bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal influence on juvenile growth rates in Belding's ground squirrel (Spermophilus beldingi)
Authors: Trombulak Stephen C.
Published: August 2008

The influence of food acquisition by pregnant and lactating Belding's ground squirrels (Spermophilus beldingi) on the body mass and growth rate of their offspring was assessed in a free-ranging population. In late spring and early summer of 1985 and 1986, individual females in a population of Belding's ground squirrels in the Sierra Nevada Mountains of California were given 300–500 g of sunflower seeds daily at the entrances to their burrows. Juveniles born to mothers who received supplemental food emerged from natal burrows on average 28% heavier than did controls (73.0 vs. 57.1 g, P < 0.001) and maintained a greater body mass throughout the remainder of the summer (P < 0.01). Also, females had a nonsignificant tendency towards greater survivorship during their first winter (P = 0.09). Supplemental feeding had no effect on litter size or sex ratio of offspring, or on the mass of the mothers up to the time of weaning, indicating that extra food available in the spring to reproductive females is converted primarily, if not exclusively, into larger offspring. Because the lengths of gestation and lactation are relatively invariable, the greater body mass of emerging juveniles must result from faster growth prior to weaning.
Time of hatching affects development, size, yolk volume, and mortality of newly hatched Macrozoarces americanus (Pisces: Zoarcidae)
Authors: Methven David A. , Brown Joseph A.
Published: August 2008

The ocean pout, Macrozoarces americanus, is well developed at hatching and strongly resembles the adult. Developing embryos and newly hatched larvae have teeth, are well ossified and pigmented, and have a complete complement of fin rays. The feeding repertoire is simple and lacks the dramatic behavioural changes that usually occur in less-developed larvae of other species. Length and weight at hatching are positively correlated with time of hatch and differ significantly for early- and late-hatched individuals. Early-hatched individuals have no ossified bones, are smaller, and have higher rates of mortality than late-hatched individuals; however, early-hatched individuals have higher growth rates and larger yolk-sac volumes than late-hatched individuals. The large size at hatching, simple feeding repertoire, short time to first feeding (< 24 h), presence of numerous teeth, rapid yolk absorption, and low mortality are characteristic of newly hatched M. americanus and suggest that the larval stage is of very short duration, if present at all. We suggest that a larval stage is absent and that M. americanus hatch as juveniles.
Over-winter activity and body temperature patterns in northern beavers
Authors: Smith Douglas W. , Peterson Rolf O. , Drummer Thomas D. , Sheputis Daniel S.
Published: August 2008

Transmitters were implanted in three adult, one yearling, and one kit beaver (Castor canadensis) in northern Minnesota and upper Michigan to determine if core body temperature (Tb) declined in winter. Beaver Tb and activity were automatically recorded from late autumn through early spring. In late October through early November, mean daily Tb of adults was 36.3 °C (range 34.5–37.6 °C), with a mean daily Tb fluctuation of 1.4 °C. From fall to winter adult beaver Tb declined at a mean rate of 0.01 °C/day, and the mean daily winter (17 November – 15 April) Tb was 35.3 °C (range 32.5–38.8 °C). Mean daily winter Tb fluctuation was 2.5 °C. In early March, mean adult daily Tb began increasing at a rate of 0.03 °C/day. Tb and activity were positively correlated, except for the kit beaver, which did not undergo a significant Tb decline during winter. The yearling beaver Tb declined at a slower rate than adult Tb, and its Tb was intermediate between that of the kit and the three adults. Continued body growth in winter in young beavers is probably enhanced by high body temperature. For adult beavers, reduced body temperature in winter may be an adaptation that facilitates survival during extreme resource scarcity.
Functional morphology of lenticular accommodation in the young chicken (Gallus domesticus)
Authors: West J. A. , Sivak J. G. , Doughty M. J.
Published: August 2008

The morphology of the accommodative apparatus in chicks has not been fully characterized, and the accommodative mechanism is not well understood. A detailed study of the ciliary muscle and ciliary process morphology in newly hatched and 2-week-old chicks has been carried out in this investigation. The methods include light microscopy and scanning and transmission electron microscopy. Accommodation is induced with nicotine sulphate in young chicks to compare the morphology of the accommodative apparatus in a relaxed and accommodated state. This study confirms the striated nature of the ciliary muscle in the developing chick eye and the direct articulation of the ciliary processes with the annular pad of the lens. The muscle fibers of the nicotine-treated eyes are shorter than those of the control eyes and appear contracted. Quantitatively, the fibers of the nicotine-treated eyes have a significantly shorter sarcomere length than control eye muscle fibers. The ciliary folds of the nicotine-treated eyes are very convoluted and are significantly shorter in length than control eye folds. Evidence from this investigation suggests that the contraction of the ciliary muscle causes the ciliary folds to exert direct force onto the annular pad of the lens during accommodation.
The relationship between parasite load, crawling behaviour, and growth rate of Macoma balthica (L.) (Mollusca, Pelecypoda) from Hudson Bay, Canada
Authors: Lim Shirley S. L. , Green Roger H.
Published: August 2008

At ebb tide Macoma balthica makes crawling tracks on the intertidal sand flats near Churchill, Manitoba, on Hudson Bay. Clams from two tidal levels, mean low water and 1.0 m above mean low water, were sampled to compare the parasite load and growth rate of crawling versus buried Macoma. For each clam the number of trematode metacercariae present were counted and the growth rate was determined by the measurement of annual growth rings. Clams were infected by more metacercariae at the higher than at the lower tidal level, larger clams more than smaller ones and crawling clams more than buried ones. Increased exposure of the clams at the higher tidal level to shorebirds, the final host of the trematodes, is proposed as the reason for the difference in parasite load between the tide levels. High-tide clams (more parasitized) grew faster than low-tide ones (less parasitized), and crawlers (more parasitized) grew faster than the buried (less parasitized) clams. Enhanced somatic growth as a result of parasitic castration is proposed to be the most logical explanation to account for the faster growth of the parasitized clams.
Effects of reproduction on activity and foraging behaviour of adult female Columbian ground squirrels
Authors: MacWhirter R. Bruce
Published: August 2008

In this study I evaluated six ways in which adult female Columbian ground squirrels (Spermophilus columbianus) potentially alter their overall activity and foraging behaviour to satisfy the increased energetic needs of reproduction, all of which may involve a trade-off with predation risk. A sample of nonparous females was obtained by administering a short-term chemosterilant at the time of breeding. Relative to nonparous females, parous females spent more time above ground, more time foraging, and less time vigilant, particularly during lactation, and had a longer active season. Thus, in absolute terms, parous females spent more time exposed to aboveground predators than did nonparous females. Parous females spent less time at burrow entrances and, during lactation, were active farther from escape burrows than were nonparous females. Parous and nonparous females did not differ in the percentage of time spent vigilant during foraging bouts. These results indicate that females respond to the energetic demands of reproduction by increasing the absolute amount of time spent foraging, which entails an acceptance of an increase in exposure to predators, and not by modifying their behaviour during foraging bouts.
Description of the mature larva of Pedilus flabellatus (Coleoptera: Pyrochroidae: Pedilinae), with phylogenetic implications of the discovery
Authors: Young Daniel K. , Pollock Darren
Published: August 2008

The larva of Pedilus flabellatus (Horn) was collected from debris associated with the base of a dead, standing Pseudotsuga menziesii in the Mount Hood National Forest, Oregon; it is described and illustrated. Species identity was established by rearing a larva to the adult stage. The larva of Pedilus flabellatus holds meaningful phylogenetic implications. The presence of an uninterrupted transverse series of asperities on sternum 9 is unique among larvae of Pedilus, and supports the previously hypothesized classification of the Pyrochroidae: Pyrochroinae + Pedilinae + Cononotinae. This character is discussed with respect to its presence in the Pyrochroidae and other families of Heteromera.
L'importance des interactions dans une population de l'araignée Lepthyphantes flavipes (Blackwall) (Araneida: Linyphiidae)
Authors: Leclerc Jacques , Blandin Patrick
Published: August 2008

The significance of interactions between spiders was evaluated in a population of Lepthyphantes flavipes (Blackwall) that occurs on a deciduous forest litter. Three hypotheses are presented: (i) H0, interactions, mainly interference competition for web sites, are not important in structuring the population; (ii) H1, spiders tend to use silk from deserted webs; (iii) H2, dominant spiders tend to displace resident subordinate spiders from their web sites. Because spinning a new web is costly in Lepthyphantes, substantial gain may be obtained when moving to a new web site under hypotheses H1, and H2. These hypotheses were tested in a field experiment by means of plastic rings introduced on litter as web sites. Results confirm hypothesis H0. Hypothesis H1 is not rejected for small-sized spiders and needs to be explored through more field experiments. Hypothesis H2 is rejected.
Changes induced by Hymenolepis diminuta (Cestoda) in the behaviour of the intermediate host Tenebrio molitor (Coleoptera)
Authors: Hurd Hilary , Fogo Sharon
Published: August 2008

Metacestodes of the rat tapeworm, Hymenolepis diminuta, have been shown to induce behavioural changes in the intermediate host Tenebrio molitor (Coleoptera). Male and female beetles, examined 11–12 days postinfection, were shown to exhibit a significant decrease in activity and photophobic behaviour. In addition, a significant loss of response to aggregation pheromone occurred in both sexes. No differences in host behaviour were detected 4–5 days postinfection. It thus appears that behavioural changes are associated with parasite maturity. We were unable to demonstrate a dose-dependent loss of photophobic behaviour.
Ressources en maïs et stationnement hivernal des grues cendrées (Grus grus) dans le sud-ouest de la France
Authors: Génard Michel , Lanusse Denis , Béreyziat Thierry
Published: August 2008

The influence of distribution and abundance of food (maize) on Common Crane behaviour and distribution patterns in time and space was analysed in the farmlands of south-western France. The maize stock most likely to be exploited by cranes gradually decreases from November to March because of autumnal germination, seed mass loss during winter, and burial during tilling of the soil. The variation of crane numbers over time does not depend on seed stock changes. The feeding behaviour of these birds does not change with decreasing seed availability, whereas gregariousness increases. The plots most likely to be selected by cranes offer accessibility to seeds and the best food supplies: crushed maize, in the first instance, and when this is not available, pulverized maize. Feeding behaviour and gregariousness do not vary with plot quality.
Suitability of moose, elk, mule deer, and white-tailed deer as hosts for winter ticks (Dermacentor albipictus)
Authors: Welch D. A. , Samuel W. M. , Wilke C. J.
Published: August 2008

We evaluated the suitability of four species of North American Cervidae as hosts for the winter tick (Dermacentor albipictus) by comparing the numbers and weights of engorged female ticks recovered from experimentally infested moose (Alces alces), elk (Cervus elaphus), mule deer (Odocoileus hemionus), and white-tailed deer (Odocoileus virginianus). Each host was exposed to approximately equivalent infestations (~1 larva/cm2). A higher percentage of ticks were recovered as engorged females from moose (8.0%) than from elk (0.23%) or mule deer (0.60%). No engorged female ticks were recovered from white-tailed deer. Female ticks engorged on moose were larger (0.533 ± 0.169 (SD) g) than those engorged on elk (0.414 ± 0.136 g) or mule deer (0.418 ± 0.138 g). Alopecia occurred on all infested animals but was extensive only on moose. Our findings support field data suggesting that moose are the most important and the most severely affected hosts of winter ticks.
Unusual carotenoid use by the Western Tanager (Piranga ludoviciana) and its evolutionary implications
Authors: Hudon Jocelyn
Published: August 2008

I used spectrophotometric, chromatographic, and chemical means to establish that rhodoxanthin, a 3-keto-retrodehydro carotenoid, was the only red pigment in the head feathers of the Western Tanager (Piranga ludoviciana). In contrast, the red head and body feathers of a close relative, the Scarlet Tanager (P. olivacea), exhibited several 4-keto-carotenoids. Other tanagers and emberizids also displayed 4-keto-carotenoids. The deposition of presumed canary xanthophylls and phaeomelanins differed quantitatively between the Western Tanager and other tanagers belonging to the genus Piranga. Uniquely among the Piranga spp. examined, the head feathers of the Western Tanager had flattened bards without barbules. Partly because the head colors of the Western and Scarlet tanagers were indistinguishable either in the hand or when examined by reflectance spectrophotometry, I excluded selection for a variant color as the basis for the observed chemical and morphological differences. Biochemical costs, including putative costs associated with the endogenous production of 4-keto-carotenoids, could have led to the conversion in the Western Tanager to an available dietary pigment. This tanager, unlike the other species studied, has access to an abundant source of rhodoxanthin in the coniferous forests of western North America. The pigment changes in the Western Tanager could have taken place with minimal effect on head color.
Redescription of Diclidophora nezumiae (Monogenea: Diclidophoridae) from Nezumia bairdi (Macrouridae), from the Gulf of St. Lawrence
Authors: Rubec Louise A.
Published: August 2008

Diclidophora nezumiae Munroe, Campbell, and Zwerner, 1981 is redescribed from the common grenadier, Nezumia bairdi (Macrouridae), in the Gulf of St. Lawrence. A prostatic vesicle is present in the terminal male genitalia. A complete lamellate extension attached to peripheral sclerite c1, is present in the clamp anterior jaw of Diclidophora nezumiae. Variability in the appearance of the clamp of Diclidophora nezumiae is presented.
The influence of apparent predation risk on the foraging behaviour of eastern chipmunks (Tamias striatus)
Authors: Kieffer James D.
Published: August 2008

The hypothesis that foraging behaviour is affected by the presence of a predator was tested in the field by presenting a stuffed marten (Martes americanus) to foraging eastern chipmunks (Tamias striatus). With a stuffed predator present, chipmunks approached the seed source more slowly. The closer the marten was to the seed tray, the smaller the loads collected by the chipmunks and the fewer the seeds consumed at the tray.
Some diagnostic characters of copepodid stages of the cyclopoid copepod Cyclopina schneideri T. Scott and adults of arctic marine Cyclopinidae
Authors: Grainger E. H. , Mohammed A. A.
Published: August 2008

Copepodid stages I–V of the arctic marine cyclopoid copepod Cyclopina schneideri T. Scott are partly described and illustrated with emphasis on diagnostic characters. Additional morphological information is given on adults of both sexes, the only stages of the species previously portrayed. Diagnostic characters of adults are included for Cyclopina gracilis Claus, Arctocylopina pagonasta Mohammed and Neuhof, Cyclopinoides longicornis (Boeck), and Cyclopinodes elegans (T. Scott), the other species of the family Cyclopinidae reported to occur in marine waters of the Canadian Arctic.
Trypanosome occurrence and prevalence in the marine leech Johanssonia arctica and its host preferences in the northwestern Atlantic Ocean
Authors: Khan R. A.
Published: August 2008

In this study, the distribution, abundance, host selection, and prevalence of trypanosomes in the marine leech Johanssonia arctica in the northwestern Atlantic were investigated. This leech is widely distributed and is encountered more often in the Labrador – northeastern Newfoundland area, especially at depths of 165 m or more, where water temperatures of about 0 °C prevail. It rarely occurs south and west of Newfoundland, where warmer bottom temperatures occur. The highest prevalence of the trypanosome (Trypanosoma murmanensis) infection was found in leeches collected from a depth of 165 m in summer off the Labrador and north and east Newfoundland coasts in the largest leeches (~25 mm). Samples taken at 3- to 5-month intervals in Conception Bay over a 7-year period showed that prevalence of the trypanosome infection is also greater in summer–autumn than during winter. The leeches sampled had fed predominantly on pleuronectiform (flatfish) rather than perciform or gadiform fish, and rarely on elasmobranchs. High prevalences of T. murmanensis in fish coincide with the abundance of J. arctica in several areas of the northwestern Atlantic. Since six other species of marine leeches apparently do not acquire trypanosome infections after feeding on infected fish, J. arctica is probably the major vector of the parasite in the northwestern Atlantic north of latitude 45°N.
Isozyme evidence for independently derived, duplicate G3PDH loci among squamate reptiles
Authors: Sites Jr. Jack W. , Murphy Robert W.
Published: August 2008

We report evidence for several independent gene duplications for the locus encoding the enzyme glycerol-3-phosphate dehydrogenase (G3PDH) in squamate reptiles. Evidence for the duplication comes from population genetic studies demonstrating "fixed" heterozygosity in all members of some lizard species, the documentation of independent allelic heterozygosity at each of the two G3PDH loci in these same species, and tissue-specific gene expression surveys in a taxonomically diverse array of groups. The duplicated condition is present at both low and high taxonomic levels (selected populations of the phrynosomatid lizard Sceloporus grammicus, and almost all snakes, respectively), and appears to represent the derived condition in most of these groups. One notable exception is the colubrid snake genus Masticophis, which appears to be characterized by an apomorphic secondary silencing event. Evolutionary implications of the duplication and silencing events within squamates are discussed, and we suggest that the overall phylogenetic utility of this marker is low in this radiation as a result of extensive homoplasy.
Electrophoretic and vocalization comparisons among three leptodactylid frogs (Pleurodema spp.) from northwestern Argentina
Authors: McLister James D. , Lougheed Stephen C. , Bogart James P.
Published: August 2008

Enzyme electrophoresis of three species of Pleurodema (38 specimens) collected from six sites in northwestern Argentina resolved 44 allozymes for 15 loci. Pleurodema cinerea and P. borellii, which are morphologically similar, are believed to be reproductively isolated by habitat differences. Although the genetic distance was smallest between the two P. borellii populations, P. borellii was not genetically distant from P. cinerea (average values for Nei's and Rogers' intersite genetic distance indices (D) were 0.155 and 0.229, respectively). Pleurodema tucumana was genetically distant from both P. cinerea and P. borellii (average Nei's D = 1.918; average Rogers' D = 0.799). A comparison of mating calls also suggested that P. cinerea and P. borellii are very similar to each other. The calls of P. borellii and P. cinerea differed only in average pulse rate (100.4 and 59.9 pulses per second, respectively) but this difference may have been temperature related. No conclusive evidence was found in this study to indicate that P. cinerea and P. borellii are distinct species.
Hair structure of brown bears (Ursus arctos L.) from North America and Scandinavia
Authors: Elgmork K. , Riiser H.
Published: August 2008

Analysis of measurements of guard hairs from North American brown or grizzly bears and Scandinavian brown bears (Ursus arctos L.) showed variation over the body and along the hair shaft. Using the medullary index, i.e., the medullary diameter as a percentage of the hair diameter, comparisons were made among body areas, age groups, geographical areas, sexes, and seasons. Statistically significant differences were found among body areas. Hairs from the foreleg were shorter and wider, with a smaller medullary index than those from other body areas. There was a weak but statistically significant negative correlation between the medullary index and age of individuals. Medullary indices from Scandinavian bears were significantly greater than those from Alaskan bears, which in turn were greater than those from bears of the contiguous United States. There were no statistically significant differences between the medullary index and sex or season.
Parasite avoidance: the cause of post-calving migrations in Rangifer?
Authors: Folstad Ivar , Nilssen Arne C. , Halvorsen Odd , Andersen Johan
Published: August 2008

Intensities of warble fly larvae, Hypoderma tarandi (L.), were examined in slaughtered reindeer (Rangifer tarandus tarandus L.) from different summer grazing areas of Finnmark County, northern Norway. To test the hypothesis that larval abundance decreases with increase in post-calving migration distance (i.e., distance from calving grounds), herds with differing migration distances were sampled. The prevalence of infection in the total sample of 1168 animals was 99.9%. The study revealed significant differences in larval abundance among herds from different summer grazing areas. Herds with post-calving migrations have significantly lower larval abundances than herds remaining on or near the calving grounds for the whole summer. Between-herds variation in abundance of H. tarandi larvae is assumed to reflect differing densities of the infective stage (adult flies) on the herds' summer ranges. Larval abundance in a herd is in turn negatively correlated with the distance between the main larval shedding areas (i.e., calving grounds) and the areas of greatest transmission (i.e., summer pastures). These results are discussed in relation to transmission of other parasites common to Rangifer and suggest that this host's post-calving migration may be a behavioural adaptation that reduces levels of parasitic infections.
Musculature of the pelvic appendages of the treecreepers (Passeriformes: Certhiidae): myological adaptations for tail-supported climbing
Authors: Moreno Eulalia
Published: August 2008

The hind-limb myology of the treecreepers is highly modified compared with the normal passerine pattern, so far as it is known. The muscular modifications involve mainly the iliotibialis cranialis, iliotibialis lateralis, flexor cruris lateralis, pubo-ischiofemoralis, iliotrochantericus medius, iliofemoralis internus, obturatorius lateralis, tibialis cranialis, fibularis longus, plantaris, and some toe flexor muscles. An investigation was carried out into whether the morphological changes in these muscles are related to the specialized mode of locomotion of treecreepers, that is, whether they are adaptations for tail-supported climbing in these species. So far as the principal action of the modified muscles is concerned, it was found that the modifications observed in the hind limb favour flexion of the leg joints or reduce their extension. The adaptative hypothesis is tested using the out-group comparison method on the basis of an available phylogeny.
Distributions of diploid and pentaploid brine shrimp Artemia parthenogenetica in an illuminated thermal gradient
Authors: Lefcort Hugh , Zhang Lei , King Charles E.
Published: August 2008

We explored the behavioral response to horizontal gradients of light and heat of sympatric diploid and pentaploid Artemia parthenogenetica. When exposed to a uniformly illuminated thermal gradient, pentaploids had a mean distribution that was oriented toward temperatures 2.9 °C higher than that of diploid animals. In a light gradient, diploids were distributed at higher light intensities than pentaploids. When the distributions in an evenly illuminated thermal gradient were compared with those occurring when thermal and light gradients ran in opposite directions, it was found that diploids tended to occur at lower temperatures, whereas pentaploid distributions were not significantly different for the two conditions. Our findings suggest that pentaploids are not as strongly attracted to light as diploids, in either the presence or the absence of a thermal gradient. We predict that in the field, warmer areas of a pond may be exploited by pentaploids during the day and by diploids during the night.
Changes in food intake, mass, and fat accumulation in association with variations in thyroid hormone levels of harbour seals (Phoca vitulina)
Authors: Renouf Deane , Noseworthy Elizabeth
Published: August 2008

Food intake, mass, fat, locomotor activity, and thyroid hormones were monitored in five captive harbour seals (Phoca vitulina) over an 18-month period. Food intake ranged from anorexia to 11% body weight, with changes in body mass reaching 59% in the males. Food intake was negatively related to changes in mass and blubber except during a 6-week period in the fall when the three variables were positively correlated. From the end of November until June, when food intake decreased progressively, mass and fat increased, but not in what was otherwise direct association. Changes in fat were more consistently negatively related to water temperature than were changes in mass. When the male seals were losing weight despite rising food consumption, free thyroxine (T4) levels were positively correlated with food intake and water temperature but negatively correlated with mass and fat changes; the reverse relationships held for ratios of tri-iodothyronine (T3) to free T4. Over the winter months, when mass and blubber were augmenting despite lowered food intake, free T4 levels were significantly lower, whereas T3 and its ratio to both free and total T4 were reduced when food intake and mass accumulation were directly related. In the female seal, these hormones were not clearly associated with any of the variables measured. Locomotor activity was positively related to food intake but not in any clear way to levels of thyroid hormones. These results are discussed in the context of the metabolic defense of fat levels for insulation in cooling water.
Testosterone potentiates the serum gonadotropin response to gonadotropin-releasing hormone in the common carp (Cyprinus carpio) and Chinese loach (Paramisgurnus dabryanus)
Authors: Trudeau V. L. , Lin H. R. , Peter R. E.
Published: August 2008

The effects of gonadal steroids on gonadosomatic index (gonad weight/total body weight × 100), pituitary gonadotropin content, and serum gonadotropin response to [D-Ala6, Pro9, N-ethylamide]-luteinizing hormone releasing hormone (LHRH-A) were investigated in common carp (Cyprinus carpio) and Chinese loach (Paramisgurnus dabryanus). Gonad-intact female fish were implanted intraperitoneally (i.p.) for 5 days with Silastic pellets containing no steroid (blank), testosterone (100 μg/g), or estradiol (100 μg/g). The serum gonadotropin response at 6 h following i.p. injection of saline or 0.1 μg/g LHRH-A was assessed. In blank-implanted female common carp, i.p. injection of LHRH-A increased serum gonadotropin levels approximately 4-, 13-, and 2-fold relative to those in saline-injected controls for sexually recrudescent, preovulatory, and post-spawning females, respectively. Implantation of estradiol in female carp did not affect basal or LHRH-A-induced gonadotropin secretion at any time of the year. Implantation of testosterone did not affect basal gonadotropin levels, but potentiated the gonadotropin response to LHRH-A in sexually recrudescent and preovulatory female carp but not in post-spawning female carp. Injection of LHRH-A-stimulated gonadotropin release in female Chinese loach both prior to and in the middle of the spawning period. Treatment with testosterone or estradiol did not affect basal gonadotropin levels. Implantation of testosterone but not estradiol potentiated LHRH-A-stimulated gonadotropin release at both times of testing. These results demonstrate that testosterone but not estradiol can increase pituitary responsiveness to exogenous LHRH-A in sexually recrudescent and sexually mature female common carp and Chinese loach.
Effect of parental heterozygosity on pink salmon (Oncorhynchus gorbuscha) embryonic and alevin survival and development at extreme temperatures
Authors: Beacham Terry D. , Varnavskaya Nataly V.
Published: August 2008

Heterozygosity of 59 pink salmon (Oncorhynchus gorbuscha) families was compared with embryo and alevin survival, hatching time, and emergence time for developmental temperatures of 4, 8, and 15 °C. There was no consistent association between heterozygosity determined at 23 loci and either embryo or alevin survival or development rate at any of the three rearing temperatures. Embryos and alevins from more heterozygous parents did not have higher survival rates during development at the more extreme temperatures (4 and 15 °C). Hatching and emergence timing was unrelated to parental heterozygosity. For pink salmon, there is no evidence to indicate that heterozygosity is correlated with any phenotypic trait yet examined.
Funduscopic morphology of the light- and dark-adapted eye of the toadfish (Opsanus tau) in vivo
Authors: Grover Donald A. , Zigman Seymour
Published: August 2008

Intraocular funduscopy and photography permitted serial examination and documentation of time-related changes in the living toadfish (Opsanus tau) eye as it went from the dark-adapted to the light-adapted state. In the present study, the fully dark-adapted eye showed virtually no choroidal, pigment epithelial, or retinal vascular detail. The optic nerve was chalky white with indistinct borders. Grayish brown to chalky white retinal streaks radiated from the optic nerve into the periphery. As light adaptation began, the retinal streaks faded, with the retinal vasculature and the underlying choroidal and pigment epithelial detail becoming more discernible. Once the eye became fully light adapted, the typical geographic orange and black mottled appearance of the underlying pigment epithelium and choroid was visible, and the optic nerve head developed a pink hue with a distinct border. Even in the fully light-adapted eye, a vague radiation of lines could be seen extending from the optic nerve. This was superimposed on a cross-hatched mosaic of black dots seen throughout the fundus, not visible in the fully dark-adapted eye. Histological examination of the retina indicated forward migration of pigment in the pigment epithelium in the light-adapted state.
Carabodes niger Banks, C. polyporetes n.sp., and unverified records of C. areolatus Berlese (Acari: Oribatida: Carabodidae) in North America
Authors: Reeves R. Marcel
Published: August 2008

Adults and immatures of Carabodes polyporetes n.sp. are described and the adults are compared with those of Carabodes niger Banks. The distribution of C. niger is corrected, from Nova Scotia south along the Atlantic Coast to South Carolina, west from Pennsylvania to Missouri and Arkansas; the distribution of C. polyporetes is from Newfoundland west to Manitoba and south to North Carolina and Arkansas. Adults of both species are abundant in forest leaf litter, decayed wood, and polyporous fungi. The occurrence of Carabodes areolatus Berlese in North America is shown to be undocumented.
Juvenile dispersal in Gray Jays: dominant brood member expels siblings from natal territory
Authors: Strickland Dan
Published: August 2008

Breeding pairs of Gray Jays (Perisoreus canadensis) in Quebec and Ontario were accompanied in the autumn significantly more often by one nonbreeder, and less often by none or two, than expected from initial brood size frequencies. Among the rare cases of two nonbreeders accompanying a pair, there was no evidence that both were from the same brood. These observations, and the fact that 30.6% of single nonbreeders closely associated with autumn pairs of known, same-year breeding history were unrelated to those adults, indicated the division of juvenile Gray Jays into "stayers," which remained with their parents at no more than one per pair, and "leavers," which left their natal territory and sometimes joined an unrelated pair. The weight distribution of 62 stayers indicated that about two-thirds were males. Leavers had a more equal sex ratio and showed a strong tendency to associate with failed breeders. Stayers apparently had much higher first-summer survival than leavers but no significant chance to inherit their natal territory. Gray Jay broods broke up in June, through intrabrood aggression, when the young were 55–65 days old. Stayers were the dominant juveniles that forced out the leavers. Partial June dispersal may function as a type of brood reduction that permits the dominant juvenile to have exclusive access to a parental subsidy of stored food that is reliably adequate for the survival of only one extra bird on the territory. The best models describing the origin and winter acquisition of such a subsidy postulate recovery of stored food by memory and require that the expulsion of subordinate siblings occur at the beginning of the food storage season. The models predict that food stored by Gray Jays in June survives in significant enough quantities to enhance winter survival.
Dispersal of wolves (Canis lupus) in northeastern Minnesota, 1969–1989
Authors: Gese Eric M. , Mech L. David
Published: August 2008

We examined the dispersal patterns of radio-collared wolves (Canis lupus) from 21 packs in the Superior National Forest, Minnesota, from 1969 to 1989. A total of 316 wolves (542 wolf-years) were captured, radio-collared, and followed during 21 years of radio-tracking; 75 were identified as dispersers. Both sexes dispersed equally. Of the adults, yearlings, and pups, 8, 75, and 16%, respectively, dispersed. Most dispersers left when they were 11–12 months old, only a few wolves dispersing as adults. Dispersal occurred mainly in February–April and October–November. Adults dispersed short distances into nearby territories, but yearlings and pups dispersed both short and long distances. Yearling and pup dispersal rates were highest when the wolf population was increasing or decreasing and low when the population was stable. Adults had the highest pairing and denning success. Yearlings had moderate pairing and low denning success, and pups had low pairing and denning success. Yearlings and pups that dispersed a short distance had a higher success of settling in a new territory, likely reflecting available vacancies in nearby territories. Thirty-five percent of the known-age wolves remained in their natal territory for >2 years; two wolves were known to have remained for >7 years. The relative weight of pups at capture apparently did not affect their age or success of dispersal or the tendency to disperse.
Reproductive success in female mountain goats
Authors: Bailey James A.
Published: August 2008

Kid production by marked females, age ratios from a 24-year study, and the literature are used to evaluate hypotheses that three intrinsic and three extrinsic factors affect reproduction by female Rocky Mountain goats (Oreamnos americanus). On Sheep Mountain – Gladstone Ridge, Colorado, mountain goat age ratios declined while the herd grew during 1966–1979, and continued to decline with population stability during 1980–1989, suggesting a continued increase in ecological density of goats 39 years after they were introduced in 1950. Among intrinsic factors, age and persisting individual characteristics have influenced reproductive success of females. Reproductive success in any year has not limited success in the following year, except in 4-year-olds. Among extrinsic factors, reproductive success of female mountain goats has been negatively influenced by density or ecological density and by snowpack during gestation. Reproductive success of females may have been positively influenced by snowpack that enhanced forage conditions prior to breeding. The relative importance of these six factors in determining reproductive success of females may vary among and (temporally) within herds. Most hypotheses regarding reproductive success in female mountain goats remain poorly tested. Short-term observational studies hold little promise for testing hypotheses, owing to large among-years variation in reproductive success. Long-term, intensive observational studies, or manipulative experiments, are suggested.
Oxygen-transporting function of hemoglobin in Daphnia magna
Authors: Kobayashi Michiyori , Tanaka Yuko
Published: August 2008

The in vivo oxygenation of hemoglobin (Hb) in living Daphnia magna was studied at various oxygen pressures by an optical method. Two populations were studied: a normoxia-adapted (Hb-poor) population, and a hypoxia-adapted (Hb-rich) population. The enhancement of Hb oxygenation caused by adding 2 mM KCN to completely inhibit cell respiration was measured to clarify the oxyen-transporting function of Hb in the two groups. Hemoglobin was 50% oxygenated in vivo at ambient oxygen pressures of 15 and 35 torr for Hb-rich and Hb-poor animals, respectively. In the presence of KCN, 50% oxygenation occurred at ambient oxygen pressures of 7.5 and 14 torr for Hb-rich and Hb-poor animals, respectively.
Metabolic responses to freezing by organs of hatchling painted turtles Chrysemys picta marginata and C. p. bellii
Authors: Churchill Thomas A. , Storey Kenneth B.
Published: August 2008

Organ-specific metabolic responses to freezing were monitored over the course of 4 h exposure to freezing at −4 °C for autumn-collected hatchlings of midland (Chrysemys picta marginata) and western (Chysemys picta bellii) painted turtles. Both subspecies accumulated glucose and lactate in seven organs during freezing for possible use as cryoprotectants. Overall levels of both were higher in C. p. bellii than in C. p. marginata, with glucose ranging up to 16 μmol/g wet weight and lactate up to 25 μmol/g in C. p. bellii organs. Glucose accumulation by C. p. bellii organs appeared to be initiated during prefreeze cooling, whereas glucose production in C. p. marginata was triggered by the initiation of freezing; this difference may explain the higher overall accumulations of both glucose and lactate in C. p. bellii organs. Glucose content in most organs declined over the course of the 4-h freezing exposure, suggesting that the main function of the sugar may be as the substrate for lactate production. Analysis of changes in the levels of glycolytic intermediates in liver revealed an accumulation of glucose-6-phosphate, indicating activation of liver glycogenolysis during freezing. An increase in liver fructose-6-phosphate and a decrease in fructose-1,6-bisphosphate concentrations over the course of freezing were consistent with an inhibition of liver phosphofructokinase that would support glucose export to other organs.
Interspecific and intraspecific mitochondrial DNA variation in North American bears (Ursus)
Authors: Cronin Matthew A. , Amstrup Steven C. , Garner Gerald W. , Vyse Ernest R.
Published: August 2008

We assessed mitochondrial DNA variation in North American black bears (Ursus americanus), brown bears (Ursus arctos), and polar bears (Ursus maritimus). Divergent mitochondrial DNA haplotypes (0.05 base substitutions per nucleotide) were identified in populations of black bears from Montana and Oregon. In contrast, very similar haplotypes occur in black bears across North America. This discordance of haplotype phylogeny and geographic distribution indicates that there has been maintenance of polymorphism and considerable gene flow throughout the history of the species. Intraspecific mitochondrial DNA sequence divergence in brown bears and polar bears is lower than in black bears. The two morphological forms of U. arctos, grizzly and coastal brown bears, are not in distinct mtDNA lineages. Interspecific comparisons indicate that brown bears and polar bears share similar mitochondrial DNA (0.023 base substitutions per nucleotide) which is quite divergent (0.078 base substitutions per nucleotide) from that of black bears. High mitochondrial DNA divergence within black bears and paraphyletic relationships of brown and polar bear mitochondrial DNA indicate that intraspecific variation across species' ranges should be considered in phylogenetic analyses of mitochondrial DNA.
Short-term association patterns of humpback whale (Megaptera novaeangliae) groups on their feeding grounds in the southern Gulf of Maine
Authors: Weinrich Mason T. , Kuhlberg Anne E.
Published: August 2008

Humpback whale (Megaptera novaeangliae) feeding ground associations show a distinct pattern of group size and composition. Median group size was 2 (mean 1.67), and frequency decreased as group size increased. Adult females and juvenile males were observed in pairs significantly more often than singly, whereas adult males and juvenile females were more often alone. Adult female–female pairs occurred significantly more frequently than adult male–male pairs, and adult female – juvenile male pairs formed more frequently than adult male – juvenile female pairs. The majority of groups remained associated for at least 10 min; however, as the size of a group increased, so did its tendency to separate within that period. Adult male–male pair associations were of significantly shorter duration than female–female or male–female pair associations. It is hypothesized that adult males may avoid other males on the feeding ground as an extension of breeding competition. The energetic burden of reproduction, and hence the need to forage cooperatively to maximize efficiency, may account for the adult female's social nature. Juveniles of both sexes, less constrained by reproductive costs, exhibit less structured social behavior.
Stable social associations among humpback whales (Megaptera novaeangliae) in the southern Gulf of Maine
Authors: Weinrich Mason T.
Published: August 2008

Groups of humpack whales (Megaptera novaeangliae) were observed from 1980 to 1987 on their feeding grounds in the southern Gulf of Maine. Although most groups were together for only brief periods, two types of stable association were found: 'continuous' (individual whales associated for at least 7 consecutive days; n = 30) or 'recurring' (individuals associated at least five times in a 6-week period; n = 21). Thirty-seven stable pairs and 3 stable trios involving 56 individual whales were recorded; 11 stable pairs re-associated during more than 1 year. Continuous associations lasted up to 79 days (mean 29.65). Thirty of the 40 associations (75.0%) contained only adults. Females were present in 22 adult associations (73.3%), whereas males were present in only 8 (26.6%). Females sighted with a calf the following year, and therefore pregnant, were members of 6 of the 11 (54.5%) associations that reformed. It is hypothesized that stable associations allow adult females to maximize their net energy gain through cooperative feeding, and may be comprised of closely related animals or individuals with compatible feeding styles.
Spermatozoon ultrastructure and its systematic implications in fishes
Authors: Mattei Xavier
Published: August 2008

We have studied approximately 280 species spread over more than 100 families. New data on 80 species are reported. The spermatozoon of Chondrichthyes is characterized by two synapomorphies in the midpiece and the flagellum. Within the Chondrichthyes the subclass Holocephali is characterized by two spermatic apomorphies that distinguish it from the Elasmobranchii. The Osteichthyes, on the other hand, show great spermatic diversity. In each of the most primitive among them, the Actinistia, Dipnoi, Cladistia, Chondrostei, and Ginglymodi, the spermatic model is different, constituting many autapomorphies. The neopterygians possess a common character that distinguishes them from the other fishes: the lack of an acrosome. We propose a structure for the ancestral model of the spermatozoon of Neopterygii that resembles the gamete of aquatic invertebrates employing external fertilization. This simplified gamete exhibits several derived forms in teleosteans. It is mainly in the primitive Teleostei that these evolved forms are of taxonomic interest, as we demonstrate in the Mormyroidea and the Elopomorpha. In the evolved Teleostei we define a spermatozoon of the "perciform type." The distribution of this gametic type within the Perciformes may provide useful data for use with this ill-defined group whose phylogenetic interrelations are so little known.
Seasonal distribution, abundance, and life-history traits of Greenland cod, Gadus ogac, at Wemindji, eastern James Bay
Authors: Morin Bernard , Hudon Christiane , Whoriskey Frederick
Published: August 2008

Greenland cod populations near Wemindji, eastern James Bay, were studied in 1987 and 1988 to describe the species' general ecology and life-history characteristics. During the summer, they principally occupied shallow (2–5 m) coastal waters. This habitat was characterized by a belt of eelgrass (Zostera marina) at depths of 1–3 m, salinities between 20 and 23‰, and temperatures of 3–20 °C. Daily trap catches were highly variable, and more fish were caught at night than during the day. In winter, more cod were found inshore, in the estuary, than in coastal waters. This movement corresponds to the completion of sexual maturity; spawning occurs in April to June. Growth rate was linear for males and females. The age at maturity was 3 years and no trade-off was observed between growth and reproduction. Greenland cod spawned every year, and the maximum age was 9 years. Life-history variables for Greenland cod differ from those of most arctic benthic fishes; this species shows rapid growth, high fecundity, low age at maturity, and high mortality. These characteristics may represent important adaptations allowing cod to sustain life in James Bay coastal waters, where environmental conditions are different from those in arctic waters.
Moose selection of canopy cover types related to operative temperature, forage, and snow depth
Authors: Schwab Francis E. , Pitt Michael D.
Published: August 2008

Simple linear and muliple regressions were used to determine the contribution of operative temperature (Te), forage, and snow depth to moose (Alces alces) selection of canopy cover types. The number of degree-hours for which Te exceeded the thermal limit at which panting is required to dissipate metabolic heat contributed significantly to selection during summer (1 June – 15 September) and late winter (16 January – 15 April). Forage explained canopy cover selection in early winter (16 November – 15 January) and contributed significantly to the best equation describing habitat selection during late winter. Snow depth contributed to habitat selection in early winter but was not related to habitat selection during late winter. During summer, moose generally selected against sites where Te exceeded 30 °C, the thermal limit requiring panting to dissipate metabolic heat. During late winter, moose also generally avoided canopy covers where Te commonly exceeded 8 °C, the temperature at which panting is required to dissipate heat. During early winter, moose apparently suffered minimal heat stress, as Te remained below 0 °C; consequently, moose selected canopy cover types that provided comparatively high forage availability.