bluuebunny/crossref_metadata_2025 huggingface dataset:
Primary and secondary ookinetes of Babesia microti in the larval and nymphal stages of the tick Ixodes dammini
Authors: Karakashian Stephen J. , Rudzinska Maria A. , Spielman Andrew , Lewengrub Sondra , Campbell James
Published: August 2008

The ultrastructure of ookinetes (kinetes) of Babesia microti and their relationship to the larval and nymphal stages of the tick vector Ixodes dammini are described. Ookinetes in the larva are elongate, straight, or gently curved, more than 8 μm long, with a clearly defined anterior end, and surrounded by a pellicular complex composed of a plasma membrane and two inner discontinuous membranes. At 13 days following cessation of feeding, the parasite was detected in larval tissues, including salivary glands, fat body, and nephrocytes. A sequence of stages in the asexual reproduction of the parasite is described. In the larva, primary ookinetes dedifferentiate to form a kinetoblast that grows and then redifferentiates yielding secondary ookinetes. Ookinetes reinvade the salivary glands of unfed nymphs beginning immediately after completion of the molt and continuing for a short time thereafter. There they once again dedifferentiate and grow into a vast ramifying sporoblast meshwork, which lies quiescent until feeding stimulates the redifferentiation and formation of infective sporozoites through an asexual process. Babesia microti thus resembles some other species of Babesia in that the parasite can invade somatic tissues other than salivary glands and yet differs from them in the apparent absence of transovarial transmission.
Age-related differential catabolism in the snail, Viviparus georgianus, and its significance in the bioenergetics of sexual dimorphism
Authors: Aldridge David W. , Russell-Hunter W. D. , Buckley Daniel E.
Published: August 2008

Catabolic partitioning of carbon and nitrogen was investigated to clarify the sexual dimorphism of bioenergetics in Viviparus georgianus. Experiments involved summer stocks of 3-, 15-, 27-, and 39-month-old male and female snails grazing on an artificial high protein diet and, for 15-month snails only, comparison tests using a lower protein diet. Per snail ingestion and partitioning rates and growth are generally maximal for 15-month snails and decline with age in both sexes. In each age group, females have lower rates for weight-specific ingestion of protein carbon and nonprotein carbon than males. For protein carbon, females also show lower rates of catabolism. Compensation for the lower protein diet is more marked in females, which increase total carbon intake by 58% and reduce catabolic use of protein carbon by 40% (against a male reduction of 25%). When discussing evolutionary problems in terms of actuarial bioenergetics, quantification of both physiological rates and ecological efficiencies can be of value in a broadly adaptational approach.
Nest associates and ectoparasites of the eastern wood rat, Neotoma floridana, in Indiana
Authors: Cudmore Wynn W.
Published: August 2008

Ectoparasites and other invertebrate associates were collected from eastern wood rats, Neotoma floridana, and their nests insouthern Indiana. Although many major associates on wood rats were also common in nests (Androlaelaps fahrenholzi, Ornithonyssus bacoti, Orchopeas sexdentatus, Epitedia cavernicola), attached forms such as ticks (Ixodidae) and chiggers (Trombiculidae) were underrepresented in nest collections. Chortoglyphus arcuatus, Tyrophagus sp., Cheyletus malaccensis, and various oribatid mites were the most abundant mites in nests, while Aplodontopus sp., Eutrombicula alfreddugesi, Ornithonyssus bacoti, and Myocoptes neotomae were the most abundant mites on wood rats. The chigger Eutrombicula alfreddugesi was collected almost exclusively in summer while Euschoengastia spp. and Neotrombicula spp. were more abundant in other seasons. Ticks, chiggers, Myocoptes neotomae, and Aplodontopus sp. demonstrated site specificity on the host.
Helminth parasites of Canada lynx (Felis canadensis) from northern Ontario
Authors: Smith J. D. , Addison E. M. , Joachim D. G. , Smith L. M. , Quinn N. W. S.
Published: August 2008

Six helminths were common in lynx (Felis canadensis) throughout northern Ontario: Troglostrongylus wilsoni (Stough, 1953) Sarmiento &Stough, 1956 in the lung (54% of 127 infected), Cylicospirura felineus (Chandler, 1925) Sandground, 1932 in the stomach (91% of 360), Toxascaris leonina (von Linstow, 1902) and Toxocara cati (Schrank, 1788) in the stomach and intestine(97% and 22% of 274, respectively), and Taenia laticollis Rudolphi, 1819, and Taenia rileyi Loewen, 1929 in the intestine (94% and 47% of 275, respectively). Only Toxascaris leonina is transmitted by both lynx and canids in northern Ontario. Lynx is the only definitive host of the other common parasites. Seven helminths usually found in canids occurred infrequently in lynx: Alaria marcianae (LaRue, 1917) Walton, 1949 and immature Taenia pisiformis (Bloch, 1780) Gmelin, 1790 in 4% of those examined; and Capillaria aerophila (Creplin, 1839) Travassos, 1915, Physaloptera rara Hall &Wigdor, 1918, Ancylostoma caninum (Ercolani, 1859), Uncinaria stenocephalia (Railliet, 1884), and Taenia serialis (Gervais, 1847) Baillet, 1863 in one to three lynx each. Abundances of the common parasites varied only slightly among five forest regions, and did not differ between male and female lynx or among lynx older than kits. Cylicospirura felineus and Taenia rileyi were less abundant in kits, and Taenia laticollis and Toxocara cati tended to be more abundant in kits than in older lynx. Host condition and numbers of many of the common helminths tended to be positively correlated, but the inclusion of kits affected the result. The few helminth species established in lynx and their apparent uniform distribution in the host population may reflect the dominance of snowshoe hare in the diet.
Spring and summer time budgets and feeding behaviourof the red squirrel (Tamiasciurus hudsonicus)
Authors: Ferron J. , Ouellet J. P. , Lemay Y.
Published: August 2008

The purpose of the study was to attempt to understand how feeding requirements, reproductive constraints, and fluctuating environmental conditions (specifically, ambient temperature and food availability) are integrated in the time budget of the red squirrel (Tamiasciurus hudsonicus), an arboreal sciurid of the North American coniferous forest that remains active year-round. It appears that ambient temperature and food availability have important influences on the allocation of time among different activities. Reproductive constraints apparently do not affect differently the time budgets of males and females during the spring breeding season. The analysis of food habits of the red squirrel demonstrates that the species is opportunistic and takes advantage of the continuously changing food availability during the growing season. Fluctuations in diet influence whether feeding and foraging are arboreal or terrestrial, as well as affecting the relative importance of these two activities in the time budget of the red squirrel.
The vocal repertoire of white whales, Delphinapterus leucas, summering in Cunningham Inlet, Northwest Territories
Authors: Sjare B. L. , Smith T. G.
Published: August 2008

The underwater vocalizations of white whales, Delphinapterus leucas, summering at Cunningham Inlet, Northwest Territories, were recorded from mid-July to mid-August 1981 to 1983. A total of 807 tonal calls (whistles) were classified into 16 contour types. The following acoustic parameters were measured for each whistle: minimum, maximum, and mean frequency of the fundamental, contour or shape of the fundamental, duration, and the slope of the frequency changes during the call. Some 436 pulsed calls were classified into three major categories: click series, pulsed tones, and noisy vocalizations. Acoustic parameters measured for each of these calls included pulse repetition rate, range and mean frequency of the call, and duration. Results show that the whistle repertoire of white whales is more varied than has been previously reported. Mean frequencies for the whistle contour types ranged from 2.0 to 5.9 kHz; mean duration ranged from 0.25 to 1.95 s. Although whistles were the most commonly emitted type of vocalization, pulsed tones and noisy vocalizations made up a significant proportion of the white whales' vocal repertoire. The mean pulse repetition rate of pulsed tones ranged from 203.9 to 1289.0 pulses/s. There does not appear to be any between-year variation in the vocal repertoire of these white whales.
Microbe-mediated effects of low pH on availability of detrital energy to a shredder, Clistoronia magnifica (Trichoptera: Limnephilidae)
Authors: Frankenhuyzen K. van , Geen G. H.
Published: August 2008

We tested the hypothesis that microbe-mediated changes in nutritional quality of leaf litter conditioned at low pH enhanced larval growth of the caddisfly shredder Clistoronia magnifica. Alder leaves conditioned for more than 3 weeks at pH 4 had greater fungal biomass and bacterial abundance than leaves conditioned at pH 6. Differential microbial colonization did not affect ingestion rates. Radioisotope experiments indicated that late-instar larvae assimilated microbe-derived energy from leaves conditioned at pH 4 with a 10–15% higher efficiency than microbial energy from leaves conditioned at pH 6 and suggested a concomitant 5% increase in assimilation of leaf-derived energy. Enhanced growth of C. magnifica at low pH could be accounted for by increased fungal biomass on leaves conditioned at low pH and increased availability of leaf energy, presumably due to additional modification of the leaf substrate by fungal enzymes.
Demographic characteristics of an unexploited population of fox squirrels (Sciurus niger)
Authors: Nixon Charles M. , Hansen Lonnie P. , Havera Stephen P.
Published: August 2008

Demographic changes in an unexploited population of fox squirrels (Sciurus niger) were studied between 1971 and 1978 on 45.2 ha of upland forest in east-central Illinois. Known numbers of squirrels varied between 69 and 142. Adult squirrels (>15 months old) comprised >50% of the known population during the study, with annual survival exceeding 60%. Young-of-the-year made up <20% of the livetrapped population. Increasing populations were characterized by increases (P < 0.05) in numbers of yearling–adult males and young-of-the-year of both sexes. Recruitment depended on both immigration and on production of young by resident females. Recruitment success (proportion of new squirrels resident at least 6 months after initial capture) of immigrants was best for adults and yearlings and poorest for subadults. Adult female breeding success was highest in the winter and correlated negatively with the number of females conceiving the previous breeding period. The size and composition of the seed crop of trees in autumn had no effect (P > 0.05) on recruitment, conception, survival rates, or changes in overall density when at least some winter-storable tree seed was available. In most years, adult females were dispersed evenly, but adult males and young of both sexes showed an aggregated or random dispersion. Breeding rates for yearling females, recruitment success of immigrants and of juveniles born on the study area, and overall changes in squirrel densities between trapping periods correlated negatively (P < 0.05) with the number of adult females but not with the number of males or younger females. Interpretation of dispersion of adult females and the relationship of numbers of adult females to population change suggest that fox squirrels stabilize their numbers in the absence of obvious environmental stresses through aggressive interactions between adult females and resident young and immigrants of all ages.
Spring pond water chemistry and the reproduction of the wood frog, Rana sylvatica
Authors: Gascon Claude , Planas Dolors
Published: August 2008

To determine the impact of snowmelt water quality on egg mass abundance and embryo survival of the wood frog (Rana sylvatica) in Québec, 15 breeding ponds, with an early spring pH range between 3.4 and 6.7, were surveyed. Acidity and total organic carbon were correlated with the density of egg masses. Hatching success was reduced (and mould increased) in low pH ponds.
Tail loss, tail color, and predator escape in Eumeces (Lacertilia: Scincidae): age-specific differences in costs and benefits
Authors: Vitt Laurie J. , Cooper Jr. William E.
Published: August 2008

The tail loss adaptation in Eumeces of the southeastern United States is complex. Juveniles possess tails that are colored differently from those of adults and apparently distract the attention of potential predators from the body to the tail. Adult tails are cryptically colored. Frequency of tail loss is high across size groups. Experiments on growth of tailed and tailless juveniles suggest no effect of tail loss on growth and, thus, there may be little cost of tail loss to juveniles other than the temporary loss of the autotomy adaptation. Lipids in adult tails constitute nearly 50% of total standing lipids and are reduced during reproduction similar to other lipid reserves. This suggests that tail loss in adults is expensive, particularly prior to or during the breeding season. We suggest that the high costs of tail loss in Eumeces are offset by the increased probability of predator escape via tail loss. Tail loss data are minimal estimates of escape via distraction of a predator's attack to the tail as indicated by predation experiments. The presence, coloration, and behaviors of the tail may result in a high proportion of predation attempts being redirected to the tail followed by total misses.
Condition bias of hunter-shot mallards (Anas platyrhynchos)
Authors: Greenwood Hamilton , Clark Robert G. , Weatherhead Patrick J.
Published: August 2008

We tested the hypothesis that hunters using decoys disproportionately shot ducks in poor condition. We compared weights of 316 hunter-shot mallards (Anas platyrhynchos) with those of 156 mallards we collected by jump or pass shooting at a roost. Data were subdivided by age, sex, and sampling period. In support of the hypothesis, in 11 of 12 comparisons, hunter-shot ducks weighed less than ducks collected at the roost and those differences were significant for five of the seven largest samples. Also consistent with the hypothesis, weights of hunter-shot birds were less variable than weights of birds collected at the roost in 9 of 12 comparisons. Through the fall collection period, the mean weight of ducks shot by hunters remained constant, while the weight of ducks sampled at the roost increased by 5.4%. Our results support the argument that caution must be exercised when using data from hunter-shot waterfowl for management programs based on band-recovery analysis or for any other purpose for which a condition bias could influence the interpretation of those data.
A comparison of time-specific and cohort-specific life tables for Belding's ground squirrels, Spermophilus beldingi
Authors: Zammuto Richard M. , Sherman Paul W.
Published: August 2008

Eight years of age-specific survival data and 6 years of fecundity data from a free-living population of Belding's ground squirrels (Spermophilus beldingi) at Tioga Pass, California, were used to test the hypothesis that time-specific life tables, based on data from individual years, were different from the cohort-specific life table, based on the combined data from all years. The results indicated that neither the age structure of the male nor the female population significantly differed among years (all P > 0.05). Furthermore, the means and the variances in the sizes of weaned litters did not differ among years either in the population at large or within individual age-classes (all P > 0.05). A 27-day snowstorm that occurred in the spring of 1977 increased mortality and reduced reproduction, but it did not change the ground squirrels' age-specific survival or fecundity patterns. Taken together, our analyses revealed that each time-specific life table provided age-specific survival and fecundity estimates that were statistically indistinguishable (P > 0.05) from the composite, cohort-specific life table for each sex, regardless of severe environmental conditions. This is the first demonstration of the equivalence of time- and cohort-specific life tables for a free-living population of mammals.
Behavior of gray whales summering near St. Lawrence Island, Bering Sea
Authors: Würsig Bernd , Wells Randall S. , Croll Donald A.
Published: August 2008

The behavior of gray whales was studied near St. Lawrence Island, Alaska, in July and September 1982. Most behavior involved apparent benthic feeding, as evidenced by mud plumes around surfacing whales and kittiwakes landing near whales at the surface. There was little socializing by whales in July, but more in late September. Numbers of blows per surfacing, durations of surfacings, and durations of dives were all correlated. Percent of time at the surface was about 21% in July and 23% in September. There were fewer blows per surfacing, shorter surface times, and shorter dive times when whales were not feeding than when they were feeding. Intervals between successive blows were longer in nonfeeding whales; however, the blow rate (number of blows per minute) did not differ between feeding and nonfeeding whales. Number of blows per surfacing and duration of surfacing increased with increasing water depth (from < 20 to 80 m). Dive duration did not change appreciably with depth in July, but did so in September. Blow rates by feeding whales increased in deeper water, indicating the need for whales to respire more as depth of dives increased. Time of day affected surfacing–dive–respiration characteristics differently in different months. Whales fed more from 1800 to 2100 local Bering Sea time than at other times of day. During an average surfacing, feeding whales moved about 50 m; during a dive, their net horizontal movements were 90–100 m. Speed averaged around 2 km/h and was twice as fast at the surface (3.4 km/h) as compared with net underwater speed (1.7 km/h).
Effect of varying temperature regimes on the development of pink salmon (Oncorhynchus gorbuscha) eggs and alevins
Authors: Murray Clyde B. , Beacham Terry D.
Published: August 2008

Eggs and alevins from six odd-year, brood-line stocks of pink salmon (Oncorhynchus gorbuscha) spawning in southern British Columbia were incubated under varying temperature regimes and subjected to rapid temperature changes at specific developmental stages. Increasing or decreasing temperature regimes had no significant effect on egg and alevin survival. The inclusion of 2 or 4 °C in the temperature regime reduced egg survival. Rapid temperature changes from 12 to 1 °C late in development reduced alevin survival when compared with transfers from 8 to 1 °C. Hatching and emergence time varied inversely with mean incubation temperature. Decreasing temperature regimes produced longer and heavier alevins and fry than increasing temperature regimes. Low mean incubation temperatures from fertilization to fry emergence resulted in longer and heavier alevins and fry than those at higher mean temperature. Transfers from 8 or 12 °C to 1 °C early in development had a greater effect on alevin length and weight than transfers late in development. Temperature regimes can be manipulated to enhance survival, control development time, and increase alevin and fry size.
Hookear sculpins (genus Artediellus) of the North American Atlantic: taxonomy, morphological variability, distribution, and aspects of life history
Authors: Guelpen Louis Van
Published: August 2008

Difficulty in identifying the two nominal species of hookear sculpins (genus Artediellus) from the North American Atlantic has led to confusion in their taxonomy and reported distributions. The species were found to be separable using nine meristic and six morphological characters, as well as collection locality. Sexual dimorphism and clinal geographic variation occurred in several characters of both species. The known northern limit of A. atlanticus (the Atlantic hookear) in North America was extended to southeast Baffin Island, also the northern limit for A. uncinatus (the snowflake hookear). The southern limits were off Cape Cod for A. atlanticus and northern Nova Scotia for A. uncinatus. Artediellus uncinatus inhabited a shallower depth range (13–183 m) than A. atlanticus (0–384 m), indicating at least partial ecological separation. The latter species had a positive size–depth relationship, with the largest fish inhabiting the deep northern waters. Artediellus atlanticus seemed to prefer softer bottom sediments, while A. uncinatus showed no preference. Overall, sex ratios were similar (1.29 males to females in A. atlanticus and 1.12 in A. uncinatus). In North American waters, A. atlanticus spawns from approximately May to November and A. uncinatus during summer. Both nominal species warrant full specific status; however, subspecies designations appear unfounded.
Enzymes of energy metabolism and gluconeogenesis in the Pacific blue marlin, Makaira nigricans
Authors: Suarez Raul K. , Mallet Maryse D. , Daxboeck Charles , Hochachka Peter W.
Published: August 2008

Enzymes of energy metabolism were measured in marlin red and white muscle and heart to determine the relative capacities for various pathways. Red muscle and heart are highly aerobic tissues with the capacity to oxidize carbohydrate, fat, and amino acids. White muscle possesses an extremely high capacity for anaerobic glycolysis as well as a capacity for carbohydrate oxidation which is unusually high by teleost white muscle standards. The great similarity in metabolic potential between tuna and marlin muscles suggests a similar capacity for metabolic heat production. However, tuna muscles are "hot" while marlin muscles are "cold." The implications of this are discussed in the context of energy metabolism and endothermy in the scombroid fish. Levels of gluconeogenic enzymes in liver and kidney as well as enzymes possibly involved in glycogenesis in white muscle suggest that the major substrate for glycogenesis in this tissue is endogenous lactate and that the major route for conversion of pyruvate to phosphoenolpyruvate is reversal of the pyruvate kinase reaction.
Optimal prey size for stream resident brown trout (Salmo trutta): tests of predictive models
Authors: Bannon Eileen , Ringler Neil H.
Published: August 2008

The time required to handle different-sized prey (crickets) was measured in an artificial stream for eight wild brown trout (Salmo trutta L.) in two size classes (mean total lengths, 186 and 214 mm). Handling times (HTs) scaled by mouth size were described by an exponential equation: HT = 1 + 0.84e2.35(ps/ms) (ps, prey size; ms, predator (mouth) size). Cost curves based on handling time/prey weight were used to predict optimal prey lengths of 22 mm for small trout and 24 mm for large trout. A second model based on J. W. J. Wankowski's empirical results predicted slightly smaller optima. Physical constraints provided estimated minimum prey lengths of 2.8 and 3.2 mm for large and small fish, respectively; maximum prey lengths were 89 and 97 mm, respectively. We compared the predicted optimal prey size with the size distribution of invertebrates in drift and brown trout stomachs sampled in a second-order stream from July to September 1982. The most abundant prey sizes in the study stream were near the minimum size that can be effectively handled by brown trout. Prey of the predicted optimum size were rare, but feeding was size selective in spite of a limited food resource. The growth rates of these stream-dwelling brown trout were slower than the brown trout in other streams in this region. This may reflect diets consisting largely of suboptimal-sized prey.
Reproduction of the winter tick, Dermacentor albipictus, under field conditions in Alberta, Canada
Authors: Drew Mark L. , Samuel W. M.
Published: August 2008

Total egg production and timing of reproduction by engorged female winter ticks (Dermacentor albipictus) were studied in three habitat types (aspen forest, bog, and grassland) of central Alberta. Results for the aspen forest included lower survival of engorged females, a longer incubation period, fewer eggs hatched, and a lower survival of larvae. Presence of snow resulted in decreased survival of engorged females in all habitats. Onset of oviposition in the three habitats was synchronous (early June) and, possibly, stimulated by photoperiod. Incubation period appeared temperature dependent.
Protean behaviour of a neustonic insect: factors releasing the fright reaction of whirligig beetles (Coleoptera: Gyrinidae)
Authors: Newhouse N. J. , Aiken R. B.
Published: August 2008

Whirligig beetles are common neustonic insects whose response to approach of any object is a rapid, irregular swimming. We recorded the incidence of swimming and diving of individual Gyrinus pleuralis Fall in response to the movement of black and white circular models. The frequency of response increased with model size up to 5 cm diameter beyond which no increase occurred. Swimming occurred more often in response to black models. The role of this response in a more comprehensive antipredator stategy is considered.
Redescription of Pennella instructa Wilson, 1917 (Copepoda: Pennellidae) from the swordfish (Xiphias gladius L.)
Authors: Hogans W. E.
Published: August 2008

Two specimens of Pennella instructa Wilson, 1917 are described from swordfish (Xiphias gladius L.) collected off Georges Bank in the northwest Atlantic Ocean. This mesoparasitic copepod is characterized by two lateral horn holdfasts extending posteriorly parallel to the neck, distinct groups of papillae on the anterior end of the cephalothorax, and five-segmented and setose first antennae.
Inter- and intra-sexual interactions in a New Guinea skink, Emoia physicae
Authors: Zwickel Fred C. , Allison Allen
Published: August 2008

Three experiments were conducted in outdoor arenas with a small, New Guinea skink, Emoia physicae, to examine inter- and intra-sexual interactions. There were statistically significant differences in behaviour between adult males and adult females and in interactions within the sexes. Within sexes, larger lizards dominated smaller ones. Females dominated males, even though females are smaller. Intrasexual encounters were more likely to be agonistic than were intersexual encounters. Intrasexual encounters were more likely to be overtly agonistic among males than among females, but females often avoided one another. Both sexes of E. physicae exhibit behaviors that could function in a territorial context.
Avian Haemoproteidae. 20. The haemoproteids of the avian families Apodidae (swifts), Bucconidae (puffbirds), and Indicatoridae (honeyguides)
Authors: Bennett G. F. , Caines J. R. , Whiteway M. A.
Published: August 2008

The haemoproteids of the avian families Apodidae (swifts), Bucconidae (puffbirds), and Indicatoridae (honeyguides) are examined. Haemoproteus apodus n. sp., H. bucconis n. sp., and H. indicator n. sp. are described and represent the first named haemoproteids from these families.
Avian Haemoproteidae. 21. The haemoproteids of the parrot family Psittacidae
Authors: Bennett G. F. , Peirce M. A.
Published: August 2008

The haemoproteids of the avian family Psittacidae (the parrots) are reviewed. Haemoproteus handai Maqsood, 1943 is redescribed from the type host, Psittacula cyanocephala (L.). Parahaemoproteus desseri Miltgen, Landau, Rabanaworbhan and Yenbutra, 1981 is designated a synonym of H. handai.
A comparison of hibernation in the black-tailed prairie dog, white-tailed prairie dog, and Wyoming ground squirrel
Authors: Harlow Henry J. , Menkens Jr. George E.
Published: August 2008

Black-tailed prairie dogs have been reported to be active above ground during periods throughout the year and have, therefore, been described as being incapable of hibernation. Previous laboratory studies, however, have suggested that this may not be true. We have found that during the winter when maintained under identical conditions, Wyoming ground squirrels and white-tailed prairie dogs will enter torpor at an ambient temperature of 7 °C, while black-tailed prairie dogs will not. However, when deprived of food and water, black-tailed prairie dogs can be induced into a state of torpor that is characterized by a shorter duration of continuous dormancy than that of the ground squirrels or white-tailed prairie dogs. A comparison of these sciurid rodents offers a good example of alternate strategies for winter survival among closely related species. While two of these species readily utilize torpor, black-tailed prairie dogs may rely on alternate physiological capacities to cope with food and water shortage as a partial substitute for winter torpor.
Physiological consequences of nighttime temperature for a tropical, herbivorous lizard (Cyclura nubila)
Authors: Christian Keith A.
Published: August 2008

Hatchling Cuban iguanas (Cyclura nubila) were reared for 38 weeks under three experimental conditions: nighttime temperatures of 15, 25, and 35 °C. All groups experienced a temperature of 35 °C during the day, and all were given food and water ad libitum. Growth rate (in terms of mass and length) increased with increasing nighttime temperature. The iguanas held at constant 35 °C were also more robust (defined as mass/length); this difference was not explained by the amount of fat. Passage time of food through the gut was shorter for the constant temperature group, which also consumed more food per day. There was no difference in digestive efficiency among groups, and the differences in growth rates were a result of the differences in food consumption. Constant temperature was apparently not detrimental for this tropical, herbivorous lizard. More data are required before useful generalizations concerning voluntary hypothermia in reptiles can be made.
The response of four terrestrial molluscs to the presence of herbivore feces: its influence on infection by protostrongylids
Authors: Cabaret J. , Vendroux P.
Published: August 2008

The response of three snails (Cernuella virgata, Helix aspersa, and Cepaea nemoralis) and of the slug Arion sp. to herbivore feces was tested. The fresh feces of herbivores were not attractive; however, the feces of small ruminants were less repulsive than those of cattle or horses. The scale of decreasing positive response towards sheep or goat feces for the land snails was C. nemoralis, H. aspersa, and C. virgata. The banded individuals of the latter were more attracted to feces than the unbanded ones.
The effects of food on midsummer demography of white-footed mice, Peromyscus leucopus
Authors: Wolff Jerry O.
Published: August 2008

At mid-latitudes, white-footed mice (Peromyscus leucopus) breed in spring and autumn with a decrease in breeding activity in July and August. A food supplement of sunflower seeds and oats was applied to two 1-ha live-trapping grids from 1 May to 13 August 1984 to determine if a high quality food supplement would stimulate reproduction in Peromyscus leucopus during the midsummer breeding hiatus. Breeding activity on treatment and control grids was high from May through June, declined considerably from early July through August, and increased again in September and October. Food had no apparent effect on the decline in reproductive activity during midsummer. During the spring breeding season, the number of females was higher on treatment than control grids, but food had no effect on number of males, pregnancy rates, home-range size, length of residence, or body weights. The breeding activity and upper limits of population density are apparently determined by factors other than food.
Homosequential species 2a and 2b within the Prosimulium onychodactylum complex (Diptera): temporal heterogeneity, linkage disequilibrium, and Wahlund effect
Authors: Henderson Christine A. P.
Published: August 2008

Prosimulium onychodactylum 2 within the P. onychodactylum complex comprises two homosequential forms designated P. onychodactylum 2a and P. onychodactylum 2b (L. J. Newman. 1983. Can. J. Zool. 61: 2816–2835). The present paper presents evidence that forms 2a and 2b are reproductively isolated by demonstrating the existence of temporal heterogeneity, inversion linkage disequilibrium, and heterozygote deficiencies in larval samples from five sites where both forms occur. On the basis of differential frequencies of shared inversion polymorphisms, these samples could be partitioned into subsamples of 2a and 2b which were in Hardy–Weinberg equilibrium and exhibited random association of inversions. Form 2a consistently developed first and is the more widespread with samples from Alaska, the Yukon, British Columbia, Alberta, Washington, Idaho, Montana, Wyoming, and Colorado. Form 2b is restricted to the provinces and states south of Alaska and the Yukon Territory.
Ecophysiological responses in life-history evolution: evidence for their importance in a geographically widespread insect species complex
Authors: Tauber Catherine A. , Tauber Maurice J.
Published: August 2008

Geographical patterns of variation among North American populations of Chrysoperla carnea provide strong evidence that ecophysiological traits are central to the evolution of life histories. Selection pressure and the types and amounts of genetic variability underlying the traits vary geographically. Western populations exhibit considerable genetic variability in their reproductive responses to both photoperiod and prey. This variability is expressed both at the interpopulation level by the diversity of locally adapted populations and at the intrapopulation level in the form of genetic polymorphisms. By contrast, eastern, midwestern, and northwestern regions contain two types of reproductively isolated, monomorphic populations. The two types differ in their photoperiodic requirements for reproduction, but neither uses prey as a cue to stimulate reproduction. Although most of the characteristic responses to photoperiod and prey can vary independently of each other, the separate traits tend to covary to form coadaptive sets. The covariance of a few responses appears to have a genetic or physiological basis, a condition that places constraints on the evolution of life histories. Our results also demonstrate that comparative studies at the intraspecific level are highly significant to the analysis of life-history evolution and to the taxonomic treatment of species complexes.
Dispersal in pond snails: potential role of waterfowl
Authors: Boag D. A.
Published: August 2008

Young pond snails of three species (Lymnaea stagnalis, Stagnicola elodes, and Helisoma trivolvis) were allowed free access to waterfowl feathers floating on the surface of shallow containers. Snails adhering to the feathers were subjected to simulated flight conditions by placing them in an air stream. The size of these snails, the length of time they adhered to the feathers while in the air stream, and their survivability for various lengths of time under these conditions were recorded. Those snails that adhered to the feathers were mainly small individuals (< 2.5 mm long in all three species). The proportion that remained clinging to the feathers declined sharply with time; after 15 min of exposure only 6% of L. stagnalis, 18% of S. elodes, and 15% of H. trivolvis remained. Survivability also declined with time exposed to the simulated flight conditions; after 15 min only 50% of L. stagnalis, 23% of S. elodes, and 15% of H. trivolvis were still alive. Larger individuals tended to survive better than smaller ones for any given exposure time, but they also tended to fall off the feathers sooner than smaller ones; no snail more than 3 mm long was recorded adhering to the feathers for more than 4 min under the test conditions of simulated flight (air speed of 41 km/h). These results suggest that despite a low proportion of the snail population adhering to the feathers (< 1% of those available at any given time) and the relatively high rates of loss, either by falling off the feathers or dying in situ after adhering, the probability of successful dispersal for distances up to 10 km remains high (a mallard flying for 15 min at 41 km/h was deemed capable of carrying at least three surviving individuals of any of the species tested over a distance of about 10 km). Of the three species tested, S. elodes had the greatest probability of successful dispersal, which may explain its almost ubiquitous distribution in the water bodies of central Alberta.
Sibling recognition and olfactory sensitivity in juvenile coho salmon (Oncorhynchus kisutch)
Authors: Quinn Thomas P. , Hara Toshiaki J.
Published: August 2008

Previous experiments indicated that juvenile coho salmon (Oncorhynchus kisutch) can distinguish the chemical traces of siblings from nonsiblings of their own population. The present study confirmed the finding that coho salmon use chemoreceptor systems to distinguish tankmate siblings from nonsiblings that they have not been reared with. However, salmon did not distinguish siblings from nonsiblings or maternal half-siblings if they had been reared together. Electrophysiological experiments demonstrated that the olfactory sense of young coho salmon can detect certain amino acids and a bile acid at concentrations of about 10−8 to 10−9 M. Additional tests suggest that bile acids are probably of primary importance in chemically characterizing conspecifics and amino acids play a secondary role.
Responses of migrating adult sockeye salmon (Oncorhynchus nerka) to population-specific odours
Authors: Groot C. , Quinn T. P , Hara T. J.
Published: August 2008

The ability of homing sockeye salmon (Oncorhynchus nerka) to discriminate between two populations of their own species on the basis of odours was tested in a Y-maze choice apparatus and by electrophysiological recordings from the olfactory rosette. The tests were performed with adult sockeye captured at the entrances to Great Central Lake and Sproat Lake on Vancouver Island, British Columbia, Canada. In behaviour experiments, Great Central Lake sockeye salmon were significantly attracted to chemical traces of their own population but no such preference was evident for the Sproat Lake sockeye salmon. The electrophysiological experiments indicated that Sproat Lake sockeye salmon discriminated between water conditioned by their own population from water conditioned by Great Central Lake sockeye. Great Central Lake sockeye salmon failed to show differential responses to the two population waters. The experiments revealed that the olfactory system of migrating adult sockeye salmon was sensitive to amino acids and a bile acid, but that the major active components in water responsible for olfactory stimulation were bile-acid-like components. We conclude that adult sockeye salmon can discriminate between population specific odours, but that differences exist between stocks.
Sex-related dispersion of breeding deer mice in the Kananaskis Valley, Alberta
Authors: Xia Xuhua , Millar John S.
Published: August 2008

Snap trapping of small mammals in the Kananaskis Valley, Alberta, during the breeding seasons of 1982 and 1983 provided data used to analyse sex-related dispersion patterns of adult Peromyscus maniculatus. A dispersion pattern of regular alternation of males and females, within-sex avoidance, and strong between-sex association was found. Within-sex exclusion was better exhibited by females than by males. These data are consistent with what would be expected for a promiscuous mating system. Intraspecific resource partitioning between different sexes may occur through adjustments in spatial relationships.
Escape responses of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae): influence of predator type and temperature
Authors: Brodsky Lynn M. , Barlow C. A.
Published: August 2008

The escape responses exhibited by pea aphids were examined at three different temperatures, 15, 20, and 25 °C, using two different predators: syrphid larvae and coccinellid beetles. Coccinellid beetles foraged more vigorously at higher temperatures resulting in greater vibrations on the host plant as they searched for aphids. Foraging rates for syrphids were slower by comparison and did not vary with temperature. We found that most aphids dropped off the host plant when confronted by coccinellid beetles, especially at higher temperatures, and backed up when confronted by syrphid larvae regardless of temperature. We conclude that individual aphids do not have characteristic escape responses, but rather the response adopted depends in part on the foraging rate and species of predator.
Genetic differentiation in populations of Canada geese (Branta canadensis)
Authors: Wagner Carol E. Van , Baker Allan J.
Published: August 2008

Electrophoretic data for 35 structural gene loci were obtained from 249 individuals in 11 populations of Branta canadensis across North America. Twenty-four loci were polymorphic in at least one population sample, average observed heterozygosity ranged from 0.031 to 0.083, Rogers' genetic distance ranged from 0.014 to 0.063, and Wright's measure of genetic structuring among populations was 0.065. Samples of B. c. minima from Willows, California, and B. c. interior from Akimiski Island, Northwest Territories, exhibited both the highest levels of genetic variability within populations and the greatest divergence from other populations. Principal coordinates analysis on the genetic distances, followed by nonmetric scaling in three dimensions and supplemented by construction of a minimum spanning tree, gave a more informative and less distorted picture of relationships among populations than cluster analysis. Differentiation in structural genes was neither equivalent to morphometric differentiation (in magnitude and pattern) nor consistent with conventional subspecies designations. This suggests that structural genes are selectively neutral in Branta canadensis and are differentiating through random drift, in contrast to morphometric characters which have diverged markedly under different selective pressures.
Anatomy of the avian membrana nictitans
Authors: Sivak Jacob G. , Glover Rebecca F.
Published: August 2008

The anatomy of the membrana nictitans was examined in the rockhopper penguin (Eudyptes crestatus) and in two ducks, a diver (Mergus cucullatus, hooded merganser) and a nondiver (Anas platyrhynchos, common mallard), by light and transmission electron microscopy. In general, the nictitans is organized in a manner reminiscent of the cornea; i.e., an external epithelium, an internal endothelium, and a fibrous stromal layer in between. However, it is thinner than the cornea, a fact reflected by the relatively thin stroma. Nictitans organization varies between species and in different regions of the same membrane. The cellular and acellular components are less organized and not as tighltly packed in the nondiver than in the two other species. In addition, portions of the nictitans that would be coincident with the cornea when it is in place in front of the eye are more highly organized in both divers. The anatomy of the leading edge of the nictitans, including the marginal plait, which may help lock the membrane in position, is described.
Ancyrocephalids (Monogenea) from Morone spp. (Percichthyidae) in North America, including redescriptions of Onchocleidus mimus Mueller, 1936 and O. interruptus Mizelle, 1936
Authors: Beverley-Burton Mary , Bruce-Allen Lorraine , Murith Danièle , Dechtiar A. O.
Published: August 2008

The ancyrocephalids (Monogenea) parasitizing the temperate basses (Percichthyidae) of North America are reviewed. Onchocleidus mimus Mueller, 1936 is redescribed from material found on the gills of Morone chrysops (white bass) taken in Ontario. Onchocleidus rogersi (Hanek and Fernando, 1972) Beverley-Burton, 1984 is declared a synonym of O. mimus. Onchocleidus interruptus Mizelle, 1936 is redescribed from paratype material (14 specimens) found on M. mississippiensis (yellow bass) taken in Illinois. Additional morphometric and morphologic data for O. chrysops (Mizelle and Klucka, 1953) Beverley-Burton, 1984 are provided. Cleidodiscus sp. of S. Tedla and C. H. Fernando and "Tetraonchinae" of C. J. Sindermann are considered to be referrable to the genus Onchocleidus sensu Beverley-Burton. Following a study of type specimens of Aristocleidus hastatus Mueller, 1936 from M. saxatilis (striped bass) taken in Florida, the genus and species are recognised as valid. However, there is need for a revision of the generic diagnosis when new material becomes available as the morphology of the male copulatory complex appears to be distinctive and of a "type" as yet undescribed. Urocleidus nactus Mayes and Johnson, 1975 found on M. americana (white perch) taken in coastal waters of North Carolina is transferred to Pterocleidus Mueller, 1937 as Pterocleidus nactus (Mayes and Johnson, 1975) n. comb. The possibility that ancyrocephalids found on M. americana taken in estuarine waters of the Hudson River by V. M. Liguori and identified as U. biramosus (Mueller, 1937) are conspecific with P. nactus is discussed. Ancyrocephalids possessing the spiral filament penis type occur almost exclusively on fishes of the Percoidae. Possible evolutionary pathways involving ancestral dactylogyridans (sensu Beverley-Burton) parasitizing estuarine Percichthyidae or freshwater Centrarchidae are presented with particular reference to the ancryrocephalids found on Morone spp.
Mitochondrial DNA analysis of Pacific salmonid evolution
Authors: Thomas W. Kelley , Withler Ruth E. , Beckenbach Andrew T.
Published: August 2008

The salmonids of Pacific North America are a group of closely related species with complex life histories and interesting distribution. Previous studies of their evolution and population structure have involved classical morphological and genetic techniques. We have analysed both intra- and inter-specific variation in mitochondrial DNA sequences of the five North American species of the genus Oncorhynchus and the rainbow trout species, Salmo gairdneri. Cleavage sites for 13 different restriction enzymes were sampled, comparing an average of 48 sites per individual, or approximately 1.7% of the genome. No obvious size variation in the 16 500 ± 500 base pair length was observed. Levels of intraspecific variation detected in the chum salmon and rainbow trout were 0.24 ± 0.23 and 0.45 ± 0.26%, respectively. This variation was population specific; no variation was detected within any of the populations sampled, suggesting the existence of population substructuring. Estimates of divergence between species range from 2.46 ± 0.72% in the coho–chinook salmon comparison to 6.88 ± 1.27% between coho and chum salmon. The phylogenetic relationship among these species, based on the levels of sequence divergence, organizes the species into three distinct groups. One group includes the pink and chum salmon while a second group contains the coho and chinook salmon, as well as the rainbow trout. The sockeye salmon are distinct from both groups. Although most of these results are in accordance with classical analyses, the relationship of the rainbow trout to the coho and chinook salmon suggests different interpretations of the evolution of life histories and morphological traits in these closely related species.