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Organizational structure for the proposed IsoBank. A central executive group would oversee four subcommittees (SC): Information technology, integrative disciplinary, education and training, and analytical expertise. GNIP, Global Network of Isotopes in Precipitation; IAEA, International Atomic Energy Association; QA/QC, quality assurance/quality control.

Although resource specialization occurs along a continuum, species are often defined as either specialists or generalists. In general, specialists are more prone to extinction than generalists and, thus, are often the first species to be lost when habitats are modified. The two-toed sloth (Choloepus hoffmanni) and the three-toed sloth (Bradypus variegatus) are arboreal herbivores distributed across the Neotropics. The two-toed sloth is considered a generalist while the three-toed sloth is more specialized. Both species inhabit shade-grown agro-ecosystems but, at least at one study site, only the two-toed sloth was viable. To quantify specialization in sloth species and explore how it influences population viability, we characterized the resource use for 68 adult and 12 subadult sloths across 3 y. The two-toed sloth used 14 tree species relatively uniformly across habitats, while the three-toed sloth largely depended on only two species of tree regardless of habitat type. Both species selected for patches of intact tropical forest, strongly avoided monocultures regardless of spatial scale and generally used cocoa similarly in proportion to availability. However, the sloth species differed in their use of cattle pastures, with the two-toed sloth selecting for pastures and the three-toed sloth avoiding them. Overall, the two-toed sloth exhibited greater plasticity in tree and habitat use, which is likely contributing to its enhanced resilience within this modified agro-ecosystem.

The American marten (Martes americana), the only state-listed endangered mammal in Wisconsin, has undergone serial reintroductions within the state. Recovery has been slower than anticipated and the limiting factors remain unidentified. The lack of basic knowledge on marten foraging in the Great Lakes Region led us to quantify the diet of martens inhabiting the Chequamegon-Nicolet National Forest (CNNF) in northern Wisconsin using a dual approach of scat and stable isotope analyses. We collected marten scat at winter rest sites within the CNNF from 2000–2011. We identified prey items based on morphological characteristics of indigestible prey remains and calculated percent occurrence for each prey item. We sampled marten hair from museum specimens, and opportunistically from carcasses within the CNNF for isotopic analysis. We collected hair and feather samples from potential prey species in the CNNF in 2010–2013. Our concurrent analyses revealed that shrews and deer were most important to the diet of martens in Wisconsin. These findings contrast with studies conducted elsewhere that report voles as the principle diet items, and shrews as one of the least used prey items. Consequently, such a strong reliance on secondary, less profitable or high-risk prey could be contributing to the delayed recovery of martens in Wisconsin. © 2014 The Wildlife Society.

Summary The development of shade-grown agro-ecosystems has increasingly been identified as a strategy for conserving tropical biodiversity. While biodiversity tends to be higher in agro-ecosystems than in monocultures, the extent to which shade-grown crops support viable populations of sensitive and specialized tropical species has not been assessed. We conducted a comparative demographic study between Hoffmann's two-toed sloth Choloepus hoffmanni and the brown-throated three-toed sloth Bradypus variegatus in a shade-grown cacao farm in Costa Rica. Choloepus hoffmanni bred year-round, whereas B. variegatus bred seasonally, with females giving birth to young over a 6-month period peaking in late February. Relatively short time to offspring independence allowed B. variegatus females to breed annually, but longer periods of maternal care prevented C. hoffmanni from doing so. Annual survival rates for adult males of both species derived from radiomarking and known fates models were high (>0·90). Most adult mortality was the result of predation by domestic dogs Canis lupus familiaris and coyotes Canis latrans. Estimates of population growth rates derived from a matrix population model indicated that the abundance of C. hoffmanni, but not B. variegatus, was stable in the absence of immigration. However, genetic parentage methods indicated that significant immigration of B. variegatus into the study area occurred and that the local population may be stable. Synthesis and applications. Our results suggest that shade-grown crops embedded within an agro-ecosystem can support viable populations of some specialized tropical animals; other species, however, may require immigration from surrounding forests to maintain stable populations. More broadly, the value of human-modified landscapes for biodiversity may be overestimated when some species are dependent on immigration from intact habitats.

The extirpation of black-footed ferrets ( Mustela nigripes ) from the wild resulted from the rangewide decline of prairie dogs ( Cynomys spp.) brought about by poisoning campaigns, the arrival of an exotic disease, and habitat loss. It is widely accepted that ferrets are an obligate, near monophagous, dietary specialist of prairie dogs and that high-density prairie dog colonies are necessary for effective recovery. To test the extent to which ferrets are dietary specialists, we measured the stable isotopic values of 321 ferrets of known age and sex as well as of their potential prey (e.g., prairie dogs, mice, ground squirrels, and rabbits). Our results confirmed that prairie dogs are the most common diet item for ferrets, although ferrets possessed greater foraging plasticity than previously reported, consuming substantial quantities of other species. The degree to which ferrets were specialized on prairie dogs differed between age–sex groups. Adult male and juvenile ferrets had equivalent diets, with prairie dogs constituting nearly 75% of their assimilated diet. In contrast, adult females obtained over one third of their diet from other species, notably mice. However, female ferrets appeared to have provisioned prairie dogs to their dependent offspring. Conservation of ferrets, one of North America’s most endangered mammals, will require prairie dogs, not just as prey, but also for the prey-rich habitat that their colonies provide.

For many terrestrial organisms in the Northern Hemisphere, winter is a period of resource scarcity and energy deficits, survivable only because a seasonal refugium – the “subnivium” – exists beneath the snow. The warmer and more stable conditions within the subnivium are principally driven by snow duration, density, and depth. In temperate regions, the subnivium is important for the overwintering success of plants and animals, yet winter conditions are changing rapidly worldwide. Throughout the Northern Hemisphere, the impacts of climate change are predicted to be most prominent during the winter months, resulting in a shorter snow season and decreased snow depth. These climatic changes will likely modify the defining qualities of the subnivium, resulting in broad-scale shifts in distributions of species that are dependent on these refugia. Resultant changes to the subnivium, however, will be spatially and temporally variable. We believe that ecologists and managers are overlooking this widespread, crucia...

There is growing recognition that developed landscapes are important systems in which to promote ecological complexity and conservation. Yet, little is known about processes regulating these novel ecosystems, or behaviours employed by species adapting to them. We evaluated the isotopic niche of an apex carnivore, the cougar (Puma concolor), over broad spatiotemporal scales and in a region characterized by rapid landscape change. We detected a shift in resource use, from near complete specialization on native herbivores in wildlands to greater use of exotic and invasive species by cougars in contemporary urban interfaces. We show that 25 years ago, cougars inhabiting these same urban interfaces possessed diets that were intermediate. Thus, niche expansion followed human expansion over both time and space, indicating that an important top predator is interacting with prey in novel ways. Thus, though human-dominated landscapes can provide sufficient resources for apex carnivores, they do not necessarily preserve their ecological relationships.

By exploiting unutilized resources, organisms expand into novel niches, which can lead to adaptive radiation. However, some groups fail to diversify despite the apparent opportunity to do so. Although arising multiple times, arboreal folivores are rare and have not radiated, presumably because of energetic constraints. To explore this hypothesis, we quantified the field metabolic rate (FMR), movement, and body temperature for syntopic two- and three-toed sloths, extreme arboreal folivores that differ in their degree of specialization. Both species expended little energy, but three-toed sloths (162 kJ/day*kg(0.734)) possessed the lowest FMR recorded for any mammal. Three-toed sloths were more heterothermic and moved less than two-toed sloths. We then compared FMRs and basal metabolic rates (BMRs) for 19 species of arboreal folivores along a spectrum of specialization. Overall, arboreal folivores had lower BMRs and FMRs than other mammals, and increasing specialization led to lower FMRs but not BMRs. Thus, reduced energetic expenditure in specialized species was the result of thermoregulatory and behavioral strategies, rather than simply a proportionate reduction in BMR. Altogether, our findings support the concept that arboreal folivores are tightly constrained by nutritional energetics and help to explain the lack of radiation among species exploiting a lifestyle in the trees.

Specialized species, like arboreal folivores, often develop beneficial relationships with symbionts to exploit ecologically constrained lifestyles. Although coevolution can drive speciation by specialization of a symbiont to a host, a symbiotic relationship is not indicative of coevolution between host and symbiont. We tested for coevolved relationships between highly specialized two- and three-toed sloths (Choloepus spp. and Bradypus spp., respectively) and their symbiotic algae using cophylogenies and phylogeography. Our phylogeographic analysis showed a biogeographic pattern for the sloth distribution that was not found in the algal phylogeny. We found support for congruence between the sloth and algae phylogenies, implying cospeciation, only in the Bradypus lineage. Algae host-switching occurred from Bradypus spp. to Choloepus spp. Our results support a previously hypothesized symbiotic relationship between sloths and the algae in their fur and indicate that coevolution may have played a role in algae diversification. More broadly, convergent evolution may facilitate host switching between deeply diverged host lineages.

The effects of climate change on biodiversity have emerged as a dominant theme in conservation biology, possibly eclipsing concern over habitat loss in recent years. The extent to which this shifting focus has tracked the most eminent threats to biodiversity is not well documented. We investigated the mechanisms driving shifts in the southern range boundary of a forest and snow cover specialist, the snowshoe hare, to explore how its range boundary has responded to shifting rates of climate and land cover change over time. We found that although both forest and snow cover contributed to the historical range boundary, the current duration of snow cover best explains the most recent northward shift, while forest cover has declined in relative importance. In this respect, the southern range boundary of snowshoe hares has mirrored the focus of conservation research; first habitat loss and fragmentation was the stronger environmental constraint, but climate change has now become the main threat. Projections of future range shifts show that climate change, and associated snow cover loss, will continue to be the major driver of this species' range loss into the future.

Theory predicts that mating systems are influenced by sex-specific selection pressures and the dispersion of females, but potential constraints imposed by a species' life history and physiology are rarely considered. Sloths, or ‘perezosos’ (the ‘lazies’) in Spanish, are one of the most sedentary terrestrial mammals on Earth, and we hypothesized that their low mobility would constrain the ability of males to take advantage of the ‘polygamy potential’ of their environment. We characterized the reproductive strategy of Hoffmann's two-toed sloths, Choloepus hoffmanni, in an agro-ecosystem in northeastern Costa Rica by assigning paternity, characterizing the spatial distribution of related individuals and describing the space use of 157 individuals. Spatial patterns of relatedness suggested that natal dispersal was female biased and sufficient to avoid inbreeding. Five (36%) adult males sired offspring with more than one female, and we observed three apparent extraterritorial matings, indicating that sloths were not strictly monogamous. Generally, adult males were segregated and appeared to show some territoriality in core areas, although home ranges of adjacent males overlapped in areas of low use. On average, male home ranges encompassed more than three females, and females usually occurred within the home range of more than one male. These patterns of space use and relatedness suggest males monopolize space more than they do females, and that the mating system of Hoffmann's two-toed sloth involves a mixture of polygyny and promiscuity. Neighbouring males were more closely related than expected, suggesting that a certain level of tolerance among males may stem from the benefits of kin selection and the limited ability of males to monopolize breeding opportunities.

The identification of population bottlenecks is critical in conservation because populations that have experienced significant reductions in abundance are subject to a variety of genetic and demographic processes that can hasten extinction. Genetic bottleneck tests constitute an appealing and popular approach for determining if a population decline has occurred because they only require sampling at a single point in time, yet reflect demographic history over multiple generations. However, a review of the published literature indicates that, as typically applied, microsatellite-based bottleneck tests often do not detect bottlenecks in vertebrate populations known to have experienced declines. This observation was supported by simulations that revealed that bottleneck tests can have limited statistical power to detect bottlenecks largely as a result of limited sample sizes typically used in published studies. Moreover, commonly assumed values for mutation model parameters do not appear to encompass variation in microsatellite evolution observed in vertebrates and, on average, the proportion of multi-step mutations is underestimated by a factor of approximately two. As a result, bottleneck tests can have a higher probability of 'detecting' bottlenecks in stable populations than expected based on the nominal significance level. We provide recommendations that could add rigor to inferences drawn from future bottleneck tests and highlight new directions for the characterization of demographic history.

Advances in the application of stable isotopes have allowed the quantitative evaluation of previously cryptic ecological processes. In particular, researchers have utilized the predictable spatial patterning in natural abundance of isotopes to better understand animal dispersal and migration. However, quantifying dispersal via natural abundance alone has proven to be of limited utility for species exhibiting short- or mid-distance dispersal events, including most mammalian species. In previous experimental work, we demonstrated that consumption of 1 dose of isotopically enriched baits elicited a distinct ‘‘mark’’ in hair of captive martens (Martes spp.). Herein, we report findings from a field test of our isotopic enrichment approach to mark freeranging animals and quantify dispersal of martens across forest stands at sites in southeastern Alaska and northern British Columbia. In the field, we supplemented bait used in single-capture hair traps with the amino acid glycine artificially enriched in 2 H, 13 C, or 15 N. By applying unique combinations of artificially enriched isotopic markers within discrete forest stands, the isotopic signature of collected hair reflected the forest patch where the individual originated. From our isotopic marks, we were able to infer dispersal events between forested stands and, thus, estimate rates and approximate dispersal distances. Our findings demonstrate that isotopic enrichment can be a cost-effective method to mark the hair of midsized mammals for the quantification of dispersal.

Demographic structure is central to understanding the dynamics of animal populations. However, determining the age of free-ranging mammals is difficult, and currently impossible when sampling with noninvasive, genetic-based approaches. We present a method to estimate age class by combining measures of telomere lengths with other biologically meaningful covariates in a Bayesian network. We applied this approach to American and Pacific martens (Martes americana and M. caurina) and compared predicted age with that obtained from counts of cementum annuli. Using telomere length and the covariates sex, species, and estimates of population density obtained from commercial trapping records, we assigned martens to juvenile (

Although dispersal is an important attribute of animal population ecology, knowledge of dispersal rates or distances for many wide-ranging species is lacking. Current methods require capturing and restraining animals, which can be costprohibitive, fail to collect sufficient samples or change animal ranging behaviors. Herein, we describe a novel, cost-effective and non-invasive method, using bait enriched with stable isotopes to mark the hair of American martens Martes americana. Captive martens that consumed isotopically labeled glycine exhibited significant and progressive enrichment in the isotopic signature of 13 C, 15 N and 2 H in both whole blood and hair. A distinct mark in hair, 42 standard deviations above natural abundance, occurred within 14 days of the second dose. The rate of isotopic labeling of hair was higher in spring, possibly because labeled amino acids became diluted among the many hairs growing during the autumn. Because hair and feathers can be collected non-invasively from large geographic areas without capturing animals, this labeling method can be used to mark and study the movement and dispersal rates of animals across landscapes efficiently.

Summary 1. Traditional understanding of how hunting affects vertebrate populations emphasizes competitive release and density dependence of vital rates, but more recent thinking has proposed complex non-lethal responses to hunting disturbance and predation risk. Colonial species have been proposed to be more vulnerable than dispersed, solitary species to disturbance and perceived risk from hunting. However, empirical comparisons of density dependence vs. risk disturbance in hunted species are few. 2. To compare density dependence with risk-disturbance effects of hunting on individuals and populations of a colonial species, we tested the response of black-tailed prairie dogs Cynomys ludovicianus to shooting in a before‐after, treatment‐control experiment. We subjected five colonies to a pulse of shooting, and compared individual and colony attributes to those of five control colonies, protected from shooting. 3. Surviving prairie dogs increased alert behaviours eightfold and reduced both aboveground activity and time spent foraging by 66%. Changes in behaviour lowered the body condition of surviving adults by 35%. Survivors of shooting, especially juveniles, exhibited elevated stress levels; faecal corticosterone concentrations increased by 80% among juveniles. Unexpectedly, overwinter survival rates did not increase in response to reduced prairie dog density. Colonies subjected to shooting experienced reproductive near-collapse the summer after shooting; pregnancy rates declined by 50% and reproductive output fell by 82%. 4. Risk-disturbance overwhelmed any possible density-dependent effects of shooting in prairie dogs, which exhibited additive mortality in response to hunting, and reproductive failure 1 year after shooting. Risk-disturbance was the predominant mechanism whereby individuals and colonies were affected by hunting. 5. Synthesis and applications. Because of their coloniality, prairie dogs possess certain life-history traits that predisposed them to be particularly susceptible to huntingassociated disturbances, which had cascading effects on population-level processes. Our findings contradict the general belief that small-bodied mammals quickly rebound from hunting exploitation via compensatory mortality and reproduction. Managers should consider measures to reduce recreational shooting intensity and duration in regions where black-tailed prairie dog colony growth and persistence is desired, yet allow shooting in areas where colonies conflict with landowner interests.

Although lead shot has been banned for waterfowl hunting in North America, some predators continue to exhibit elevated lead burdens, which has been attributed to ingesting metallic lead from other projectiles. Few studies have investigated residual lead fragments in hunted upland animals. Therefore, specific portals for lead entering wildlife food chains remain largely unknown. Prairie dogs (Cynomys spp.) are shot for recreation with minimal regulation in western North America. Because recreational shooters mostly use expanding bullets and rarely remove or bury carcasses, shot prairie dogs could make lead accessible to predators and scavengers. To determine whether and to what degree shot prairie dogs carry lead fragments, we analyzed carcasses shot by recreational shooters with 2 bullet types. Bullet type influenced the probability of bullet fragments being retained in carcasses; 87% of prairie dogs shot with expanding bullets contained bullet fragments, whereas 7% of carcasses shot with non-expanding bullets did. The amount of bullet fragments per carcass also differed between bullet types; carcasses shot with expanding bullets contained a mean of 228.4 mg of the lead-containing bullet core and 74.4 mg of the copper-alloy jacket, whereas carcasses shot with non-expanding bullets averaged only 19.8 mg of the core and 23.2 mg of the jacket. Lead fragments in carcasses shot with expanding bullets were small in size; 73% of all lead mass in each carcass was from fragments that weighed

Community structure and interspecific interactions are particularly vulnerable to rapidly changing climatic regimes. Recent changes in both climate and vertebrate community assemblages have created a unique opportunity to examine the impacts of two dynamic forces on population regulation. We examined the effects of warming winter conditions and the reestablishment of a previously extirpated predator, the fisher (Martes pennanti), on regulatory mechanisms in a northern-adapted mammal, the porcupine (Erethizon dorsatum), along their southern range boundary. Using a long-term (17-year) capture-recapture data set, we (1) quantified the impacts of climate change and increased fisher predation on the survival of adult porcupines at their regional southern terminus, (2) assessed recruitment (via both adult fecundity and juvenile survival) of porcupines, and (3) modeled the relative importance of predation and winter conditions on the demography and population growth rate (λ). Severe winters and abundant predators interacted synergistically to reduce adult survivorship by as much as 44%, while expanding predator populations led to near reproductive failure among porcupines. Increasing predatory pressure, disruptions in this community module, and more frequent extreme winter weather events led to predicted extirpation within 50 years, whereas in the absence of predators, the population was viable. Our results provide a mechanistic understanding behind distributional shifts resulting from climate change and may be broadly relevant for predicting future distributional shifts in other northern-adapted mammalian species.

Symbiotic microbial communities are critical to the function and survival of animals. This relationship is obligatory for herbivores that engage gut microorganisms for the conversion of dietary plant materials into nutrients such as short-chain organic acids (SCOAs). The constraint on body size imposed by their arboreal lifestyle is thought to make this symbiosis especially important for sloths. Here, we use next-generation sequencing to identify the bacteria present in the fore and distal guts of wild two- and three-toed sloths, and correlate these communities with both diet and SCOAs. We show that, unlike other mammalian herbivores, sloth gut communities are dominated by the bacterial phyla Proteobacteria and Firmicutes. Specifically, three-toed sloths possess a highly conserved, low-diversity foregut community with a highly abundant Neisseria species associated with foregut lactate. In contrast, two-toed sloths have a more variable and diverse foregut microbiota correlated with a variety of SCOAs. These differences support the hypothesis that feeding behaviour selects for specific gut bacterial communities, as three-toed sloths subsist primarily on Cecropia tree leaves while two-toed sloths have a more generalist diet. The less diverse diet and gut microbiota of three-toed sloths may render them more susceptible to habitat loss and other diet-altering conditions.

In seasonally snow-covered environments, many organisms endure winter by using the subnivium, a below-snow thermally stable seasonal refugium. Because the insulation of snow is dependent on snow depth and density, the stability of temperatures within the subnivium varies across land cover types. Additionally, across much of the Northern Hemisphere snow extent, depth and duration are generally decreasing while snow density is increasing due to climate change. These changes are likely to destabilize the thermal profile of the subnivium, although they have not yet been quantified. To explore the effects of land cover and climate change on the subnivium, we measured snow pack characteristics (depth and density), and ambient and subnivium temperatures from three different land cover types (prairie, deciduous forest, and coniferous forest) and within a micro-greenhouse (2.5 x 2.5 x 2 m) that maintained a temperature of 5 °C warmer than outdoor ambient temperatures, and automatically opened during snow events throughout the winter of 2013/14. We found that the mean daily subnivium temperature was significantly colder in the deciduous cover type than the prairie cover type, and that prairie had higher maximum subnivium temperatures than both of the other cover types. Our climate change simulation revealed that, although ambient temperatures within the micro-greenhouse were 5 °C warmer than outside the greenhouse, the daily minimum subnivium temperature was significantly lower inside the greenhouse. Our findings suggest that climate change could have considerable effects on the refuge quality of the subnivium, and that some cover types appear to be more susceptible to these effects than others.

Over 150,000 ha of standing forest was altered as a result of a large-scale blowdown in the Boundary Waters Canoe Area Wilderness, Minnesota in 1999. We collected data in summers 2000 and 2001 to assess the effects of windthrow perturbation on small mammal communities in northern coniferous forests. Small mammal diversity, as well as density of the two most common species, red-backed voles (Clethrionomys gapperi) and woodland jumping mice (Napaeozapus insignis), were determined in three different treatments with varying proportions of blowdown ( 66% blowdown). Diversity of small mammals increased from 2000 to 2001 and was highest in forest stands with 25 individuals/ha) at sites most affected by blowdown. In contrast, density of woodland jumping mice exhibited an inverse relationship with r...

While kayaking in Lake Superior, I observed a red squirrel (Tamiasciurus hudsonicus) swimming. I followed the squirrel for approximately 1.5 km until it safely arrived on an island, which is approximately 2 km from the shores of mainland Wisconsin. This is the first published observation of a red squirrel swimming in one of the Great Lakes, as well as the longest documented swim of a red squirrel. Further investigations are needed to determine whether swimming is a significant form of dispersal and island colonization for red squirrels in North America.

Exotic prey species can dramatically alter trophic interactions by functionally replacing native prey species. This pattern has been observed in the southern Neotropics, where introduced haresLepus europaeus Pallas, 1778 and rabbitsOryctolagus cuniculus (Linnaeus, 1758) have become the staple prey for native predators. Despite their importance as prey, no data are available on the mass and relative age of the lagomorphs on which native predators feed. We used linear regression models to predict the mass of lagomorphs from their hind-foot length, and investigated the influence of sex, season, and collection site on this relationship. Hind-foot length was a good predictor of body mass for both species and accounted for 58.4 and 71.6% of the variability in body mass for hares and rabbits, respectively. Sex and season significantly influenced the relationship, whereas the effect of collection site was negligible. Hind-foot length was also a good predictor of age class for hares and rabbits, allowing the discrimination between nonreproductive and reproductive classes for both species. Future research can use this method to determine the biomass and age class of exotic lagomorphs consumed by predators.

Within North America, northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels occupy distinct ranges with limited overlap. Sympatry in northern latitudes coincides with northern hardwood vegetation from Minnesota to New England. Strongyloides robustus is an intestinal parasite that infects both species but appears to be deleterious only to northern flying squirrels. As a result, S. robustus could be a critical determinant of flying squirrel population characteristics in at least some areas of sympatry. However, cold weather could potentially limit the distribution of S. robustus in northern climates. Therefore, we assessed fecal samples from both flying squirrel species to determine the presence of the nematode in Wisconsin. Strongyloides robustus was found in 12 flying squirrel scat samples and infected 52% of southern flying squirrels and 11% of northern flying squirrels. Prevalence of S. robustus infection for northern flying squirrels was substantially lower than previously reported from more southern regions. This is the northernmost documentation of S. robustus in flying squirrels and the first documentation of S. robustus parasitizing flying squirrels in Wisconsin.

The brown-throated three-toed sloth (Bradypus variegatus) is an extremely sedentary arboreal mammal found in many Neotropical forests. Because of its low dispersal potential and ease in capture, it has the potential to serve as a model species to investigate the effects of land cover change in the Neotropics on gene flow and population connectivity. To better understand aspects of B. variegatus biology, such as mating system and dispersal rates, we isolated and characterized 18 polymorphic microsatellite markers. Markers were tested using 32 B. variegatus individuals sampled from a site in northeastern Costa Rica. Each locus contained between three and 12 alleles, while mean expected and observed heterozygosity were equal to 0.72. No loci deviated from Hardy–Weinberg equilibrium, and one locus was significantly linked to two others. These markers have sufficient polymorphism to identify individuals and assign parentage, and can further be used to investigate dispersal rates, mating structure, and other aspects of three-toed sloth ecology.

Hoffmann’s two-toed sloth (Choloepus hoffmanni) is an arboreal mammal found throughout the Neotropics. Due to its limited dispersal power and reliance on forested habitats, C. hoffmanni could serve as a model species for understanding the response of mammals to land cover change. To better understand sloth life history and their response to tropical forest fragmentation and loss, we developed and characterized 16 polymorphic microsatellite markers. We tested each locus with 16–23 C. hoffmanni individuals sampled in northeastern Costa Rica. The number of alleles per locus ranged from three to seven, while mean observed heterozygosity was 0.56 and ranged from 0.33 to 0.75. All loci met Hardy–Weinberg expectations and none of the loci exhibited significant linkage disequilibrium. The microsatellite markers developed herein will be used to investigate dispersal rates and gene flow among habitat patches in Costa Rica, as well as provide insights into the life history of two-toed sloths.

Conservation biologists are generally united in efforts to curtail the spread of non-native species globally. However, the colonization history of a species is not always certain, and whether a species is considered non-native or native depends on the conservation benchmark. Such ambiguities have led to inconsistent management. Within the Tongass National Forest of Alaska, the status of American marten (Martes americana) on the largest, most biologically diverse and deforested island, Prince of Wales (POW), is unclear. Ten martens were released to POW in the early 1930s, and it was generally believed to be the founding event, although this has been questioned. The uncertainty surrounding when and how martens colonized POW complicates management, especially because martens were selected as a design species for the Tongass. To explore the history of martens of POW we reviewed other plausible routes of colonization; genetically and isotopically analyzed putative marten fossils deposited in the late Pleistocene and early Holocene to verify marten occupancy of POW; and used contemporary genetic data from martens on POW and the mainland in coalescent simulations to identify the probable source of the present-day marten population on POW. We found evidence for multiple routes of colonization by forest-associated mammals beginning in the Holocene, which were likely used by American martens to naturally colonize POW. Although we cannot rule out human-assisted movement of martens by Alaskan Natives or fur trappers, we suggest that martens be managed for persistence on POW. More generally, our findings illustrate the difficulty of labeling species as non-native or native, even when genetic and paleo-ecological data are available, and support the notion that community resilience or species invasiveness should be prioritized when making management decisions rather than more subjective and less certain conservation benchmarks.

Although techniques to analyze and quantify DNA-based data have progressed, methods to noninvasively collect samples lag behind. Samples are generally collected from devices that permit coincident sampling of multiple individuals. Because of cross-contamination, substantive genotyping errors can arise. We developed a cost-effective (US$4.60/trap) single-capture hair trap for American martens (Martes americana). In the field, traps effectively targeted martens; >75% of all hair samples were identified as marten. Eighty percent of marten hair (n = 180) contained sufficient quality for DNA-based analyses. This effective and affordable trap can be used by managers to monitor mesocarnivore populations noninvasively.

It was back in 1982, when the United States was mired in the Cold War and a recession, that the National Institutes of Health awarded a five-year, $3.2 million grant to a group of scientists at the Los Alamos National Laboratory to develop GenBank. It now houses nearly 200 billion bases from 178 million sequences representing more than 300,000 species and is the largest and most frequently accessed collection of experimental data in the world (Strasser 2011). Although it is now difficult to imagine a world without GenBank and the opportunities it provides, its creation did not come without questions—about data collection and distribution, attribution of credit and authorship, and design of infrastructure and access (Strasser 2011). Still, the need for a unifying database of genetic sequences commanded wide agreement. Now is the time to invest in a parallel special-purpose database for a burgeoning field of research with enormous promise: the use of stable isotopes. Isotopic ratios are often idiosyncratic, encoding information about the origin and history of particular matter, whether it be an ancient ice core, a Martian rock, or a fossil. In biological systems, elements such as hydrogen, carbon, nitrogen, and oxygen are light enough for isotopes to be differentially affected by biochemical processes such as photosynthesis and respiration, creating isotopic variation. This is extraordinarily useful for studying biological processes. For example, stable isotopes are routinely used for studies of animal and plant physiology, community and ecosystem ecology, biomedicine, paleobiology, evolution, and climatology. The diversity of questions that can be answered with stable isotopes, coupled with advancements in instrumentation that now enable the analysis of hundreds of samples per week on a single mass spectrometer, is what makes the growth of this field parallel that of DNA sequencing. Thus, in this era of “big data” there is a need for IsoBank, a database to house, organize, vet, and make isotopic data readily available.

In response to our review of the use of genetic bottleneck tests in the conservation literature (Peery etal. 2012, Molecular Ecology, 21, 3403-3418), Hoban etal. (2013, Molecular Ecology, in press) conducted population genetic simulations to show that the statistical power of genetic bottleneck tests can be increased substantially by sampling large numbers of microsatellite loci, as they suggest is now possible in the age of genomics. While we agree with Hoban and co-workers in principle, sampling large numbers of microsatellite loci can dramatically increase the probability of committing type 1 errors (i.e. detecting a bottleneck in a stable population) when the mutation model is incorrectly assumed. Using conservative values for mutation model parameters can reduce the probability of committing type 1 errors, but doing so can result in significant losses in statistical power. Moreover, we believe that practical limitations associated with developing large numbers of high-quality microsatellite loci continue to constrain sample sizes, a belief supported by a literature review of recent studies using next generation sequencing methods to develop microsatellite libraries. conclusion, we maintain that researchers employing genetic bottleneck tests should proceed with caution and carefully assess both statistical power and type 1 error rates associated with their study design.

The effects of climate change on biodiversity have emerged as a dominant theme in conservation biology, possibly eclipsing concern over habitat loss in recent years. The extent to which this shifting focus has tracked the most eminent threats to biodiversity is not well documented. We investigated the mechanisms driving shifts in the southern range boundary of a forest and snow cover specialist, the snowshoe hare, to explore how its range boundary has responded to shifting rates of climate and land cover change over time. We found that although both forest and snow cover contributed to the historical range boundary, the current duration of snow cover best explains the most recent northward shift, while forest cover has declined in relative importance. In this respect, the southern range boundary of snowshoe hares has mirrored the focus of conservation research; first habitat loss and fragmentation was the stronger environmental constraint, but climate change has now become the main threat. Projections of future range shifts show that climate change, and associated snow cover loss, will continue to be the major driver of this species' range loss into the future.

The identification of population bottlenecks is critical in conservation because populations that have experienced significant reductions in abundance are subject to a variety of genetic and demographic processes that can hasten extinction. Genetic bottleneck tests constitute an appealing and popular approach for determining if a population decline has occurred because they only require sampling at a single point in time, yet reflect demographic history over multiple generations. However, a review of the published literature indicates that, as typically applied, microsatellite-based bottleneck tests often do not detect bottlenecks in vertebrate populations known to have experienced declines. This observation was supported by simulations that revealed that bottleneck tests can have limited statistical power to detect bottlenecks largely as a result of limited sample sizes typically used in published studies. Moreover, commonly assumed values for mutation model parameters do not appear to encompass variation in microsatellite evolution observed in vertebrates and, on average, the proportion of multi-step mutations is underestimated by a factor of approximately two. As a result, bottleneck tests can have a higher probability of 'detecting' bottlenecks in stable populations than expected based on the nominal significance level. We provide recommendations that could add rigor to inferences drawn from future bottleneck tests and highlight new directions for the characterization of demographic history.

Promiscuous mating strategies are much more common than previously appreciated. So much so, that several authors have proposed that promiscuity is the "rule" rather than the exception in vertebrate mating systems. Decreasing species mobility and increasing habitat fragmentation have both been suggested to reduce the "polygyny potential" of the environment and promote other mating strategies like promiscuity in females. We explored the social and genetic mating system for one of the most sedentary extant mammals, the brown-throated three-toed sloth (Bradypus variegatus), within a highly fragmented Neotropical habitat. Surprisingly, we found that three-toed sloths were strongly polygynous, with males excluding male competitors from their core ranges, and exhibiting strong reproductive skew. Indeed, only 25% of all resident adult males sired offspring and one individual sired half of all sampled juveniles. Paradoxically, a sedentary life-history strategy seems to facilitate polygyny in fragmented landscapes because multiple females can persist within small patches of habitat, and be monopolized by a single male. Our work demonstrates that strong polygyny can arise in systems in which the polygyny potential should be extremely low, and other strategies, including promiscuity, would be favoured. Mating systems can be influenced by a multitude of factor and are dynamic, varying among taxa, over time, and across habitats; consequently, mating systems remain difficult to predict based on general ecological principles.

We evaluated the accuracy of sex identification using the SRY marker for American marten (Martes americana) and Pacific marten (Martes caurina) using samples collected from commercial trappers and those obtained via noninvasive sampling. We determined that sex identification from Lut-SRY primers is accurate at >90% for muscle and hair samples collected noninvasively. We found much lower accuracy when using hair samples plucked from trapper-killed carcasses, errors presumably incurred from contamination from the DNA of trappers, who were entirely male. We also found that the sequence generated from Lut-SRY primers, originally developed for Eurasian otters (Lutra lutra), differed slightly for martens, and recommend that new primers be developed from the sequences we provide. The SRY marker can be reliably used for sex identification in both species of marten, provided that samples have low probabilities of contamination. Researchers should avoid samples collected from external locations on trapper-killed carcasses for DNA-based analyses.

Plague is the primary cause for the rangewide decline in prairie dog (Cynomys spp.) distribution and abundance, yet our knowledge of plague dynamics in prairie dog populations is limited. Our understanding of the effects of plague on the most widespread species, the black-tailed prairie dog (C. ludovicianus), is particularly weak. During a study on the population biology of black-tailed prairie dogs in Wyoming, USA, plague was detected in a colony under intensive monitoring, providing a unique opportunity to quantify various consequences of plague. The epizootic reduced juvenile abundance by 96% and adult abundance by 95%. Of the survivors, eight of nine adults and one of eight juveniles developed antibodies to Yersinia pestis. Demographic groups appeared equally susceptible to infection, and age structure was unaffected. Survivors occupied three small coteries and exhibited improved body condition, but increased flea infestation compared to a neighboring, uninfected colony. Black-tailed prairie dogs are capable of surviving a plague epizootic and reorganizing into apparently functional coteries. Surviving prairie dogs may be critical in the repopulation of plague-decimated colonies and, ultimately, the evolution of plague resistance.

Arboreal herbivory is rare among mammals. The few species with this lifestyle possess unique adaptions to overcome size-related constraints on nutritional energetics. Sloths are folivores that spend most of their time resting or eating in the forest canopy. A three-toed sloth will, however, descend its tree weekly to defecate, which is risky, energetically costly and, until now, inexplicable. We hypothesized that this behaviour sustains an ecosystem in the fur of sloths, which confers cryptic nutritional benefits to sloths. We found that the more specialized three-toed sloths harboured more phoretic moths, greater concentrations of inorganic nitrogen and higher algal biomass than the generalist two-toed sloths. Moth density was positively related to inorganic nitrogen concentration and algal biomass in the fur. We discovered that sloths consumed algae from their fur, which was highly digestible and lipid-rich. By descending a tree to defecate, sloths transport moths to their oviposition sites in sloth dung, which facilitates moth colonization of sloth fur. Moths are portals for nutrients, increasing nitrogen levels in sloth fur, which fuels algal growth. Sloths consume these algae-gardens, presumably to augment their limited diet. These linked mutualisms between moths, sloths and algae appear to aid the sloth in overcoming a highly constrained lifestyle.

Soboliphyme baturini, a stomach-dwelling nematode of American martens (Martes americana), reaches high levels of infection; however, its effects on the nutritional condition of the host are unknown. To understand the effects of this parasite on American martens, we collected S. baturini and measured abdominal fat deposits from 155 marten carcasses on Prince of Wales Island, southeastern Alaska, in the winter 2006–2007. We analyzed how the dried mass of abdominal fat varied as a function of S. baturini intensity. Parasite intensity and nutritional condition were not correlated; these results suggest that American martens were able to withstand even very high levels of S. baturini infection (up to 178 parasites per host).

Science, and ecology, is fundamentally a social endeavor. As such, central aspects of the scientific process, like innovation or the exchange of ideas, can be influenced by the geographic distribution of scientists and resources. Nonetheless, the spatial patterning of ecological research within the United States has never been measured. By using an approach similar to that used to map global biodiversity hotspots, we quantified ecological research activity across the United States. We assigned members of Ecological Society of America, recipients of National Science Foundation grants, and authors of publications in leading ecological journals to the ZIP code of their home institution. Using these data we mapped the density of ecologists, and the magnitude of their inputs and outputs, and quantified an “ecological activity” index to measure the spatial intensity of ecological research within the United States. We also examined spatial patterns of collaboration. Our quantification of ecological activity and subsequent cluster analysis revealed distinct centers, or hotspots, of ecological research. Our analyses also indicated that such hotspots of ecological activity achieved their status via different pathways. Furthermore, ecologists within hotspots of ecological research were highly connected via collaborations with researchers across the country and within their own ZIP code.