bluuebunny/crossref_metadata_2025 huggingface dataset:
Foraging tactic as a potential selection pressure influencing geographic differences in body shape among populations of dace (Phoxinus eos)
Authors: Toline C. Anna , Baker Allan J.
Published: July 2008

Geographic differences in body shape among 18 populations of northern redbelly dace in three regions of Ontario (Sudbury, Algonquin Provincial Park, and Kingston) were quantified with truss analysis. Principal component analysis of size-adjusted residuals of the trusses revealed that 35.11% of the morphological variation in body shape is explained on principal component I. This axis describes the major trend in body shape variation, ranging from populations in which fish are relatively deep-bodied to those in which fish are more shallow-bodied. Shape variation among populations in Algonquin Park spanned the range observed among all three regions in Ontario. Experiments were thus conducted on two Algonquin populations differing considerably in body shape, and it was found that deeper bodied fish from one population were significantly more adept at capturing evasive prey than were relatively shallow-bodied fish from another population. This finding is not only consistent with functional analysis of fish shape but also fits predictions from foraging theory. Fish catching plentiful but evasive prey should rely on ambush predation, and thus have a large body depth, which increases body area relative to mass, in order to optimize acceleration. Conversely, fish catching less evasive food occurring at low density should use a tactic of wide foraging, for which they need a streamlined anterior body suitable for cruising over extended periods of time. Samples from the natural population revealed that deep-bodied fish had a significantly greater number of evasive prey in their guts, and that the more shallow-bodied fish had relatively few. Furthermore, the pond in which the deeper bodied fish occurred had significantly higher prey density than the pond inhabited by the shallow-bodied fish. Because the Algonquin populations experience sufficient gene flow to prevent differentiation due to drift alone, the most likely explanation for population differentiation resides in selection on body shape for foraging tactic.
Division of goldfish erythrocytes in circulation
Authors: Murad Ajmal , Everill Susan , Houston Arthur
Published: July 2008

Erythrocyte division occurs in the blood of goldfish, Carassius auratus L., and is particularly prominent during response to respiratory stresses. The process involves nuclear elongation followed by cellular elongation, central constriction, and attenuation culminating in cell separation. Cytomorphic criteria developed in an earlier study of red cell maturation in this species suggest that the process is restricted to juvenile cells: those possessing the organelles required for hemoglobin synthesis. Consistent with this, but in distinct contrast to mature erythrocytes, dividing cells resemble juvenile cells in their incorporation of 55Fe. This is subsequently detectable by autoradiography in hemoglobin electropherograms. Immuno-fluorescent antibody probes for tubulin and actin revealed an ordered sequence of cytoskeletal changes during the division process. However, the nuclei of dividing cells do not take up [3H]thymidine, and although colchicine and nocodazole treatment led to the appearance of metaphase figures in pronephric and splenic erythroid cells, these were not evident in dividing cells. The nature and possible significance of the process are discussed.
Cortisol levels in red deer (Cervus elaphus) and fallow deer (Dama dama) after an acute ACTH administration
Authors: Bubenik George A. , Bartos Ludek
Published: July 2008

Cortisol levels were determined in seven 2.5-year-old male red deer (Cervus elaphus) and 8 yearling male fallow deer (Dama dama) after an acute intramuscular injection of 0, 10, or 40 international units (IU) of ACTH, administered in June, July, or August. In both species a highly significant increase in cortisol concentration was observed within the first hour after both doses of ACTH. At the end of the rapid cortisol elevation (60 min post ACTH) the response in both species was equal for the 10 and 40 IU doses. Average pretreatment levels were around 1–2 μg/100 mL; peak levels registered in red deer were around 10 μg/100 mL, and in fallow deer maximal concentrations reached around 8 μg/100 mL. Although all deer responded to ACTH, strong interindividual differences in intensity of cortisol elevation were detected. The extent of increase of blood cortisol levels in response to ACTH appears to be an evolutionary adaptation of various cervid species to their respective environmental conditions.
Use of aquatic plants by moose: sodium hunger or foraging efficiency?
Authors: MacCracken James G. , Ballenberghe Victor Van , Peek James M.
Published: July 2008

Use of submergent aquatic plants by North American moose (Alces alces) has been linked to sodium hunger. Habitat preferences, seasonal diets, forage abundance and quality, and population surveys indicated that emergent plants in small shallow ponds were important to moose on the Copper River Delta, Alaska. However, sodium was abundant in terrestrial browse. We propose that foraging in aquatic habitats, particularly on emergent species, may be highly efficient based on the following habitat attributes and behavioral observations: (i) ponds dominated by either emergent or submergent species produced about 4 times more forage than terrestrial habitats, (ii) emergent and submergent plants were more digestible and had higher concentrations of minerals than browse, (iii) use of aquatic habitats followed trends in forage production over the growing season, (iv) indirect evidence suggested that forage intake rates were greater in aquatic habitats, and (v) use of aquatic habitats by male and female moose was in proportion to the sex structure of the population. These data provide consistent circumstantial evidence that use of emergent species, and possibly submergents, may maximize the intake of nutrients and also reduce conflicts between cropping forage and vigilance during a foraging bout.
Intersexual differences in growth, mortality, and size at maturity in bullfrogs in central Ontario
Authors: Shirose L. J. , Brooks R. J. , Barta J. R. , Desser S. S.
Published: July 2008

A population of bullfrogs (Rana catesbeiana) in Algonquin Provincial Park, Ontario, Canada, was studied from May 1985 through October 1987. Of 1187 individuals marked with tattoos, 567 were recaptured at least once. The age of each marked individual was estimated using size–frequency distributions. A negative relationship between age and sex ratio indicated lower survivorship for mature males than for mature females. The average age at maturity was estimated to be 5 years post-transformation (YPT), at 113 mm standard length (snout to urostyle) for females, and 3 YPT, at 91 mm, for males. The minimum age at maturity was 4 YPT, at 94 mm standard length, for females, and 3 YPT, at 90 mm, for males. Age at maturity was greater, and size at maturity smaller, than reported for other populations. A logistic growth model fitted to the data, and comparison of age-specific mean standard lengths, indicate an intersexual difference in the pattern of growth. The asymptotic maximum standard length, as derived from the logistic model, was 181 mm for females and 148 mm for males. The estimated growth constant, r, was greater for males than for females, indicating that males attained their maximum size at a younger age than did females.
Topography of the digital cutaneous sensilla of the tokay gecko, Gekko gecko (Reptilia, Gekkonidae), and their potential role in locomotion
Authors: Lauff Randolph F. , Russell Anthony P. , Bauer Aaron M.
Published: July 2008

The external morphology of the cutaneous sensilla of the dorsal digital scales of the tokay gecko, Gecko gecko, is described and the distribution of the various sensillar types is mapped. Three types of sensilla are identified: bristleless, bristled unbranched, and bristled branched. Bristleless sensilla occur only on glabrous scales and are largely restricted to the toe base and phalangeal scales. They may register stimuli other than those associated with scale-to-scale contact. Bristled unbranched sensilla are recessed and are located on the paralamellar, phalangeal, paraphalangeal, and toe base scales, but the bristled branched variety is largely restricted to the paraphalangeal region. The mechanoreceptive role of the bristle-bearing sensilla is related to their placement on individual scales and their distribution across the digit. Placement of the sensilla accords well with patterns of scale-to-scale and scale-to-substrate contact that occur during digital hyperextension and plantarflexion. Such proprioceptive monitoring of regions of the digit during locomotion may be of considerable significance in the control of the establishment and sundering of the adhesive bond that occurs between the setae and the locomotor substrate.
Classification, phylogeny, and zoogeography of the pond skater genus Gerris Fabricius (Hemiptera: Gerridae)
Authors: Andersen N. Møller
Published: July 2008

The primarily Holarctic pond skater genus Gerris Fabricius is redescribed and compared with two other northern temperate water strider genera, Aquarius Schellenberg and Limnoporus Stål. The subgenus Gerriselloides Hungerford and Matsuda is redefined and Macrogerris subgen.nov. is described to hold a group of eight eastern Palearctic species. Monophyletic species-groups of the subgenus Gerris s.str. are diagnosed and their species composition is delimited. Gerris brevirostris Bergroth is synonymized with G. lacustris (L.), syn.nov. Keys for identification are provided for all species of Gerris. The phylogenetic relationships among species of Limnoporus, Aquarius, and Gerris are analyzed. The data set comprises 63 structural characters coded for 2 species of Limnoporus, 7 species of Aquarius, and 19 species of Gerris. In particular, the metathoracic scent apparatus, male genitalia, female ovipositor, and gynatrial complex reveal characters of phylogenetic importance. The data set is subjected to cladistic analyses using the parsimony program Hennig86. Character polarities are determined using either a hypothetical taxon or the species Gigantometra gigas (southeastern Asia) as out-group. Through cladistic analysis, evidence is brought forward supporting one particular hypothesis of the relationships between Aquarius, Limnoporus, and Gerris, and between subgenera and monophyletic species-groups of Gerris. The reconstructed phylogeny is used to infer evolutionary sequences in patterns of wing polymorphism, habitat preferences, and sexual size dimorphism among temperate water striders, and to discuss their geographical distribution and historical biogeography.
Effects of body size, population density, and maternal characteristics on age at first reproduction in bighorn ewes
Authors: Jorgenson Jon T. , Festa-Bianchet Marco , Lucherini Mauro , Wishart William D.
Published: July 2008

The factors affecting variation in age at first reproduction of bighorn ewes (Ovis canadensis) were investigated in two marked populations in Alberta. One population was studied for 20 years, the other for 11 years. As yearlings, females that lactated at 2 years of age were on average heavier and larger, and had longer horns than females that did not lactate at 2 years. However, there was wide overlap in body mass between early and late producers, and increases in body mass over the threshold for reproduction had little effect on the probability of early lambing. The body mass of females at 4 months of age explained less than half of the variance in female body mass at 1 year or at 15 months. In one population, the proportion of 2-year-old ewes lactating was not correlated with density and declined after a pneumonia epizootic. In the other population, the proportion of 2-year-old ewes lactating was higher during an experimental reduction of density, and dropped to near zero as density increased. There was a significant interaction effect of body mass and population density upon the probability that a ewe would lactate at 2 years of age. Independently of body mass, yearlings were less likely to lactate at 2 years of age at high population density than at low density. The number and age distribution of rams did not affect the proportion of 2-year-old ewes lactating. The mothers of lactating 2-year-olds were not older or heavier than the mothers of ewes that did not lactate at 2 years. Although some of the variation in age at first reproduction was due to differences in mass and population density, much of it remained unexplained and could be due to genetic factors.
Growth and reproduction in island and mainland populations of the vole Microtus epiroticus
Authors: Yoccoz Nigel G. , Ims Rolf A. , Steen Harald
Published: July 2008

The vole Microtus epiroticus was accidentally introduced from Russia to the high arctic archipelago of Svalbard between 30 and 70 years ago. Data on growth patterns were collected in the laboratory for animals originating from the unique Svalbard population and from a population in Finland, close to northern Russia. Gestation period, birth mass, litter size, and age at first reproduction were similar in both populations. Longitudinal growth data were analyzed using polynomial growth curve models. Growth was bimodal, with an early peak at 8–10 days and a later peak at 15 days. The Finnish animals differed from the Svalbard animals by a higher growth rate at 12–15 days. In the field, adult body masses were much greater on Svalbard than in Finland. This difference might have been due to a phenotypic response to the cold arctic climate. We discuss the lack of clear predictions regarding microtine adaptation to the unpredictable arctic environment, and emphasize that in terms of high reproductive rates in mammals, M. epiroticus represents an extreme case.
Distribution of lamprey gonadotropin-releasing hormone in the brain and pituitary gland of larval, metamorphic, and adult sea lampreys, Petromyzon marinus
Authors: Wright Glenda M. , McBurney Kim M. , Youson John H. , Sower Stacia A.
Published: July 2008

Lamprey gonadotropin-releasing hormone was demonstrated in the brains of larval, metamorphic, and adult sea lampreys, Petromyzon marinus, using an immunoperoxidase technique. Gonadotropin-releasing hormone was observed in the neurohypophysis and preoptic area of the brain of larval, metamorphic, juvenile, and prespawning adults. The occurrence of immunoreactive cells and the intensity of the immunostaining was lowest in larvae, but by stage 5 of metamorphosis there was a marked increase in the prevalence and staining of these cells, which continued into adults. In larvae and lampreys in metamorphic stages 1–4, most immunoreactive fibres were confined to the dorsal region of the neurohypophysis. During stage 5 there was an expansion of immunopositive fibres into the ventral portion of the neurohypophysis. Prominent immunoreactivity was observed throughout the neurohypophysis from stage 5 onward through the adult stages. Changes in immunoreactivity of these cells and fibres in the brain and neurohypophysis correlate well with increased concentrations of hormone in the brain during development and with the timing of presumed changes in activity of cells in the adenohypophysis during metamorphosis.
Isostatic rebound and its effects on fish colonization and distribution in the western Lake Superior basin
Authors: Stephenson S. A. , Momot W. T.
Published: July 2008

Ichthyofaunal surveys of the Huron Mountains and Isle Royale, Michigan, and the Sibley Peninsula, Ontario, allow for both a comparative study of colonization events and the effects of sequential isostatic rebound within a large portion of the western Lake Superior basin. The distribution of some fish species in these areas is the result of catastrophic events related to glacial retreat. The highest Huron Mountain lakes were colonized during channel events occurring shortly after the Marquette readvance began its retreat. Some species present on the Sibley Peninsula were likely carried by overflows from Lake Agassiz. Most lakes within these areas, however, were colonized well after 9700 BP, when large numbers of species had gained entrance to Lake Superior, mainly from Mississippi basin refugia. Several species, presumably because of earlier warming periods, had a wider distribution than they exhibit today. Some colonization of Isle Royale was probably through the straying of a few individuals from these populations. Lake Superior remains a formidable barrier to many species, restricting them to favourable areas within the western basin.
Diving behaviour of narwhals (Monodon monoceros) on their summer grounds
Authors: Martin A. R. , Kingsley M. C. S. , Ramsay M. A.
Published: July 2008

Three adult female narwhals from the population that summers in the sheltered waters of northern Baffin Island, Canada, were fitted with satellite-linked UHF radio packages. The units logged and transmitted diving and swim-speed data and revealed the location of the study animals for periods of up to 19 days. Most diving activity was in the top 40 m and bottom 40 m of the water column. Shallow dives were characterized by low rates of descent and ascent (<0.5 m∙s−1), short submersions, and frequent changes of vertical direction. Deep dives were normally to, or near to, the seabed in depths of up to 257 m, and involved both faster rates of vertical movement (1–2 m∙s−1) and longer periods underwater (up to 15.1 min). Midwater dives were intermediate in all respects. Deeper dives were of a characteristic "square" profile and provided an average of 7 min at the chosen depth, representing 57% of the time submerged. No dives were demonstrably longer than the estimated aerobic dive limit for this species. Activity at depth, including rapid swimming and many changes of vertical direction, was indicative of foraging and consistent with a diet of many small prey items. Overall, a relatively small proportion of time was devoted to presumed foraging activity, suggesting either that feeding is a low priority at this time of year or that the whales' nutritional needs could be easily met by the food stocks available.
Comparative study of gill dimensions of three erythrinid species in relation to their respiratory function
Authors: Fernandes Marisa Narciso , Rantin Franscisco Tadeu , Kalinin Ana Lúcia , Moron Sandro EsteVAN
Published: July 2008

Gill dimensions were analysed in relation to body mass in three erythrinid fish, an air-breathing species, Hoplerythrinus unitaeniatus, and two ecologically distinct water-breathing species, Hoplias malabaricus and Hoplias lacerdae. Evidence was obtained of remarkable differences in patterns of increase in filament length, number of secondary lamellae, bilateral area of the secondary lamellae, total area of the secondary lamellae, and mass-specific area of the secondary lamellae among these three species. The analysis showed a large increase in respiratory surface area relative to body mass in H. malabaricus (b = 1.14) compared with Hoplias lacerdae (b = 0.81) and H. unitaeniatus (b = 0.66). This difference is mainly attributed to an increase surface area of individual secondary lamellae together with an increase in filament length and total number of secondary lamellae. The results indicate that the increased respiratory surface area of the H. malabaricus gill facilitates oxygen uptake in hypoxic environments as the fish grows and this suggests that gill dimensions may reflect ecological factors and not only respiratory requirements.
Comparison of food habits and of nutrients in the stomach contents of summer- and winter-trapped voles (Microtus pennsylvanicus)
Authors: Bergeron Jean-Marie , Jodoin Louise
Published: July 2008

Meadow voles (Microtus pennsylvanicus) have low fat reserves in winter. Since plant parts with high nutritive values are less abundant at this period, we hypothesize that voles must select different items or face a lower quality diet than during summer. Food habits determined from epidermal plant fragments of fecal matter showed that summer- and winter-trapped voles were using the same plant species though in somewhat different amounts. Nutritive constituents evaluated from stomach contents varied significantly by season. Stomach contents of winter-trapped voles had lower levels of protein and total phenolics and higher levels of total nonstructural carbohydrates. Forage quality ratios involving protein/total phenolics did not vary between seasons. These results suggest that overwintering voles of this study, trapped during low density, did not face obvious nutritive constraints. However, voles living under more crowded conditions could still face foraging constraints.
Cumulative pattern in pH change alters response to food in the crayfish Cambarus bartoni
Authors: Uiska Erin , Dunham David W. , Harvey Harold H.
Published: July 2008

In the relatively acid-tolerant crayfish Cambarus bartoni, locomotory response to food was tested (as delay in response, or latency) at both a circumneutral and a sublethal acid pH. Crayfish moved through a Y-maze toward a food source. Sequential tests were at pH 7.5, 4.5, and 7.5, and then again at pH 4.5 and 7.5. One group of 21 crayfish experienced a series of smaller pH shifts (7.5 to 6.5 to 5.5 to 4.5 at 5-day intervals), immediately followed by a larger pH shift (7.5 to 4.5). A second group of 20 crayfish experienced the large shift first, and then the series of smaller shifts. Both groups showed gradually decreasing latency through the first cycle, but then a large latency increase with the second shift to pH 4.5 (P < 0.005 and P < 0.03), and subsequent recovery at pH 7.5 by the first group (P < 0.006) but not the second (P < 0.32). This effect would seem to be due to the previous pH shift, which apparently exceeded their tolerance within our 45-day testing period. An initial tendency to approach the food (P < 0.01 and P < 0.12) became food avoidance (P < 0.01) and (or) no preference during either the first or second exposure to acidic pH.
Avoidance of a putative pheromone, 17α,20β-dihydroxy-4-pregnene-3-one, by precociously mature chinook salmon (Oncorhynchus tshawytscha)
Authors: Dittman Andrew H. , Quinn Thomas P.
Published: July 2008

To test the hypothesis that the gonadal steroid, 17α,20β-dihydroxy-4-pregnene-3-one (17α,20β-P) acts as a pheromone for mature male salmon, we examined the behavioral responses of precociously mature chinook salmon (Oncorhynchus tshawytscha) to this odorant. These males avoided water scented with 17α,20β-P in a two-choice maze. This avoidance response was not shown by immature chinook salmon of the same age or by mature males to a second steroid hormone, testosterone. Taken together, these results suggest that 17α,20β-P is a behaviorally relevant odorant for precociously mature male salmon. The avoidance response observed may reflect the sneaker spawning tactic employed by precociously mature fish, as attraction to the odorant was predicted for mature males in general.
Development of two methods to estimate body composition of bears
Authors: Farley Sean D. , Robbins Charles T.
Published: July 2008

The measurement of body composition in black bears (Ursus americanus), brown bears (U. arctos), and polar bears (U. maritimus) was investigated by means of isotopic water dilution and bioelectrical impedance analysis (BIA). The basic relationships between body lipid, water, protein, and ash were determined by direct chemical measurement of 13 black and 6 brown bears. Body water and lipid content as a percentage are highly correlated (r2 = 0.98, standard error of the estimate (SEE) = 1.1%) and inversely proportional. The dry, lipid-free mass averaged 83.5 ± 1.6% protein and 16.5 ± 1.6% ash. Either isotopic water dilution or BIA can be used to estimate body lipid content of healthy, uninjured bears (r2 = 0.93, SEE = 2.7% and r2 = 0.96, SEE = 2.2%, respectively). Isotopic water equilibrated with body water by 150 min. Abscesses and recent injuries (i.e., gunshot or snare wounds) produced erroneous body composition estimates when BIA was used, but only when the injury was in the conductor path between the BIA electrodes. Dilution estimates were not affected by injuries. Currently, neither method can be used on dead bears.
Life cycle and pathogenicity of Eimeria strakonicensis n.sp. (Apicomplexa: Eimeriidae) in experimentally infected common voles (Microtus arvalis)
Authors: Koudela B. , Vítovec J.
Published: July 2008

The oocysts of Eimeria strakonicensis n.sp. are described from the feces of the common vole, Microtus arvalis. Sporulated oocysts were broadly ellipsoidal and measured 28.3 × 25.2 μm. The oocyst wall was composed of a yellowish rough outer layer and colourless smooth inner layer. The sporulated oocysts contained a compact blackberry-like residuum. The sporocysts, with a small Stieda body, measured 11.5 × 9.5 μm. Sporulation was completed within 7 days at 20–23 °C. Endogenous development of E. strakonicensis was found to take place in the middle and posterior jejunum. Asexual development comprised two generations of meronts, which were seen at 3 and 4 days postinfection. The first fully developed macrogametes, microgametes, and oocysts were seen at 5 days postinfection. The prepatent period was 5 days and the patent period was 3–4 days. The pathological changes caused by E. strakonicensis consisted of villous atrophy, crypt hyperplasia, and inflammatory infiltration of the lamina propria of the middle and posterior jejunum. During the acute phase, the villous tips were eroded and numerous trophozoites of Spironucleus sp. and Giardia sp. and necrotic debris filled the cryptal and intestinal lumina.
Coexistence of fish and large Hesperodiaptomus species (Crustacea: Calanoida) in subalpine and alpine lakes
Authors: Donald David B. , Anderson R. Stewart , Mayhood David W.
Published: July 2008

In western Canada, the large diaptomids Hesperodiaptomus arcticus and (or) H. shoshone (> 2.5 mm) usually coexist with fish in large subalpine and alpine lakes located 1800 – 2455 m above sea level, but not in small lakes with area 2–16 ha and maximum depth 4–16 m. The char (Salvelinus) and trout (Oncorhynchus) species that inhabit these lakes are usually caught at depths of < 10 m and feed near shore. The profundal and offshore pelagic habitats of the large lakes provide a refuge from salmonid predation, permitting coexistence of large zooplankton and fish.
Regional and sexual differences in fluke pigmentation of humpback whales (Megaptera novaeangliae) from the North Atlantic Ocean
Authors: Allen Judith M. , Rosenbaum Howard C. , Katona Steven K. , Clapham Philip J. , Mattila David K.
Published: July 2008

The relative amount of pigmentation on the flukes of 3812 humpback whales from five feeding and three breeding regions in the western North Atlantic Ocean was ranked subjectively into categories 1 (white) through 5 (black). The distribution of rankings was examined to determine whether differences existed between regions or sexes. Fluke pigmentation differed significantly among whales photographed in the five northern feeding regions (Iceland, southwestern Greenland, Newfoundland (including the Labrador coast), the Gulf of St. Lawrence, and the Gulf of Maine). Whales photographed in the Gulf of Maine were characterized by a significantly higher proportion of dark-colored flukes than whales in all feeding regions except Iceland. Whales photographed near Greenland were characterized by significantly more light-colored flukes than other feeding regions. Fluke pigmentation also varied significantly among whales photographed in the three southern breeding regions (Virgin Bank, Puerto Rico, and the Dominican Republic). The flukes of whales photographed near Virgin Bank differed from those of whales near the Dominican Republic and included a higher proportion of light flukes. Fluke pigmentation of males and females differed significantly in the Gulf of Maine and in the Dominican Republic. Both areas showed higher proportions of dark-fluked females and light-fluked males. Sex bias differences in other regions were not examined because sample sizes were small. Fluke pigmentation of whales photographed only on the summer range did not differ significantly from the pigmentation of those photographed only on the winter range, supporting the belief that all northern feeding aggregations mix on the southern breeding grounds. Regional differences in fluke pigmentation suggest that the western North Atlantic humpback whale population includes a number of relatively isolated subunits, as suggested previously by photoidentification and DNA studies.
In vitro analysis of volume and pH regulation in the red blood cells of a primitive air-breathing fish, the bowfin, Amia calva
Authors: Tufts B. L. , Drever R. C. , Bagatto B. , Cameron B. A.
Published: July 2008

In the bowfin (Amia calva), a decrease in extracellular pH in vitro was associated with an increase in the water content and chloride concentration in the red blood cells that could be inhibited by the anion-exchange blocker, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS). After a step increase in CO2 tension, the extracellular total CO2 concentration was also significantly reduced by DIDS. Finally, over most of the experimental pH range, the red blood cell pH observed in the presence of DIDS was significantly elevated compared with that of controls. Taken together, these results indicate that as in most other fishes, chloride–bicarbonate exchange is clearly present and functional in bowfin red blood cells. Moreover, within the physiological pH range, ion movements across the anion exchanger have a marked influence on both the volume and the pH of bowfin red blood cells. In sharp contrast to the rainbow trout (Oncorhynchus mykiss), catecholamines had no effect on the volume, pH, or intracellular sodium concentration of red blood cells in the bowfin. Following osmotic swelling, rainbow trout red blood cells were able to regulate their volume back to control levels within 2 h. In the bowfin, however, there was no regulation of red blood cell volume after osmotic swelling. Thus, in contrast to many other fishes examined to date, it would appear that in the bowfin, the physiological mechanisms involved in the adrenergic response and in the regulatory volume decrease after osmotic swelling may be less active or possibly even absent in the red blood cells.
Geographic distribution of mitochondrial cytochrome b DNA haplotypes in New Zealand fur seals (Arctocephalus forsteri)
Authors: Lento Gina M. , Mattlin Robert H. , Chambers Geoffrey K. , Baker C. Scott
Published: July 2008

Nucleotides spanning 361 base pairs of the 5′ portion of the mitochondrial cytochrome b gene were sequenced from 16 New Zealand fur seals, Arctocephalus forsteri, representing seven rookeries in three different regions: the east and west coasts of New Zealand, and Western Australia. Five different mitochondrial haplotypes were observed in these novel sequence data for this species. The geographical distribution of the cytochrome b haplotypes was shown to be heterogeneous by three statistical tests. The major finding of this study is the difference between haplotypes found in fur seals from Western Australian rookeries and haplotypes found in fur seals from New Zealand rookeries. The nucleotide sequence difference found in pairwise comparisons among the surveyed individuals is in the range 0.3–0.8%. One individual showed an unexpectedly large sequence divergence (range 3.3–4.2%) from all other fur seals in this study. We compare alternative hypotheses that this individual is a descendant of an ancient maternal lineage which survived a population bottleneck, that New Zealand fur seals exhibit a rather large amount of genetic variability at this locus, or that this particular individual is a hybrid. Western Australian rookeries were extirpated as a result of sealing during the early 1800s. The geographic distribution of mitochondrial cytochrome b haplotypes suggests that the extirpated Australian rookeries were not recolonized by migrants from New Zealand. No genetic division between fur seal populations sampled from the east and west coasts of New Zealand is revealed using this region of the mitochondrial genome as a genetic marker, but we suggest that it should be possible to create a more discriminating test by examining a more variable DNA target such as the mitochondrial control region.
Genetic variability of the Cascade mantled ground squirrel (Spermophilus saturates) in British Columbia
Authors: Leung Maria C.-Y. , Cheng Kimberly M.
Published: July 2008

The rare Cascade mantled ground squirrel (Spermophilus saturatus) occurs only in southwestern British Columbia, Canada, and Washington State, U.S.A. Genetic variation in the British Columbia population was assessed using allele frequencies of blood enzymes encoded by a total of 24 presumptive gene loci. All 24 loci were fixed for the same alleles in 48 specimens of S. saturatus collected, but 8 of these 24 loci were segregating in 46 specimens from neighbouring S. lateralis populations examined. The apparent genetic uniformity of S. saturatus may be due to founder effects because of recent northern extensions of the range of the species. In S. saturatus, two loci were fixed for alleles that were absent in S. lateralis.
Use of faeces for scent marking in Iberian wolves (Canis lupus)
Authors: Vilà C. , Urios V. , Castroviejo J.
Published: July 2008

The study of the characteristics of 232 wolf (Canis lupus) scats from northwestern Spain reveals that faeces were not left at random. They accumulated near trail junctions, where the probability of interception by other traveling wolves is maximal, and were commonly associated with evident reference points (i.e., ashes, decaying bark, isolated shrubs, carrion, promontories, etc.) that may visually or olfactorily increase the signal's effectiveness. The center of the trail was clearly preferred to the borders, facilitating location of the scat by other individuals. If one side of the trail was more exposed to the wind, scats accumulated more on that side than on the other, and their deposition on the trail margin may increase the radius of their influence even more. These results suggest that faeces may be more important for spacing among Iberian wolves than expected, considering the minor role assigned to the scats in most previous studies of wolf scent marking.
Identification of larvae: the zebra mussel (Dreissena polymorpha), quagga mussel (Dreissena rosteriformis bugensis), and Asian clam (Corbicula fluminea)
Authors: Nichols S. J. , Black M. G.
Published: July 2008

There are presently four freshwater bivalves in the United States that produce larvae or veligers commonly found in the water column: two forms of Asian clams and two species of dreissenids. Portions of the geographic range of three of these bivalves, one species of Asian clam (Corbicula fluminea), zebra mussels (Dreissena polymorpha), and quagga mussels (Dreissena rosteriformis bugensis), overlap, causing problems with larval identification. To determine which characteristics can be used to separate larval forms, adult Asian clams, quaggas, and zebra mussels were brought into the laboratory and induced to spawn, and the resulting larvae were reared. Hybrids between quaggas and zebra mussels were also produced, but not reared to maturity. Characteristics allowing for the most rapid and accurate separation of larvae were hinge length, shell length/height, shell shape, shell size, and the presence or absence of a foot and velum. These characteristics were observed in laboratory-reared larvae of known parentage and field-caught larvae of unknown parentage. In most cases, larvae of the Asian clam can be readily separated from those produced by either type of dreissenid on the basis of shell size and presence of a foot. Separating the gametes and embryos of the two types of dreissenids is not possible, but after shell formation, most of the larval stages can be distinguished. Hinge length, shell length/height, and the similarity in size of the shell valves can be used to separate straight-hinged, umbonal, pediveliger, and plantigrade larvae. Quagga × zebra mussel hybrids show characteristics of both parents and are difficult to identify.
The relationship between responsiveness and elusiveness of heat-shocked goldfish (Carassius auratus) to attacks by rainbow trout (Oncorhynchus mykiss)
Authors: Webb Paul W. , Zhang Hongbao
Published: July 2008

We measured reaction distance, escape velocity, and the apparent looming threshold (ALT) of heat-shocked goldfish (Carassius auratus) attacked by trout (Oncorhynchus mykiss). We tested fish at the acclimation temperature of 15 °C after heat-shocking prey for 2 min at temperatures ranging from 34 to 39 °C. Escape speeds were unaffected by heat shock. Reaction distance decreased from about 21 cm for fish shocked at 35 °C to about 6 cm for those shocked at 39 °C. ALT increased from 0.2 rad∙s−1 for controls to 0.4 rad∙s−1 for goldfish heat-shocked at 39 °C. The elusiveness of prey, E, was measured as the number of attacks required per prey capture. E was related to ALT as: E = 1.29 (±0.47)∙ALT−0.82(±0.25) (mean (±2 SE)). Factors that decrease responsiveness of prey have large effects on the ability of prey to avoid predators.
The milliped family Nearctodesmidae in northwestern North America, with accounts of Sakophallus and S. simplex Chamberlin (Polydesmida)
Authors: Shelley Rowland M.
Published: July 2008

In northwestern North America, the milliped family Nearctodesmidae is comprised of four genera, Nearctodesmus Silvestri, Kepolydesmus Chamberlin, Ergodesmus Chamberlin, and Bistolodesmus, new genus, and six species, N. insulans (Chamberlin), N. cerasinus (Wood), N. salix Chamberlin, K. anderisus Chamberlin, E. compactus Chamberlin, and B. bonikus (Chamberlin). These species occur along the Pacific coast from San Francisco Bay to Prince Rupert, British Columbia, including all offshore island groups, with an eastward extension into Lewis and Clark County, Montana, east of the Continental Divide. An allopatric population of N. insulanus occurs in the Shuswap Highlands of British Columbia, and an allopatric species, E. remingtoni (Hoffman), inhabits caves in western and southern Illinois. The principal taxonomic characters are the number of secondary projections from the gonopodal telopodite, the configuration of the longer of these, and the length and configuration of the distal zone of the acropodite. Polydesmus bonikus is a nearctodesmid and is assigned to the new genus, Bistolodesmus. The following new synonymies are proposed: Jaliscodesmus Hoffman under Sakophallus Chamberlin; J. alticola Hoffman under S. simplex Chamberlin; N. brunnior, N. campicolens, and N. malkini, all by Chamberlin, under N. cerasinus; N. amissus, N. pseustes, N. renigens, N. carli, and N. boydi, all by Chamberlin, and N. olympus and N. cochlearius, both by Causey, under N. insulanus; K. mimus, K. hesperus, and K. pungo, all by Chamberlin, under K. anderisus; and Ectopodesmus cristatus and E. c. dentatus, both by Loomis and Schmitt, under Ergodesmus compactus. Modern diagnoses and illustrations are presented for the family and all northwestern taxa, along with keys to the genera and species of Nearctodesmus. Accounts and gonopod drawings are also presented of Sakophallus and S. simplex Chamberlin in Michoacan and Jalisco, Mexico.
The costs of raising nidifugous offspring: brood rearing by giant Canada geese (Branta canadensis maxima)
Authors: Seddon Laura M. , Nudds Thomas D.
Published: July 2008

Competing hypotheses that have been advanced to explain the phenomenon of posthatch brood mixing by waterfowl can be distinguished by whether they assume that adults experience costs in rearing nidifugous offspring. To test this, time budget data were collected for giant Canada geese (Branta canadensis maxima) at Cambridge, Ontario, in 1990. Breeding adults with broods devoted more time to vigilance (p = 0.001) and less time to feeding (p = 0.001) than adults that hatched clutches but were without broods, suggesting a cost to rearing nidifugous young. However, as goslings matured, parents allocated less time to vigilance (p < 0.001) and more time to locomotion (p = 0.005), and time spent feeding did not change (p = 0.336). In addition, brood size did not affect the time parents allocated to vigilance (p = 0.543) or feeding (p = 0.727), suggesting that caring for additional young has negligible effects on parents. Goslings were selective about the adult with which they associated (they were positioned closer to females than to males), but neither brood size nor brood age affected the feeding time of goslings (p = 0.94 and 0.76, respectively) or time spent vigilant (p = 0.22 and 0.69, respectively), suggesting that goslings gained no obvious advantage from greater foraging opportunities or better predator detection by congregating in larger broods.
Effects of parasitic infections on clutch size of lesser snow geese from a northern breeding colony
Authors: Clinchy Michael , Barker Ian K.
Published: July 2008

A density-dependent decline in the average clutch size of lesser snow geese (Anser caerulescens caerulescens) occurred from 1973 to 1989 at the breeding colony on the shores of La Pérouse Bay, Manitoba. An increase in average parasite load was hypothesized to be one of the two most likely causes of this decline. We shot 28 incubating adult female lesser snow geese at the La Pérouse Bay colony and examined the carcasses for parasites to determine if there was any proximate association between parasitic infections and the size of the clutch a female laid. We found no convincing evidence that parasitic infections were the proximate cause of any reduction in clutch size. In the absence of evidence of any direct effect of parasites, we conclude that an increase in the average parasite load is probably not the cause of the long-term decline in clutch size at La Pérouse Bay. By default, we suggest that increased intraspecific competition for food at the staging areas on the migratory flyway is the most likely cause of the decline in clutch size.
Un indice de préférence normalisé pour la mesure des choix alimentaires individuels
Authors: Desportes Jean-Pierre , Gallo Alain , Cézilly Frank
Published: July 2008

Standardized indices (I) have been created to determine and analyze individual food preferences in choice tests between A types of food presented in the form of N items entirely consumable within the course of one test. For each food type, I represents the ratio between the cumulative area under the curve of the proportion of items consumed as a function of the order in which are consumed the A∙N items, and the sum of the areas for all A items. I varies from 0 (for food in which no item is consumed) to 1 (for food items consumed exclusively); I = 1A for A types of food for which there is no preference; the sum of all indices (I) for all A foods equals 1 in all tests. These standardized indices have been used in tests on Barbary doves (Streptopelia risoria) to study intra-individual coherence and interindividual correspondance in reference to preferences for canary grass (Phalaris canariensis L.), oats (Avena sativa L.), wheat (Triticum vulgare Vill.), hemp (Cannabis sativa L.), and millet (Panicum miliaceum L.).[Translated by the Journal]
Tag loss in grey seals (Halichoerus grypus) and potential effects on population estimates
Authors: Stobo Wayne T. , Horne John K.
Published: July 2008

Cumulative tag loss among 4064 grey seal (Halichoerus grypus) pups observed on Sable Island was less than 1% during the first 5 months of life, 13% by the end of the first year, and continued to increase with age. Cumulative tag loss among grey seals aged 6 and older was over 40.0%. A double-tagging study indicated that pre-punching of flippers, the colour of tags applied, and application to the left or right flipper significantly affected tag loss. The addition of a flag to the tag had no significant effect. A comparison of scientific observations of tag loss with commercial bounty return data indicated that casual observers probably missed tags on double-tagged animals. Overlooked tags in single-tagging experiments result in population overestimates. In double-tagging experiments, overlooked tags result in correction factor overestimates and population underestimates. Age-specific tag loss correction factors should be used if population estimates include more than one age group.
New insight on survivorship of female chamois (Rupicapra rupicapra) from observation of marked animals
Authors: Loison A. , Gaillard J. M. , Houssin H.
Published: July 2008

A population of about 1500 chamois (Rupicapra rupicapra) was monitored in the French Alps between 1985 and 1991 by observing individually marked animals. Data on resighting of marked females were analyzed using capture–recapture models. Resighting probabilities were time dependent and survival rates were age dependent. The annual survival rate was low in juveniles (0.58) and high in adults (0.96). Maturing animals (1.5–3.5 years old) had lower survival rates (0.91) than adults. Older age-classes exhibited no significant decline in survival rates. Survival patterns are compared with those from a previous study in New Zealand, and biological and methodological differences between the two studies are discussed.
Diving behavior in relation to ambient water temperature in northern elephant seals
Authors: Hakoyama Hiroshi , Boeuf Burney J. Le , Naito Yasuhiko , Sakamoto Wataru
Published: July 2008

Our aim was to describe changes in ambient water temperature during the course of migration by northern elephant seals (Mirounga angustirostris) and to examine evidence for the seal using abrupt temperature gradients for locating prey. During migration in the post breeding season, the diving patterns of 10 adult females and 7 breeding-age males from Año Nuevo, California, were recorded with time–depth recorders in 1989–1991. Recorded sea surface temperatures declined from 11–13 °C to a low of 3–9 °C as the seals moved north and increased as they returned. Depth of diving was not closely linked to sharp thermal gradients. A thermocline was evident only at the beginning and end of the migration in less than 100 m of water, where less than 2% of diving takes place. There were sex differences in the temperature range at the depths where 75% of diving and foraging occurred, owing in part to habitat separation. The temperatures were lower and the range narrower for females (4.2–5.2 °C at 388–622 m) than for males (5.3–6.0 °C at 179–439 m). We conclude that the northern elephant seal habitat does not provide abrupt changes in temperature that might serve as important cues for locating prey.
A review of the classification and distribution of five opalinids from Africa and North America
Authors: Affa'a Felix-Marie , Lynn Denis H.
Published: July 2008

Five multinucleate opalinids from Canada and Cameroon, Africa, commensal in anuran amphibians, are redescribed. The relative size of the falx and the presence or absence of a posterior zone of convergence of kineties in silver-impregnated specimens support three new combinations: Cepedea sudafricana (Fantham, 1923), Cepedea virguloidea (Metcalf, 1923), and Cepedea obtrigonoidea (Metcalf, 1923). These new combinations suggest that Cepedea may be a much more common genus in the Nearctic region than was previously realized.