar bear origin . under this scenario , brown bears in the brown / polar mtdna clade are the recipients of introgression from polar bears .
we recently proposed that the abc islands brown bear population descends from an admixture event with polar bears ( cahill et al . 2013 ) . we observed that abc islands brown bears show evidence of increased polar bear ancestry relative to other brown bear populations throughout their autosomal genomes . however , polar bear ancestry is further elevated on abc island brown bear x chromosomes compared to their autosomes ( cahill et al . 2013 ) , and they contain mitochondria that are more similar to those of polar bears than to other brown bears .
that isn ' t enough for the abc bears to have maintained their original genetic identity , she said .
) . comparisons between bears in this larger panel reveal a more widespread pattern of polar bear admixture into brown bears . we find evidence of polar bear admixture in abc islands brown bears and in brown bears from the alaskan mainland . within the abc islands , we identify a geographic cline of admixture , with more retained polar bear ancestry in bears further from the mainland . finally , we find no evidence of gene flow from brown bears into polar bears , in stark contrast to the widespread signal of gene flow in the other direction .
d - statistic and z score for admixture test between three abc islands brown bear and polar bears , using the american black bear as outgroup . brown bears admiralty and baranof are the two abc islands brown bears recently published by miller and colleagues , and are labeled according to island of origin . our abc island brown bear is also from admiralty island , and is labeled abc ( adm ) . other abbreviations are as in table s2 . significant deviations from d = 0 are highlighted in bold . the lancaster sound polar bear is not included as either i1 or i2 .
the polar bears appear to be part of the brown bear population in the mitochondrial ( mtdna ) tree , with a divergence time 150 , 000 years ago . abc shows the relationship of the abc island brown bears .
a further unexpected result is that in contrast to the excess of polar bear ancestry on the x chromosomes relative to autosomes among abc islands bears , we see the opposite pattern within non - abc island brown bears ; that is , these bears have lower levels of polar bear ancestry within their x chromosomes vs . their autosomes ( fig .
shapiro and her colleagues analyzed genome - wide dna sequence data from seven polar bears , an abc islands brown bear , a mainland alaskan brown bear , and a black bear . the study also included genetic data from other bears that was recently published by other researchers . shapiro ' s team found that polar bears are a remarkably homogeneous species with no evidence of brown bear ancestry , whereas the abc islands brown bears show clear evidence of polar bear ancestry .
these bears , brown bears in appearance and behaviour , carry dna that match polar bears more closely than other brown bears .
as the weather started to get warmer and warmer , brown bears — males , as it turns out — could swim across the channel that separated the abc islands from the alaskan mainland and colonize these islands . there they ran into this isolated , trapped population of polar bears and they started hybridizing with them .
at the end of the last ice age , a population of polar bears was stranded by the receding ice on a few islands in southeastern alaska . male brown bears swam across to the islands from the alaskan mainland and mated with female polar bears , eventually transforming the polar bear population into brown bears .
assembly ) and re - sequenced at 3 . 5x to 22x coverage 79 greenlandic polar bears and ten brown bears from fennoscandia , mainland us and the admiralty , baranof , and chichagof ( abc ) islands off the coast of alaska (
estimates of polar bear ancestry in abc islands brown bears ranges from 5 . 9 % to 8 . 8 % of the autosomes and 7 . 5 to 9 . 7 % of the x chromosome . as noted above , all of the abc islands brown bears’ x chromosomes are enriched for polar bear ancestry compared to their autosomes . within the abc islands , x chromosome bias of polar bear ancestry increases as total polar bear ancestry decreases . the brown bears of admiralty island , the island closest to the mainland , have the least polar bear ancestry , and polar bear ancestry is the most x chromosome biased ( tables
the genome - wide analysis presented here indicates that ( 1 ) polar bears are a remarkably homogeneous species and show no evidence of brown bear ancestry , ( 2 ) the abc islands brown bears show clear evidence of polar bear ancestry , and ( 3 ) this polar bear ancestry of abc islands brown bears is conspicuously enriched in the x - chromosome . abc islands brown bears show a simple positive correlation between how maternally biased a genetic locus is ( mtdna > x chromosome > autosomes ) and how much polar bear ancestry is present ( 100 % , 6 . 5 % , 1 % ) . given this observation , and our knowledge about the natural history of these islands through the pleistocene and holocene , we present the following model .
their conclusion is based on known similarities in the mitochondrial dna ( mtdna ) between abc brown bears and polar bears plus their finding that 6 . 5 % of the genetic material on the x chromosome of abc brown bears ( which is nuclear dna ) is like polar bears , indicating that genetic material likely came from female polar bears .
if you have inside knowledge of a topic in the news , contact the abc .
research reveals that at the end of the last ice age , a population of polar bears was stranded by the receding ice on a few islands in southeastern alaska . male brown bears swam across to the islands from the alaskan mainland and mated with female polar bears , eventually transforming the polar bear population into brown bears .
shapiro ' s paper suggests that the abc bears are a remnant of an ancient population of polar bears that lived in the area during the last ice age . as that period ended and the ice slowly retreated , the abc population got cut off from other polar bears .
the combination of genetics and the known behavior of brown and polar bears hybridizing in the wild today tells us how the abc islands bears came to be : they are the descendants of many male brown bear immigrants and some female polar bears from long ago ,
stirling said .
cahill et al . argue that a population of polar bears got trapped on the abc islands of se alaska towards the end of the last glacial maximum ( lgm : 26 , 000 - 11 , 500 calendar years ago or 24 , 000 - 13 , 000 radiocarbon years before present , rcybp ) and then hybridized with male brown bears that swam to the islands from mainland alaska , “ eventually transforming the polar bear population into brown bears ” ( see fig . 1 below ) . as a consequence , they say , “ abc islands brown bears are more closely related to female polar bears than to male polar bears ” ( see the press release here ) .
young male brown bears tend to leave the area where they were born in search of new territory . they may well have dispersed across the water from the alaskan mainland to the abc islands and hybridized with polar bears stranded there when the sea ice disappeared .
even if this occurred , polar bears did not “turn into” brown bears – a much better and more accurate way to describe this phenomenon is that abc brown bears appear to retain a genetic scar from ancient hybridization with polar bears .
our simplified model - little or no brown bear ancestry in polar bears and matrilineal - biased polar bear ancestry in the abc islands brown bears - is consistent with several important comparative genomic observations . first , mtdna and nuclear genome diversity within both extant and a ∼115kya polar bear is extremely low . this low level of polar bear diversity is consistent with no admixture from brown bears . brown bears , in contrast , show much higher levels of diversity including many deep genetic lineages that have not completely sorted since their population divergence from polar bears . the abc islands brown bears show genome - wide evidence of admixture with polar bears concentrated on the x chromosome . importantly , the level of admixture inferred from d - statistic analyses is only compatible with polar bear admixture into the abc islands brown bear x chromosomes and not the other way around . conveniently , this model explains the presence of the polar bear mtdna haplotype in all abc islands brown bears : the mtdna haplotype of the male brown bear immigrants is lost , regardless of how many male brown bear immigrants arrived .
previous dna evidence has linked polar bears to alaskan brown bears originating in the abc islands ( which consists of admiralty , baranof , and chichagof ) about 14 , 000 years ago . while both groups are brown bears , bradley said that the alaskan bear genetics doesn ' t match the polar bear as well as the irish bears ' does .
mitochondrial genome phylogeny for brown and polar bears showing clade numbers . during last glacial maximum , a population of polar bears lived off shore of the abc islands . after glaciers receded , male mediated introgression of brown bears into the polar bear population resulted in a brown bear population but with a polar bear genome .
but first , a bit of background and my personal caving adventure in abc brown bear country .
) ; that is , non - abc island brown bears have less polar bear ancestry on the x chromosome relative to their autosomes .
a new study shows the mixed dna is not evidence for divergence ; it is evidence of distinctly different brown and polar bears mating . beth shapiro , from the university of california santa cruz , working with other scientists , conducted an analysis of brown and polar bears , and compared it to the dna of an abc island bear . the results were unexpected : polar bears have very pure dna—that is , their dna is consistent across the species and distinct from that of other species . the abc islands bear dna came out to be 1 % similar to that of polar bears , lending credence to the postulate that these bears were brown bears . but when the researchers compared only the x chromosomal dna from the abc islands bears and polar bears , they found a 6 . 5 % degree of similarity .
now a new paper , published thursday in the journal plos genetics , suggests a reason for some of the confusion : researchers misunderstood the history of one particular set of bears in the mix , the brown bears living on alaska’s admiralty , baranof and chichagof ( abc ) islands .
previously , we measured the impact of admixture on the nuclear genomes of abc bears using the d - statistic test for admixture ( green et al . 2010 ; durand et al . 2011 ) . we showed that a brown bear from the abc islands carried more polar bear matching alleles than a brown bear from denali national park . while the result was statistically well supported , this framework – using a single , non - abc islands brown bear for comparison – lacks the power to assess whether the mainland brown bear is devoid of polar bear ancestry or simply has less polar bear ancestry than does the abc islands bear . we were therefore unable to explore the geographic extent to which this admixture event affected bear populations or to explore hypotheses about frequency of admixture between the two bear lineages . recently , a study calculated d - statistics suggesting that other abc islands brown bears and a brown bear from glacier national park in montana , usa , possessed polar bear ancestry ( liu et al . 2014 ) .
. dna studies by james cahill , a graduate student in ecology and evolutionary biology at the university of california - santa cruz , and his colleagues revealed that abc - island brown bears show clear evidence of polar bear ancestry and share more dna with female polar bears than with males . this evidence suggests that at the end of the last ice age a polar bear population became isolated on the abc islands and that male brown bears , which when young tend to leave the area where they were born , swam to the islands and
this entry was posted in evolution , hybridization and tagged abc bears , genetics , polar bear evolution , southeast alaska . bookmark the permalink .
previous analysis indicated that the genomes of abc islands brown bears contain more polar bear ancestry than do those of mainland alaskan brown bears . however , this analysis was performed using only a single genome representing each population . to more fully explore the spatial distribution of the signal of polar bear ancestry within the abc islands , we collected a larger panel of brown and polar bear genomes . we sequenced three previously unpublished brown bears one from sweden and two from chichagof island . we analysed these samples along with samples from two previously published data sets ; two brown bears , seven polar bears and an american black bear published in cahill
the new study looks at the
nuclear dna
carried on the chromosomes in the cell nucleus . it is the latest in a series of genetic studies of polar bears published in recent years , each of which has prompted new ideas about the relationship between polar bears and brown bears . a 2010 study of fossils and mitochondrial dna supported the idea that polar bears evolved from the abc islands brown bears . but a 2011 study of mitochondrial dna from extinct irish brown bears showed an even closer match to polar bears and suggested that polar bears got their mitochondrial dna from hybridization with irish bears . shapiro , a coauthor of that study , said she now thinks the irish brown bears may be another example of what happened in the abc islands , but she can ' t say for sure until she studies their nuclear dna .
) . because the denali bear has a significant amount of polar bear ancestry on the autosomes , this led to an underestimate of the amount of polar bear ancestry on the autosomes of the abc islands brown bear .
black bears ( ursus americanus ) have many color phases , from cinnamon to the rare blue glacier bear , and lack the massive size and hump of the brown bear . brown bears and black bears range the mainland . brown bears are found on the admiralty , baranof , and chichagof ( abc ) islands , and black bears live on the islands south of frederick sound . both species demand respect from all who go into the woods , as their behavior is unpredictable and dangerous . if common sense and care are exercised , most direct confrontations with bears can be avoided .
the hereditary analysis of parts of the mtdna led to a great surprise , as it suggested that polar bears do not represent a distinct species . according to the data gained , the polar bears’ nearest relatives appeared to be a group of brown bears now living on the admiralty , baranof and chichagof islands off the alaskan coast – the so - called abc islands . also , the genetic dating yielded an unexpectedly recent date for the separation of the polar bears and brown bears : approximately 100 , 000 to 150 , 000 years ago .
but it turns out there were also abc - type brown bears in haida gwaii ( formerly the queen charlotte islands ) , which lie just south of pow in british columbia , canada . as for pow , haida gwaii does not have brown bears today . but so far , none of the bears found on haida gwaii predate the lgm .
what could account for this ? like humans , bears have an x chromosome from their mother and a y chromosome from their dad . the research team concluded that the abc bears must have been the result of female polar bears mating with male brown bears . we know this is possible—in northwest canada , male brown bears and female polar bears mate regularly .
locations g and h ) . in fact , these brown bear mitochondria are more similar to the mitochondria of polar bears than they are to other brown bear mitochondrial lineages . this finding led to early speculation that the abc islands population was a very ancient population of brown bears and therefore the most closely related population to polar bears ( talbot & shields
to back up the promise , mr turnbull announced several new initiatives at the pacific islands forum in apia , samoa .
abc teams share the story behind the story and insights into the making of digital , tv and radio content .
brown bear sow and two young cubs on a mainland se alaska shore ( misty fiords national monument , tongass national forest ) , i . e . not abc bears . photo courtesy jim baichtal , usfs , june 2008 . note the white collars on the cubs . brown bears often have white markings – they are not unique to non - abc bears .
dna analysis of one of the early holocene fossil brown bears from a nearby cave on the same mountain , ‘blown in the wind cave’ ( dated to 9995 + / - 75 radiocarbon years ) closely matches modern abc bears that now live only on islands to the north ( barnes et al . 2002 ) . [ another early holocene bear , from ‘bumper cave’ on pow , is also an ‘abc’ bear ( heaton and grady 2009 ) ] .
“the key to solving this mystery was to analyze dna from the abc islands bears’ nuclear genomes , and in particular their x - chromosomes , ” said beth shapiro from the university of california at santa cruz , who led the research . “focusing on the x gave us a surprising result . ”
to this topic , which contains information on the so - called ‘abc’ bears of southeast alaska ( as well as some notes on my adventures in abc bear territory a few years ago ) . it’s worth taking a look at doug hoffman’s excellent aug . 5 summary of the original paper
but male brown bears – and only male brown bears – swimming over from the mainland ? a population of resident polar bears on the islands , stranded because of sea ice retreat , surviving long enough for male brown bears to find them and mate with their females ? these components of the scenario just don’t wash .
previous researchers have suggested that the polar bear ' s
eve
lived on the abc islands – the alaskan islands of admiralty , baranof and chichagof – only 14 , 000 years ago . but a new international team , lead by beth shapiro from penn state university , has found a much earlier interbreeding event that led to brown bear mtdna creeping into the polar bear gene pool .
brown bears in the abc islands of alaska the story of brown bears in alaska is different in several ways . first , brown bears came to north america from asia ; whereas black bears speciated in north america . the first wave of brown bears were in southern canada before the last glacial maximum , while the second wave came during the last glacial maximum . phylogeography of brown bear mitochondrial genomes shows that the first wave had clade 4 haplotypes , while the second wave had clade 3 haplotypes .
proving their genetic compatibility , brown bears and polar bears can mate and produce viable , or fertile , offspring . it is this reproductive viability that establishes that an animal belongs within a given species . in 2006 , a hybrid grizzly / polar bear , which some call a “pizzly , ” was discovered in the canadian arctic , providing researchers proof that polar bears and grizzly bears can interbreed , even in the wild . and when researchers in alaska compared the dna of brown bears from around the world , looking for genetic links , they made an interesting discovery about one population of brown bears in particular . analysis of the dna of a distinct population of brown bears living on alaska’s abc islands , 900 miles south of the nearest polar bear , revealed that the abc bears were even more closely related to polar bears genetically than they were to other brown bears .
green noted that efforts to understand the relationship between polar bears and brown bears has been complicated by the unusual case of the abc islands brown bears .
it ' s as if you were studying the relationship between humans and chimpanzees and your analysis included dna from some weird population of humans that had hybridized with chimps . you would get very strange results until you figured that out ,
he said .
estimated polar bear ancestry of 3 . 17 % on the autosomes and 1 . 04 % on the x chromosome . the denali brown bear , which was the only mainland brown bear sample from our previous report , had the highest rate of polar bear allele matching among all non - abc islands brown bears in this larger sample of brown bears ( fig .
) . one of these individuals ( abc06 ) was from admiralty , the island located closest to the us mainland . the mitochondrial genome of abc06 clustered with the other five abc individuals from baranof and chichagof islands , as a sister group to the polar bear (
so what are “abc” bears ? physically and behaviourally , not noticeably different from other coastal brown bears , as far as i understand ( see photos below ) . genetically , however , they appear to stand out as distinct from other brown bears and are similar in some respects to polar bears . more on that later .
the researchers then ran a series of test simulations to determine what could have occurred demographically to cause these hybrid bears . the most likely scenario ? when the earth warmed and glaciers started melting , male brown bears probably swam across from the mainland to the islands . it is a regular behavior for male brown bears to go searching for new habitats ( they do this today ) . there they found female polar bears living on the islands and mated with them , producing hybrid offspring . the bear demographic eventually shifted from polar bears to brown bears , which are more suited to warmer weather . ( read more about today’s bear behaviors and how they helped bring light to the abc bear population at urltoken )
these recent efforts were spurred on , no doubt , by earlier work that showed a close genetic relationship between brown bears and polar bears , and an unexpectedly close relationship between polar bears and the so - called “abc” brown bears that live exclusively on three islands in southeast alaska — admiralty , baranof , and chichagof ( e . g . barnes et al . 2002 ; cronin et al . 1991 ; talbot and shields 1996a , b ) , see map below .
d - statistic measure of admixture in brown bears . distribution of d - statistic tests between two brown bears and a polar bear candidate introgressor with an american black bear out - group . each dot represents an independent test with a different polar bear as the candidate introgressor . abc islands bears , particularly those from baranof and chichagof islands , show the highest amount of polar bear introgression . admiralty island brown bears show the greatest bias toward polar bear ancestry on the x chromosome vs . the autosomes . the denali brown bear shows the greatest bias toward polar bear ancestry on the autosomes relative to the x chromosome .
but looking at genome - wide sequences from a number of bears ( including seven polar bears ) for the current study , shapiro and her colleagues found little variation among the polar bears — and no brown bear ancestry at all . now she thinks that the irish brown bears , now extinct , may have been like the abc brown bears : a population of polar bears that were overrun by genetic contributions from brown bear interlopers .
this scenario is consistent with the known behavior of brown bears and polar bears , according to coauthor ian stirling , a biologist at the university of alberta in edmonton , canada . mixing of polar bears and brown bears is seen today in the canadian beaufort sea , where adult male brown bears wander onto the remaining sea ice in late spring and sometimes mate with female polar bears , he said . in areas such as western hudson bay and the russian coast , polar bears are spending more time on land in response to climate warming and loss of sea ice , a behavior that could have left polar bears stranded on the abc islands at the end of the last ice age .
polar bears , for example , are expert swimmers , whereas brown bears are more adept at climbing .
i have to say though , that having crawled through a cave where ancient abc bears might have lived drove my long - standing interest in polar bear evolution to even greater heights .
figure 2 . the coastal forebulge effect , as it affected haida gwaii ( formerly the queen charlotte islands ) in northern british columbia ( see fig . 1 ) , down to northern vancouver island . while sea level declined about 120 - 130m during the lgm , glacial ice on the mainland uplifted the strait between the islands well as the islands themselves , creating a huge ice - free land mass that appears to have supported brown and black bears . from hetherington et al . 2003 .
online ) . brown bears were divided into a western lineage ( clades 1 , 2a , and 2b ) and an eastern lineage ( clades 3a1 , 3a2 , 3b , 4 , and 5 ) , with clade 3a further subdivided into clades 3a1 and 3a2 based on five parsimony - informative sites . the polar bears formed clade 2b embedded within the western lineage , which otherwise contained brown bears , and which was the sister clade to the abc islands group of brown bears ( clade 2a ) .
3 ) as far as we know , there were no brown bears on the alaska mainland ready to swim to the abc islands ( or pow island ) to mate with female polar bears at the end of the lgm ( but see footnote # 2 below ) , because the mainland was completely ice - covered , from alaska to southern british columbia , until at least 13 , 500 rcybp .
map showing the approximate current geographic ranges of brown bears ( brown ) and polar bears ( blue ) .
shapiro and her team decided to look more closely at the abc bruins . they employed sophisticated dna analysis to look deeply into their past .
these brown bears are closely related to the brown bears that evolved into the polar bears . however , the only difference is that they didn ' t mutate . reply
today’s post is an introduction to this issue , with some notes and pictures from my recent adventures in southeast alaska , that included a crawl through a cave that might once have housed abc bears .
these processes are not mutually exclusive , and both biased dispersal and selection against polar bear ancestry on the x chromosome may play a role in explaining the lower polar bear ancestry on the x chromosome of non - abc islands brown bears . at this stage , it seems likely that there is insufficient understanding of the demography of bears throughout alaska and northern canada to make a definitive assessment of the role of each .
authorities in southeast alaska noted no one in that region of the 49th state had been killed by a bear since 2000 . a camper was that year killed in the tiny town of hyder on the canadian border at the southern tip of the state . the last time a bear killed someone in the so - called abc islands - - admiralty , baranof , chichagof - - was in 1988 . the islands have some of the densest grizzly bear populations in north america .
this entry was posted in evolution , hybridization and tagged abc bears , black bears , brown bears , cahill , genetics , haida gwaii , hybridization , jim baichtal , last glacial maximum , polar bear evolution , prince of wales island , ringed seals , se alaska , sea ice extent , tim heaton . bookmark the permalink .
sample map . map of the present - day geographic range of brown bears ( red ) and polar bears ( blue ) . letters indicate location from which bears were sampled .
the presence of both pre - and post - lgm brown and black bears in these caves ( along with other terrestrial mammals ) , suggests strongly that a small population of abc bears survived the ice age on pow island because of its unique position relative to coastal ice sheets .
multi - locus gene analyses show the polar bear as a separate species , with a divergence time of 600 , 000 years . abc – see upper figure .
the findings suggest that continued climate warming and loss of arctic sea ice may lead to the same thing happening more broadly , said coauthor richard e . ( ed ) green , an assistant professor of biomolecular engineering in ucsc ' s baskin school of engineering .
as the ice melts in the arctic , what is going to happen to the polar bears ? in the abc islands , the polar bears are gone . they ' re brown bears now , but with polar bear genes still present in their genomes ,
he said .
the authors of a new paper out in plos genetics ( cahill et al . 2013 , entitled “genomic evidence for island population conversion resolves conflicting theories of polar bear evolution” ) propose to explain how and why the brown bears ( aka grizzlies ) of the abc islands of southeast alaska ( admiralty , baranof , and chicagof – see previous post here ) , got to be so genetically distinct from brown bears on the alaska mainland and so surprisingly similar ( genetically ) to polar bears . the authors determined ( using a model ) that this genetic pattern could be explained by an ancient hybridization event resulting from female polar bears cavorting with male brown bears in se alaska .
we ' ve seen that polar bears are hybridizing with brown bears now , at the edge of their range in canada .
the key to the new insight lay in figuring out that the portion of abc island bear dna that had the largest contribution from polar bears was the genetic material passed directly from mother to offspring . that suggests that female polar bears , stranded on the islands as ice receded at the end of the last glacial period , mated with generations of migrating male brown bears who swam to the island . over time , most of the polar bear dna was overrun by brown bear dna , but the maternal polar bear dna was harder to crowd out .
among experts , hybridization – and possible grizzly gene swamping – isn ' t seen as a primary threat . andrew derocher , the head of the university of alberta ' s polar bear lab , said that polar bears are likely to disappear at a rate that far outpaces hybridization , though there have been isolated incidents of polar bears being subsumed into grizzlies throughout history .
there were polar bears on alaska ' s abc islands at one time , but once the climate warmed the polar bears left , and the individuals that remained saw their genes flooded by brown bear genes coming from the mainland ,
said derocher .
but polar bears and grizzly bears were bred more than 100 years ago in german zoos — and unlike most other hybrids , the females were able to give birth to other beige - coloured bears .
always take time to carefully observe groups of two or more bears . bears are usually quite solitary unless they are siblings or are breeding . the odds are good that two or three bears together may be a group of young bears or a sow with older cubs .
proportion of polar bear ancestry of the abc islands brown bears calculated using f . the proportion of polar bear ancestry inferred for the autosomes ( dark blue ) and x chromosome ( light blue ) is shown for each abc islands brown bear ; ( a ) the admiralty island brown bear sequenced in this study , ( b ) the admiralty island brown bear of miller et al , ( c ) the baranof island brown bear of miller et al [ 6 ] . the bears from admiralty island show similar amounts of polar bear ancestry but the amount inferred for the baranof island bear is much greater . this may be due to the greater distance from the mainland of baranof island limiting brown bear immigration to a greater degree than on the more accessible admiralty island . the inverse correlation of x chromosome : autosome ratio and total amount of polar bear ancestry is also consistent with our model of population and genome conversion form polar bears to brown bears via sex biased brown bear introgression ( figure s10 ) .
some individuals of both these brown bears populations ( from pow and haida gwaii ) had the same mtdna type as modern abc bears ( heaton and grady 2009 ) . unfortunately , none of the pre - lgm bears yielded dna when they were tested about 15 years ago . however , i think there is still hope that newer ancient dna techniques might eventually tell us if these animals also had typical “abc - type” mtdna . see also heaton and grady ( 2003 ) ; heaton et al . 1996 and paleontologist timothy heaton’s university of south dakota website .
to further elucidate the migration history of the three lineages of brown bears on hokkaido island , it is important to clarify the phylogenetic relationships between the southern hokkaido and tibetan brown bears , and among brown bears from hokkaido and neighboring areas such as the southern kuril islands ( etorofu and kunashiri ) and sakhalin . in this study , we analyzed complete mtdna sequences from 35 brown bears from hokkaido , the southern kuril islands ( etorofu and kunashiri ) , sakhalin , and the eurasian continent ( russia , bulgaria , and tibet ) to reconstruct maternal phylogeny . we also determined the complete mtdna sequences from four polar bears . using bayesian analysis , we inferred times of divergence of these bear populations to shed light on their migration history .
to understand how hybridization could lead to this unexpected result , the team ran simulations of various demographic scenarios .
of all the models we tested , the best supported was the scenario in which male brown bears wandered onto the islands and gradually transformed the population from polar bears into brown bears ,
said first author james cahill , a graduate student in ecology and evolutionary biology at uc santa cruz .
“it’s as if you were studying how humans are related to chimpanzees and were looking at dna from some weird population of hybrid humans who had mated with chimps , ” said uc santa cruz biomolecular engineer ed green , a coauthor of the study . “the bears that are confusing everything are these abc island bears . ”
d - statistic and z score for admixture test between brown bears , polar bears and the american black bear . the highest coverage polar bears were selected for this analysis . abbreviations are as in table s2 .
bear from the yukon ( courtesy government of yukon territory ) . these bears also occur across the north slope of alaska and are the bears that occasionally hybridize with polar bears this time of year , as explained
nuclear phylogeny between three groups of black bears . new data suggests the refugial location for black bears was in beringia instead of ice free haida gwaii . currently , alaska and yukon have black bears from the alaskan group , but the southern alexander archipelago also has western group bears .
) . overall , our data support a scenario of polar bears evolving rapidly and being under strong positive selection following the divergence from brown bears .
scientists have struggled to understand the nature of the evolutionary relationship between brown bears and today’s polar bears , said a news release about the research .
earth ' s climate swung saw warmer and colder periods during the irish bears ' reign . as it changed , so did the bears ' habitat . during cool times , the brown bears may have encountered polar bears on the ice that covered their normal habitat , while in warm times , the polar bears might have left their watery homes in search of food .