bluuebunny/crossref_metadata_2025 huggingface dataset:
Food-anticipatory activity of groups of golden shiners during both day and night
Authors: Laguë Martin , Reebs Stéphan G
Published: April 2011

For 12 days, captive groups each containing four golden shiners (Notemigonus crysoleucas) were fed by automatic feeders at two diametrically opposed daily times. These two times could be midday and midnight, late day and late night, or early day and early night. As measured by interruptions of an infrared beam underneath the feeder, golden shiners almost always expressed food-anticipatory activity. Beam interruptions started to increase a few hours before mealtime, reaching a peak within 1.5 h of food delivery. In at least half of the groups tested, food-anticipatory activity developed for both daily times simultaneously. This double anticipation was maintained for at least 5 days after food was withheld. These results show that golden shiner groups (though not necessarily individuals) can express two peaks of food anticipation at widely separated daily times, even if one occurs during the day and the other at night, providing further evidence for the great variability that fishes can display in their activity patterns.
A geographic analysis of snowshoe hare population demography
Authors: Murray Dennis L
Published: April 2011

Snowshoe hare (Lepus americanus) populations across northern Canada and Alaska undergo 8- to 11-year cycles in numbers, but population trends in southern Canada and the contiguous United States are apparently either weakly cyclic, irruptive, or largely stable. Although the demographic attributes (population density, reproductive rates, and survival rates) of northern and southern hare populations should differ considerably to account for such differential trends, to date limited rangewide analyses of hare demography have been undertaken. I reviewed hunter harvest estimates and basic demographic attributes for hare populations across North America, and assessed the effect of latitude, longitude, and latitude × longitude interaction on the magnitude and variation of such attributes. Harvest estimates tended to be synchronous across the Great Lakes area and along the St. Lawrence River, whereas they varied more dramatically along a westward gradient and in hare populations suspected of being cyclic. Hare densities tended to be higher among apparently noncyclic than cyclic populations at numerical lows, as well as among studies where hare numbers were apparently increasing. Populations from northern latitudes tended to breed later than those in the south, and females from western areas produced larger, but fewer litters, than those from eastern populations; total productivity was similar across geographic areas. Survival rates for both adult and juvenile hares were higher in increasing populations than in decreasing populations. Survival of adults also decreased along a northwest gradient, whereas that of juveniles decreased across a western gradient and with longitude, was lower in apparently noncyclic populations, and was also lower in populations in areas of high lynx (Lynx canadensis) densities. I conclude that, although disparity clearly exists in the trends of various hare populations, the absence of strong latitudinal gradients in demographic attributes fails to support the hypothesis that differential survival/predation is responsible for the regional differences in numerical trends.
Influence des conditions climatiques sur le comportement du Lièvre d'Amérique (Lepus americanus) en semi-liberté
Authors: Théau Jérôme , Ferron Jean
Published: April 2011

Snowshoe hare (Lepus americanus) behavior has been analyzed over a1-year period to understand the influence of climatic factors. Six animals were observed with a video camera in a 1350-m2 outdoor enclosure located in a wood stand andequipped with a computerized weather station. Temperature (°C), relative humidity (%), windspeed (km/h), and barometric pressure (hPa) were recorded every 5 min during the entire study period. Every month, 72 h of observation were recorded to correlate those factors with feeding, locomotion, grooming, and resting behavior. Results indicate a marked influence of climatic conditions on hare behavior patterns. All patterns are more frequent when relative humidity is high or increasing. Locomotion and feeding are more common when temperature is low or decreasing, or when barometric pressure is increasing. Wind speed has a negative effect on the frequency of all behavioral patterns. Those effects are discussed in relation to hare biology. It appears that energetic constraints associated with harsh weather conditions have forced the snowshoe hare to adopt a flexible behavioral strategy.
Cold hardiness in two helminth parasites of the freeze-tolerant wood frog, Rana sylvatica
Authors: Woodhams Douglas C , Costanzo Jon P , Kelty Jonathan D , Lee, Jr. Richard E
Published: April 2011

Wood frogs, Rana sylvatica, tolerate the freezing of their body tissues as an overwintering adaptation. Various parasites infect wood frogs of northern populations, but nothing is known about their strategies for surviving within a frozen host. We examined winter-conditioned wood frogs that were experimentally exposed to 0°C (nonfrozen) or 4°C (frozen) to determine whether endoparasites survive the freezing of their host. We found no differences in the prevalence or intensity of adult lungworms Rhabdias ranae (Nematoda) or of larvae of an unidentified species of digenetic trematode between these groups. Live individuals of both species were observed in hosts that recovered from experimental freezing at 4°C. Within the host, R. ranae also tolerated exposure to 5°C, a temperature near the lower limit of survival of the wood frog. Cryostage experiments showed that, like its host, R. ranae was highly susceptible to inoculative freezing and tolerant of the freezing of its tissues. Rhabdias ranae frozen in vitro in the presence or absence of 250 mM glucose, the cryoprotectant used by wood frogs, recovered from a 10-h exposure to 4°C. The mechanism of cold tolerance used by larval trematodes was not investigated; however, we hypothesize that freeze avoidance by supercooling may be important in this species. Freeze-tolerant anurans, such as the wood frog, are useful subjects in the study of coevolution of thermal tolerance in parasites and their host.
Eurasian beavers (Castor fiber) behavioral response to simulated territorial intruders
Authors: Rosell Frank , Johansen Geir , Parker Howard
Published: April 2011

Eurasian beavers (Castor fiber) live in family groups that defend territories against other conspecifics. Part of this territorial defence involves constructing scent mounds near the stream bank within territories and marking them with castoreum, a urine-based fluid from the castor sacs, and (or) anal-gland secretion. The aim of this study was to test the hypothesis that Eurasian beavers show one or more forms of territorial behavior when an intruder, simulated in the form of experimental scent mounds (ESMs), has scent-marked inside the territory. We predicted that beavers would show a stronger response to ESMs with castoreum than to those without. Results showed that 85% of all beaver families (N = 20) made one or more behavioral responses to ESMs marked with castoreum from foreign adult males, whereas no ESMs presented without castoreum received a response. We therefore conclude that a main function of territorial marking by beavers is to advertise spatially related dominance status, thereby providing opportunities for intruders to assess the presence of the owner and reducing the cost and risks of agonistic conflict for both the owner and intruders. Additionally, it appears to be the scent emitted from an ESM and not the sight of it to which beavers respond.
Proliferative activity of follicles and serum steroid concentration in Scotophilus heathi (vespertilionid bat) during periods of delayed ovulation
Authors: Krishna A , Abhilasha S
Published: April 2011

Follicular kinetics were studied using immunocytochemical localization of proliferating cell nuclear antigen (PCNA) and changes in circulating steroid concentrations to investigate the cause of prolonged survival of Graafian follicles and delayed ovulation in the vespertilionid bat Scotophilus heathi. PCNA immunoreactivity was limited to the granulosa cells and varied with stage of follicular development and reproductive phase. Two waves of follicular growth appear to be initiated in October and February. The first wave resulted in the appearance of some late antral follicles in November. These antral follicles grew slowly and differed from typical mammalian Graafian follicles, as the cells of their cumulus oophoricus were large and hypertrophied. The second wave of follicular development resulted in fresh recruitment and selection of dominant follicles in February. The steroid-hormone profile showed an unusually high concentration of circulating androstenedione from October to December. The estradiol concentration showed two peaks coinciding with two peaks of PCNA immunoreactivity. The results show that the unusually high androstenedione concentration might be responsible for the development of non-ovulatory Graafian follicles with hypertrophied granulosa cells, which survive for a prolonged period. The decline in androstenedione concentration allows the development of ovulatory follicles in S. heathi.
The thermoregulatory potential of Ovis horn cores
Authors: Hoefs Manfred
Published: April 2011

Cranial measurements were taken from 378 Ovis skulls (258 male, 120 female), covering most subspecies of wild sheep. Horn core length and circumference data were used to estimate the core surface. This highly vascularized plexus constitutes the radiating area. A simple index of heat-exchange capacity was calculated by dividing the combined surfaces of two horn cores by the mass of the animal. This index provided a standard by means of which different types of sheep could be compared, as well as allowing the detection of correlations with environmental gradients, which would point to a thermoregulatory role for horn cores. It can be assumed that, for sheep living in cold climates, heat conservation is important, while for those living in hot environments, enhanced heat dissipation would be advantageous. Our data confirm this hypothesis. The thinhorn sheep (Ovis dalli and Ovis nivicola) of subarctic and arctic northwestern North America and northern Siberia have the smallest horn cores, with indices of 6.9-7.3 cm2/kg, while desert-dwelling types have indices of more than twice these values. For instance, the desert subspecies of the American bighorns (Ovis canadensis nelsoni, Ovis canadensis mexicana, Ovis canadensis cremnobates) have indices ranging from 15.1 to 16.5 cm2/kg. Other sheep types have indices of intermediate sizes. It is our position that this evolutionary trend to vary core size in response to ambient temperature is independent of a parallel trend to increase horn size for the benefit of enhancing reproductive success.
Geographical variation in the male intromittent organ of the Trinidadian guppy (Poecilia reticulata)
Authors: Kelly Clint D , Godin Jean-Guy J , Abdallah Ghada
Published: April 2011

Sexual selection may favour the evolution of elaborated genital traits in males, particularly when phenotypic variation in such traits results in corresponding variation in reproductive success among males in the population. Compared with insects, very little is known about the natural variation in any male genital trait, and its causes, in vertebrates. Here we report on variation in a male intromittent organ both within and between natural populations of a vertebrate, the Trinidadian guppy (Poecilia reticulata). Male guppies inseminate females using an intromittent organ called the gonopodium. We demonstrate that males from populations that have evolved under high fish-predation intensity have, on average, a relatively longer gonopodium than males originating from populations under low fish-predation intensity. Compared with body coloration, the gonopodium exhibited relatively low phenotypic variation, but nonetheless was within the range of known variation for sexually selected traits. The male gonopodium was positively allometric in general. To our knowledge, this is the first report of within-species variation in an intromittent organ and of a positive allometric relationship between male genitalia and body size in a vertebrate species. Our results suggest that the length of the male intromittent organ in the guppy is under selection, which varies geographically.
Female mimicry in garter snakes: behavioural tactics of "she-males" and the males that court them
Authors: Shine Richard , O'Connor David , Mason Robert T
Published: April 2011

Red-sided garter snakes (Thamnophis sirtalis parietalis) in central Manitoba court and mate in early spring soon after emerging from communal overwintering dens. Some males ("she-males") produce female-like skin pheromones, and hence attract courtship from other males. Studies at a den near Inwood, Manitoba, support and extend results from work at other dens. She-males were males that had recently emerged from hibernation and had not yet regained full locomotor capacity or muscle strength. She-males resembled "he-males" rather than females in their antipredator responses, including the thermal threshold at which they fled from a simulated predator (a plastic crow) rather than remaining stationary and displaying. Males courting she-males were cooler than those courting females; nonetheless they were more likely to flee when we approached them. Compared with courting groups focussed on females, groups around she-males were smaller, consisted predominantly of smaller he-males, and were found over a more restricted time of day (early afternoon). Arena trials confirmed that she-males are disproportionately courted by small rather than large he-males, and clarified other aspects of she-male attractiveness and behaviour. She-males attracted more intense courtship when large females were absent. She-males courted less vigorously when large he-males were present, especially when they were vigorously courted themselves. Overall, our data reveal hitherto-unsuspected complexity in the behavioural tactics of reproducing garter snakes.
Effects of parasitism on the octopamine content of the central nervous system ofManduca sexta: a possible mechanism underlying host behavioural change
Authors: Adamo Shelley A , Shoemaker Kelly L
Published: April 2011

The parasitic wasp Cotesia congregata lays its eggs inside the larva of Manduca sexta (tobacco hornworm). Beginning about 12 h before the wasp larvae emerge from the host, host feeding and locomotion decline. The octopamine content of the central nervous system (CNS) of parasitized hosts was measured using high-performance liquid chroma tography with electrochemical detection. Concomitant with the decrease in host feeding and locomotion, the octopamine content of the host's brain (supra- and sub-esophageal ganglia), thoracic ganglia, and abdominal ganglia increased. In nonparasitized M. sexta, the octopamine content of the CNS did not change significantly during moult sleep, a stage in which the behaviour superficially resembles that of M. sexta after the wasps have emerged. Neither result is consistent with the hypothesis that the octopamine content within the CNS is lower in inactive insects. Nevertheless, the close temporal correlation between the change in host behaviour and CNS octopamine content suggests that alterations in the functioning of the octopaminergic system may play a role in depressing host feeding and (or) locomotion.
Stable carbon, nitrogen, and sulfur isotope ratios in riparian food webs on rivers receiving sewage and pulp-mill effluents
Authors: Wayland Mark , Hobson Keith A
Published: April 2011

We examined spatial trends in ratios of stable isotopes of nitrogen (δ15N), carbon (δ13C), and sulfur (δ34S) in riparian food webs leading to a riparian, insectivorous bird species, the tree swallow (Tachycineta bicolor), on rivers receiving pulp-mill effluent and municipal sewage and compared them with ratios of these isotopes in components of the effluents themselves. The study was conducted on two rivers in western Canada at sites upstream and downstream from sewage and pulp mill effluent sources. Municipal sewage contained materials with δ15N or δ13C values that were distinct from background conditions in the receiving environment. Pulp-mill effluent contained materials with δ34S values that were distinct from those at upstream sites on the rivers. At both locations, effluent-derived nitrogen and sulfur were observed in algae and suspended sediments at sites downstream from the effluent sources. This was also observed in adult aquatic insects, the one exception being that uptake of effluent-derived nitrogen was detected isotopically at only one location. Tree swallows' use of sewage-derived nitrogen was evident only at one location, while use of pulp-mill-derived sulfur was evident only at the other location. Our study demonstrates the usefulness and limitations of measuring stable isotopes for tracing the movement of nutrients derived from sewage and pulp-mill effluent in freshwater ecosystems and, further, indicates that such tracing may be extended to riparian species feeding on aquatic prey.
Biodiversity series: ForewordScience and the conservation of biodiversity
Authors: Morris Douglas W
Published: April 2011

Humans are most likely to conserve biodiversity when they derive direct utilitarian benefit by doing so. High biodiversity, for example, may often reduce the frequency of disease and pestilence. Scientists are morally and professional obliged to (i) make society aware of such benefits and (ii) promulgate the value and practice of science.
Orientation of rainbow trout (Oncorhynchus mykiss) to multiple patches of linearly polarized light
Authors: Degner Shelee L , Hawryshyn Craig W
Published: April 2011

Orientation responses of juvenile rainbow trout (Oncorhynchus mykiss) to two linearly polarized light patches were examined under controlled laboratory conditions. Fish were trained to swim the length of the training tank under a polarized light field created by two linearly polarized stimuli that were oriented either parallel or perpendicular to the length of the tank. Trained fish were released in a circular tank and their angular responses were recorded. For each testing paradigm, the E-vector (electric vector) orientation of one of the two linearly polarized light patches was varied by 15° between 0° and 90°. Each fish was therefore tested in seven different paradigms in which the two E-vector orientations differed by 0°, 15°, 30°, 45°, 60°, 75°, and 90°. Rainbow trout oriented in a bimodal distribution when the two E-vector orientations differed by 0°, 15°, 30°, 45°, and 90°. These results suggest that rainbow trout perceived the two stimuli as being the same when the two E-vector orientations differed by 45° or less. Conversely, rainbow trout did not significantly orient when the two E-vector orientations differed by 60° and 75°. Rainbow trout may be able to discriminate two E-vector orientations that differ between 60° and 75°, and therefore they do not significantly orient, since they perceive two distinct E-vectors to orient to instead of one. When rainbow trout were exposed to a depolarized light field, they did not exhibit significant orientation subsequent to the E-vector cue.
Use of stable-carbon and -nitrogen isotopes to assess weaning and fasting in female polar bears and their cubs
Authors: Polischuk S C , Hobson K A , Ramsay M A
Published: April 2011

In some species, stable-isotope techniques can provide insights into dietary regimens where there are temporal shifts in trophic level or feeding frequency. We determined stable carbon (δ13C) and nitrogen (δ15N) isotope values for plasma and milk proteins and δ13C values for milk lipids from female polar bears (Ursus maritimus) and cubs to (i) ascertain whether cubs are at a higher trophic level than their mothers as a result of nursing and whether we can determine when weaning occurs, and (ii) determine the impact of seasonal fasting on δ13C and δ15N values. The plasma δ13C values for mothers and cubs were similar to milk-protein δ13C values and were significantly enriched in 13C compared with those for milk lipid. Plasma from cubs of the year (COYs) in spring, when milk was their only diet, was isotopically enriched in 15N by 1.0 over that of their mothers (δ15N = 21.5 ± 0.8 (mean ± SD) for cubs and 20.5 ± 0.5 for mothers) and depleted in 13C by 0.8  (δ13C = 19.6 ± 0.5 for cubs and 18.8 ± 0.8 for mothers). For bears who fasted between summer and fall (34 months), plasma became depleted in 13C by 0.5 and in 15N by 1. Plasma from females, who had fasted from summer to spring (78 months) and given birth to cubs, became enriched in 13C by 0.7 and in 15N by 2. By using stable-isotope analyses we were able to show that (i) young cubs were at a higher trophic level than their mother when milk was their only food source, and (ii) seasonal fasting influenced δ13C and δ15N values. However, we were not able to use stable-isotope analyses to determine the exact time of weaning.
Production of antifreeze glycoproteins in cultured and wild juvenile Atlantic cod (Gadus morhuaL.) in a common laboratory environment
Authors: Purchase C F , Goddard S V , Brown J A
Published: April 2011

Many fishes accumulate antifreeze proteins or antifreeze glycoproteins (AFGPs) in the blood to increase their chances of survival in cold seawater. Cod (Gadus morhua L.) from colder environments have been found to produce more AFGPs than those from warmer areas, but the genetic and environmental contributions to this variation have not been determined. Populations of cultured (from the Grand Banks; Gulf of Maine) and wild (from Fortune Bay; Bonavista Bay) juvenile cod were kept in a common laboratory environment to investigate differences in AFGP production. All the populations were capable of producing AFGPs, and the AFGP levels were similar in cultured and wild cod. The results indicate that high temperatures associated with the production of cultured cod do not negatively affect the ability to produce AFGPs. In addition, young cod from as far south as the Gulf of Maine are capable of producing AFGPs at levels similar to those from the northeast coast of Newfoundland.
Habitat use by Loggerhead Shrikes in Ontario and Quebec
Authors: Chabot Amy A , Titman Rodger D , Bird David M
Published: April 2011

Once common throughout northeastern North America, the migrant race of Loggerhead Shrike (Lanius ludovicianus migrans) has undergone a drastic decline since the middle of the last century. The subspecies was designated as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 1991. To gain a better understanding of the factors affecting the decline of this species in eastern Canada, habitat selection by Loggerhead Shrikes breeding in Ontario (Smith's Falls, Napanee, and Carden limestone plains) and southern Quebec was studied in 1991 and 1992. Nest trees used by breeding shrikes were compared with similar arbitrarily identified trees in suitable unoccupied habitat to determine if there was a nest-tree preference. Territories where successful nesting attempts were made (i.e., young fledged from at least one of the eggs laid) were located over a 2-year period; data were not collected for unsuccessful nests or nests used for double-brooding. Thirty-seven nests (50%) were located in hawthorn shrubs (Crataegus spp.) and 29 nests (40%) in red-cedar trees (Juniperus virginianus). White cedar (Thuja occidentalis), buckthorn (Rhamnus catharticus), and ash (Fraxinus spp.) were used infrequently (10%). Sixty-two nests (86%) were located in isolated trees or in a copse. Ten nests (14%) were located in hedgerows. Fifty-one (64%) nest sites were located in an actively grazed pasture. The other nest sites were located in idle pasture, hayfields, or old fields. Nest trees and arbitrarily chosen trees in suitable unoccupied habitat did not differ significantly in average height, width, or canopy concealment. Few differences were detected in the average height of the vegetation or the composition of ground cover within a 10-m radius of nest trees and arbitrarily chosen trees. The average numbers of shrubs per hectare did not differ between breeding sites and suitable unoccupied habitat. Nest trees in the Smith's Falls core breeding area were located significantly closer to roads than arbitrarily chosen trees in suitable unoccupied habitat. Habitat suitability was also assessed according to the density of perches (trees and shrubs), which directly affects the amount of actual utilizable habitat in a territory. Significant differences were found in the amounts of actual habitat and potential habitat. The amount of habitat around active nest sites, historic nest sites, and suitable unoccupied sites was significantly greater around active nest sites. Since few statistically significant differences were found between habitat occupied by shrikes and that which was not used, it is not possible to build a predictive model of suitable breeding habitat for shrikes in this study area.
Effects of seasonal change and prolonged anoxia on metabolic enzymes of Littorina littorea
Authors: Greenway Steven C , Storey Kenneth B
Published: April 2011

The effects of seasonal change (July versus November) and prolonged anoxia (N2 atmosphere at 5 or 10°C for 6 days) exposure in vivo on the activities of 18 enzymes, as well as the kinetic properties of phosphofructokinase (PFK) and pyruvate kinase (PK), were investigated in foot muscle and digestive gland of the marine periwinkle Littorina littorea L. Seasonal differences in enzyme maximal activities were tissue-specific, with generally increased activities during the summer and changes in a greater number of enzymes in digestive gland than in foot muscle. Seasonal differences in the kinetic properties of PFK and PK were observed in both tissues. PK from digestive gland of winter animals showed a much higher S0.5 for phosphoenolpyruvate and stronger changes in enzyme kinetic properties in response to anoxia than did the enzyme in summer animals; this may suggest the presence of seasonal isozymes. The effects of anoxia were tissue- and season-specific. Anoxia exposure during the winter induced a greater number of changes in enzyme maximal activities in foot muscle than in digestive gland. Anoxia-induced changes in the kinetic properties of both PFK and PK were also seen in both organs. For PK, these changes were consistent with less active enzyme forms in the anoxic state. Hence, both seasonal and environmental (anoxia) factors influence enzyme maximal activities and kinetic properties in L. littorea.
Tarsal asymmetry, trait size, and extreme phenotypes in a sexually size-dimorphic water boatman Callicorixa vulnerata
Authors: Nosil P
Published: April 2011

Fluctuating asymmetry (FA) in morphological traits can vary with the size of characters and the mode of selection acting on them. In a previous study, mid-leg tarsal FA (tarsal spine number and tarsal length) in the water boatman Callicorixa vulnerata was inversely related to fitness in both sexes. The mid-legs of water boatmen are used to cling to bottom substrate during underwater feeding and if under stabilizing selection, extreme phenotypes are predicted to exhibit elevated FA. In this study, it is shown that water boatmen with large or small mid-leg tarsal traits tend to have higher levels of tarsal FA than modal phenotypes, possibly because of increased homozygosity, poor genomic balance, or greater stress during development in extreme phenotypes. This relationship suggests selection against asymmetry per se will indirectly impose stabilizing selection on trait size. Regression analyses revealed that the relationship between FA and trait size differed between the sexes and was best described by a U-shaped distribution in females but by a relatively flat, negative linear association in males. These results indicate possible directional selection on male tarsal traits. Alternatively, they suggest associations between FA and trait size do not always reflect the mode of selection acting on a trait.
Quantifying errors associated with using fecal samples to determine the diet of the California sea lion (Zalophus californianus)
Authors: Orr Anthony J , Harvey James T
Published: April 2011

The purpose of this study was to quantify the errors associated with using fecal samples to determine the diet of the California sea lion (Zalophus californianus). Fishes and squids of known size and number were fed to five sea lions held in enclosures with seawater-filled pools. Enclosures were washed and pools were drained periodically so that sea lion feces could be collected using a 0.5 mm mesh bag. Fish otoliths and squid beaks were collected from feces and used to estimate number and size of prey eaten. An average of 50.7% (SE = 6.4%) of 430 fishes and 73.5% (SE = 12.0%) of 49 cephalopods fed to sea lions were represented by otoliths and beaks in feces, respectively. Estimated lengths of fish from feces were less than lengths of fish fed to sea lions by an average of 30.1% (SE = 2.8%). Beaks were not digested significantly; estimated lengths of squid were underestimated by an average of only 3.3% (SE = 1.5%) relative to actual lengths. Passage rates of otoliths varied, but more than 70% were recovered within 48 h after the fish was consumed. Passage rates of beaks were generally less than those of otoliths; six beaks (11%) were collected in feces 4 days after the squid were eaten. Correction factors were created to more reliably estimate the number and size of fishes and cephalopods eaten by California sea lions.
Phenotypic assortative mating and within-pair sexual dimorphism and its influence on breeding success and offspring quality in Magellanic penguins
Authors: Forero M G , Tella J L , Donázar J A , Blanco G , Bertellotti M , Ceballos O
Published: April 2011

We examined within-pair sexual dimorphism and phenotypic assortative mating in Magellanic penguins (Spheniscus magellanicus) breeding in six colonies located on the Patagonian coast (Argentina). All measured phenotypic traits except the number of pectoral spots differed between the sexes; bill depth and flipper length were the most and least dimorphic traits, respectively. We found assortative mating by bill depth and body mass. The similarity in body condition within pairs was close to significant. When we performed separate correlations for birds that bred successfully, i.e., raised one or two offsprings, and birds that did not attempt to breed or bred unsuccessfully, only the successful breeders showed assortative mating by body mass. In addition, we attempted to relate the body size of each member of the pair and the degree of sexual dimorphism within pairs to the breeding performance of individuals, which was measured as brood size, and body condition and immunocompetence of offspring. We found that pairs that were less dimorphic in flipper length raised more offspring. This effect was due to female flipper length per se and not to the relative difference in flipper length between members of the pair. Females with larger flippers had a higher probability of raising two chicks. No effects of body measurements or degree of sexual dimorphism on body condition or T-cell-mediated immune response of offspring were found. We discuss these results in the context of potential factors responsible for the maintenance of sexual size dimorphism in this species.
Patterns of behavior in the Texas tortoise, Gopherus berlandieri: a multivariate ordination approach
Authors: Kazmaier Richard T , Hellgren Eric C , Synatzske David R
Published: April 2011

We compared the distribution of 19 categories of behavior exhibited by 47 adult Texas tortoises (Gopherus berlandieri) over 3 years with the use of detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). DCA revealed a gradient from passive to active behavior along axis 1. Tortoises were more active in 1994 and less active in 1996. This pattern was likely due to the extremely hot and dry conditions in 1996. Year was the most significant variable explaining variability in behavior when sex, age, size, year, and grazing treatment (pastures grazed versus ungrazed by cattle) were used as environmental variables in CCA. Age, size, and grazing treatment were not significant variables in CCA. Tortoises used proportionally more burrows, shallow surface depressions termed pallets, and cavity pallets, and ate more cactus in 1996. More foraging and active behaviors, like courtship, were observed in 1994. Sex was a significant variable in explaining behavioral variability after the effects of year were controlled for. Males tended to exhibit more active behaviors than females. Our analyses suggested that the grazing regime used in Chaparral Wildlife Management Area did not affect the patterns of behavior exhibited by this protected tortoise.
Ecological correlates of pneumonia epizootics in bighorn sheep herds
Authors: Monello Ryan J , Murray Dennis L , Cassirer E Frances
Published: April 2011

Bighorn sheep (Ovis canadensis) populations commonly experience pneumonia outbreaks caused by Pasteurella spp. that result in a partial or complete dieoff. Although several factors can contribute to Pasteurella spp. transmission or infectivity in bighorn sheep, to date the importance of such factors in population declines has not been rigorously examined. We evaluated the relationship between pneumonia-induced dieoffs in bighorn sheep and environmental and biological factors by analyzing demographic information for 99 herds across the species' geographic range. Our analysis revealed that 88% of pneumonia-induced dieoffs occurred at or within 3 years of peak population numbers, which implies that density-dependent forces such as food shortage or stress contribute to bighorns' susceptibility to pneumonia. There were few differences in the growth rates of dieoff and non-dieoff populations, suggesting that pneumonia did not manifest itself demographically prior to an outbreak. On average, abundance of lambs was most dramatically reduced post outbreak (66%) relative to that of either rams (35%) or ewes (42%). Deviations in normal precipitation and temperature regimes were not associated with the onset of pneumonia outbreaks, but herds found in proximity to domestic sheep tended to be more susceptible to dieoff. Our results suggest that bighorn sheep herds are rendered vulnerable to pneumonia principally through density-dependent factors, as well as through horizontal transmission of Pasteurella spp. from domestic sheep serving as reservoir hosts.
Age, growth, and survivorship in the viviparous salamander Mertensiella luschani from southwestern Turkey
Authors: Olgun Kurtulus , Miaud Claude , Gautier Patrick
Published: April 2011

We describe the life-history traits (body size, age at maturity, longevity, and survivorship) of a terrestrial salamander, Mertensiella luschani, from a population living in the Mediterranean environment of southwestern Turkey. We used phalangeal skeletochronology to estimate the age of juveniles and adults. Lines of arrested growth, deposited during the winter cessation of bone growth, allowed us to estimate the age at maturity to be 3 years old in both sexes. Males attained a maximum age of 8, whereas females attained a maximum age of 10. Juveniles ranged from 1 to 3 years old. Males were smaller than females. Growth curves fitted to von Bertalanffy's equation revealed similar growth coefficients in adults and larger average maximum body lengths in males. Adult annual survivorship and adult life expectancy were 0.79 and 5.4 years, respectively. Knowledge of age, growth, and survivorship in this species under the constraints of a seasonal Mediterranean climate, and a comparison of similar traits in other salamandrid species, allow us to test predictions regarding optimal timing of growth and reproduction in these species.
Geographic diversification in the call repertoire of the genus Pyrrhocorax (Aves, Corvidae)
Authors: Laiolo Paola , Rolando Antonio , Delestrade Anne , Sanctis Augusto De
Published: April 2011

We analysed the call repertoires of the Red-billed Chough (Pyrrhocorax pyrrhocorax) and the Alpine Chough (Pyrrhocorax graculus) across three continents (Europe, Asia, and Africa) for intraspecific and interspecific differences in call-repertoire size and discuss the factors that could have promoted its evolution. The overall call repertoire of the Red-billed Chough was twice as large as that of the Alpine Chough, but the number of calls recorded in each population did not differ significantly between the two species. The greater fragmentation of the range of the Red-billed Chough possibly induced its remarkable call-repertoire diversification. Some populations (i.e., those from Ethiopia, Central Asia, Canaries) had a peculiar call repertoire that overlapped very little with those from other regions; consequently, the overall numbers of call types within the species were heavily influenced by these unusual populations and were very large. The call-repertoire size and call-repertoire similarity of populations of both species were affected and constrained by geographic distance. More closely situated or continental populations tended to have a more similar pool of calls (this is probably due to mingling among close populations).
Hybridization in leopard frogs (Rana pipiens complex): terrestrial performance of newly metamorphosed hybrid and parental genotypes in field enclosures
Authors: Parris Matthew J
Published: April 2011

Terrestrial ecology has been largely neglected in the study of amphibian life histories because it is difficult to manipulate most species during the terrestrial stage. I examined the terrestrial performance of Rana blairi, Rana sphenocephala, and four hybrid (two F1 and two advanced generation) genotypes in replicated experimental enclosures to test for differences in traits related to juvenile terrestrial fitness. I produced all genotypes by means of artificial fertilizations using frogs collected from natural populations in central Missouri, and juvenile frogs were obtained from larvae reared in experimental ponds. Following metamorphosis, froglets were raised in single-genotype groups in terrestrial enclosures through the first overwintering. The proportion surviving did not vary among genotypes, but the power to detect significant differences was low. F1 hybrid genotypes BS and SB demonstrated significantly higher growth rates than either parental species or advanced-generation hybrid genotypes. Observation of growth rates of advanced-generation hybrids equal to those of the parental species, and heterosis in F1 hybrids for growth rate, suggests that natural hybridization between R. blairi and R. sphenocephala can produce novel and relatively fit hybrid genotypes. Direct measurement of multiple fitness components for hybrid and parental genotypes is critical for assessing the evolutionary potential of natural hybridization in organisms with complex life cycles.
Effects of 5-HT (serotonin) on reproductive behaviour in Heterodera schachtii (Nematoda)
Authors: Jonz Michael G , Riga Ekaterini , Mercier A Joffre , Potter John W
Published: April 2011

The effects of serotonin (5-hydroxytryptamine or 5-HT) on the reproductive behaviour of Heterodera schachtii was examined. Male and juvenile H. schachtii were incubated in 5-HT for 15 min. Stylet thrusting was stimulated by 10 mM 5-HT, whereas 0.1 mM 5-HT was without effect. Prolonged treatment of males with 10 mM 5-HT induced eversion of the spicules and extrusion of materials from the reproductive tract. Treatment with 60 mM triethanolamine and Wright's stain indicated that extrusions did not contain spermatids or spermatozoa. We confirm the effects of 5-HT on reproductive behaviour and suggest that the stylet and pharynx may subserve a reproductive function during later life stages in H. schachtii.
Modulation of claw-closing behavior in the crayfishProcambarus clarkiiby extrinsic factors and biogenic amines
Authors: Copp Newton H , Su Tony
Published: April 2011

Claw closure in the crayfish can be elicited by tactile stimulation of the closer-field sensory hairs located along the biting surfaces of the apposed dactyl and propodite. The possibility that this simple behavior can be extrinsically modulated was examined by stimulating closer-field hairs in specimens of the crayfish Procambarus clarkii while the animals were either unrestrained, restrained, or bathed in chemical feeding stimulants. Restraint increases both the probability of closure and the average angular velocity of the dactyl during closure compared with responses in unrestrained specimens. Chemical feeding stimulants increase the probability, but not the average angular velocity, of closure compared with the unrestrained condition. Injection of octopamine into unrestrained animals produces effects on claw closure that resemble those accompanying restraint. Injection of serotonin, however, is followed by decreases in both the probability and the average angular velocity of closure. It is argued that extrinsic factors modulate claw-closure behavior in ways appropriate to current circumstances, and that biogenic amines are implicated as "gain-setters" in this process.
Changes in nesting-habitat use of large gulls breeding in Witless Bay, Newfoundland
Authors: Robertson Gregory J , Fifield David , Massaro Melanie , Chardine John W
Published: April 2011

We counted herring gull (Larus argentatus) and great black-backed gull (Larus marinus) nests in the Witless Bay Seabird Ecological Reserve in southeastern Newfoundland, Canada, in 1999 and 2000 and compared our results with previous nest counts from the 1970s. On Gull Island, herring gull nest numbers were 27.5% (1999) and 30.0% (2000) lower than in 1979. Similarly, on Great Island, by 2000 the numbers of herring gull nests had declined 40.8% from numbers in 1979. Counts of great black-backed gull nests were more variable, but suggest a slight or no reduction since 1979. Numbers of herring gulls nesting in rocky and puffin-slope habitats were much reduced (5070%), while numbers nesting in meadows and forests have actually increased since the 1970s. Great black-backed gulls showed a similar change in nesting distribution. For herring gulls, these changes in nesting numbers matched differences in reproductive success previously documented in these habitats. We suggest that the decline in gull numbers and the change in breeding-habitat selection were caused by changes in the food availability for gulls. Reduced amounts of fisheries offal and the delayed arrival onshore of capelin (Mallotus villosus), an important fish prey species for gulls, have all likely led to the decline in gull reproductive output. Gulls nesting in meadows and forests may be maintaining adequate reproductive output by focusing on alternative prey, such as adult Leach's storm-petrels (Oceanodroma leucorhoa), rather than scarce refuse and fish.
Nesting biology and social organization of Halictus sexcinctus (Fabricius) in southern Greece
Authors: Richards M H
Published: April 2011

Halictus sexcinctus is a large halictine bee species widely distributed across central Europe and into the Middle East. Although its behaviour had not previously been studied in detail, it is known to exhibit solitary behaviour in central Europe. An aggregation nesting beside the seashore at Pyla-Daimonia, Demos Molai, in the southeastern Peloponnesos, Greece, was studied during the summers of 1997 and 1998. In southern Greece, H. sexcinctus exhibits weakly eusocial colonies, based on a partially bivoltine colony cycle, so across its range it is socially polymorphic. Weak eusociality in this Mediterranean population is characterized by haplometrotic nest-founding, a relatively high degree of queenworker size dimorphism, high rates of worker mating and ovarian development, relatively short queen life-spans, and relatively low second-brood productivity. Overall, the sex ratio of the first brood is highly female-biased, while that of the second brood is variable, the proportions of males and females varying significantly in the 2 years. An unusual characteristic of nest foundresses in this population is that some are un-inseminated and produce all-male first broods rather than workers.
Estimates of adult survival and migration for diamondback terrapins: conservation insight from local extirpation within a metapopulation
Authors: Tucker Anton D , Gibbons J Whitfield , Greene Judith L
Published: April 2011

As a case study we analyze a recent extirpation within a metapopulation of diamondback terrapins (Malaclemys terrapin) in a South Carolina salt marsh. Survival and migration probabilities were estimated by means of a multistratum approach in CormackJollySeber markrecapture models to obtain transition probabilities among four tidal creeks adjoining a river. Terrapins showed high fidelity to each subpopulation and the low migration rates were insufficient for recolonizing a creek that had suffered extirpation. Annual survival rates for adult female terrapins averaged 0.84 across all creeks, ranging from 0.748 to 0.971. Survival rates were converted to instantaneous mortality rates (M) for the purpose of calculating the mean life-span as 1/M. When re-expressed in terms of mean life-span, the results confirmed that the average female terrapin did not survive to its estimated age at maturity, as might be predicted if additional mortality of females in crab pots was implicated. The results emphasize that incidental mortality of terrapins in crab pots is a conservation concern. Simple modifications of crab-pot design, such as an entrance reducer, can successfully mitigate this threat to the survival of terrapin populations.
Effects of age and gender on immune function of dragonflies (Odonata, Lestidae) from a wild population
Authors: Rolff Jens
Published: April 2011

Immunity is a crucial determinant of fitness. Despite this, very few studies have addressed the expression of immune function in insect populations in the wild. I present data on two immune parameters, hemocyte load and expression of phenoloxidase, in adult damselflies (Lestes viridis) from a wild population. In a comparison of newly emerged with sexually mature adults, it was found that the latter had higher hemocyte loads but lower phenoloxidase expression. Mature females showed significantly higher phenoloxidase expression than mature males. The sexual differences might be explained by gender differences in life history.
THE EFFECT OF TEMPERATURE ON THE SPONTANEOUS ACTIVITY OF SPECKLED TROUT BEFORE AND AFTER VARIOUS LESIONS OF THE BRAIN
Authors: Fisher Kenneth C. , Sullivan Charlotte M.
Published: April 2011

The frequency of spontaneous movements made by speckled trout was determined at a number of different constant temperatures. The relation between the frequency and temperature was found to be complex, showing two maxima. One of these constantly occurred at approximately the temperature selected by normal trout in a horizontal temperature gradient and the other occurred two to three degrees below the upper lethal temperature.The relation between frequency of movements and temperature was not affected by (1) destruction of the forebrain, (2) by section of the lateral line nerves, or (3) by destruction of both the forebrain and the dorsal part of the cerebellum. Destruction of only the dorsal part of the cerebellum profoundly changed the relation between frequency of movements and temperature: it caused the disappearance of the first peak.Brief consideration was given to the legitimacy of relating the activity of animals in different constant levels of environmental factors with behavior in gradients of these factors.