bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal succession and spatial–temporal distribution patterns of six larval cytospecies of the Simulium venustum/verecundum complex (Diptera: Simuliidae)
Authors: McCreadie John W. , Colbo Murray H.
Published: July 2008

The seasonal succession of S. venustum/verecundum cytospecies found in both sublacustrine and downstream habitats on the Avalon Peninsula, Newfoundland, was investigated. EFG/C venustum (= Simulium truncatum Lundström) appeared 1–5 weeks earlier than other cytospecies. ACD verecundum (= S. rostratum Lundström) and AA verecundum usually appeared later and remained in streams longer than EFG/C, AC(gb) venustum, CC2 venustum, or CC3 venustum. Seasonal occurrence of sympatric cytospecies often overlapped, though development was typically staggered and population peaks were asynchronous. EFG/C, and probably CC3, are univoltine in Newfoundland. AC(gb) may have a second generation at a few sites. CC2 has two or more generations per year in Newfoundland, though generation number varied among sites. ACD and AA are multivoltine. Proportionally more ACD and AA were found on vegetation than on rocks, whereas the reverse was true for EFG/C. As well, the density of a mixed ACD–AA population was usually higher on vegetation than on rocks. Cytospecies composition at sublacustrine sites was different from sites farther downstream. The results of the present investigation were also combined with those of a previous study on spatial distribution to construct spatial–temporal ecological profiles for four cytospecies (EFG/C, AC(gb), ACD, AA). Each cytospecies showed a distinct profile.
Prey selectivity of wolves in Banff National Park. I. Prey species
Authors: Huggard David J.
Published: July 2008

I examined the components generating selectivity in wolves preying on five ungulate species in Banff National Park, Alberta. Overall selectivity for elk and deer species, and apparent avoidance of bighorn sheep and mountain goats, were due primarily to lower habitat overlap of wolves with the latter two species, and therefore lower encounter rates. For social ungulates, I argue that the herd should be considered the unit of encounter, with encounter rates proportional to the number of herds rather than the number of individuals. However, large herds predictably associated with certain areas may be visited intentionally by wolves, increasing effective encounter rates. Foraging theory suggests that all ungulate prey should be equally profitable to wolves upon encounter and therefore the factors affecting encounter rates are critical in determining prey selectivity. A simple model incorporating different habitat overlap, herd sizes, and predictable herds predicts qualitatively different functional responses of wolves to changes in density of the different prey types. The model also demonstrates how apparent selectivity for a prey type can result from the different ways in which prey are encountered.
Prey selectivity of wolves in Banff National Park. II. Age, sex, and condition of elk
Authors: Huggard David J.
Published: July 2008

Wolf predation on elk was studied in Banff National Park, Alberta. Overall, wolves took a higher proportion of adult males and calves than occurred in the population. However, wolves encounter elk as herds rather than individuals, and when the herd is considered to be the unit of available prey, calves are highly selected for compared with both adult males and females. Adult elk killed by wolves were older than those killed on the road or railway, but a simple model showed that this result can be caused by a bias in obtaining the population age distribution from a mortality source. Jaw lengths and antler characteristics of wolf kills did not differ from those of road and rail kills. Adult elk, but not calves, killed by wolves had lower reserves of marrow fat than elk killed on the road and railway.
The milliped genus Underwoodia (Chordeumatida: Caseyidae)
Authors: Shelley Rowland M.
Published: July 2008

The milliped genus Underwoodia comprises three species that are characterized primarily by the configurations of branches a and c of the anterior gonopod colpocoxites and the degree to which the latter is segregated from process b. Underwoodia iuloides ranges across Canada from Newfoundland to Saskatchewan, extending southward in the United States to New York, Michigan, Wisconsin, North Dakota, and northeastern New Mexico. Underwoodia tida Chamberlin, whose questionable referral to this genus is confirmed, ranges from the Rocky Mountains of Alberta to the Wasatch and Oquirrh Mountains of northern Utah, and probably extends westward to the Coast Range of British Columbia and the Alaska panhandle. Underwoodia hespera Chamberlin is placed in synonymy under this species. Underwoodia kurtschevae Golovatch occurs in east Asia, being known from Sakhalin Island, the Kurile Islands, and mainland sites in the Russian Far East. The genus is thus Holarctic and demonstrates a clear trans-Beringian distribution pattern. Parthenogenesis appears to be an autapotypy, as females greatly outnumber males in all three races.
The kinematics and performance of escape responses of the knifefish Xenomystus nigri
Authors: Kasapi M. A. , Domenici P. , Blake R. W. , Harper D.
Published: July 2008

The kinematics and performance of the escape responses of the knifefish Xenomystus nigri, a fish specialized for low-speed, undulatory median-fin propulsion, were recorded by means of high-speed cinematography. Two types of escape were observed, one involving the formation of a C-shape along the longitudinal axis of the fish (stage 1), followed by a slow recoil of the body (single bend); the other (double bend) involved stage 1 followed by a contralateral bend (stage 2). The pectoral fins were extended throughout escapes of both types. The average maximum acceleration for double bend escapes was 127.98 m∙s−2; acceleration was usually greatest in stage 1. In double bend escapes, turning angles for stages 1 and 2 were not correlated. Pitch and roll orientations change during escapes. In stage 1, the average roll and average pitch were linearly correlated, suggesting that roll was partly responsible for establishing pitch. Knifefish achieved high maximum acceleration relative to other fish. Therefore, performance was not compromised by morphological specialization for low-speed swimming; however, a negative correlation of pitch with acceleration in stage 1 suggested that escapes involve a trade-off between acceleration and confusing a predator by changing planar orientation.
Spatial distribution and microhabitat use in the five-lined skink (Eumeces fasciatus)
Authors: Seburn Carolyn N. L.
Published: July 2008

Patterns of spatial distribution and microhabitat use in Eumeces fasciatus were examined in a population at Point Pelee National Park, Canada. Each individual was uniquely marked and classified as adult male, adult female, yearling, or hatchling. In each census the location of individuals was recorded. At each microsite, I measured thickness and surface area of cover, degree of shading, and distance to nearest neighbouring microsite.Significant aggregation was found among individuals within age and sex classes. Males and females associated significantly during the breeding season but not at other times. The number of captures made at a microsite was positively correlated with cover surface area and negatively correlated with cover thickness. Nest sites were the most used subset of all sites at which individuals were captured. Evidence was found to suggest that some females shift home range, once prior to oviposition, and again after hatching of eggs. Males demonstrated reduced activity after oviposition and may aestivate.
Reciprocal hybridization between white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) in western Canada: evidence from serum albumin and mtDNA sequences
Authors: Hughes Glenys A. , Carr Steven M.
Published: July 2008

The extent and direction of hybridization between white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) in western Canada were investigated by two genetic approaches, protein electrophoresis and DNA sequencing. Species-specific allelic variants at the serum albumin locus were examined for 25 white-tailed deer and 30 mule deer from 24 localities. The two species were essentially fixed for alternate alleles; one mule deer was heterozygous. The polymerase chain reaction was used to amplify a 359 base-pair portion of the mitochondrial cytochrome b gene from these same animals. DNA sequencing revealed 10 variable nucleotide positions that define nine mtDNA sequence genotypes. Two deer were anomalous. The mule deer that was an albumin heterozygote had an mtDNA genotype otherwise confined to the white-tailed deer. This suggests that the animal has a white-tailed female and a mule deer male as ancestors. One white-tailed deer, which had the expected albumin genotype, had a sequence genotype that is otherwise found only in O. hemionus elsewhere in North America. This animal appears to be a backcross or later generation hybrid. Hybridization between deer species in western Canada has resulted in a low level of reciprocal genetic introgression.
Colonization patterns and life-history dynamics of Culex mosquitoes in artificial ponds of different character
Authors: Williams D. Dudley , Tavares-Cromar Annette , Kushner Donn J. , Coleman John R.
Published: July 2008

The relationship between the biology and habitat of larval mosquitoes was studied in a series of artificial ponds of differing characteristics established across a terrestrial vegetation gradient from open fields to deep woods. The ponds were uniformly colonized by two widespread species of Culex, both characteristic of small bodies of water, including artificial, "container" habitats. First-instar larvae of Culex restuans were found within 2 days of filling the ponds with water and four or five generations were produced from May until the end of September. One very long generation occurred in July, which corresponded to maximum larval densities. Overall, there was a strong relationship between larval development time of C. restuans and larval density. A few larvae of Culex pipiens pipiens occurred sporadically throughout the summer, but numbers did not increase until C. restuans populations began to wane in late July. Thereafter two, or possibly three, generations were produced into the autumn. The patterns of colonization, synchrony of life history, and growth of these two species were remarkably consistent amongst the ponds, despite considerable variation in both their physical and biological environments (e.g., over the 2 years of study, conductivity ranged from 20 to 890 μS, pH from 6.4 to 10.7, dissolved oxygen from 0 to 13.5 ppm, and water temperature from 5 to 29.8 °C). Density of C. restuans was related to water temperature and pH at the "open" site and to water temperature, dissolved oxygen, percent algae, and percent detritus at the "edge of the woods" site. At the "deep woods" site, larval numbers were related to temperature, pH, conductivity, and dissolved oxygen. At both the edge and deep wood sites, larval development time of C. restuans increased with mean water temperature to 20 °C. Above this temperature, larval development time tended to decrease.
The proximate basis of inter- and intra-population variation in female plumage coloration in the House Finch
Authors: Hill Geoffrey E.
Published: July 2008

As in many sexually dichromatic species in which males are brightly colored, female House Finches (Carpodacus mexicanus) show a subdued expression of the same coloration as males. I quantified the carotenoid plumage coloration of females from the subspecies C. m. frontalis in Michigan, New York, Hawaii Island, and two sites in California, and from the subspecies C. m. griscomi in Guerrero, Mexico. The proportion of females with detectable carotenoid pigmentation differed significantly among populations, as did the median plumage brightness of colorful females. In Michigan, but not California, yearling females tended to be more colorful than older females. Among C. m. frontalis populations, there was a significant positive correlation between the plumage brightness of females and males, but in the C. m. griscomi population males were brightly colored while females were drab. In aviary experiments, females of all ages and from all populations converged on a similar plumage brightness after molt when fed a common diet. Moreover, females from all populations showed maximum color expression when provided with abundant red carotenoid pigments. These observations suggest that local and regional variation in the plumage brightness of females reflects local and regional variation in the availability of dietary carotenoid pigments and that female House Finches do not actively forage for carotenoids.
Specificity of tannin-binding salivary proteins relative to diet selection by mammals
Authors: Hagerman Ann E. , Robbins Charles T.
Published: July 2008

The tannin-binding specificity of salivary proteins in several mammals was investigated as a possible explanation for observed food habits. Moose (Alces alces) and beaver (Castor canadensis) produce salivary proteins that only bind the linear condensed tannins common in their preferred foods, such as willow, aspen, or birch. The mule deer (Odocoileus hemionus), which has a more generalized diet, produces salivary proteins that bind linear and branched-chain condensed tannins and gallotannins, but not an ellagitannin. The omnivorous black bear (Ursus americanus) produces salivary proteins that bind all types of tannins. In feeding trials beaver and mule deer were fed tannins that were not bound by salivary tannin-binding proteins in the in vitro assays. The results confirmed that these tannins reduce digestibility more than tannins that are bound by salivary proteins. Thus, salivary tannin-binding proteins are not always generalized scavengers of dietary tannins, but can be very specific for the types of tannins that are consumed in the preferred diet. The diversity of tannin chemistry and the specificity of salivary tannin-binding proteins must be considered in optimal foraging studies and in cost-benefit models of herbivore diet selection.
Movements and biological statistics of lake sturgeon (Acipenser fulvescens) populations from the St. Lawrence and Ottawa River system, Quebec
Authors: Fortin Réjean , Mongeau Jean-René , Desjardins Gilles , Dumont Pierre
Published: July 2008

Our objective was to compare movements and biological statistics of lake sturgeon (Acipenser fulvescens) populations from two fluvial lakes on the St. Lawrence River, Lac Saint-Louis and Lac Saint-Pierre, which are main commercial fishing sectors, and from Lac des Deux Montagnes on the Ottawa River. Sturgeon can move freely among these three lakes. Lac des Deux Montagnes sturgeon differ from the other groups by their higher degree of sedentariness, slower growth, and lower condition factor. Lac Saint-Louis and Lac Saint-Pierre sturgeon are also sedentary, but some movement between the two lakes was observed. Sturgeon tagged on the Rivière des Prairies and Rivière L'Assomption spawning grounds, located in the central part of the study area, and also on pre- and post-spawning concentration sites, were recaptured throughout the St. Lawrence River, from Lac Saint-Louis to Lac Saint-Pierre. Length, weight, and age composition of the commercial catch, growth, and total mortality varied between Lac Saint-Louis and Lac Saint-Pierre. Higher commercial exploitation rates in the latter could be responsible for some differences. The management implications of these results are discussed.
Space use and the social system of muskrats
Authors: Marinelli Lui , Messier François
Published: July 2008

We investigated the space-use patterns of adult muskrats in a small (77 ha) marsh on the Canadian Prairies during two breeding seasons. During the study, population size was relatively low and the adult sex ratio was biased towards females. Adult muskrats were territorial with little intrasexual home-range overlap. The exclusivity of home ranges was maintained throughout the breeding season, and appeared to decrease at the end of the season. Male movements often extended over the territory of more than one female, but the overlap was more extensive with primary than with secondary females. Lactation appeared to reduce the space use and mobility of female muskrats. Male muskrats tended to range over smaller areas when weaned young were present within their home range. The results suggest that the sexual pair is the basic social unit of muskrats but that polygyny was common. A female-biased sex ratio appeared to be responsible for the tendency of males to mate polygynously during this study, thus illustrating the plasticity of this social system.
A taxonomic reevaluation of North American Daphnia (Crustacea: Cladocera). I. The D. similis complex
Authors: Hebert Paul D. N. , Finston Terrie L.
Published: July 2008

Allozyme analysis of 28 populations of Daphnia similis s.l. from the western United States and Canada indicated the presence of three different species. One taxon, D. salina, is newly described and a second species, D. exilis, previously synonymized with D. similis, is also shown to be distinct. Species recognition is not solely reliant on allozyme analysis, as morphological differences among the species are conspicuous. Daphnia salina is a halophile, while the other two species occur in habitats of lower but variable salinity. All three taxa appear to reproduce by cyclic parthenogenesis, although levels of genetic diversity were so low in D. salina that determination of its breeding system was tentative. Genetic distance analysis suggested that D. salina diverged from the other two species some 27 million years ago, whereas D. exilis and D. similis separated 9 million years ago.
Mineral content and wildlife use of soil licks in southwestern Nepal
Authors: Moe Stein R.
Published: July 2008

Twelve species of mammals were recorded at mineral licks during the dry season in lowland Nepal. When analyzed for extractable phosphorus, potassium, magnesium, calcium, sodium, and sulphur concentrations and pH, only sodium concentration and pH were significantly higher than in control soil samples taken in both sal forest (Shorea robusta), in which all the licks were found, and adjacent riverine forest and grassland habitats. The axis deer (Axis axis) and common langur (Presbytis entellus) were the most common species on the licks. Axis deer used the licks intensively in January, just after grass sprouting, while most common langurs were recorded in March, after flushing of browse species. Sodium appeared to be the main element sought at the licks, based on both concentration differences between licks and controls and the significant relationship between axis deer use and the sodium content of the lick.
Fraseroscyphus sinuosus n.gen. (Cnidaria, Hydrozoa, Leptomedusae, Sertulariidae), an epiphytic hydroid with a specialised clinging organ
Authors: Boero F. , Bouillon J.
Published: July 2008

Fraseroscyphus, a newly proposed genus of the family Sertulariidae, is characterized by having gonothecae arising from hydrothecae. It is founded for the single species originally described as Sertularella sinuosa, a hydroid known from California. A previously undescribed specialised clinging organ allows this species to colonise coralline algae growing adjacent to colonised thalli.
High-latitude-area composition of humpback whale competitive groups in Samana Bay: further evidence for panmixis in the North Atlantic population
Authors: Clapham Phillip J. , Mattila David K. , Palsbøll Per J.
Published: July 2008

Competitive groups of humpback whales, Megaptera novaeangliae, were observed in Samana Bay, Dominican Republic, West Indies. Photographs of ventral fluke patterns were used to identify individuals, and skin biopsies were taken for molecular determination of sex. Nine groups contained two or more whales previously identified from different high-latitude areas. In seven groups, males from different feeding grounds were observed to compete with each other, and in six cases the group's female was from a different area than at least one of her male escorts. These results provide further support for the hypothesis that the western North Atlantic population of this species can be considered a single panmictic unit.
Transit time of digesta in captive harbour seals (Phoca vitulina)
Authors: Markussen Nina Hedlund
Published: July 2008

Stomach-content analysis can be used to identify the species and size of prey fishes eaten by marine mammals, and has been used for both qualitative and quantitative estimates of their food requirements. Methods that use mass or volume to determine the amount of fish eaten depend on the degree of digestion and the time required for the stomach to empty. The transit time of digesta was estimated by recording the initial defecation time and the time required for the stomach to empty in four harbour seals (Phoca vitulina). The seals were given meals varying in size from 0.5 to 2.1 kg and in caloric content from 4940 to 12 770 kJ/kg, and containing carmine or barium sulphate as a marker. The time from eating until red faeces were observed was between 2 h 35 min and 6 h 15 min. Also, barium sulphate was injected into the food given, and X-rays were used to estimate the time required for the stomach to empty. The stomach started to empty less than 1 h after the meal. Some prey remained in the stomach 5 h after eating.
Variations in courtship activity among male blue grouse: do some males breed more than others?
Authors: Hervieux David P. , Zwickel Fred C. , Lewis Richard A.
Published: July 2008

We developed a primary feather wear index (WI) for blue grouse (Dendragapus obscurus) to examine variations in courtship activity among males. Three percent of 276 yearling males, and less than 1% of 144 yearling and adult females examined throughout spring and summer showed evidence of such wear. Among 630 adult males, 48% exhibited "courtship wear." Mean courtship wear among males 2 years old and older increased steadily throughout the spring and summer, generally paralleling what would be predicted from cumulative reproductive activity. However, there was much variation among males, ranging from no wear to heavy wear, even by late summer. These data are consistent with earlier suggestions that breeding may be skewed among male blue grouse, as in lek-breeding tetraonines. Limited samples indicate that primary feather wear was not related to the age of males (more than 1 year old) or their occupancy of persistent or transient territorial sites.
The reproductive success of tree swallows nesting near experimentally acidified lakes in northwestern Ontario
Authors: St. Louis Vincent L. , Barlow Jon C.
Published: July 2008

We examined a number of reproductive parameters of tree swallows (Tachycineta bicolor) breeding near experimentally acidified lakes in northwestern Ontario. We found that near acidified lakes, eggs were smaller in certain dimensions, hatching success was lower (and by definition fewer nestlings fledged per nest box), certain nestling body characters were smaller 4 days posthatch, nestling wing length was shorter near time of fledging, and growth functions were different from those near unmanipulated reference lakes. These results are consistent with earlier findings that calcium-rich food items needed for egg production by laying females and growth of nestlings are more scarce at acidified lakes than at nonacidic reference lakes, and that potentially toxic metals accumulate to higher concentrations both in the chironomids that swallows consume and in nestling swallows at acidified lakes. Our results clearly show that even nonaquatic organisms are affected by acidification of freshwater ecosystems.
Nest site selection and cost of nest building by Cliff Swallows (Hirundo pyrrhonota)
Authors: Gauthier Marc , Thomas Donald W.
Published: July 2008

We studied the amount of energy and time required for the construction of nests by Cliff Swallows (Hirundo pyrrhonota) and examined whether swallows select sites that minimize their energy and time investment. Cliff Swallows build nests that may be detached (sharing no walls with neighbours at the time of initiation), semidetached (sharing one wall), or row nests (sharing two walls). Detached nests weigh 13.9% more than row nests (652.8 vs. 573.1 g, respectively), require 97.2 km more commuting (797.7 vs. 700.5 km), and cost 0.91 kJ/individual more during each day of construction (daily investment 7.49 vs. 6.58 kJ/individual). When building nests, swallows commuted from 50 to 320 m to mud sources and they increased their flight speeds as commuting distances increased. This limited the time required for nest construction while increasing the energy cost. Swallows showed a preference for sites where they could build attached nests and we argue that they act to minimize their time investment.
Factors affecting egg viability and incubation time in prairie dabbling ducks
Authors: Arnold Todd W.
Published: July 2008

I determined hatching success for 328 dabbling duck (Anas spp.) eggs that were experimentally subjected to varying lengths of preincubation delay and then artificially incubated. Hatchability declined as unincubated eggs were exposed to longer preincubation delays. This effect was more pronounced at higher ambient temperatures and later in the nesting season, but did not vary with egg size or among duck species. These results are largely consistent with observed patterns of clutch-size variation among prairie-nesting waterfowl. Clutch size may be smaller later in the year and at lower latitudes owing to the negative effects of date and temperature on the ability of eggs to withstand preincubation delay. The timing of embryo mortality was bimodal, with peaks occurring during early development (<6 d) and just before hatching (>22 d); however, only early mortality was affected by preincubation delay. Eggs lost up to 2.6% of their initial mass as water vapor during preincubation delay, but the amount of water loss did not affect hatching success. Eggs subjected to preincubation delay required about 1 additional day to hatch. Incubation time was related to egg size in northern shovelers (Anas clypeata) and in all species combined, but not in blue-winged teal (Anas discors) or mallards (Anasplatyrhynchos). These data provide only weak support for the hypothesis that large eggs are costly because they take longer to hatch.
The milliped genus Isaphe Cook (Polydesmida: Xystodesmidae)
Authors: Shelley Rowland M.
Published: July 2008

The harpaphine xystodesmid milliped genus Isaphe, characterized by two telopodal branches and a prefemoral process that angles across the medial face of the telopodite, comprises two species. Isaphe convexa Cook occurs in montane forests of northern Idaho and Montana, and I. tersa (Cook) is known from riparian woodlands in canyons of the Snake, Salmon, and Palouse river basins in southeastern Washington and west-central Idaho. They are distinguished by the degree of dorsal convexity, strong in I. convexa and weak in I. tersa, and by the length of the prefemoral process, which is long and slender and extends well beyond the caudal margin of the telopodite stem in I. convexa, and is short and broad and terminates well before the margin in I. tersa. The strong convexity in I. convexa results from greater expression of the dorsal curvature than is the case in most xystodesmids because of a lower than usual origin of the paranota, rather than from depression of the latter. The following new synonymies are proposed: Hybaphe Cook under Isaphe Cook, H. curtipes Cook under I. tersa, and Leptodesmus (Isaphe) simplex Chamberlin under Harpaphe haydeniana haydeniana (Wood). Modern descriptions are provided for the genus and species, and anatomical illustrations and a distribution map are presented.
Effects of two juvenile hormone analogs on hemolymph and fat-body metabolites of the eastern spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae)
Authors: Mulye Hemendra , Gordon Roger
Published: July 2008

Early sixth instar larvae of Choristoneura fumiferana were treated with LD50 doses of the juvenile hormone analogs fenoxycarb and methoprene. Fenoxycarb caused an initial decrease, then an increase, in hemolymph carbohydrate concentration; fat-body glycogen was depleted initially, then increased in concentration (cf. controls) toward the end of the 6-day experimental period. Methoprene caused an opposite effect on hemolymph carbohydrates, but a similar effect (cf. fenoxycarb) on fat-body glycogen. Protein concentrations in the hemolymph of fenoxycarb-treated and methoprene-treated insects were lower than those of controls. The concentration of fat-body soluble protein of fenoxycarb-treated insects was initially lower, then higher, than that of controls. Methoprene did not alter soluble protein levels in the fat bodies. Lipids in the hemolymph of fenoxycarb-treated insects were depleted (cf. controls) throughout the experimental period; in the fat bodies, lipid concentration was elevated initially, then lowered. In methoprene-treated insects, hemolymph lipid levels were similar to those of controls up to 96 h post-treatment, then declined to lower than control levels; fat-body lipid content was initially higher, then lower, and finally higher, than that of controls. Fenoxycarb and methoprene caused severe, yet dissimilar, disruptions in metabolism of all three nutrients.
Brazil nut fruit capsules as phytotelmata: interactions among anuran and insect larvae
Authors: Caldwell Janalee P.
Published: July 2008

Under experimental conditions, body size, and thus indirectly priority effects, determines the outcome of predator–prey interactions among the aquatic larvae of a small assemblage of anuran and insect species using a patchily distributed microcosm. This assemblage occurs naturally in fallen fruit capsules of the Brazil nut tree, Bertholletia excelsa (family Lecythidaceae), in lowland tropical forest in Amazonian Brazil. Three of the species (the tadpole of a poison frog and the larvae of a giant damselfly and a culicid mosquito) are predators in the system and form a guild in which all are capable of feeding mutually on smaller individuals of the other two species. The larvae of the two insects are also cannibalistic, although the tadpole is not. Predator–prey experiments among certain pairs of these three species revealed size-related intra-guild predation. The results of these experiments and observations on naturally occurring capsules indicate that only one individual of any species per fruit capsule will survive to adulthood. Field-sampled capsules revealed low densities of guild members, with few co-occurrences among them. Whether this is due to the timing of the study in the early part of the rainy season or some other factor limiting accessibility to the fruit capsules is unknown. Although priority effects are well known among assemblages of competitors, this study reveals that potentially they can significantly affect predator-structured systems. The larva of a fourth species in the assemblage, a small bufonid toad, is detritivorous and palatable to the three predaceous species. In the presence of one of the three predaceous species, survival of the bufonid larvae depends on a rapid time to metamorphosis and on saturation of the microcosm with enough individuals in a clutch that some will survive to metamorphosis.
Winter energy balance and activity of female caribou on Coats Island, Northwest Territories: the relative importance of foraging and body reserves
Authors: Adamczewski J. Z. , Hudson R. J. , Gates C. C.
Published: July 2008

Reduced availability of forage in winter is the dominant limiting factor for the isolated, predator-free caribou (Rangifer tarandus groenlandicus) population on Coats Island, Northwest Territories. Pregnant females in this population typically begin winter with large fat reserves but catabolize most of them by spring. We modelled net energy requirements of a pregnant female during two winters (1982 – 1983 and 1983 – 1984) to evaluate energy requirements for maintenance, activity, and pregnancy, and to estimate the contribution of body reserves in supplying these requirements. A secondary objective was to determine whether winter activity budgets were related to energy balance, quality of winter diets, or body condition. Estimated net energy requirements were lowest during midwinter (16 MJ/d for an average female) but increased rapidly toward spring. Maintenance was at all times the largest component of requirements, but gestation costs increased to 12 – 14% of total requirements by winter's end, and activity costs tended to increase from 3.8–4.0 MJ/d (23–25% of requirements) at the beginning of winter to 4.6–4.8 MJ/d (26 – 29% of costs) in late winter. Body reserves supplied an estimated 14.2% (1982 – 1983) and 19.2% (1983 – 1984) of overall winter requirements. The contribution from body reserves varied from 9 to 24% during different portions of the two winters and, in late winter 1982 – 1983, reserves may have been a crucial supplement at a time of decreased forage availability and rising energy costs. Caribou were least active in early winter, when they were fattest, and most active at winter's end when their energy needs were increasing. These patterns were not consistent with activity budgets of most mainland caribou, and winter activity budgets were not consistently related to either diet quality or body condition.
Morphological changes in a marine population of threespined stickleback, Gasterosteus aculeatus, recently isolated in fresh water
Authors: Klepaker T.
Published: July 2008

A marine population of Gasterosteus aculeatus recently isolated in fresh water was found in Bergen, western Norway. This discovery offered the opportunity to study early changes in a population isolated in an environment quite different from what it previously experienced. The population was sampled in 1982, 1987, and 1991. Variation of plate morph frequencies was studied, and a prediction model for the change in frequencies is proposed. An increasing frequency of specimens with four dorsal spines is observed. This may be related to high summer temperature. Changes in morphology were recorded and compared with those in the marine population from which the isolated population originated. Discriminant analysis was used to reveal differentiation in morphometric characters. The main morphometric change recorded was that the isolated population had developed a more compact body, which is probably an adaptation to a less active, more benthic way of living.
Disconnecting metabolism from adenylate control during extreme oxygen limitation
Authors: Hochachka P. W. , Nener J. C. , Hoar J. , Saurez R. K. , Hand S. C.
Published: July 2008

When deprived of oxygen, the desert locust (Schistocerca gregaria) enters a state of apparent dormancy, from which it can recover when oxygen is again made available. Calorimetric measurements show that with an atmosphere of 100% nitrogen, energy flow in locusts reaches a new steady-state rate of heat dissipation of only 6 – 7% of aerobic values. Metabolite analysis shows large decreases in concentrations of arginine phosphate and adenosine triphosphate during anoxia, while adenosine monophosphate, lactate, α-glycerophosphate, and Pi accumulate to significantly elevated levels during anoxia. Time-course studies on whole animals and flight muscle paradoxically show declining metabolic rates when changes in metabolite (especially adenylate) concentration would normally be expected to activate metabolism.
Competition between juvenile pink (Oncorhynchus gorbuscha) and chum salmon (Oncorhynchus keta) and its effect on growth and survival
Authors: Beacham Terry D.
Published: July 2008

Pink (Oncorhynchus gorbuscha) and chum salmon (Oncorhynchus keta) fry have the potential for significant interactions in estuarine and nearshore waters of the Fraser River. Potential competitive effects were investigated by rearing both species for 60 d from fry emergence in monoculture and five duoculture environments (0, 10, 25, 50, 75, 90, and 100% pink salmon, and 100, 90, 75, 50, 25, 10, and 0% chum salmon, respectively), with the total number of fish in each environment constant. As the relative abundance of chum salmon increased, the mean weight of both pink and chum salmon declined, and reduced phenotypic variation in weight was observed. No marked trends in survival were observed in either species, but there was some indication that pink salmon survival was higher at intermediate relative densities of pink and chum salmon. Pink salmon biomass increased from 0.8 to 1.8%/d depending on the environment, and chum salmon biomass increased from 3.2 to 3.8%/d.
Morphological adaptations of the sand dollar Echinarachnius parma to righting itself
Authors: Cabanac A. , Hamel J.-F. , Himmelman J. H.
Published: July 2008

Though the radial symmetry of the sand dollar Echinarachnius parma is striking, we show that the mass and thickness of the anterior portion is greater than that of the posterior portion. By adding weights to either portion and quantifying the righting response, we demonstrate that the asymmetry in body mass is required to allow the sand dollar to right itself.
Population structure, body mass, activity, and orientation of an aquatic snake (Seminatrix pygaea) during a drought
Authors: Dodd Jr. C. Kenneth
Published: July 2008

The snout – vent length, tail length, weight, sex, activity, and orientation of a population of swamp snakes (Seminatrix pygaea) in north – central Florida were recorded from 1985 through 1990. A small temporary pond was monitored for 1343 days, using a drift fence – pitfall trap sampling regime. I captured 123 different snakes, plus 45 recaptures. Juveniles comprised 89% of the snakes at the pond. Females were generally longer and weighed more than males, although regression analysis showed no differences between the sexes in the relationship of length versus wet body mass. Males had longer tails than females. The sex ratio of snakes with a snout – vent length of more than 150 mm was 1:1. Activity occurred throughout the year but peaked during summer. Hydroperiod and weather conditions did not appear to influence snake activity. During the latter years of the study, a regional drought that began in the mid-1980s became quite severe. However, drought had little direct effect on overland migration or body condition but caused snakes to leave or to shorten the amount of time they spent within the pond basin. Snakes immigrated and emigrated nonrandomly; orientation was directed to and from the nearest large water body. Certain temporary ponds may comprise developmental habitat for Seminatrix pygaea. The dynamic wet – dry climatic cycles in southeastern North America may lead to the formation of metapopulations in some aquatic snakes.
Habitat separation by sympatric forest grouse in Fennoscandia in relation to boreal forest succession
Authors: Swenson Jon E. , Angelstam Per
Published: July 2008

Sympatric forest grouse in intensively managed conifer-dominated forests of the southern boreal zone in Sweden occupied different forest successional stages. Black grouse (Tetrao tetrix) selected forest stands 0 – 20 years old, hazel grouse (Bonasa bonasia) selected those 20 – 50 years old, and capercaillie (Tetrao urogallus) selected those ≥90 years old. Moreover, hazel grouse also selected stands with 1 – 10% deciduous trees, whereas capercaillie selected stands with no deciduous trees. The relative numbers of each grouse species were similar in two areas of intensively managed industrial forest, but differed in an area where forestry was less intensive and where forests had old-growth characteristics, i.e., they were old and multi-layered. Black grouse dominated in the intensively managed areas, whereas hazel grouse dominated in the less intensively managed area. We suggest that under natural conditions, black grouse inhabited the early-successional stages of forest following burns, hazel grouse inhabited the next, denser, successional stage and also old-growth spruce-dominated forests in fire refugia, and capercaillie inhabited stands of open, old, pine-dominated forest maintained by forest fire. The black grouse appears to be preadapted to the modern system of clearcut forest management. However, this system is clearly detrimental to the hazel grouse and capercaillie. To maintain all three species in a managed landscape, forest managers must strive to mimic more closely the natural variation in types and sizes of forest stands.
Inheritance models of North American red fox coat color
Authors: Johnson Donald R. , Hersteinsson Pall
Published: July 2008

The monohybrid and two dihybrid models of red fox (Vulpes vulpes) coat-color inheritance were evaluated using phenotypic frequency data available in the fur trade literature. The monohybrid model fit 62% (N = 21) of the samples from the Northwest Territories and the insular and coastal parts of Alaska. The Warwick – Hanson (allelic interaction) and modified Iljina (dominance modifier) models fit 97% (N = 133) of the samples from other regions. We favor the Warwick – Hanson model over the modified Iljina (Haldane) model with its restrictive assumption that the B locus is fixed for single allele. The results of some of Iljina's experiments suggest that a part of her silver-phase breeding stock was misidentified as to phenotype. If that was the case, a modifier locus is obviated and the Iljina model is identical with that of Warwick and Hanson.
Effects of environmental concentrations of calcium and sodium on the calcium flux in stressed 34-day-old striped bass
Authors: Grizzle John M. , Cummins Keith A. , Ashfield C. J.
Published: July 2008

Whole-body influx and efflux of Ca2+ were determined for juvenile striped bass, Morone saxatilis, weighing 0.06 g. Experiments were conducted during the 6 h immediately after transfer of the fish into flux chambers and within 24 h of the fish being harvested from a pond and transported. Fish were reared in water containing 0.13 mM Na+ and 0.68 mM Ca2+ and were transported and held in water containing 85 mM NaCl and 2.6 mM CaCl2 until the experiment. Water with 85 mM Na+ and 0.12 mM Ca2+, a combination that is lethal within 24 h to striped bass of this size, caused the Ca2+ efflux to increase from 89 ± 5.6 (SEM) to 140 ± 14 μmol∙kg−1∙h−1 and was the only treatment that resulted in a net loss of Ca2+. Influx of Ca2+ increased from 126 ± 15 to 229 ± 11 μmol∙kg−1∙h−1 when environmental Ca2+ was increased from 0.12 to 2.6 mM, but the Ca2+ influx was not affected by the Na+ concentration of the water. The high Ca2+ flux values for fish in this study were probably related to the rapid growth rate of striped bass at this age (influx) and the stressful conditions before the flux measurements (efflux). The increased mortality rates in water with high Na – low Ca concentrations did not appear to be related to changes in concentrations of water or soluble Ca, Na, Mg, or K in these fish.
Olfactory cues from conspecifics inhibit the web-invasion behavior of Portia, web-invading araneophagic jumping spiders (Araneae: Salticidae)
Authors: Willey Marianne B. , Jackson Robert R.
Published: July 2008

Portia is a genus of web-invading araneophagic spiders that use aggressive mimicry to capture their spider prey. In an experimental study, we demonstrate that adult females of Portia africana, P. fimbriata, P. labiata, and P. schultzi produce olfactory cues that affect the behavior of conspecific adult males, adult females, and juveniles. The olfactory cues of Portia spp. inhibit aggressive mimicry of conspecific spiders that are on a prey spider's web even if the prey spider is visible. This inhibition occurs regardless of the prey spider's web geometry. Prey pursuit by Portia is also inhibited when conspecific females provide olfactory cues in cases where the prey is a spider inhabiting a web. Olfactory cues from adult females elicit courtship displays of conspecific males when males are on the prey spider's web. Portia spp. do not alter their behavior when exposed to olfactory cues of heterospecifics.
Hematologic, biochemical, and endocrine characteristics of bobcats during a prey decline in southeastern Idaho
Authors: Knick Steven T. , Hellgren Eric C. , Seal Ulysses S.
Published: July 2008

We studied the hematology and blood chemistry of 33 adult bobcats (Felis rufus) captured from 1982 through 1985 in southeastern Idaho during a decline in lagomorphs, their major prey. Our objectives were to relate blood physiology of bobcats to sex, season, and a decline in abundance of black-tailed jackrabbits (Lepus californicus) and Nuttall's cottontail rabbits (Sylvilagus nuttallii). Males had higher (P < 0.10) erythrocyte counts (RBC) and hemoglobin levels (Hb) and lower (P < 0.10) insulin concentrations than females. Bobcats sampled during spring had higher (P < 0.10) mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and'insulin levels, and lower (P < 0.10) Hb, packed cell volume (PCV), RBC, and cholesterol levels than bobcats captured in autumn. The decline in lagomorph prey abundance from 1982 to 1983 was reflected in bobcat blood by lower (P < 0.10) phosphorus and insulin levels and higher (P < 0.10) Hb, RBC, and PCV. Progesterone levels in females reflected field results indicating that reproduction was curtailed when prey was scarce.
Relationships between scan and interscan durations in three avian species
Authors: Desportes Jean-Pierre , Metcalfe Neil B. , Popp James W. , Meyer Richard M. , Gallo Alain , Cézilly Frank
Published: July 2008

Foraging birds interrupt a feeding bout to scan the environment for potential predators; their behaviour can therefore be described as an alternating sequence of scans (S) and interscan intervals (I). The ratio of I to S oscillates rhythmically during a foraging period; this is consistent across three avian species (Barbary dove, Streptopelia risoria; chough, Pyrrhocorax pyrrhocorax; and goldfinch, Carduelis tristis) and in a variety of social and foraging contexts. Thus, although there are differences in the mean ratio (possibly related to differences in food-handling time), all samples show the same pattern of cycling in the ratio of I to S. In addition to these oscillations, the length of an interscan interval tends to vary in direct proportion to the length of the preceding scan in solitary individuals (Barbary doves); however, in flock foragers (choughs and goldfinches) there is an inverse relationship between I and S.
Molecular identification of a backcross between a female common murre × thick-billed murre hybrid and a male common murre
Authors: Friesen V. L. , Barrett R. T. , Montevecchi W. A. , Davidson W. S.
Published: July 2008

Reports of interspecific hybrids that are based on morphological characters are often questioned, but new techniques in molecular genetics permit reliable identification of hybrids as well as sensitive detection of introgression. As part of a larger population survey, morphology, allozymes, and mitochondrial DNA were compared among 239 thick-billed murres (Uria lomvia) from five Atlantic colonies and 143 common murres (Uria aalge) from four Atlantic colonies. One murre possessed the morphology and electrophoretic profile of a common murre, and the mitochondrial cytochrome b genotype of a thick-billed murre. Its genetic constitution suggests that a female thick-billed murre bred with a male common murre, producing a daughter that subsequently bred with a male common murre.