bluuebunny/crossref_metadata_2025 huggingface dataset:
Predator-recognition training enhances survival of brook trout: evidence from laboratory and field-enclosure studies
Authors: Mirza Reehan S , Chivers Douglas P
Published: April 2011

In this study we tested whether brook trout (Salvelinus fontinalis) can learn to recognise predators through releaser-induced recognition learning and whether this learning enhances survival of trout during encounters with a predator. In our initial experiment, we exposed hatchery-reared predator-naïve brook trout to chemical stimuli from predatory chain pickerel (Esox niger) paired with alarm signals released by damaged trout, disturbance signals, or distilled water. In subsequent tests 24 h later, when only pickerel odour was presented, trout conditioned with damage-released alarm signals exhibited antipredator behaviour (i.e., decreased movement and altered foraging patterns), in contrast to the other treatments, thereby demonstrating learned recognition of the predator. In our second experiment we showed that trout retained the ability to recognise the predator for at least 10 days. In the next series of experiments we explicitly tested whether training trout to recognise predators confers a survival benefit. During staged encounters with chain pickerel (in both the laboratory and the field), trained fish were better able to evade the predator than nontrained fish. Ours is the first study to demonstrate that fish trained to recognise predators gain a survival benefit during staged encounters with a predator.
Low-frequency sounds emitted by Sotalia fluviatilis guianensis (Cetacea: Delphinidae) in an estuarine region in southeastern Brazil
Authors: Monteiro-Filho Emygdio LA , Monteiro Karin DKA
Published: April 2011

Recordings of the vocalizations of the dolphin Sotalia fluviatilis guianensis were made in an estuarine complex at Cananéia in southeastern Brazil over a period of 10 years (19891998). This area is characterized by mangroves and the constant presence of dolphins. Recordings were obtained at depths of 24 m using digital and analog recorders at a speed of 19 cm/s. Four classes of sounds were identified. "Whistles," which are used in social activities, occurred with the greatest frequency (χ2 = 58.92, df = 3, P < 0.001). "Calls," which were very variable in form, were the second most common class used by family groups (χ2 = 10.96, df = 2, 0.005 > P > 0.001). There were no differences in the rates at which schools emitted whistles and calls (χ2 = 2.12, df = 1, 0.25 > P > 0.10). "Gargles" were apparently emitted by calves and were similar in structure to a low-frequency call. The fourth class, "clicks," are used in echolocation. Clicks varied considerably in their frequency of occurrence and frequency of emission, and were not always detected. There were significant differences in emission rates among the four classes (χ2 = 18.73, df = 3, P < 0.001). In addition, which class of sound was emitted depended on the type of activity exhibited by the dolphins (displacement, fishing, social) and on the social structure (family or school) adopted.
Biodiversity series: The function of biodiversity in the ecology of vector-borne zoonotic diseases
Authors: Ostfeld Richard S , Keesing Felicia
Published: April 2011

This is a critical evaluation of the influence of species diversity within communities of vertebrates on the risk of human exposure to vector-borne zoonoses. Vertebrates serve as natural reservoirs of many disease agents (viral, bacterial, protozoal) that are transmitted to humans by blood-feeding arthropod vectors. We describe the natural history of the Lyme disease zoonosis to illustrate interactions among pathogens, vectors, vertebrate hosts, and risk to humans. We then describe how the presence of a diverse assemblage of vertebrates can dilute the impact of the principal reservoir (the white-footed mouse, Peromyscus leucopus) of Lyme disease spirochetes (Borrelia burgdorferi), thereby reducing the disease risk to humans. Exploring the logic of what we call the dilution effect reveals four conditions that are necessary for it to apply generally to vector-borne zoonoses: (1) the feeding habits of the vector are generalized; (2) the pathogen is acquired by the vector from hosts (as opposed to exclusively transovarial transmission); (3) reservoir competence (the ability of a particular host species to infect a vector) varies among host species; and (4) the most competent reservoir host tends to be a community dominant, as defined by the proportion of the tick population fed by that species. When these conditions are met, vertebrate communities with high species diversity will contain a greater proportion of incompetent reservoir hosts that deflect vector meals away from the most competent reservoirs, thereby reducing infection prevalence and disease risk. Incorporating the likelihood that the abundance of competent reservoirs is reduced in more diverse communities, owing to the presence of predators and competitors, reinforces the impact of the dilution effect on the density of infected vectors. A review of the literature reveals the generality, though not the universality, of these conditions, which suggests that the effects of diversity on disease risk may be widespread. Issues in need of further exploration include (i) the relative importance of diversity per se versus fluctuating numbers of particular species; (ii) the relevance of species richness versus evenness to the dilution effect; (iii) whether the dilution effect operates at both local and regional scales; and (iv) the shape of empirically determined curves relating diversity to measures of disease risk. Further studies linking community ecology with epidemiology are warranted.
Ultrastructure of the postcorpus of the esophagus of Teratocephalus lirellus (Teratocephalida) and its use for interpreting character evolution in Secernentea (Nematoda)
Authors: Zhang Y C , Baldwin J G
Published: April 2011

The ultrastructure of the postcorpus of the putative outgroup of Secernentea (Nematoda), Teratocephalus lirellus (Teratocephalida), is compared with previous observations of representative species Zeldia punctata (Cephalobina), Caenorhabditis elegans (Rhabditina), and Diplenteron sp. (Diplogastrina) in order to interpret the evolution of feeding structures within Secernentea. The postcorpus of T. lirellus consists of 6 marginal, 13 muscle, 3 gland, and 11 nerve cells. In both T. lirellus and Z. punctata, one duct from each of two subventral glands opens into the esophageal lumen at the junction of the isthmus and the basal bulb, whereas in C. elegans and Diplenteron sp., homologous openings are at the posterior end of the median bulb. Caenorhabditis elegans and Z. punctata each have two additional glands that open within the basal bulb. The postcorpus of each taxon has four anterior-to-posterior layered sets of radial muscle cells, except in Diplenteron sp., which lacks a grinder and has homologs to the anterior two sets only. The anterior set of muscles of T. lirellus and Z. punctata includes six mononucleate cells, whereas the homolog in C. elegans and Diplenteron sp. includes three binucleate cells. Evaluation of character polarity defines Rhabditina and Diplogastrina as sister taxa, and suggests that the character of five glands may result from functional convergence.
New underwater and aerial vocalizations of captive harp seals (Pagophilus groenlandicus)
Authors: Serrano A
Published: April 2011

Pinnipeds are ecologically and socially diverse, attributes that are reflected in their systems of communication. The purpose of this investigation was to document the vocal repertoire and annual cycle of vocal activity in the harp seal (Pagophilus groenlandicus), a species that communicates mainly under water, but whose social and communicative systems outside the breeding season are poorly known. The repertoire comprised 18 vocal classes, or call types; 7 that had not been described previously are described here. Vocal activity varied seasonally and with time of day. Calls of low frequency and with few pulse repetitions were predominantly used outside the breeding season, and calls of high frequency and with a high number of pulse repetitions predominated in the breeding season. The new vocalizations described here differed in several ways from those described previously. First, calls were relatively brief, with an average duration of 1.75 s (except call types 22 and 23, which averaged >2 s in duration). Second, some calls differed in mean fundamental frequency, the average being 677 Hz. Call types 22 and 23 differed the most, with an average of 838 Hz. The vocal repertoire described previously comprise calls with a fundamental frequency of approximately 400500 Hz. Third, call types 22 and 25 differed from the rest of the vocalizations. The mean maximum frequency of call types 22 and 25 was 3.4 kHz, while the mean maximum frequency of the other call types is around 7.7 kHz.
Parturition in Anodonta cygnea induced by selective serotonin reuptake inhibitors (SSRIs)
Authors: Cunha E M , Machado J
Published: April 2011

The selective serotonin reuptake inhibitors (SSRIs) fluoxetine (Nodep) and fluvoxamine (Dumyrox) are drugs commonly prescribed for the treatment of depression in humans. They act to increase serotonin (5-hydroxytryptamine) neurotransmission by inhibiting reuptake transport proteins at synapses. A similar effect of SSRIs seems to occur naturally in one group of invertebrates, the molluscs. In this study the action of these drugs at different concentrations and under different conditions was tested in the freshwater mussel Anodonta cygnea. Fluoxetine was more potent than fluvoxamine, inducing an intense release of larvae (parturition) at a concentration of 1 × 106 M in the presence of light. The non-SSRI antidepressants trazodone (Triticum), mianserine (Tolvon), and L-5-hydroxytryptophan (Cincofarm), which are known to have different serotoninergic mechanisms, had a strong, no, and a weak effect, respectively, on larval parturiton in A. cygnea. These effects suggest that serotonin could be a normal and relevant mediator of larval parturition in A. cygnea. Other parallel visible signs due to incubation with SSRIs were an increase in the volume of the foot and gills through water uptake and stimulation of valve movements. These results indicate that incubation with SSRIs is potentially important in culturing the larvae of freshwater bivalves, since it facilitates control of the intensity and timing of larval parturition.
Immune defense and biological responses induced by toxics in Annelida
Authors: Dhainaut André , Scaps Patrick
Published: April 2011

The phylum Annelida comprises primitive coelomates that possess specially developed cellular immunity against pathogens. Active phagocytosis by coelomocytes occurs in the struggle against bacteria in Polychaeta and Oligochaeta. Encapsulation plays an important role in defense against parasites, and experimental studies have demonstrated that cooperation between different coelomocyte populations occurs in this process. Spontaneous cytotoxicity of coelomocytes against xenogenic or allogenic cells is analogous with that of vertebrate natural killer cells. Graft rejection is a model for studying the activity of these cells. Accelerated rejection following multiple transplantation reveals that the cellular immune defense system has a short-term memory. In humoral immunity, agglutinins aggregate foreign material and their level is enhanced by antigens; in Annelida, however, no specificity analogous to vertebrate antibodies has been revealed, except for weak specificity of some antigen-binding proteins. Hemolytic substances have been detected, particularly in Oligochaeta, where a fetidin possesses bactericidal activity. Lysozyme and some antibacterial proteins also occur in Polychaeta. Annelida react to physical and chemical insults by various processes. These responses are mainly due to synthesis of stress-induced proteins, inhibition of enzyme activity, and modulation (inhibition or stimulation) of the activity of enzymes involved in the detoxification of xenobiotics. Moreover, these responses frequently differ from those of vertebrates, particularly in terms of the nature of inducers. In other respects, these responses are extremely variable in Annelida, even in closely related species.
Effects of habitat fragmentation on population genetic structure in the white-footed mouse (Peromyscus leucopus)
Authors: Mossman Catherine A , Waser Peter M
Published: April 2011

Habitat fragmentation may have significant consequences for population genetic structure because geographic distance and physical barriers may impede gene flow. In this study, we investigated whether habitat fragmentation affects fine-scale genetic structure of populations of the white-footed mouse (Peromyscus leucopus). We studied 27 populations of P. leucopus, 17 in continuous forest and 10 in isolated woodlots. Populations were trapped in pairs that were either 500 or 2000 m apart. We estimated genetic variation at eight P. leucopus specific microsatellite DNA loci. We discovered significant genetic variation within all populations, but no significant differences in numbers of alleles or heterozygosity between populations. For given population pairs, we found significant genetic differentiation even at very short distances, based on multilocus FSTestimates. The amount of genetic differentiation between population pairs was similar in the two habitats. Distance had a marginal effect on genetic differentiation when comparing paired populations separated by 2000 m with those separated by 500 m. However, at a larger geographic scale, there was no evidence of isolation by distance. This study confirms that microsatellite-based studies have the potential to detect interpopulation differentiation at an extremely local scale, and suggests that habitat fragmentation has surprisingly few effects on P. leucopus genetic structure.
Small-mammal responses to peat mining of southeastern Canadian bogs
Authors: Mazerolle Marc J , Drolet Bruno , Desrochers André
Published: April 2011

Bogs, or ombrotrophic peatlands, are well represented in parts of southeastern Canada but are subjected to increasing pressure from the peat industry. We assessed the impact of peat mining on small mammals inhabiting unexploited bog fragments on the periphery of mined bogs. We conducted two separate studies in bogs mined to different levels (0-83%) in southeastern Québec and New Brunswick. The first study used a low sampling effort over 1 month in 26 bogs, while the second used a high sampling effort of 6 months spread across 2 years in 12 bogs. Of the 15 small-mammal species encountered, only 2 were bog specialists. Abundance and species richness of small mammals in bog fragments increased significantly with percentage of area mined and, in some cases, increased with bog area. Both studies suggest that disturbances resulting from peat mining facilitate the invasion of more generalized small-mammal species. Furthermore, small mammals were more abundant near forest or mined edges than at bog centers, and some species responded strongly to vegetation cover. The response of small mammals to peat mining contrasts with the one documented for birds, amphibians, and plants.
Habitat selection and use by a hybrid of white and Tibetan eared pheasants in eastern Tibet during the post-incubation period
Authors: Lu Xin , Zheng Guang Mei
Published: April 2011

We investigated habitat selection and use by a recently discovered hybrid of the white eared pheasant (Crossoptilon crossoptilon) and Tibetan eared pheasant (Crossoptilon harmani) in the forests of eastern Tibet (93°39'E, 32°24'N) during the post-incubation period in 1995. The frequency of encountering molted feathers was used as an indicator of the relative abundance of eared pheasants in order to analyze patterns of habitat selection and use. Forests on south-facing slopes, dominated by the hollyleaf-like oak (Quercus aquifolioides) and Tibetan juniper (Sabina tibetica), were the habitats preferred by eared pheasants. North-facing slopes with coniferous forest, which is the most preferred habitat of eared pheasant species in other areas, were completely avoided, probably because moisture-heat conditions there are beyond the birds' physiological tolerance. We conclude that climatic conditions are the main determinant of macrohabitat selection by eared pheasant species. In preferred habitats, oak and juniper woodland accounted for a larger proportion of home ranges of family flocks. Daily movements of a flock might cover a large altitudinal range, from the base of the mountain to the area above tree line, with an apparent preference for sites that can be used for foraging and dusting.
Physiological and behavioural responses of female mountain white-crowned sparrows to natal- and foreign-dialect songs
Authors: MacDougall-Shackleton Scott A , MacDougall-Shackleton Elizabeth A , Hahn Thomas P
Published: April 2011

The objective of this study was to determine the effect of early song learning on physiological and behavioural responses to song in adulthood in female mountain white-crowned sparrows (Zonotrichia leucophrys oriantha). Juvenile females were captured before they had dispersed from their natal region. In experiment 1, natal-dialect song, foreign-dialect song, and heterospecific song were played back to the birds during photostimulation when they were 1 year old and physiological responses were measured. The physiological responses (luteinizing hormone and ovarian growth) did not indicate that natal-dialect song was more stimulating than foreign-dialect song. In experiment 2, behavioural responses (solicitation displays) to the same songs were measured when the birds were 2 years old. The birds showed a clear preference for natal-dialect song, exhibiting more displays to natal-dialect song than to foreign-dialect or heterospecific song. This effect was attenuated in birds that had heard heterospecific or foreign-dialect song when they were 1 year old. These results indicate a dissociation between behavioural preferences and longer-term physiological responses to song. Although there was a behavioural preference for natal-dialect song, this did not translate into enhanced physiological response as measured here. Moreover, natal dialect song preferences may be attenuated by adult experience.
Coping with darkness and low temperatures: foraging strategies in Steller's eiders, Polysticta stelleri, wintering at high latitudes
Authors: Systad Geir Helge , Bustnes Jan Ove
Published: April 2011

To examine how Steller's eiders, Polysticta stelleri, wintering at 70°N cope with adverse winter conditions in terms of darkness and low temperatures, we studied their feeding behaviour during four periods between late autumn and early spring. Steller's eiders were most likely to feed during daylight and twilight, but they also fed during darkness. The incidence of feeding was highest at low tide, and there was a significant interaction between tidal cycle and winter period. Hence, the birds fed more intensively at low tide in midwinter (January) than during the other periods. Air temperatures were between 8 and 10°C lower in midwinter than during the other periods, and during this period the eiders also fed more by means of nondiving techniques (up-ending, surface feeding). The total estimated feeding time was highest in late autumn and midwinter (5.9 and 6.3 h were spent actively feeding, respectively) and lower in late winter and spring (5.1 and 4.6 h, respectively). Thus, as energy requirements increased as a result of low temperatures, Steller's eiders increased their feeding effort, but also reduced feeding costs by reducing diving depth. The results of this study suggest that the Steller's eider is behaviourally well adapted to survive winter at high latitudes at relatively low stress.
Phylogenetic relationships of extant echinoderm classes
Authors: Janies Daniel
Published: April 2011

A well-supported phylogeny of echinoderm classes has eluded morphological, embryological, molecular, and combined analyses. From this body of work it is apparent that (i) echinoids (sea urchins) and holothuroids (sea cucumbers) are related, and (ii) crinoids (sea lilies) are the sister taxon to extant eleutherozoan classes (asteroids, ophiuroids, echinoids, and holothuroids). However, the relationships of asteroids and ophiuroids to other echinoderm classes have been difficult to recover. To address relationships between the asteroids and ophiuroids and other echinoderms, I have sequenced additional nuclear loci and taxa and used novel computational approaches for co-optimizing morphological with molecular evidence at the level of sequence alignment. Support for the monophyly of each class is strong. Support for a monophyletic Asteroidea + Xyloplax is as strong as for Asteroidea. Support for Asterozoa (Asteroidea + Ophiuroidea) is apparent, albeit not as strong as for other clades (e.g., Echinozoa, Eleutherozoa, and Echinodermata). I also present detailed sensitivity analyses to provide (i) a test of the monophyly of groups under a variety of evolutionary models and (ii) a statement of the evidential value of various character systems.
Not all written in stone: interdisciplinary syntheses in echinoderm paleontology
Authors: Mooi Rich
Published: April 2011

The fossil record of the Echinodermata is relatively complete, and is represented by specimens retaining an abundance of features comparable to that found in extant forms. This yields a half-billion-year record of evolutionary novelties unmatched in any other major group, making the Echinodermata a primary target for studies of biological change. Not all of this change can be understood by studying the rocks alone, leading to synthetic research programs. Study of literature from the past 20 years indicates that over 1400 papers on echinoderm paleontology appeared in that time, and that overall productivity has remained almost constant. Analysis of papers appearing since 1990 shows that research is driven by new finds including, but not restricted to, possible Precambrian echinoderms, bizarre new edrioasteroids, early crinoids, exquisitely preserved homalozoans, echinoids at the K-T boundary, and Antarctic echinoids, stelleroids, and crinoids. New interpretations of echinoderm body wall homologies, broad-scale syntheses of embryological information, the study of developmental trajectories through molecular markers, and the large-scale ecological and phenotypic shifts being explored through morphometry and analyses of large data sets are integrated with study of the fossils themselves. Therefore, recent advances reveal a remarkable and continuing synergistic expansion in our understanding of echinoderm evolutionary history.
Expression of prolactin receptor (PRL-R) mRNA in the caudal gland of Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884)
Authors: Suzuki Masatsugu , Kamewaka Yuri , Yamanaka Masami , Iwanaga Toshihiko , Ohtaishi Noriyuki
Published: April 2011

We applied the in situ hybridization technique to the Hokkaido sika deer (Cervus nippon yesoensis) caudal glands using probes designed from the red deer (Cervus elaphus) prolactin receptor cDNA. Prolactin receptor mRNA expression was consistently detected in the secretory epithelial cells collected from fawns and lactating hinds. This suggests that the presence of developed caudal glands during late pregnancy and lactation may be caused by increased blood levels of prolactin. During late pregnancy and lacation, visual range is limited for deer in forests and grasslands because of the flourishing leaves and sprigs. Therefore, we suggest that the scent emitted from the caudal gland in a particular season coordinates with and reinforces the visual alarm effect of the rump patch and tail.
Deterring arctic fox predation: the role of parental nest attendance by lesser snow geese
Authors: Samelius Gustaf , Alisauskas Ray T
Published: April 2011

High parental attendance at nests can improve nesting performance in birds by shortening the nesting period and by deterring predators that do not force birds off of nests. We examined how parental nest attendance by lesser snow geese (Chen caerulescens caerulescens) affected (i) foraging behaviours of arctic foxes (Alopex lagopus) and (ii) egg loss by geese exposed to arctic foxes at a large goose colony on Banks Island, N.W.T., Canada. Unattended nests and nests attended by single females suffered much greater egg loss to foxes than nests attended by paired geese. This resulted from foxes attacking unattended nests and single females far more frequently than expected by chance and from geese associated with such nests offering little or no resistance to foxes. Paired geese, in contrast, were avoided by foxes and also showed greater resistance to foxes than single females and unattended nests. Nest attendance by male geese can therefore be important in reducing egg loss to arctic foxes, but it may play an even greater role in reducing egg loss to arctic foxes in small colonies or during colony formation, when the ratio of predators to nests is generally high.
Nutritional influences on breeding dynamics in elk
Authors: Cook Rachel C , Murray Dennis L , Cook John G , Zager Peter , Monfort Steven L
Published: April 2011

Nutrition in summer and early autumn may influence pregnancy rates and recruitment in ungulate herds in temperate regions, yet this influence on the reproductive endocrinology of wild ungulates is poorly understood. We examined the effects of 3 levels of summerautumn nutrition on timing of breeding, pregnancy rates, and concentration of fecal progestagens (P4) in 30 captive female elk (Cervus elaphus nelsoni). Digestible energy (DE) content for females on the high-nutrition treatment was maintained at 12.35 kJ/g, while DE content for females on the medium- and low-nutrition treatments was gradually reduced to 10.89 and 9.42 kJ/g, respectively, by the end of the breeding season (all feed was offered ad libitum) to mimic the natural decline in forage quality during summer and autumn. In addition, we used three females as a control; they were maintained on a high-nutrition diet and kept separate from a bull. Based on fecal P4 concentrations and visual observations, 90, 90, and 10% of the elk on the high-, medium-, and low-nutrition treatments bred, respectively. Nutritional restriction delayed breeding by an average of 8 and 28 days in the medium- and low-nutrition animals. Females in the low- and medium-nutrition treatments excreted significantly higher P4 concentrations prior to breeding than did animals in the high-nutrition treatment. Diet failed to affect P4 concentration during pregnancy, but we found evidence that P4 concentrations were positively correlated with body condition (ingesta-free body fat content) during early gestation. Females that did not breed failed to exhibit estrous behavior, and hormone-excretion profiles confirmed that these animals failed to ovulate. These results suggest that inadequate nutrition in summer and autumn reduce pregnancy rates by preventing estrus and ovulation rather than by inducing early-embryo mortality.
The influence of herbivores and neighboring plants on risk of browsing: a case study using arctic lupine (Lupinus arcticus) and arctic ground squirrels (Spermophilus parryii plesius)
Authors: Frid Leonardo , Turkington Roy
Published: April 2011

We examined how herbivore distribution and density, neighboring plant density and species composition, and individual plant morphology all influence the risk that individual arctic lupines (Lupinus arcticus) will be browsed by arctic ground squirrels (Spermophilus parryii plesius). Risk of being browsed was significantly influenced by the number of resident ground squirrels but not by overall squirrel density at a site. As the leaf density of neighboring conspecifics increased, risk of browsing to an individual lupine decreased except when palatable neighbors were also present. The presence of other palatable species increased the risk of browsing. Risk was highest when both lupine and other palatable neighbors were present. The presence of unpalatable neighbors reduced the risk of browsing of individual lupines. We discuss these results in the context of three hypotheses: (1) attractant decoy, (2) resource concentration, and (3) repellent plant. No single hypothesis accounts for our observations, but an interaction between herbivores, neighbors, and individual lupine morphology determined risk of browsing.
Are long digits correlated with high forepaw dexterity? A comparative test in terrestrial carnivores (Carnivora)
Authors: Iwaniuk Andrew N , Pellis Sergio M , Whishaw Ian Q
Published: April 2011

The relationship between manus proportions and forepaw dexterity in 33 species of carnivores (Carnivora) was examined. Both the analysis of "raw" data and independent contrasts revealed no significant correlation between the metacarpalphalanx (MCP) ratio and forepaw dexterity. This result was corroborated by a common origins test, which indicated that changes in the MCP ratio were not coincident with changes in forepaw dexterity throughout carnivore evolution. Together, these results suggest that the morphological basis for variations in manipulative behaviour may be quite complex. Other morphological features, such as manus and carpal shape and myology, may play a critical role in forepaw dexterity, but are not manifested as changes in manus proportions. Behavioural observations also suggest that manus proportions may be correlated more closely with locomotion rather than non-locomotory forepaw usage.
Seasonal changes in lipids, diet, and body composition of free-ranging black-tailed prairie dogs (Cynomys ludovicianus)
Authors: Lehmer Erin M , Horne Beatrice Van
Published: April 2011

Black-tailed prairie dogs (Cynomys ludovicianus) enter torpor intermittently during winter in the field but do not hibernate continuously from fall to spring. Previous studies have established that hibernators rely primarily on stored lipids during winter and that the storage of n6 PUFAs in white adipose tissue (WAT) is required to maintain low body temperatures during this continuous torpor. Adult (>1 year) black-tailed prairie dogs were livetrapped in the fall, winter, spring, and summer (n = 1012). To determine whether free-ranging black-tailed prairie dogs rely heavily on stored proteins during winter, we investigated seasonal changes in body composition of the prairie dogs with dual-energy X-ray absorptiometry scans. We also examined seasonal changes in lipid composition of the WAT and diet using gasliquid chromatography to determine whether black-tailed prairie dogs lack the lipids necessary for hibernation. Seasonal changes in fat, lean, and total body mass indicate that black-tailed prairie dogs relied heavily on stored lipids during the winter and appeared to rely on proteins primarily during periods that coincided with reproductive activity. Seasonal changes in dietary and WAT lipids indicate that WAT n6 PUFAs are used during winter and stored during summer, while WAT n3 PUFAs are stored during winter and used during summer. These patterns of lipid use are different than those reported in free-ranging hibernators and may explain why black-tailed prairie dogs experience shallow and infrequent torpor bouts.
Embryonic aestivation and emergence behaviour in the pig-nosed turtle, Carettochelys insculpta
Authors: Doody J Sean , Georges Arthur , Young Jeanne E , Pauza Matthew D , Pepper Ashe L , Alderman Rachael L , Welsh Michael A
Published: April 2011

Two related aspects of hatchling emergence were studied in a population of pig-nosed turtles (Carettochelys insculpta) in northern Australia. Using emergence phenology data, nest temperatures, historical weather data, and a developmental model, we tested the hypothesis that delayed hatching occurs in C. insculpta, and that such a delay would allow hatchlings to time their emergence to match the onset of the wet season. Carettochelys insculpta hatchlings emerged, on average, 17 days after dates predicted from a developmental model. Combined with observations of hatchlings remaining in eggs until emergence, these results confirmed delayed hatching in nature. This delay was synchronized with initial river rises associated with the onset of wet-season rains, and is consistent with published criteria for embryonic aestivation. On a diel scale, we generated predictions of two potentially competing models of nocturnal emergence in hatchling turtles based on the knowledge that air temperatures decrease with season during the emergence period. A test of these predictions for C. insculpta produced ambiguous results. However, further analysis indicated that C. insculpta, and probably other nocturnally emerging turtle species, respond to a decline in diel temperature rather than to an absolute temperature. The former would ensure nocturnal emergence, while the latter is experienced during the day as well as at night. Nocturnal emergence may be associated with nesting in open microhabitats.
Variation in colour within a population of northern flickers: a new perspective on an old hybrid zone
Authors: Wiebe K L , Bortolotti G R
Published: April 2011

We used a digital camera to quantify the colour of the tail feathers of 245 northern flickers (Colaptes auratus) in central British Columbia and investigate the frequency of colour morphs in the population of hybrids. The colour values generated by the camera corresponded well to the conventional method of ranking colours by eye, but was advantageous because it provided finer discrimination and a continuous colour variable. Rectrix colour varied in a continuum from the yellow of C. a. auratus to the red of C. a. cafer. By experimentally exposing red and yellow feathers to sunlight we showed that the intermediate orange colours were not a result of secondary fading of the carotenoid pigments. The distribution of colours in the population was bimodal. A paucity of intermediate phenotypes (orange birds) could not be explained by their mortality because return rates of birds to our study area was not associated with colour. New immigrants into the population tended to resemble parental types more often than hybrids. Assortative mating by colour in this population may tend to keep the subspecies separate, contrary to the situation in more southerly areas of the hybrid zone.
Multiple ecological interactions: nectar robbers and hummingbirds in a highland forest in Mexico
Authors: Arizmendi María del Coro
Published: April 2011

Nectar robbers are animals that extract the nectar produced by plants without effecting pollination. These animals can have negative, positive, or neutral effects on the interaction, depending on the direct and indirect effects of each participant in the system. The purpose of this work was to analyze the prevalence of nectar robbing and its temporal dynamics in a tropical highland forest in western Mexico. The system was studied in terms of the seasonal changes in (i) specific composition and abundance of hummingbird pollinators, their hosts, and the nectar robbers, (ii) use of resources by the nectarivorous birds and flowers, and (iii) prevalence of flower piercing by the cinnamon flowerpiercer, Diglossa baritula. The guild consisted of 17 species of hummingbirds, 2 species of nectar robbers, and 21 plant species that were visited by nectarivorous birds (robbers and pollinators). The relative abundance of birds and available flowers showed two peaks, one in winter and the other in the rainy season. Some plant species were used more than expected from their abundance. Overlap in the use of flowers among hummingbirds and also between hummingbirds and the nectar robbers was high. Nectar robbing was found to be widespread, occurring in almost all of the plants known to be hummingbird pollinated. The ratio of hummingbirds to nectar robbers was around 10 throughout the year.
Eye degeneration in the blind cave-dwelling fish Phreatichthys andruzzii
Authors: Berti Roberto , Durand Jacques Pierre , Becchi Samuele , Brizzi Rossana , Keller Nicole , Ruffat Gisèle
Published: April 2011

The blind cave-dwelling fish Phreatichthys andruzzii shows rapid eye development, and at a temperature of 29.5°C, maximal eye differentiation is reached 36 h after egg laying. Very rapid eye degeneration then occurs, and a rudimentary and very degenerated ocular cyst is all that remains 1 month later. This may explain why this species has so often been erroneously considered anophthalmic. Ocular degeneration starts with a decrease in the rate of mitosis in the neuroblastic cells of the retinal Anlage. Degeneration by means of lytic processes is clearly observed beginning 32 h after egg laying. Disappearance of the lens, transformation of the cornea into skin, and cryptic degeneration of the eyes are phenotypic variations of the fundamental mechanisms of eye development in vertebrates. These can be considered evolutionary adaptations by the ancestral fishes to the aphotic cave environment.
Diversity of spermatozoan morphology in two families of Branchiobdellida (Annelida: Clitellata) from North America
Authors: Gelder Stuart R , Ferraguti Marco
Published: April 2011

The spermatozoa of 13 species belonging to seven different genera of the branchiobdellidan families Cambarincolidae and Bdellodrilidae (Annelida: Clitellata) were examined and compared with previously described members of the family Branchiobdellidae. Based on an examination of the spermatozoa in this relatively large number of species within the order, the variation in sperm morphology is now known to be much greater than was previously expected. Considerable variation was found in nearly all characters examined: the acrosome varied in length from 3 to 60 µm and in shape from straight for most of its length to twisted for its whole length. The nuclei also varied in size (from 4 to 22 µm) and in shape from straight to twisted. Four parallel but twisted mitochondria were present in all species examined, and differed only in length. The marginal fiber that coiled around the flagellum varied in size and pitch. By comparing the present data with those from other branchiobdellidans, we found that the apical concavity of the nucleus, the presence of the marginal fiber of the tail, and the absence of a true basal body with the central apparatus of the flagellum penetrating the midpiece mitochondria are the only characters common to all members of the Branchiobdellida. Sperm characters in this taxon are extremely variable, even within a single genus, thus making the definition of "a single" sperm model for the whole group highly problematic. However, the new data will be of significant value in future phylogenetic work.
Variation in the chemical composition of adipose tissue of three species of ursids
Authors: Cattet Marc R.L , Watts Paul D , Sim Jeong S
Published: April 2011

The relationship between the water content and lipid content of adipose tissue was compared between 25 polar bears (Ursus maritimus) and 25 black bears (Ursus americanus) to determine if it was affected by species differences in the fatty-acid composition of adipose tissue. The adipose tissue of polar bears had a lower water content and a higher proportion of long-chain fatty acids than did the adipose tissue of black bears, when compared at equal lipid content. The relationship between the body water and lipid contents was also compared among 11 polar bears, 18 black bears, and 6 brown bears (Ursus arctos) to determine if this relationship could be affected by species differences in the relationship between the water and lipid contents of adipose tissue. The body-water content in marine (polar) bears was less than that in terrestrial (black and brown) bears, and the differences in body-water content between the two groups became more apparent as the body-lipid content increased. These results suggest that the fatty-acid composition of adipose tissue can affect the body-water content, especially in fat bears. These findings have implications for the use of isotope-dilution models to predict body composition in bears.
Within-call repetition may be an anti-masking strategy in underwater calls of harp seals (Pagophilus groenlandicus)
Authors: Serrano Arturo , Terhune John M
Published: April 2011

Underwater vocalizations of harp seals (Pagophilus groenlandicus) were recorded in the Gulf of St. Lawrence, Canada, during the breeding season in March of 1999 and 2000. At high calling rates (>95 calls/min) the background noise levels increase and individual calls may be masked. The purpose of the study was to determine if seals increase the number of elements per call in response to higher calling rates by conspecifics. Eight multi-element call types were analyzed. Six narrowband and one of two broadband multi-element call types showed a significant increase in the number of elements per call at higher calling rates. One broadband call type did not show a significant difference among the different calling rates. Our findings suggest that harp seals increase the number of elements per call in many call types to avoid having their calls masked by an increasing number of conspecific vocalizations.
Effects of isolation on red-backed voles (Clethrionomys gapperi) and deer mice (Peromyscusmaniculatus) in a sagesteppe matrix
Authors: Witt W Christopher , Huntly Nancy
Published: April 2011

Effects of habitat isolation can differ among species, thereby influencing populations both directly and indirectly. We used naturally occurring forest patches surrounded by a sagesteppe matrix in southeast Idaho to test the hypothesis that a habitat specialist, the red-backed vole (Clethrionomys gapperi), would have movements restricted and therefore population densities reduced on forest patches isolated by distances equal to or greater than their typical home-range diameter. We hypothesized that the more generalized deer mouse (Peromyscus maniculatus) would not show effects of isolation at this scale. We tested for effects of isolation on these small mammals in 1999 and 2000 in forest patches that varied in distance to a mainland forest. Densities of red-backed voles decreased with isolation and those of deer mice did not. However, strong relationships were also found between red-backed vole densities and habitat characteristics, which themselves varied with isolation. Livestock apparently had disproportionate effects on the more isolated patches, thereby altering ground cover. Isolation by distances up to 450 m appears to reduce (filter) rather than eliminate immigration of red-backed voles; however, effects of livestock on isolated habitat patches may prevent successful dispersers from populating patches.
Ultraviolet blocking in the ocular humors of the teleost fish Acanthocybium solandri (Scombridae)
Authors: Nelson Peter A , Zamzow Jill P , Losey George S
Published: April 2011

The humors of the eye of the pelagic predator Acanthocybium solandri (the wahoo or ono) absorb ultraviolet-A radiation of longer wavelength than that absorbed by the lens. Except for a single juvenile fish, the 50% transmission cutoff for lenses of about 1 cm diameter were of a shorter wavelength than the cutoff for 23 mm thick samples of the humors. The lens showed more absorption than the humors below 340 nm but lacked much of the ca. 360 nm absorption found in the humors. Related and ecologically similar fish show the more normal condition, with the lens as the primary short-wavelength filter. The functional significance of this design is obscure.
Why birds cannot be smaller than bees
Authors: Ahlborn Boye , Blake Robert W
Published: April 2011

Birds and mammals of body mass M that live in cold climates cannot have a body radius, Rmin, below about 2.5 cm. This criterion follows from the balance of metabolic heat production described by Kleiber's function, Γ = 3.6M0.73, and heat-conduction losses through the body insulation. Rmin differs from the critical radius calculated from a heat-flow balance at the outer edge of the organism that does not consider metabolic limitations.
Potential mechanisms of phenotypic divergence in body size between Newfoundland and mainland black bear populations
Authors: Mahoney Shane P , Virgl John A , Mawhinney Kim
Published: April 2011

Phenotypic variation in body size and degree of sexual size dimorphism of North American black bears (Ursus americanus) was quantified for populations from New Brunswick, Quebec, Ontario, Maine, Alaska, and the island of Newfoundland. Based on a model of island biogeography developed by Case, we predicted that body size should be larger in Newfoundland bears than in mainland populations. The presence of few large predators and minimal competition between herbivore prey on Newfoundland allow an appropriate test of the model (i.e., food availability for bears may differ between populations on the mainland and in Newfoundland). In addition, sexual-selection theory predicts that the coevolution of polygyny and large size will be coupled with an increase in sexual size dimorphism. Therefore, we also predicted that among the six populations, male body mass should scale hyperallometrically with female body mass (i.e., slope > 1). Analysis of deterministic growth curves indicated that bears from Newfoundland attained greater asymptotic body size than populations on the mainland, which supports our first prediction. On average, the relative difference in asymptotic body mass between females from the island and mainland populations was 55%, while the relative difference between males was 37%. However, we found that sexual size dimorphism did not increase disproportionately with body mass among the six populations, which refuted our second prediction. We discuss a range of abiotic and biotic selection pressures possibly responsible for larger body size in Newfoundland bears. We suggest that the ability to exploit seasonally abundant and spatially dispersed dietary protein by female and male black bears on the island has been and is still a primary environmental factor selecting for large body size in Newfoundland bears. Although the relationship between sexual size dimorphism and body size is tenuous (slope [Formula: see text] 1), it does suggest that (an)other adaptive mechanism(s), opposing sexual selection for extreme male size, explain(s) a large amount of the variation in sexual size dimorphism among black bear populations.
Performance and maneuverability of three species of teleostean fishes
Authors: Webb Paul W , Fairchild Antonia Gardiner
Published: April 2011

Whole-animal behavior and performance are assembled from functional capabilities that are dependent on morphology, such as body form and fin-distribution patterns. We compared hovering, median and paired fin (MPF), body and caudal fin (BCF), and burst-and-coast gaits and maneuvers permitted within these gaits, turning, backward swimming, and braking for three species: goldfish, Carassius auratus, silver dollar, Metynnis hypsauchen, and angelfish, Pterophyllum scalare. Goldfish have a fusiform body with a relatively small surface area and depth. Silver dollars and angelfish had larger areas and depths. The smaller surface area was expected to be associated with greater use and higher speeds in BCF swimming behaviors for goldfish but little support was found. Larger body depth was expected to be associated with higher turning rates and maneuverability of silver dollars versus goldfish, but data were again equivocal. Body depth may be more important in defense than in locomotion. Goldfish and silver dollars have ventral paired fins. Angelfish have more derived lateral pectoral fins, anterior pelvic fins, and larger median fins. This fin pattern was expected to be associated with greater use of MPF behaviors at higher speeds, and with greater maneuverability. Support for this expectation was found, but there were sufficient exceptions to indicate that other factors were important.