In many mammals social organization promotes genetic structuring, which can be influenced by the dispersal pattern of the species. We analyzed the population genetic structure and dispersal of white-lipped peccaries (Tayassu pecari) from the Pantanal, Brazil. We genotyped 100 individuals at 7 microsatellite loci from 2 adjacent locations with no obvious geographic barrier between them. We found a significant but low F_ST value, and the Bayesian analysis indicated a unique cluster. No significant differences were observed between mean assignment indices of resident males and females from both locations, and the probability of being born at the location sampled of >30% of the individuals analyzed was lower than average. Mean relatedness between resident female, male, and opposite-sex pairs was not statistically different in both locations. These results suggest a low degree of genetic differentiation between the locations analyzed, and dispersal by both sexes (contrary to the predicted male-biased dispersal of most mammalian species).

On 7 February 2005 a group of 9 killer whales (Orcinus orca) were trapped in drifting sea ice and died at Aidomari, Hokkaido, Japan. We carried out age determination based on tooth growth layers and examined the reproductive organs of these whales. Growth layer groups (GLGs) in the dentine and cementum were readable, even in the old specimens, and complementary to each other in decalcified and stained thin sections of lower teeth. Reliable age determination of killer whales is feasible, and GLGs are accumulated annually. The longitudinal growth of the teeth continued until about 20 years of age, which is much longer than for the corresponding age in other delphinids. Counts of corpora lutea and albicantia increased linearly with age from 3 to 7 in whales 13–34 years old, but the oldest female (59 years old) had only 8 corpora albicantia, which could indicate a decline in the ovulation rate in old females. Photographs of the original group trapped in the ice confirmed that at least 2 whales escaped or died and did not strand with the others. Therefore, this group was composed originally of a mature male, 1 possibly postreproductive female, 5 reproductively active females, 3 calves, and 2 or 3 unidentified individuals.

Molecular data have been used to show northward post-Pleistocene range expansions from a refugium in the southeastern United States for several mammal species. Fossil and historical records indicate that gray foxes (Urocyon cinereoargenteus) were not present in the northeastern United States until well after the Pleistocene (ca. 900). To test the hypothesis that gray foxes experienced a post-Pleistocene range expansion we conducted a phylogeographic analysis of gray foxes from across the eastern United States. We sequenced a variable portion of the mitochondrial control region (411 base pairs) from 229 gray fox tissue samples from 15 states, representing the range of all 3 East Coast subspecies. Phylogeographic analyses indicated no clear pattern of genetic structuring of gray fox haplotypes across most of the eastern United States. However, when haplotype frequencies were subdivided into a northeastern and a southern region, we detected a strong signal of differentiation between the Northeast and the rest of the eastern United States. Indicators of molecular diversity and tests for demographic expansion confirmed this division and suggested a very recent expansion of gray foxes into the northeastern states. Our results support the hypothesis that gray foxes 1st colonized the Northeast during a historical period of hemisphere-wide warming, which coincided with the range expansion of deciduous forest. We present the 1st study that analyzes the phylogeographic patterns of the gray fox in the eastern United States.

Wolves (Canis lupus), as both opportunistic and specialist predators, can limit and regulate ungulate dynamics. As part of understanding predator–prey interactions in the largely undisturbed system of the Besa-Prophet area in northern British Columbia, we used stable isotopes of carbon and nitrogen to infer seasonal diets of 5 wolf packs. We selected the hair, tissue, or blood sample of each prey species that could best index within-season diet composition. Seasonal isotopic differences for a given sample type were as much as 0.28‰ δ¹³C and 0.97‰ δ¹⁵N. The large biomass species of moose (Alces americanus) and elk (Cervus elaphus) dominated the diets of wolves, but caribou (Rangifer tarandus) and Stone's sheep (Ovis dalli stonei) also were locally or seasonally important to some packs. Mean isotopic determinations of summer food habits were correlated positively (P < 0.001) with proportions of prey by species determined from scat samples. This general agreement lends support for the tissue to diet discrimination values used in the Bayesian modeling and indicates that the longer-term dietary estimates from stable isotopes were reflective of shorter-term recent ingestion. Although moose have been assumed to be the most important prey item for wolves throughout the year in northern British Columbia, our results indicate that dietary dynamics of wolves in the Besa-Prophet area are more complex than previously reported.

African wild dogs (Lycaon pictus) are endangered, having disappeared from many areas where other large carnivore species have persisted. The relative vulnerability of this species has been attributed variously to its disproportionate exposure to anthropogenic threats, limitation by larger competing predators, and Allee effects caused by obligate cooperative breeding. The natural recovery of a wild dog population living on private and community land in northern Kenya provided an opportunity to investigate these potential constraints on population growth. Within a decade the population increased from near-extinction to become the 6th largest in the world. Rates and causes of mortality, and reproductive rates, were similar on community lands, where people and livestock were abundant but competing predators suppressed, and on commercial ranches, where human and livestock densities were lower but competitors more abundant. Larger packs produced larger litters, indicating a component Allee effect. However, because pack size was unrelated to population size, growth of the population was not impeded at low densities; that is, no demographic Allee effect was detectable. These results show that, despite earlier concerns, wild dogs can achieve rapid population recovery, even in a human-dominated landscape. This recovery was probably facilitated by local pastoralist traditions, which combine vigilant herding of livestock with little or no hunting of wild prey. This success might be replicated in other areas where traditional pastoralism is still practiced.

Although Southeast Asia has a high diversity of small carnivore species, little is known about their distributions and ecology, and several species are now threatened with extinction. We predicted the distributions of 8 civet and mongoose species within Southeast Asia using ecological niche modeling, determined their habitat/elevation niche preferences, examined the interspecific differences in these 2 niche parameters, and investigated possible factors that could have affected these distribution and niche patterns. We found a tendency for each civet and mongoose species to separate spatially from related species on geographical, habitat, and elevation gradients, and that 3 pairs of civet and mongoose species showed similar distribution patterns and habitat/elevation preferences. The large Indian civet (Viverra zibetha) and crab-eating mongoose (Herpestes urva) have similar distributions throughout mainland Southeast Asia, are found over a broad range of elevations, and occur primarily in evergreen forest. The large-spotted civet (Viverra megaspila) occurs in lowland areas across northern Southeast Asia and is found most frequently in deciduous forest (and less frequently in evergreen forest). The Malay civet (Viverra tangalunga) and short-tailed mongoose (Herpestes brachyurus) both occur south of the Thai–Malaysian border in Malaysia, Indonesia, and the Philippines and are found primarily in lowlands and evergreen forest. The small Indian civet (Viverricula indica) and Javan mongoose (Herpestes javanicus) are found on mainland Southeast Asia and parts of Indonesia, occur mainly at lower elevations, and appear to have no preference for forest type. The collared mongoose (Herpestes semitorquatus) is found on Borneo (and possibly Sumatra) and might occur more frequently at higher elevations and in disturbed evergreen forests. Interspecific competition, biogeography, and human interference are discussed as possible factors to explain these distribution and niche patterns.

The effects of forest fragmentation on individual space-use patterns were investigated in the European pine marten (Martes martes), considered as a forest-dependent species. The study was done in Ardennes, France, with the landscape consisting of both continuous forest and fragmented habitat, poor-quality habitat for pine martens. In this landscape context 3 predictions were tested: due to intraspecific competition, subadults should be overrepresented in fragmented habitat; according to the landscape supplementation theory, home ranges should be larger in fragmented habitat; and over seasons, home ranges should be more stable in forest than in fragmented habitat. Thirty-six individuals were trapped in both habitats, and 23 were radiotracked during 3–5 consecutive seasons. Confirming our 1st prediction, we found that the ratio of subadults to adults in fragmented habitat was higher than in forest. On the contrary, annual home ranges were larger in forest than in fragmented habitat, and temporal stability of home ranges was not significantly different between habitats. Therefore, our results indicate that the pine marten can persist in fragmented habitat and could rather be defined as a tree-dependent species.

Twinning is extremely rare in pinnipeds. Instances in which a female is observed simultaneously nursing 2 pups may represent alloparenting, or nonfilial nursing, a relatively common trait in pinnipeds. We explored the incidence of twinning in the Hawaiian monk seal (Monachus schauinslandi). We observed 7 sets of putative twins (i.e., an isolated female nursing 2 newborn pups) of 4,965 total births recorded between 1983 and 2008 (minimum twinning rate  =  0.1%). Genetic specimens from the mother and both pups were available only for 5 of the 7 sets. Microsatellite genotyping revealed all of these to be dizygotic twins, with low probability of false assignment (P < 0.001). On average, Hawaiian monk seal twins were less likely to survive to weaning than singletons born in the same year and on the same island (P  =  0.008). Those that weaned were smaller in size (i.e., axillary girths 1–4 SDs lower than singletons). In the critically endangered Hawaiian monk seal twinning appears to be a rare trait that results in overall lower survival rates but also offers a small opportunity for stock enhancement.

Endothermic mammals in cold environments have a range of adaptations enabling them to maintain a constant core body temperature. Of critical importance to many is a thick hair coat that retains air and so acts as a barrier to minimize heat exchange between the skin and ambient environment. Disruption to the pelage can increase costs of maintaining body temperature and compromise survival of the individual. Fur seals rely on a pelage of dense, dry underfur protected by guard hairs for insulation in the aquatic environment. Since 1989 a potentially serious alopecia (hair loss) syndrome has been recognized in Australian fur seals. Between September 2007 and February 2010 we investigated the prevalence and potential impacts of the condition. The syndrome manifests as bilaterally symmetrical alopecia, which occurs predominantly in juveniles and has a strong sex bias (51 of 55 juveniles captured for examination were female). It also occurs in adult females but has never been seen on postpubescent males. Prevalence of alopecia was highest at the large Lady Julia Percy Island colony (approximately 30,000 seals) in northwestern Bass Strait where it has a distinct seasonal pattern of prevalence, peaking in spring and summer with up to 50% of juvenile females affected. Thermal images indicated that alopecic and nonalopecic areas of the dorsal thorax had a mean difference of 6.6°C, and affected animals were in significantly (P < 0.001) poorer body condition than unaffected animals.

Maternal attendance patterns in free-ranging wildlife can provide insight into basic biology, foraging behavior, and population dynamics. We collected detailed visual observations of attendance patterns by adult lactating Steller sea lions (Eumetopias jubatus) from 2005 to 2007 on 6 major rookeries in the Russian Far East, including those with an increasing population trend (Sea of Okhotsk), severely depleted populations that were recovering (Kuril Islands), or those that were stable (Commander Islands). Individually identifiable females were observed during the postpartum period, with special attention paid to presence and absence during the day and to departure and arrival times. Within Russia females on several Kuril Islands rookeries exhibited extremely short foraging trip durations (median 6.5–8.0 h) and spent higher proportions of time on the rookery (75–82%), whereas females in the Sea of Okhotsk population had the longest trips (median 19.8 h) and spent the least amount of time on the rookery (60%). Most indices of attendance pattern were more favorable (longer peripartum period, higher proportion of time spent on rookery, shorter trips, and longer visits) than those reported in Alaska and much more so than those in California during El Niño years, where the proportion of time spent on the rookery was nearly half that in Russia. Females >6 years of age had shorter trips and longer visit durations than the youngest females (4–5 years), and older mothers exhibited significantly longer periods of nursing before taking their 1st trip, suggesting greater physical condition for older females. Although trip durations remained constant throughout the season, visit durations shortened significantly as the pups aged, suggesting that increasing nutritional demands of pups are met by more frequent, rather than longer, trips. No apparent relationships between attendance patterns and population status were observed; however, many of the differences in attendance patterns throughout the range of the Steller sea lion could be related to local variation in bathymetry and diet patterns.

Temporal fluctuation in abundance is common in many wildlife populations, but the causes and consequences to population dynamics of these fluctuations remain poorly understood. We used long-term (1990–2008) field data to investigate the influence of population size and environmental factors (climatic variables and predation) on the demography of golden-mantled ground squirrels (Callospermophilus lateralis). Survival varied by sex and age class, with highest survival for adult females (Φ  =  0.519, 95% confidence interval [95% CI]  =  0.462–0.576) and lowest survival for juvenile males (Φ  =  0.120, 95% CI  =  0.094–0.152). Population size negatively influenced survival with a time lag of 1 year. Among environmental factors, current year's rainfall and intensity of predation substantially influenced survival. Probability of successful reproduction (probability that a female weans ≥1 pups) was higher for older females (Ψ  =  0.816, 95% CI  =  0.734–0.877) than for yearlings (Ψ  =  0.313, 95% CI  =  0.228–0.412). Rainfall negatively influenced probability of successful reproduction of both older and yearling females with a time lag of 1 year. Litter size ranged from 1 to 8 pups, with a mean of 4.8 (95% CI  =  4.5–5.1). We found no evidence that litter size varied among age classes or over time, or was influenced by population size or environmental factors. Our results suggest that population size and environmental factors do not affect all demographic variables in the same way, and that both density-dependent and environmental factors influence the size of our study population.

We studied the simultaneous effects of social and environmental factors on the age of sexual maturity to identify the major determinants of reproductive delay in the cooperatively breeding female Cape ground squirrel (Xerus inauris). We verified inhibition of sexual maturity by monitoring reproductive behaviors and hormones (using a noninvasive fecal steroid hormone analysis) in prereproductive and reproductive females from 2 populations of squirrels found in southern Africa. We found that 2 social parameters hold the most influence on the timing of female sexual maturity; specifically, the number of adult breeding female group mates and related adult male group mates were associated with a substantial inhibition of female reproductive maturity. Subadult females in social groups with 0 or 1 adult breeding female became sexually mature significantly earlier than similar-aged females in social groups with ≥2 adult breeding females. Likewise, subadult females in social groups with <2 related adult male group mates became sexually mature significantly earlier than similar-aged females in social groups with ≥2 adult related males. Our results show the influence of multiple social parameters on sexual maturity and are consistent with the predictions of the incomplete control model of skew.

Environmental heterogeneity is an important determinant of the diversity of natural communities. Effects of heterogeneity can emanate from complementary effects of resource heterogeneity (variation in the number of resources) and structural heterogeneity (variation in the physical structure of the environment). We examined relative effects of structural and resource heterogeneity on the diversity of 31 desert rodent communities in the Mojave Desert. Both structural and resource heterogeneity significantly accounted for rodent species diversity. Nonetheless, when unique and shared effects were examined, only resource heterogeneity exhibited a significant unique effect, accounting for more variation than structural heterogeneity in diversity of rodent communities. When compared with results of previous studies the possibility emerges that effects of either structural or resource heterogeneity might be context dependent and determined by the taxon of focus and relative variation of these two forms of heterogeneity. Accordingly, future studies should distinguish between these two important forms of environmental heterogeneity to improve understanding of their relative impacts on diversity.

B chromosomes (Bs) are supernumerary chromosomes relative to the standard karyotype. The maintenance of Bs in the yellow-necked field mice (Apodemus flavicollis) was reconsidered by examining their effects on 3 components of cranial variability: canalization, developmental stability, and morphological integration. Bs do not disturb developmental homeostasis in their carriers. Moreover, Bs play a significant role in structuring cranial variation. We suggest that direct interactions between developmental pathways in mice without Bs might be a dominant mechanism for generating covariation of cranial traits, and integration of cranial traits in B carriers could be generated primarily by parallel variation of separate developmental pathways. Integration due to parallel variation is more predisposed to modifications by natural selection than integration caused by direct interactions, which could be beneficial to B carriers under variable environmental conditions. By contributing to the genetic variability of species possessing them, Bs provide themselves with long-term presence in populations. Therefore, the Bs of A. flavicollis should be considered as symbiotic genomic elements.

The relationship between prenatal and postnatal ontogenetic allometry is poorly known, and empirical studies documenting prenatal allometry are few, precluding an understanding of changes in growth patterns during life history and their relation to proximal, physiological, and ultimate evolutionary variables. In this study I compare prenatal and postnatal ontogenetic allometry of the cranium in a cleared and stained developmental series of the African striped mouse (Rhabdomys pumilio). Eighteen cranial measurements, reflecting the dimensions of individual elements, were analyzed using bivariate and multivariate estimates of allometry and methods of matrix comparison. Prenatal allometry is characterized in R. pumilio by a relative rapid lengthening of cranial elements, particularly the frontal, parietal, basisphenoid, premaxilla, and palatine, as evidenced by larger bivariate allometric coefficients (>30% increase) and, across all variables measured, a greater proportion of cranial elements growing with a positive allometry than in the postnatal period. Growth dynamics are found to shift for measurements of several elements including the parietal, frontal, and palatine, indicating a nonlinearity of ontogenetic allometry with respect to birth; similar shifts have been found between prenatal and postnatal growth for some regions of the human cranium. Application of common principal component analyses, a generalized extension of principal component analysis, revealed that the prenatal and postnatal matrices shared a highly similar structure, further quantified by high correlations (>0.78) using the random skewers method of matrix comparison. These results indicate a close correspondence between morphology-based variance structures over the course of ontogeny in R. pumilio.

We reviewed topographical homologies in the upper tooth morphology of bats and analyzed the implications to relationships among higher taxa within Chiroptera. A standardized terminology for the upper molars of bats is proposed, taking into consideration the nomenclature adopted for tribosphenic mammals. Major patterns of variation in crown morphology of chiropteran upper molars were reevaluated, and 2 new structures were identified: mesoconule and mesoconule crista. The main controversies in the literature regarding terminology and structural identity in the upper molars of chiropterans are discussed. Forty-eight dental morphological characters are presented for extant bats and the extinct Icaronycteridae, with the exception of Pteropodidae, which has lost the tribosphenic dental pattern. These were combined with 191 characters of other morphological systems from the literature. The tree obtained from parsimony analyses mostly agrees with previous proposals based on morphology. However, major differences were found: the position of Noctilionoidea at the base of the radiation of modern microchiropterans, which formed a trichotomy with Yinochiroptera (including Emballonuridae) and the remaining Yangochiroptera; Antrozoinae disassociated from the other Vespertilionidae, forming a poorly supported clade with Mystacinidae and Molossidae; and the relationship between the sister taxa Myotinae and Miniopterinae within Vespertilionidae.

We studied adult survival and population growth at multiple maternity colonies of big brown bats (Eptesicus fuscus) in Fort Collins, Colorado. We investigated hypotheses about survival using information-theoretic methods and mark–recapture analyses based on passive detection of adult females tagged with passive integrated transponders. We constructed a 3-stage life-history matrix model to estimate population growth rate (λ) and assessed the relative importance of adult survival and other life-history parameters to population growth through elasticity and sensitivity analysis. Annual adult survival at 5 maternity colonies monitored from 2001 to 2005 was estimated at 0.79 (95% confidence interval [95% CI] = 0.77–0.82). Adult survival varied by year and roost, with low survival during an extreme drought year, a finding with negative implications for bat populations because of the likelihood of increasing drought in western North America due to global climate change. Adult survival during winter was higher than in summer, and mean life expectancies calculated from survival estimates were lower than maximum longevity records. We modeled adult survival with recruitment parameter estimates from the same population. The study population was growing (λ = 1.096; 95% CI = 1.057–1.135). Adult survival was the most important demographic parameter for population growth. Growth clearly had the highest elasticity to adult survival, followed by juvenile survival and adult fecundity (approximately equivalent in rank). Elasticity was lowest for fecundity of yearlings. The relative importances of the various life-history parameters for population growth rate are similar to those of large mammals.

Fundamental differences could exist in the fitness-limiting resources between males and females; therefore, movement strategies might differ between the sexes. We used custom-designed animal-borne data loggers to record the locomotor behaviors of free-ranging Malayan colugos (Galeopterus variegatus). Locomotor behavior, and especially gliding, make up a very small percentage of a colugo's time budget. Furthermore, although glide distance is widely variable, most glides are much shorter than the maximum distance achievable. Males perform more glides and travel a greater distance each night than females. Females glide primarily to access foraging trees, but the greater distance traveled by males is from visiting trees to feed and transiting quickly among trees for other behaviors that include territorial defense and mate searching. This study recorded all locomotor behaviors for each animal during the sampling period and provides a starting point for the evaluation of hypotheses for the evolution of gliding and examining the differential effects of selective pressures between the sexes. The evidence suggests that ability to forage in a number of trees each night is an important aspect of the locomotor ecology of colugos and therefore could have played a role in the origins of gliding.

Torpor bouts of elephant shrews are intermediate in duration to those of daily heterotherms and hibernating mammals, but their body temperatures (T_bs) and metabolic rates are very low and similar to those of hibernating mammals. We quantified the thermal physiology of the Cape rock elephant shrew (Elephantulus edwardii), a species endemic to high-altitude regions of South Africa, where winters are cold and wet, and tested whether it displays multiday torpor characteristic of hibernators at low ambient temperature (T_a). E. edwardii regularly displayed torpor over a wide range of T_as. Occurrence of torpor and duration of torpor bouts increased with decreasing T_a. Whereas normothermic T_b was stable, T_b in torpid individuals fell with T_a. The mean T_b − T_a differential at the minimum T_b was 0.7°C, and the mean minimum T_b at T_a 8.9°C was 9.3°C. Duration of torpor bouts ranged from 6.5 to 44 h and was correlated negatively with T_a and T_b during torpor. Time required for the reduction of T_b to a T_b − T_a differential of <2.0°C was faster for >1-day torpor bouts than those lasting ≤1 day, suggesting that the duration of a bout might be determined at the beginning, not during, a bout. The nature of heterothermy in E. edwardii seems qualitatively similar to that of other elephant shrews, although torpor is somewhat deeper and longer in this species. Temporal patterns of torpor in E. edwardii differ from those of most cold-climate hibernators, likely for ecological rather than physiological reasons.