bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of a small heat shock/α-crystallin protein in the scleractinian coralMadracis mirabilis(Duch. and Mitch.)
Authors: Branton Margaret A , MacRae Thomas H , Lipschultz Fred , Wells Peter G
Published: April 2011

Immunological evidence is provided for the first time of a small heat shock/α-crystallin protein in the scleractinian coral Madracis mirabilis. The protein, termed cp26, had a molecular weight of 26 000; it reacted with an antibody raised to a small heat shock/α-crystallin protein fromArtemia franciscana and its production in corals was temperature sensitive. Corals collected from seawater at 25.5oC or lower lacked cp26, but the protein was produced in some of these animals when they were heat shocked experimentally. When exposed naturally to high environmental temperatures for relatively short times, corals contained cp26 and responded to heat shock in the laboratory. Corals growing at elevated temperatures tended to die when subjected to additional heat stress. Specifically, M. mirabilis died at about 31-33oC, as indicated by visual inspection of the animals, low recovery of protein in cell-free extracts, and loss of protein bands in SDS-polyacrylamide gels. Death was accompanied by the appearance of a diffuse, unidentified protein band on western blots that reacted with an antibody to cp26. Madracis mirabilis clearly reacts to heat shock by production of cp26; further study is required to determine if this small heat shock/α-crystallin protein will be a useful biomarker of stress in corals.
Genetic analysis of an endangered pine marten (Martes americana) population from Newfoundland using randomly amplified polymorphic DNA markers
Authors: McGowan Colin , Howes Lesley A , Davidson William S
Published: April 2011

The genetic diversity of an endangered pine marten (Martes americana) population from western Newfoundland was analysed using randomly amplified polymorphic DNA (RAPD) markers and compared with values obtained for three other Canadian populations. Seven different primers generated a total of 12 polymorphic markers. The average heterozygosity (Hj) within each population varied between 0.026 and 0.226 and was calculated at 0.121 (±0.053 SE) for the Newfoundland population. The estimate of genetic differentiation (theta) between the Newfoundland and Labrador populations was 0.520 ± 0.119 (SE), suggesting substantial genetic divergence. Estimates of Nei's genetic distance (Djk) ranged from 0.086 (±0.008) to 1.44 (±0.349) and placed the four populations into two distinct groups: the three populations east of the Canadian Rockies comprising a group that is genetically distant from a population in southwestern British Columbia. These results are consistent with a previous analysis based on comparisons of the nucleotide sequence of the mitochondrially encoded cytochrome b gene. Their implication with regard to the management of an endangered population is discussed. The RAPD approach proved to be an efficient, low cost means for obtaining genetic information using noninvasive tissue sampling.
Jumping performance and short-term repeatability of newly metamorphosed hybrid and parental leopard frogs ( Rana sphenocephala and Rana blairi )
Authors: Semlitsch Raymond D , Pickle Joyce , Parris Matthew J , Sage Richard D
Published: April 2011

Differential fitness between hybrid and parental genotypes plays a critical role in explaining the maintenance of natural hybrid zones as well as the production of novel genetic variation that may lead to diversification. Because locomotor performance is a reliable and practical measure of potential fitness related to morphological variation, we tested for differences in jumping performance among parental and hybrid genotypes of newly metamorphosed leopard frogs (Rana sphenocephala and Rana blairi). Tadpoles of the parental species and primary and backcross hybrid tadpoles, generated from artificial crosses (a total of five genotypes), were reared at two initial larval densities. Locomotor performance of newly metamorphosed frogs, as measured by jumping ability, was tested three times over 6 days in the laboratory at 24-25°C. Maximum and average jump lengths were greater for metamorphs reared at low larval density than for those reared at high density. Regression analyses indicated that 70-79% of the variation in jump length was due to body mass. When reared at low density, metamorphs of two F1 backcross genotypes (HB and HS) and one primary hybrid genotype (SB) jumped shorter distances than either parental species. When reared at high density, hybrid performance was indistinguishable from that of the parentals, except for one backcross hybrid (HB). Moderately high short-term repeatabilities (0.47-0.66) of metamorphs reared at the high density indicate that measures of performance in newly metamorphosed frogs can be predictive. We suggest that, owing to poor jumping performance, some hybrid frogs would be at a selective disadvantage relative to their parental species in the terrestrial environment and thus would partially reinforce mechanisms of reproductive isolation in this leopard frog system. Yet equivalent performance of some hybrids relative to the parentals, at least when reared at low density, suggests that hybrid lineages also have the potential to evolve independently in some environments.
Escape behavior by prey blocked from entering the nearest refuge
Authors: Cooper, Jr. William E
Published: April 2011

Current models of optimal antipredation behavior do not apply to prey blocked by a predator from access to the primary refuge because the predator is closer than the optimal approach distance and flight toward the refuge would increase risk. If other alternative refuges are available, the prey should flee toward the best alternative one. I studied the effect of an approaching human simulated predator interposed between prey and refuge on the use of alternative refuges and on flight-initiation distance in the keeled earless lizard, Holbrookia propinqua. When the predator approached on a line between a lizard and its closest refuge, the lizard invariably fled to or toward an alternative refuge. Lizards were significantly more likely to use alternative refuges than lizards approached on a line connecting the closest refuge, prey, and predator, but with the lizard between the predator and the refuge. Flight-initiation distance was significantly greater for lizards having free access to the closest refuge than for those blocked from it, perhaps because of the time required to assess the new risk posed by blockage of the closest refuge, to select the best alternative refuge, or to wait for the predator to commit to a closing pattern before choosing the best flight option.
Autumn stopover ecology of the Blackpoll Warbler (Dendroica striata) in thorn scrub forest of the Dominican Republic
Authors: Latta Steven C , Brown Christopher
Published: April 2011

We used mist-netting, color-banding, resighting, and behavioral observations to study the autumn stopover ecology of migrating Blackpoll Warblers (Dendroica striata) in coastal thorn scrub forest in the area of Cabo Rojo, Pedernales Province, Dominican Republic. Blackpoll Warblers were the most abundant migrant present in this habitat throughout most of October 1997. Warblers stopping over in this habitat were generally young with moderate to large fat stores. No lean birds (fat score = 0) were captured. Our behavioral observations suggest that Blackpoll Warblers are flexible in terms of social organization, with birds associating in single-species flocks and in mixed-species aggregations, but single birds were also recorded. Foraging activity consisted primarily of gleaning from leaves and was focused on lepidopteran larvae, whose high abundance coincided with Blackpoll Warbler arrival. We suggest that most stopover Blackpoll Warblers were not weakened individuals searching for emergency energy stores but were forced down owing to unfavorable weather conditions for migration; others may have been taking advantage of landfall on the south coast of Hispaniola for daytime rest before continuing across the Caribbean Sea to South America. Coastal thorn scrub forest of Hispaniola appears to be a preferred stopover habitat for a variety of migrants, providing a place to rest and replenish energy reserves following transoceanic flight.
Répartition spatiale des huîtriers pie (limicoles) en hivernage et charge parasitaire intestinale
Authors: Le Dréan-Quénec'hdu Sophie , Goss-Custard John D
Published: April 2011

Some oystercatchers are less efficient predators than others because of their age or their feeding habits. This lower feeding efficiency may reduce their survival or their chance of migrating to nesting grounds. Do these birds carry more parasites? To address this question, we studied the intestinal parasite load of oystercatchers hibernating in the Exe estuary (Great Britain) in relation to their feeding site, type of prey, and parasite load of mussels, their main prey in the estuary. We show that some birds with lower feeding efficiency carry more parasites, particularly the potentially pathogenic nematode Capillaria sp. The degree of infestation by trematodes through the mussel Ptilostomum brevicolle is not related to the degree of infestation of the mussels themselves. We suggest that some birds are resistant to infestation.

[Journal translation]
Spring and summer predation on fish by the Antarctic fur seal, Arctocephalus gazella, at King George Island, South Shetland Islands
Authors: Daneri G A , Carlini A R
Published: April 2011

The fish component of the diet of nonbreeding male Antarctic fur seals, Arctocephalus gazella, was analyzed from 70 scats collected at Stranger Point, King George Island, South Shetland Islands, during the austral spring (n = 36) and summer (n = 34) of 1993-1994. Fish occurred in approximately 70% of scats that contained food remains irrespective of season. In spring, the main fish prey were Electrona antarctica, Pleuragramma antarcticum, and Notolepis coatsi, which together gave two-thirds of the 110 otoliths recovered. In summer, 457 otoliths were retrieved; the most frequent and abundant species were Gymnoscopelus nicholsi, E. antarctica, and P. antarcticum, which represented over 80% of the otoliths recovered. A substantial increase in the amount of fish ingested by fur seals occurred from spring to summer concomitant with a change in the relative proportion of fish taxa. Most fish species identified are pelagic and feed on krill. During the study period, commercial fishing in the area was not based upon any of the fish species identified.
Effects of the tapeworm Hymenolepis diminuta on maternal investment in rats
Authors: Willis Charlene , Poulin Robert
Published: April 2011

Parasites can influence the optimal allocation of energy between present and future reproduction by changing the value of current offspring relative to that of future ones. We examined the effect of the tapeworm parasite Hymenolepis diminuta on maternal investment in rats. Litter sizes and average pup body mass did not differ between parasitised and nonparasitised mothers, either at birth or at weaning. The two groups of mothers also did not differ with respect to pup growth or pup mortality during lactation. Mass change during lactation was similar between parasitised and nonparasitised mothers. However, a pup-retrieval experiment showed that parasitised mothers were quicker at retrieving their pups to safety than nonparasitised mothers, and spent less time checking for potential sources of danger. These differences were particularly pronounced toward the end of the lactation period. It would appear that the parasite increases the relative value of the current litter and current levels of maternal investment, possibly because it reduces future reproductive success.
Responses to changes in prey availability by Common Murres and Thick-billed Murres at the Gannet Islands, Labrador
Authors: Bryant Rachel , Jones Ian L , Hipfner J Mark
Published: April 2011

We quantified Common Murre (Uria aalge) and Thick-billed (Uria lomvia) Murre chick diets, chick-feeding rates, breeding success, chick growth, adult masses, and pair members' time spent together at site at the Gannet Islands, Labrador, in 1996 and 1997, after a decline in capelin (Mallotus villosus) abundance along the coast of southern and central Labrador. These results, with the exception of time spent at the site, were compared with those collected by other researchers at the Gannet Islands in 1981-1983, before the capelin decline. The two species responded similarly to the decline. After the decline, murres fed their chicks up to 75% fewer capelin and up to 65% more daubed shannies (Lumpenus maculatus). Feeding rates of both murre species varied among years, without respect to changes in the proportion of capelin. We found no evidence for declines in colony attendance, breeding success, chick growth, and adult mass. No data on time spent at the site were available before the decline in capelin abundance, but after the decline, off-duty murres of both species spent a mean of 10 min at their sites per feeding visit. This amount of time was short with respect to that recorded for Common Murres elsewhere, suggesting that murres' foraging effort at the Gannet Islands was high and buffered the effects of prey availability on other parameters measured. Taken together, our results suggest that murres responded to changing capelin abundance by changing their chicks' diet, but were otherwise little affected.
Neighborhood effects on territorial aggregations of the burrowing wolf spider Geolycosa xera archboldi McCrone (Araneae: Lycosidae)
Authors: Marshall Samuel D
Published: April 2011

The effects of territorial neighbors on the foraging success of a burrowing wolf spider, Geolycosa xera archboldi McCrone, were examined in the field in central Florida, U.S.A. The rates of mass gain by juveniles were quantified and related to the following burrow neighborhood characteristics: mean nearest-neighbor size, mean nearest-neighbor distance, and mean number of neighbors within 1 m of the focal animal's burrow. Only nearest-neighbor size was correlated (negatively) with mass gain. Field tests with provisioned prey showed that larger neighbors were both more likely to take prey in a zone of territorial overlap and to do so sooner than smaller neighbors. Tests for exploitative competition using paired adhesive traps to mimic pairs of neighboring spiders were conducted at the mean nearest-neighbor distance for the population (30 cm) to model territorial dyads and pairs of traps at random smaller distances to model nonterritorial dyads. There was no difference in rates of prey capture by pairs of traps at the territorial distance and the shorter distances, indicating that resource depletion may not explain the patterns observed.
Twenty-year home-range dynamics of a white-tailed deer matriline
Authors: Nelson Michael E , Mech L David
Published: April 2011

We examined the seasonal migration and home-range dynamics of a multigeneration white-tailed deer (Odocoileus virginianus) matriline comprising six females from four generations spanning a 20-year period in northeastern Minnesota. All, from the matriarch to her great-granddaughter, migrated to the same summer and winter ranges, the longest individual record being 14.5 years. Three maternal females concurrently occupied exclusive fawning sites within their ancestral matriarch's summer range, while two nonmaternal females explored new areas and ranged near their mothers. One great-granddaughter expanded her summer range 1 km beyond the matriarch's summer range while essentially vacating half of her ancestors' range and becoming nonmigratory the last 4 years of her life. These data indicate that individual movements of matriline members can potentially expand their ranges beyond the areas occupied by their ancestors through a slow process of small incremental changes. This suggests that the rapid extension of deer range in eastern North America resulted from natal dispersal by yearling deer rather than from the type of home-range expansion reported here.
Terrestrial hibernation in the northern cricket frog,Acris crepitans
Authors: Irwin Jason T , Costanzo Jon P , Lee, Jr. Richard E
Published: April 2011

We used laboratory experiments and field observations to explore overwintering in the northern cricket frog, Acris crepitans, in southern Ohio and Indiana. Cricket frogs died within 24 h when submerged in simulated pond water that was anoxic or hypoxic, but lived 8-10 days when the water was oxygenated initially. Habitat selection experiments indicated that cricket frogs prefer a soil substrate to water as temperature decreases from 8 to 2°C. These data suggested that cricket frogs hibernate terrestrially. However, unlike sympatric hylids, this species does not tolerate extensive freezing: only 2 of 15 individuals survived freezing in the -0.8 to -2.6°C range (duration 24-96 h). Cricket frogs supercooled when dry (mean supercooling point -5.5°C; range from -4.3 to -6.8°C), but were easily inoculated by external ice at temperatures between -0.5 and -0.8°C. Our data suggested that cricket frogs hibernate terrestrially but are not freeze tolerant, are not fossorial, and are incapable of supercooling in the presence of external ice. Thus we hypothesized that cricket frogs must hibernate in terrestrial sites that adequately protect against freezing. Indeed, midwinter surveys revealed cricket frogs hibernating in crayfish burrows and cracks of the pond bank, where wet soils buffered against extensive freezing of the soil.
The influence of redd site selection, groundwater upwelling, and over-winter incubation temperature on survival of bull trout (Salvelinus confluentus) from egg to alevin
Authors: Baxter James S , McPhail J D
Published: April 2011

We measured survival of bull trout (Salvelinus confluentus) embryos to the alevin stage in areas selected and not selected by females for spawning. In this study we tested the hypotheses that (1) females are utilizing habitats influenced by discharging groundwater and that (2) there is a reproductive advantage to spawning at these selected sites. Embryo survival was assessed by placing fertilized eggs in capsules that could be retrieved once they were placed in selected and nonselected locations. The survival rate was significantly higher (88.6 vs. 76.1%) and less variable in the selected area, but alevin lengths did not differ significantly between areas. The selected areas were, on average, locations of groundwater discharge and higher water temperatures over the incubation period, while nonselected locations were in areas of surface-water recharge and lower water temperatures. The results suggest that appropriate reproductive habitats which offer the best incubation environments may be limited in bull trout systems, and that site selection by females may increase fitness and be critical for population viability.
Localization of a sodium-dependent high-affinity serotonin transporter and recruitment of exogenous serotonin by the cestodeHymenolepis diminuta: an autoradiographic and immunohistochemical study
Authors: Osloobi Neda , Webb Rodney A
Published: April 2011

Uptake of serotonin by tissues of intact and hemitransected Hymenolepis diminuta was studied by autoradiography and immunohistochemistry. Hemitransected worms were incubated in balanced saline containing 10 µM [3H]serotonin and washed extensively. The density of silver grains over the serotonin-immunoreactive longitudinal nerve cords and commissural rings, male reproductive system, tissues surrounding the genital pouch, and deep longitudinal muscles was significantly greater than that over the parenchyma. The presence of serotonin in spermatozoa suggested a role for this amine in spermatozoon activity. In contrast, uptake of 10 µM [3H]serotonin in sodium-free saline was significantly reduced compared with that in balanced saline in all tissues examined except the parenchyma. Analysis of the data revealed that the sodium-dependent high-affinity serotonin transport system is localized primarily in the serotonergic-like neurons of H. diminuta, which suggests possible recycling of neuronally released serotonin. Following incubation of intact worms in vitro for 12 h in 5 µM [3H]serotonin, the density of silver grains was significantly higher over the serotonin-immunoreactive nerves, elements of the male reproductive system, tissues surrounding the genital pouch, and deep longitudinal muscles than over the parenchyma. These results demonstrate recruitment of exogenous serotonin by intact H. diminuta and suggest sequestration and concentration by the serotonin-immunoreactive neurons via the sodium-dependent high-affinity transporter. These data further suggest that although H. diminuta can synthesize serotonin, it may obtain serotonin from the host. Nonetheless, the amount of serotonin recruited by H. diminuta from the host in vivo compared with that which they synthesize is not known.
Alpha status, dominance, and division of labor in wolf packs
Authors: Mech L David
Published: April 2011

The prevailing view of a wolf (Canis lupus) pack is that of a group of individuals ever vying for dominance but held in check by the "alpha" pair, the alpha male and alpha female. Most research on the social dynamics of wolf packs, however, has been conducted on non-natural assortments of captive wolves. Here I describe the wolf-pack social order as it occurs in nature, discuss the alpha concept and social dominance and submission, and present data on the precise relationships among members in free-living packs, based on a literature review and 13 summers of observations of wolves on Ellesmere Island, Northwest Territories, Canada. I conclude that the typical wolf pack is a family, with the adult parents guiding the activities of the group in a division-of-labor system in which the female predominates primarily in such activities as pup care and defense and the male primarily during foraging and food-provisioning and the travels associated with them.
Reproductive-timing-dependent alternation of offspring life histories in female threespine sticklebacks
Authors: Saito Toshihiko , Nakano Shigeru
Published: April 2011

Relationships between reproductive timing of spawners and timing of hatch and age at maturity of their offspring were examined in fluvial threespine sticklebacks, Gasterosteus aculeatus. Some age 2 and all age 3 females matured in this age-structured population, with only a few females reproducing over two successive breeding seasons. Age 2 females spawned over the relatively long breeding season (March-August), whereas age 3 females spawned mainly early in the season (March-June). Although the standard length of mature age 3 females was greater than that of age 2 females, the back-calculated standard lengths of the former were always shorter than those of the latter at an equivalent age, the most distinct differences being apparent in young of the year. Analysis of daily otolith increments showed that the earlier the young of the year were born, the larger they were at the end of the growing season. As a result of these findings, age 3 females can be expected to produce offspring that will mature at age 2, whereas the offspring of late-spawning age 2 females are more likely to mature at age 3. Therefore, a partial alternation of life histories between generations is thought to occur.
Phenology and ecology of hibernation in spotted turtles (Clemmys guttata) near the northern limit of their range
Authors: Litzgus Jacqueline D , Costanzo Jon P , Brooks Ronald J , Lee, Jr. Richard E
Published: April 2011

Using mark-recapture techniques, temperature-sensitive radio transmitters, and miniature temperature data loggers we investigated the hibernation ecology of northern temperate zone spotted turtles (Clemmys guttata) in Georgian Bay, Ontario, over 4 winters (1993-1997). We observed 18 hibernacula that were occupied by 34 turtles; 11 hibernacula were apparently occupied by single turtles, and 7 were used communally by up to 9 individuals. Hibernacula were located in swamps and were of 2 types: sphagnum moss hummock (n = 15) and rock cavern (n = 3). Almost half of the individuals (16 of 34) used the same hibernaculum in at least 2 winters. Turtles entered hibernacula between mid-September and October, when their body temperature was between 12 and 16°C, and exited them in mid to late April, when ambient temperatures ranged between 1 and 5°C. A waterproof temperature data logger attached to a turtle indicated that this turtle was protected from freezing in a thermally stable hibernaculum (body temperature range 0.3-3.9°C) despite highly variable (a 37°C change over 5 days) and low air temperatures (minimum -35°C). Loss of body mass (2%) during hibernation was not significant. We observed no mortality within hibernacula over the 4 winters; however, 3 turtles were destroyed by predators near the hibernacula. These data provide insight into the role of climate in limiting the northern distribution of this species.
Social interactions, cross-fostering, and sibling recognition in prairie voles, Microtus ochrogaster
Authors: Miño C. Guillermo Paz y , Tang-Martínez Zuleyma
Published: April 2011

Sibling recognition in prairie voles (Microtus ochrogaster) has been traditionally inferred from incest avoidance or lack of reproduction among littermates. Researchers have concluded that when sibling prairie voles are isolated from one another there is a breakdown of incest avoidance (and therefore of sibling recognition). In a reevaluation of these studies, using social interactions rather than incest avoidance, we found that the breakdown of incest avoidance was not equivalent to a breakdown of sibling recognition. We explored the effects of cross-fostering on sibling recognition by looking at changes in amicable or agonistic behaviors that were then used to infer sibling recognition. Prairie voles that were cross-fostered with nonsiblings were not able to recognize their own siblings when reunited and tested for social interactions in adulthood. Siblings reared apart treated their own siblings as if they were not closely related and nonsiblings reared together treated nonsiblings as if they were their own siblings. The mechanism of sibling recognition in prairie voles is association or familiarity. The ability to recognize siblings may be limited to individuals that are raised together. Sibling recognition in prairie voles may be a by-product of familiarity in early life and not a mechanism restricted to genetic relatedness as predicted by kin-selection theory.
Diving and foraging patterns of Marbled Murrelets (Brachyramphus marmoratus): testing predictions from optimal-breathing models
Authors: Jodice Patrick GR , Collopy Michael W
Published: April 2011

The diving behavior of Marbled Murrelets (Brachyramphus marmoratus) was studied using telemetry along the Oregon coast during the 1995 and 1996 breeding seasons and examined in relation to predictions from optimal-breathing models. Duration of dives, pauses, dive bouts, time spent under water during dive bouts, and nondiving intervals between successive dive bouts were recorded. Most diving metrics differed between years but not with oceanographic conditions or shore type. There was no effect of water depth on mean dive time or percent time spent under water even though dive bouts occurred in depths from 3 to 36 m. There was a significant, positive relationship between mean dive time and mean pause time at the dive-bout scale each year. At the dive-cycle scale, there was a significant positive relationship between dive time and preceding pause time in each year and a significant positive relationship between dive time and ensuing pause time in 1996. Although it appears that aerobic diving was the norm, there appeared to be an increase in anaerobic diving in 1996. The diving performance of Marbled Murrelets in this study appeared to be affected by annual changes in environmental conditions and prey resources but did not consistently fit predictions from optimal-breathing models.
Further development of the Spalinger-Hobbs mechanistic foraging model for free-ranging moose
Authors: Pastor John , Standke Katie , Farnsworth Keith , Moen Ron , Cohen Yosef
Published: April 2011

Spalinger and Hobbs proposed a mechanistic model of forage intake based on the mutually exclusive actions of biting and chewing. A necessary consequence of this model is that an animal postpones the intake of more food by biting when it is processing food by chewing. In previous work, the Spalinger-Hobbs model successfully predicted short-term intake in controlled experiments. Application of the model to an entire foraging bout requires the following assumptions: (i) biting and chewing are independent events; (ii) there are no periodicities in the length of consecutive bite or chew sequences; (iii) the average bite size is constant; and (iv) the bite rate does not change with the number of bites in the sequence. To test these assumptions, we videotaped entire foraging bouts of two free-ranging moose (Alces alces) feeding on dense swards of Epilobium angustifolium in midsummer. From these videotapes, we measured the time spent biting and chewing, the rates of biting and chewing, the frequency distributions of consecutive bite and chew sequences, and lengths of E. angustifolium shoots above the point of cropping. Plant samples were collected in order to determine bite mass. A total of 1050 bites and chews were analyzed for moose 1 and 1925 bites and chews for moose 2. For both moose, three chewing events occurred, on average, for each bite event. Given this 1:3 bite:chew ratio, the frequency distributions of consecutive bite and chew sequences were as expected from a geometric distribution of independent events. There were no time-series correlations or dominating frequencies in the lengths of bite and chew sequences. These findings fulfill the first three assumptions required to extend the Spalinger-Hobbs model to entire foraging bouts. However, the fourth assumption was not fulfilled, in that time spent per bite increased asymptotically with bite-sequence length. We therefore incorporated the effect of bite-sequence length on bite rate into the Spalinger-Hobbs model. The new model predicts that to simultaneously maximize the marginal intake rate with respect to both bite rate and bite mass, a moose should take single bites most often and bite mass should be approximately 3.6 g. Eighty-two percent of bite sequences were composed of single bites for both moose, and we and others independently observed a bite size of 3.24-3.75 g for free-ranging moose. These observations lend credibility to our modified model.
Pup density related to terrestrial habitat use by New Zealand fur seals
Authors: Bradshaw Corey JA , Thompson Caryn M , Davis Lloyd S , Lalas Chris
Published: April 2011

Features of the terrain are important in the selection of terrestrial habitat by otariid seals. Fur seals use rocky shorelines where terrain features such as crevices and ledges may provide shelter for pups. New Zealand fur seals (Arctocephalus forsteri) are increasing in number and expanding their range, requiring them to select new habitat for breeding. Predicting population expansion is important for assessing potential conflicts with commercial fisheries. We quantified terrain features at 25 breeding colonies and 8 nonbreeding colonies around South Island. Univariate tests demonstrated some differences in terrain between breeding and nonbreeding colonies, although principal components analysis (PCA) did not reveal any obvious differences. We suggest that the power to detect differences is reduced by the tendency for nonbreeding colonies to become breeding colonies over time as the population increases. We found a significant relationship between pup density and terrain (i.e., PCA variables) within breeding colonies. The terrain occupied by high-density colonies contained more and smaller rocks, more crevices and ledges, less-pronounced slopes, higher cliffs, and a more westerly exposure than that occupied by low-density colonies. Smaller rocks may provide more spaces in which pups can find shelter; less-pronounced slopes may facilitate pup mobility and higher cliffs may increase shading. We suggest that in addition to terrain features, other phenomena are also involved in breeding-site selection.
Marion Island elephant seals: the paucity-of-males hypothesis tested
Authors: Wilkinson I S , van Aarde R J
Published: April 2011

The southern elephant seal, Mirounga leonina, population at Marion Island has declined since the start of research activities there in 1973, as have populations at other Indian Ocean breeding sites. One suggested mechanism for the decline at Marion Island is a shortage of males, resulting in low insemination rates. We tested this "paucity-of-males" hypothesis by looking at (i) adult sex ratios, (ii) male sexual activity, and (iii) the relationship between levels of sexual activity and the probability of a cow pupping in the following season. Sex ratios were similar to those at other sites where populations are either stable (South Georgia) or increasing (Peninsula Valdes). Dominant bulls monopolised mating opportunities, achieving 98.1% of 629 observed copulations over three seasons. Of the 138 cows coming ashore, only 4 (2.9%) were not seen mating and 89% copulated with only one bull; dominant bulls copulated with all but 1 of the 134 (99.3%) cows that did mate. Cows were mated more frequently than at sites with stable and increasing populations. There was no difference in the observed level of sexual activity between cows seen pupping in the following season and those who failed to pup. This indicates that bulls monopolising harems are capable of inseminating all the cows. Such findings refute the paucity-of-males hypothesis.
Female reproductive output in exploited Nile monitor lizard (Varanus niloticus L.) populations in Sahelian Africa
Authors: de Buffrénil Vivian , Rimblot-Baly Frédérique
Published: April 2011

Sexual maturation and ontogenetic development of gametes were studied in a sample of 481 female Nile monitor lizards (Varanus niloticus L.) (18.8-71.5 cm snout-vent length (SVL)) from the Lake Chad region in Chad and Nigeria and the central delta of the Niger River in Mali. The timing of egg maturation suggests that only one large clutch can be produced in 12 months, and that egg laying occurs between late November and early January. Each year, about 45-50% of mature females, on average, lay eggs, but local sampling shows that this proportion varies greatly. Females reach sexual maturity at 36 ± 2 cm SVL and 24 months of age. Clutch size (CS) increases from 12-13 to 53-60 eggs (average values for specimens of 36 cm and 71.5 cm SVL, respectively) with increase in SVL, according to the power function CS = 0.0049 SVL2.206 (specimens from Mali) or CS = 0.0052 SVL2.163 (specimens from the Lake Chad region). Conversely, the relative mass of the clutches (RCM) and their relative energy content (RWC) decrease during growth; hence, small (young) individuals are subjected to a much higher reproductive effort than large ones. Compared with that of most other large varanids, egg mass in the Nile monitor (38.8 g) is small, but reproductive output (CS) and effort (RCM, RWC) appear to be very high. Moreover, the specimens from Mali, where the species is heavily exploited, have a higher reproductive output and shorter longevity than those from the Lake Chad region. These data are discussed with reference to the ecology and local level of exploitation of the Nile monitor.
Song variation and the structure of local song dialects in the polygynandrous Smith's Longspur
Authors: Briskie James V
Published: April 2011

I examined song structure in five populations (or neighbourhoods) of the polygynandrous Smith's Longspur (Calcarius pictus) near Churchill, Manitoba, Canada, from 1988 to 1994. All after-second-year (ASY) males sang only a single song type. This song type did not vary within ASY males over the season or from year to year and it was nearly identical among all ASY males within a neighbourhood. However, the song type of ASY males differed significantly from one neighbourhood to the next in the number of elements, total length (s), and minimum frequency (kHz). Neighbourhood dialects were readily distinguishable by the human ear and, except in one case, persisted over the duration of the study. In contrast to the uniformity of ASY male song within a neighbourhood, the song of second-year (SY) males did not match the local dialect. Only when SY males returned for a second year did their song and the neighbourhood dialect of ASY males converge. There were no differences in song structure that could be related to the complex mating system of this species. The function of neighbourhood dialects is not clear, but they may be used by both males and females as a signal of affiliation and experience with the local area.
Secondary sexual characters, energy use, senescence, and the cost of reproduction in sockeye salmon
Authors: Hendry Andrew P , Berg Ole K
Published: April 2011

Reproductive development and energy stores were characterized for sockeye salmon (Oncorhynchus nerka) maturing in the wild (Pick Creek, Bristol Bay, Alaska). Between freshwater entry and the start of spawning, ovaries increased in mass by 87.1% and secondary sexual characters increased in linear dimension by 13.0-47.4%. Between the start of spawning and death, secondary sexual characters decreased in relative size by 3.3-12.7%. Mass-specific somatic energy declined from freshwater entry (6.7% fat, 20.6% protein, 6.6 kJ·g-1) to the start of spawning (1.6% fat, 18.0% protein, 4.5 kJ·g-1) and finally to death (0.1% fat, 14.4% protein, 2.9 kJ·g-1). Stored fat appeared to be used primarily for upriver migration and egg production, whereas stored protein appeared to be used primarily for the development of secondary sexual characters and metabolism during spawning. Most development of secondary sexual characters occurred late in maturation, perhaps to forestall deterioration of muscle tissue. Relative to populations with long freshwater migrations, Bristol Bay sockeye salmon stored less fat before entering fresh water and used less fat before death. The total energy cost of reproduction (freshwater entry until death, including gonad investment) was 74.1% for females and 66.1% for males, higher than levels typically reported for iteroparous salmonids.
Histological observations on spermatogenesis in winter flounder, Pleuronectes americanus Walbaum, from Conception Bay, Newfoundland, Canada
Authors: Moulton Sonya M , Burton Margaret PM
Published: April 2011

Male winter flounder, Pleuronectes americanus Walbaum, collected from Conception Bay, Newfoundland, from late July to October 1997 were studied to provide histological insight into the cycle of spermatogenesis. The sequence of stages followed the same general pattern as that described for a variety of other teleost species, beginning with mitotic proliferation of reserve spermatogonia. Spermatogenesis was found to be very rapid compared with reports for other seasonal spawners. The onset of spermatogenesis, as indicated by the appearance of mitotic figures, occurred during September and the process was completed just over a month later. Therefore, sperm were present in the testes at least 6 months prior to the usual time of spawning. Possible reasons why spermatogenesis is completed so long before spawning in P. americanus are discussed.
The growth hormone axis, feeding, and central allocative regulation: lessons from giant transgenic growth hormone mice
Authors: Rollo C D , Kajiura L J , Wylie B , D'Souza S
Published: April 2011

Lifetime consumption rates of male transgenic growth hormone (GH) mice and normal controls were measured on either a 38% protein diet (HP), the standard rodent diet (STD) (23.5% protein), or the standard diet supplemented with a free choice of sucrose (CARB). On STD, daily intake of normal mice increased little at sizes greater than 20 g, but larger transgenic mice ate progressively more. Both kinds of mice showed declining daily mass-specific consumption with increasing age. Transgenic mice consistently ate 13.3% less food than normal mice on a mass-specific basis across all ages. On the self-selective CARB diet, normal mice exhibited increasing age-specific daily consumption, whereas transgenic mice exhibited a trend towards age-related decline in mass-specific feeding that proved significant on the basis of body mass. Transgenic mice ingested more sucrose than standard chow and this did not vary with age. In contrast, normal mice ate less sucrose than chow and chose a declining proportion of sucrose with age. Transgenic and normal mice showed a unitary relationship of daily intake of HP in relation to body mass, resulting in constant mass-specific feeding across all ages. Transgenic GH animals, including livestock, show numerous defects that we have attributed to relative energetic stress associated with excessive allocation to lean growth. This is exacerbated by failure to offset increased demands of growth by increasing mass-specific feeding. Results presented here document altered feeding regulation in transgenic GH mice and suggest underlying mechanisms.
Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology
Authors: Kelly Jeffrey F
Published: April 2011

Differential fractionation of stable isotopes of carbon during photosynthesis causes C4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C3 plants have stable-isotope ratios of carbon that are intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio (13C/12C) of plants into consumers' tissues makes this ratio useful in studies of animal ecology. The heavy isotope of nitrogen (15N) is preferentially incorporated into the tissues of the consumer from the diet, which results in a systematic enrichment in nitrogen-isotope ratio (15N/14N) with each trophic level. Consequently, stable isotopes of nitrogen have been used primarily to assess position in food chains. The literature pertaining to the use of stable isotopes of carbon and nitrogen in animal trophic ecology was reviewed. Data from 102 studies that reported stable-isotope ratios of carbon and (or) nitrogen of wild birds and (or) mammals were compiled and analyzed relative to diet, latitude, body size, and habitat moisture. These analyses supported the predicted relationships among trophic groups. Carbon-isotope ratios differed among species that relied on C3, C4, and marine food chains. Likewise, nitrogen-isotope ratios were enriched in terrestrial carnivorous mammals relative to terrestrial herbivorous mammals. Also, marine carnivores that ate vertebrates had nitrogen-isotope ratios that were enriched over the ratios of those that ate invertebrates. Data from the literature also indicated that (i) the carbon-isotope ratio of carnivore bone collagen was inversely related to latitude, which was likely the result of an inverse relationship between the proportion of carbon in the food chain that was fixed by C4 plants and latitude; (ii) seabirds and marine mammals from northern oceans had higher nitrogen-isotope ratios than those from southern oceans; (iii) the nitrogen-isotope ratios of terrestrial mammals that used xeric habitats were higher than the ratios of those that used mesic habitats, indicating that water stress can have important effects on the nitrogen-isotope ratio; (iv) there was no relationship between body mass and nitrogen-isotope ratio for either bone collagen or muscle of carnivores; and (v) there was linear covariation between stable-isotope ratios of carbon and nitrogen in marine food chains (but not in terrestrial C3 or C4 food chains), which is likely a product of increases in carbon-isotope ratio with trophic level in marine food chains. Differences in stable-isotope composition among trophic groups were detected despite variation attributable to geographic location, climate, and analytical techniques, indicating that these effects are large and pervasive. Consequently, as knowledge of the distribution of stable isotopes of carbon and nitrogen increases, they will probably become an increasingly important tool in the study of avian and mammalian trophic ecology.
Constant-frequency and frequency-modulated components in the echolocation calls of three species of small bats (Emballonuridae, Thyropteridae, and Vespertilionidae)
Authors: Fenton M B , Rydell J , Vonhof M J , Eklöf J , Lancaster W C
Published: April 2011

The echolocation calls of Rhychonycteris naso (Emballonuridae), Thyroptera tricolor (Thyropteridae), and Myotis riparius (Vespertilionidae) were recorded at the Cãno Palma Field Station in Costa Rica in February 1998. All three species produced echolocation calls at low duty cycle (signal on ~10% of the time). While T. tricolor produced low-intensity echolocation calls that were barely detectable when the bats were <0.5 m from the microphone, the other two species produced high-intensity calls, readily detectable at distances >5 m. Myotis riparius produced calls that swept from about 120 kHz to just over 50 kHz in about 2 ms. We found no evidence of harmonics in these calls. Rhynchonycteris naso and T. tricolor produced multiharmonic echolocation calls. In R. naso the calls included narrowband and broadband components and varied in bandwidth, sweeping from just under 100 kHz to around 75 kHz in over 5 ms. Most calls were dominated by the higher harmonic (ca. 100 kHz), but some also included a lower one (ca. 50 kHz). The calls of T. tricolor were 5-10 ms long and dominated by a single frequency (ca. 45 kHz), sometimes with a ca. 25 kHz component. The echolocation calls of all three species included frequency-modulated and constant-frequency components. While these terms describe the components of the echolocation calls, they do not necessarily describe the bats' echolocation behaviour.
Mechanism, kinematic performance, and fitness consequences of jumping behavior in entomopathogenic nematodes (Steinernemaspp.)
Authors: Campbell James F , Kaya Harry K
Published: April 2011

The mechanism enabling entomopathogenic nematodes (Steinernema spp.) to jump is described. Jumping performance is measured and the contribution of jumping to host finding is estimated. We used the entomopathogenic nematode Steinernema carpocapsae as a model species for the genus. Nematodes jump using a two-step process of forming and contracting a loop. During loop formation, the nematode bends the anterior half of its body until the head region makes contact with the side of the body. The two body regions are held fast by the surface tension of the water film covering the nematode. When the loop is contracted, the body becomes contorted so that the cuticle kinks. This extreme bending generates and stores sufficient energy that when the surface-tension force is broken the nematode is propelled through the air. The nematode (0.558 mm in length) can jump a distance of 4.8 ± 0.8 mm (mean ± SEM) and a height of 3.9 ± 0.1 mm. The contribution of jumping to host finding varies among species and is related to the foraging strategy used by each species.
Descriptions of two loxosomatids (Entoprocta), with emphasis on a relationship between symbiont attachment structures and host cuticle
Authors: Williams J B
Published: April 2011

Information is provided on a new species of Loxosomella, L. diopatricola, with unusual characteristics that is symbiotic with tubicolous polychaetes of the genus Diopatra. Plasticity is displayed in the morphology of the attachment organ: the new loxosomatid possesses a stalk terminating in either a persistent pedal gland or an enlarged adhesive disc. An individual animal develops one or other of the two stalk morphologies according to its exact location on the host and the thickness of the underlying cuticle. The host epidermis underlying individuals with an adhesive disc is, in turn, modified, suggesting that these symbionts may negatively affect their hosts. Females possessed a single ovary, nearly always on the left side. The larva lacks eyespots. Buds were borne only by males. A minute species of Loxosomella commensal on polychaetes of the genus Eunice, characterised by 6 tentacles and a very short stalk, is also described. A grooved foot is present in the bud and a pedal gland is retained in the adult. The larva apparently undergoes metamorphosis.