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Data from: Alternative reproductive tactics and lifetime reproductive success in a polygynandrous mammal

The widespread occurrence of alternative reproductive tactics (ARTs) highlights the diverse ways in which sexual selection can operate within a population. We studied ARTs in Columbian ground squirrels (Urocitellus columbianus), evaluating paternity, lifetime reproductive success, and life histories. Reproductively mature male Columbian ground squirrels displayed either a territorial or satellite (non-territorial) tactic. Territorial males secured a higher proportion of copulations, were more likely to mate at earlier positions in females' mating sequences and sired more offspring than satellite males. The tactic males adopted was largely a function of weight, age, and experience, with larger, older and more experienced males displaying the territorial tactic. At two years of age, males adopted the satellite tactic or deferred breeding for the season. Two-year-old satellite males were heavier than males that deferred breeding, but by age three there was no difference between their weights. Males that deferred breeding either adopted the satellite or territorial tactic in the following year, with the lighter males displaying the satellite tactic. The ARTs that males adopted at two and three years of age led to alternative life history pathways. Males that deferred breeding and only adopted the territorial tactic during their lifetime had twice the number of lifetime offspring compared to males that adopted the satellite tactic and then switched to territorial behavior in following years, although this difference was not statistically significant. Our findings show that the satellite tactic results in lower reproductive output both within a single year, except at age two, and over their lifetime.

Data from: A pipeline for metabarcoding and diet analysis from fecal samples developed for a small semi-aquatic mammal

Metabarcoding allows the genetic analysis of pooled samples of various sources. It is becoming popular in the study of animal diet, especially because it allows the analysis of the composition of feces without the need of handling animals. In this work, we studied the diet of the Pyrenean desman (Galemys pyrenaicus), a small semi-aquatic mammal endemic to the Iberian Peninsula and the Pyrenees, by sequencing COI minibarcodes from feces using next-generation sequencing techniques. For the identification of assembled sequences, we employed a tree-based identification method that used a reference tree of sequences of freshwater organisms. The comparison of freshly collected fecal samples and older samples showed that fresh samples produced significantly more sequencing reads. They also rendered more operational taxonomical units (OTUs), but not significantly. Our analyses of 41 samples identified 224 OTUs corresponding to species of the reference tree. Ephemeroptera, Diptera excl. Chironomidae, and Chironomidae were the most highly represented groups in terms of reads as well as samples. Other groups of freshwater organisms detected were Plecoptera, Trichoptera, Neuropteroida, Coleoptera, Crustacea, and Annelida. Our results are largely in line with previous morphological and genetic studies on the diet of the Pyrenean desman, but allowed the identification of a higher diversity of OTUs in each sample. Additionally, the bioinformatic pipeline we developed for deep sequencing of fecal samples will enable the quantitative analysis of the diet of this and other species, which can be highly useful to determine their ecological requirements.

opencc-zeroJul 2019View details →

Data from: Co-declining mammal-dung beetle faunas throughout the Atlantic Forest biome of South America

The millennial-scale evolutionary relationships between mammals and dung beetles have been eroded due to several drivers of contemporary biodiversity loss. Although some evidence of co-decline has been shown for mammals and dung beetles at some Neotropical sites, a biome-scale analysis for the entire Atlantic Forest of South America would strengthen our understanding of how relictual sets of mammal species can affect dung beetle co-occurrences and co-declines. We therefore collated hundreds of assemblages of both dung beetles and medium- to large-bodied mammals throughout the world's longest tropical forest latitudinal gradient to examine to what extent mammal assemblages may exert a positive influence on dung beetle species composition and functional assembly, and whether this relationship is scale dependent. We also collated several climatic and other environmental variables to examine the degree to which they shape mammal-dung beetle relationships. The relationships between local mammal and dung beetle faunas were examined using regression models, variation partitioning, dissimilarity indices, and ecological networks. We found a clear positive relationship between mammal and dung beetle species richness across this forest biome, indicating an ongoing process of mammal-dung beetle niche-mediated co-decline. We found a strong relationship between the species composition of both taxa, in which dung beetle species dissimilarity apparently track changes in mammalian dissimilarity, typically in 80% of all cases. Co-variables such as phytomass and climatic variables also influenced mammal-dung beetle patterns of co-decline along the Atlantic Forest. We conclude that dung beetle diversity and community assembly are shaped by the remaining co-occurring mammal assemblages and their functional traits, and both groups were governed by environmental features. We emphasize that ecosystem-wide effects of mammal population declines remain poorly understood both quantitatively and qualitatively, and curbing large vertebrate defaunation will ensure the persistence of co-dependent species.

opencc-zeroDec 2013View details →

Data from: Population dynamics of a northern-adapted mammal: disentangling the influence of predation and climate change

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.

Data from: Indirect effects of a large mammalian herbivore on small mammal populations: context-dependent variation across habitat types, mammal species and seasons

Multiple consumer species frequently co-occur in the same landscape and, through effects on surrounding environments, can interact in direct and indirect ways. These interactions can vary in occurrence and importance, and focusing on this variation is critical for understanding the dynamics of interactions among consumers. Large mammalian herbivores are important engineers of ecosystems worldwide, have substantial impacts on vegetation and can indirectly affect small-mammal populations. However, the degree to which such indirect effects vary within the same system has received minimal attention. We used a 16-year-old exclosure experiment, stratified across a heterogeneous landscape, to evaluate the importance of context-dependent interactions between tule elk (Cervus canadensis nannodes) and small mammals [deer mice (Peromyscus maniculatus), meadow voles (Microtus californicus) and harvest mice (Reithrodontymys megalotis)] in a coastal grassland in California. Effects of elk on voles varied among habitats and seasons: in open grasslands, elk reduced vole numbers during fall 2013 but not summer 2014; in Lupinus-dominated grasslands, elk reduced vole numbers during summer 2014 but not fall 2013; and in Baccharis-dominated grasslands, elk had no effect on vole numbers in either season. Effects of elk on the two mice species also varied among habitats and seasons, but often in different ways from voles and each other. In fall 2013, elk decreased mice abundances in Lupinus-dominated grasslands, but not in Baccharis-dominated or open grasslands. In summer 2014, elk decreased the abundance of harvest mice consistently across habitat types. In contrast, elk increased deer-mice numbers in open grasslands but not other habitats. Within the same heterogenous study system, the influence of elk on small mammals was strongly context dependent, varying among habitats, mammal species and seasons. We hypothesize that such variability is common in nature, and that failure to consider it may yield inaccurate findings and limit our understanding of interactions among co-occurring consumers.

opencc-zeroDec 2010View details →

Data from: Bayesian inference of a historical bottleneck in a heavily exploited marine mammal

Emerging Bayesian analytical approaches offer increasingly sophisticated means of reconstructing historical population dynamics from genetic data, but have been little applied to scenarios involving demographic bottlenecks. Consequently, we analysed a large mitochondrial and microsatellite dataset from the Antarctic fur seal Arctocephalus gazella, a species subjected to one of the most extreme examples of uncontrolled exploitation in history when it was reduced to the brink of extinction by the sealing industry during the late eighteenth and nineteenth centuries. Classical bottleneck tests, which exploit the fact that rare alleles are rapidly lost during demographic reduction, yielded ambiguous results. In contrast, a strong signal of recent demographic decline was detected using both Bayesian skyline plots and approximate Bayesian computing, the latter also allowing derivation of posterior parameter estimates that were remarkably consistent with historical observations. This was achieved using only contemporary samples, further emphasizing the potential of Bayesian approaches to address important outstanding problems in conservation and evolutionary biology.

Data from: An updated global dataset for diet preferences in terrestrial mammals: testing the validity of extrapolation

1. Diet is a key trait of an organism's life history that influences a broad spectrum of ecological and evolutionary processes. Kissling et al. (2014) compiled a species-specific dataset of diet preferences of mammals for 38% of a total of 5364 terrestrial mammalian species assessed for the International Union for Conservation of Nature's Red List, to facilitate future studies. The authors imputed dietary data for the remaining 62% by using extrapolation from phylogenetic relatives. 2. We collected dietary information for 1261 mammalian species for which data were extrapolated by Kissling et al. (2014), in order to evaluate the success with which such extrapolation can predict true diets. 3. The extrapolation method devised by Kissling et al. (2014) performed well for broad dietary categories (consumers of plants and animals). However, the method performed inconsistently, and sometimes poorly, for finer dietary categories, varying in accuracy in both dietary categories and mammalian orders. 4. The results of the extrapolation performance serve as a cautionary tale. Given the large variation in extrapolation performance, we recommend a more conservative approach for inferring mammalian diets, whereby dietary extrapolation is implemented only when there is a high degree of phylogenetic conservatism for dietary traits. Phylogenetic comparative methods can be used to detect and measure phylogenetic signal in diet. If data for species are needed, then only the broadest feeding categories should be used. This would ensure a greater level of accuracy and provide a more robust dataset for further ecological and evolutionary analysis.

opencc-zeroDec 2010View details →

Data from: Natural selection on a measure of parasite resistance varies across ages and environmental conditions in a wild mammal

Parasites detrimentally affect host fitness, leading to expectations of positive selection on host parasite resistance. However, since immunity is costly, host fitness may be maximized at low, but non-zero, parasite infection intensities. These hypotheses are rarely tested on natural variation in free-living populations. We investigated selection on a measure of host parasite resistance in a naturally-regulated Soay sheep population using a longitudinal data set, and found negative correlations between parasite infection intensity and annual fitness in lambs, male yearlings, and adult females. However, having accounted for confounding effects of body weight, the effect was only significant in lambs. Associations between fitness and parasite resistance were environment-dependent, being strong during low-mortality winters, but negligible during harsher high-mortality winters. There was no evidence for stabilising selection. Our findings reveal processes that may shape variation in parasite resistance in natural populations, and illustrate the importance of accounting for correlated traits in selection analysis.

opencc-zeroJan 2020View details →

Urinary suPAR: a non-invasive biomarker of infection and tissue inflammation for use in studies of large free-ranging mammals

Studies of large free-ranging mammals incorporating physiological measurements typically require the collection of urine or faecal samples, due to ethical and practical concerns over trapping or darting animals. However, there is a dearth of validated biomarkers of immune activation and inflammation that can be measured non-invasively. We here evaluate the utility of urinary measurements of the soluble form of the urokinase plasminogen activator receptor (suPAR), for use as a health marker in studies of wild large mammals. We investigate how urinary suPAR concentrations change in response to viral infection and surgical trauma (inflammation), comparing it to the measurement of a marker of cellular immune activation, urinary neopterin, in captive rhesus macaques. We then test the field utility of urinary suPAR, assessing the effects of soil and faecal contamination, sunlight, storage at different temperatures, freeze-thaw cycles, and lyophilization. We find that suPAR concentrations rise markedly in response to both infection and surgery-associated inflammation, unlike urinary neopterin concentrations, which only rise in response to the former. Our field validation demonstrates that urinary suPAR is reasonably robust to many of the issues associated with field collection, sample processing, and storage, as long as samples can be stored in a freezer. Urinary suPAR is thus a promising biomarker applicable for monitoring various aspects of health in wild primates and potentially also other large mammals.

opencc-zeroDec 2011View details →

Data from: Fine-scale spatiotemporal patterns of genetic variation reflect budding dispersal coupled with strong natal philopatry in a cooperatively breeding mammal

The relatedness structure of animal populations is thought to be a critically important factor underlying the evolution of mating systems and social behaviours. While previous work has shown that population structure is shaped by many biological processes, few studies have investigated how these factors vary over time. Consequently, we explored the fine-scale spatiotemporal genetic structure of an intensively studied population of cooperatively breeding banded mongooses (Mungos mungo) over a ten-year period. Overall population structure was strong (average Fst = 0.129) but groups with spatially overlapping territories were not more genetically similar to one another than non-contiguous groups. Instead, genetic differentiation was associated with historical group-fission (budding) events, with new groups diverging from their parent groups over time. Within groups, relatedness was high within but not between the sexes, although the latter increased over time since group formation due to group founders being replaced by philopatric young. This trend was not mirrored by a decrease in average offspring heterozygosity over time, suggesting that close inbreeding may often be avoided, even when immigration into established groups is virtually absent and opportunities for extra-group matings are rare. Fine-scale spatiotemporal population structure could have important implications in social species, where relatedness between interacting individuals is a vital component in the evolution of patterns of inbreeding avoidance, reproductive skew and kin-selected helping and harming.

Data from: Using camera trapping and hierarchical occupancy modelling to evaluate the spatial ecology of an African mammal community

Emerging conservation paradigms have shifted from single to multi-species approaches focused on sustaining biodiversity. Multi-species hierarchical occupancy modelling provides a method for assessing biodiversity while accounting for multiple sources of uncertainty. We analysed camera trapping data with multi-species models using a Bayesian approach to estimate the distributions of a terrestrial mammal community in northern Botswana and evaluate community, group, and species-specific responses to human disturbance and environmental variables. Groupings were based on two life-history traits: body size (small, medium, large and extra-large) and diet (carnivore, omnivore and herbivore). We photographed 44 species of mammals over 6607 trap nights. Camera station-specific estimates of species richness ranged from 8 to 27 unique species, and species had a mean occurrence probability of 0·32 (95% credible interval = 0·21–0·45). At the community level, our model revealed species richness was generally greatest in floodplains and grasslands and with increasing distances into protected wildlife areas. Variation among species' responses was explained in part by our species groupings. The positive influence of protected areas was strongest for extra-large species and herbivores, while medium-sized species actually increased in the non-protected areas. The positive effect of grassland/floodplain cover, alternatively, was strongest for large species and carnivores and weakest for small species and herbivores, suggesting herbivore diversity is promoted by habitat heterogeneity. Synthesis and applications. Our results highlight the importance of protected areas and grasslands in maintaining biodiversity in southern Africa. We demonstrate the utility of hierarchical Bayesian models for assessing community, group and individual species' responses to anthropogenic and environmental variables. This framework can be used to map areas of high conservation value and predict impacts of land-use change. Our approach is particularly applicable to the growing number of camera trap studies world-wide, and we suggest broader application globally will likely result in reduced costs, improved efficiency and increased knowledge of wildlife communities.

opencc-zeroFeb 2020View details →

Developmental changes in bone mechanics from Florida manatees (Trichechus manatus latirostris), obligate swimming mammals

Mammals living in aquatic environments load their axial skeletons differently than their terrestrial counterparts. The structure and mechanical behavior of trabecular bone can be especially indicative of varying habitual forces. Here, we investigate vertebral trabecular bone mechanical properties (yield strength, stiffness, and toughness) throughout development in Florida manatees (Trichechus manatus latirostris), obligate undulatory swimmers. Thoracic, lumbar, and caudal vertebrae were dissected from manatees (N=20) during necropsies. We extracted 6 mm3 samples from vertebral bodies and tested them in compression in three orientations (rostrocaudal, dorsoventral, and mediolateral) at 2 mm min-1. We determined variation in mechanical properties between sexes, and among developmental stages, vertebral regions, and testing orientations. We also investigated the relationships between vertebral process lengths and properties of dorsoventrally and mediolaterally-tested bone. Rostrocaudally-tested bone was the strongest, stiffest, and toughest, suggesting that this is the principle direction of stress. Our results showed that bone from female subadults was stronger and stiffer than their male counterparts; based on these data we hypothesize hormonal shifts at sexual maturity may partially drive these differences . In calves, bone from the posterior region was stronger and tougher than from the anterior region. We hypothesize that since animals grows rapidly throughout early development, bone in the posterior region would be the most ossified to support the rostrocaudal force propagation associated with undulatory swimming .

opencc-zeroDec 2014View details →

Data from: Random versus game trail-based camera trap placement strategy for monitoring terrestrial mammal communities

Camera trap surveys exclusively targeting features of the landscape that increase the probability of photographing one or several focal species are commonly used to draw inferences on the richness, composition and structure of entire mammal communities. However, these studies ignore expected biases in species detection arising from sampling only a limited set of potential habitat features. In this study, we test the influence of camera trap placement strategy on community-level inferences by carrying out two spatially and temporally concurrent surveys of medium to large terrestrial mammal species within Tanzania's Ruaha National Park, employing either strictly game trail-based or strictly random camera placements. We compared the richness, composition and structure of the two observed communities, and evaluated what makes a species significantly more likely to be caught at trail placements. Observed communities differed marginally in their richness and composition, although differences were more noticeable during the wet season and for low levels of sampling effort. Lognormal models provided the best fit to rank abundance distributions describing the structure of all observed communities, regardless of survey type or season. Despite this, carnivore species were more likely to be detected at trail placements relative to random ones during the dry season, as were larger bodied species during the wet season. Our findings suggest that, given adequate sampling effort (> 1400 camera trap nights), placement strategy is unlikely to affect inferences made at the community level. However, surveys should consider more carefully their choice of placement strategy when targeting specific taxonomic or trophic groups.

Data from: Birth dates vary with fixed and dynamic maternal features, offspring sex, and extreme climatic events in a high-latitude marine mammal

Reproductive synchrony tends to be widespread in diverse species of plants and animals, especially at higher latitudes. However, for long-lived mammals, birth dates for different individuals can vary by weeks within a population. A mother's birth timing can reveal useful information about her reproductive abilities and have important implications for the characteristics and survival of her offspring. Despite this, our current knowledge of factors associated with variation in birth dates is modest. We used long-term data for known-age Weddell seals in Antarctica and a Bayesian hierarchical modeling approach to study how birth dates varied with fixed and temporally varying features of mothers, whether sex allocation varied with birth timing, and annual variation in birth dates. Based on birth dates for 4465 pups born to 1117 mothers aged 4–31, we found that diverse features of mothers were associated with variation in birth dates. Maternal identity was the most important among these. Unlike most studies, which have reported that birth dates occur earlier as mothers age, we found that birth dates progressively occurred earlier in the year in the early part of a mother's reproductive life, reached a minimum at age 16, and then occurred later at later ages. Birth dates were positively related to a mother's age at primiparity and recent reproductive effort. The earliest birth dates were for pups born to prime-age mothers who did not reproduce in the previous year but began reproduction early in life, suggesting that females in the best condition gave birth earlier than others. If so, our finding that male pups tended to be born earlier than females provides support for the Trivers–Willard sex-allocation model. Average birth dates were quite consistent across years, except for 2 years that had notable delays and occurred during the period when massive icebergs were present and disrupted the ecosystem.

opencc-zeroDec 2012View details →

Data from: Ecological segregation in a small mammal hybrid zone: habitat-specific mating opportunities and selection against hybrids restrict gene flow on a fine spatial scale

The degree to which closely related species interbreed is determined by a complex interaction of ecological, behavioral, and genetic factors. We examine the degree of interbreeding between two woodrat species, Neotoma bryanti and N. lepida, at a sharp ecological transition. We identify the ecological association of each genotypic class, assess the opportunity for mating between these groups, and test whether they have similar patterns of year-to-year persistence on our study site. We find that 13% of individuals have a hybrid signature but that the two parental populations and backcrosses are highly segregated by habitat type and use. Also, we find that adult hybrids are comparable to parental types in terms of year-to-year persistence on our site but that, among juveniles, significantly fewer hybrids reach adulthood on site compared to their purebred counterparts. Our analyses show that this hybrid zone is maintained by occasional nonassortative mating coupled with hybrid fertility, but that these factors are balanced by lower apparent survival of juvenile hybrids and habitat-based preference or selection that limits heterospecific mating while promoting backcrossing to habitat-specific genotypes. This system presents a novel example of the role that sharp resource gradients play in reproductive isolation and the potential for genetic introgression.

Data from: Revealing kleptoparasitic and predatory tendencies in an African mammal community using camera traps: a comparison of spatiotemporal approaches

Camera trap data are increasingly being used to characterise relationships between the spatiotemporal activity patterns of sympatric mammal species, often with a view to inferring inter-specific interactions. In this context, we attempted to characterise the kleptoparasitic and predatory tendencies of spotted hyaenas Crocuta crocuta and lions Panthera leo from photographic data collected across 54 camera trap stations and two dry seasons in Tanzania's Ruaha National Park. We applied four different methods of quantifying spatiotemporal associations, including one strictly temporal approach (activity pattern overlap), one strictly spatial approach (co-occupancy modelling), and two spatiotemporal approaches (co-detection modelling and temporal spacing at shared camera trap sites). We expected a kleptoparasitic relationship between spotted hyaenas and lions to result in a positive spatiotemporal association, and further hypothesised that the association between lions and their favourite prey in Ruaha, the giraffe Giraffa camelopardalis and the zebra Equus quagga, would be stronger than those observed with non-preferred prey species (the impala Aepyceros melampus and the dikdik Madoqua kirkii). Only approaches incorporating both the temporal and spatial components of camera trap data resulted in significant associative patterns. The latter were particularly sensitive to the temporal resolution chosen to define species detections (i.e. occasion length), and only revealed a significant positive association between lion on spotted hyaena detections, as well as a tendency for both species to follow each other at camera trap sites, during the dry season of 2013, but not that of 2014. In both seasons, observed spatiotemporal associations between lions and each of the four herbivore species considered provided no convincing or consistent indications of any predatory preferences. Our study suggests that, when making inferences on inter-specific interactions from camera trap data, due regards should be given to the potential behavioural and methodological processes underlying observed spatiotemporal patterns.

opencc-zeroJan 2020View details →

Founder takes more: interspecific competition affects range expansion of North American mammals into deglaciated areas

Aim I assess the impact of interspecific competition on species post-glacial range expansions into previously glaciated areas. I hypothesize that expansion of one species (the founder) after the Last Glacial Maximum (LGM) into areas that were glaciated has hindered expansion of its competitor (the successor). If true, I predict that range and niche sizes of two congeners are more disproportionate within the previously glaciated areas (i.e., the areas of postglacial expansion) than within areas that were not glaciated. I also predict that niche partitioning is reduced within previously glaciated areas. If true, range and climatic niche overlap of two congeners is smaller in the previously glaciated areas than in non-glaciated areas. Location North America Taxon Non-volant mammals Methods I calculate species range size for 87 congeneric species pairs and climatic niche hypervolume for 71 pairs, separately for areas that were and were not glaciated during the LGM. I then compare (a) range and climatic niche size ratio and (b) range and climatic niche overlap for each species pair between areas that were and were not glaciated using a paired t-test. Results Congeneric species pairs exhibit more disproportionate range areas and climatic niche hypervolumes and smaller range and climatic niche overlap within previously glaciated areas in comparison with areas that were not glaciated during the LGM. Main conclusions Interspecific competition has likely hindered postglacial range expansion of some species into deglaciated areas. Similarly to the founder effect documented on the intraspecific level, the founder species may hinder the expansion of the successor species. Consequently, one species may expand over very large areas whereas its competitor may expand very little or not at all. Additionally, niche partitioning within the deglaciated areas may be reduced as the founder expands and fills biotopes that would otherwise be utilized by its competitor.

Data from: Australian native mammals recognise and respond to alien predators: a meta-analysis

Prey naiveté is a failure to recognise novel predators and thought to cause exaggerated impacts of alien predators on native wildlife. Yet there is equivocal evidence in the literature for native prey naiveté towards aliens. To address this, we conducted a meta-analysis of Australian mammal responses to native and alien predators. Australia has the world's worst record of extinction and declines of native mammals, largely due to two alien predators introduced some 150 years ago: the feral cat, Felis catus, and European red fox, Vulpes vulpes. Analysis of 94 responses to predator cues show that Australian mammals consistently recognise alien foxes as a predation threat, possibly because of thousands of years experience with another canid predator, the dingo, Canis lupus dingo. We also found consistent recogntion responses towards feral cats, however in 4 of the 7 studies available, these responses were of risk-taking behaviour rather than antipredator behaviour. Our results suggest that a simple failure to recognise alien predators is not behind the ongoing exaggerated impacts of alien predators in Australia. Instead, our results highlight an urgent need to better understand the appropriateness of antipredator responses in prey towards alien predators in order to understand native prey vulnerability.

opencc-zeroDec 2012View details →

Data from: Mammals across the K/Pg boundary in northeastern Montana, U.S.A.: dental morphology and body-size patterns reveal extinction selectivity and immigrant-fueled ecospace filling

The Cretaceous/Tertiary (K/Pg) mass extinction has long been viewed as a pivotal event in mammalian evolutionary history, in which the extinction of non-avian dinosaurs allowed mammals to rapidly expand from small-bodied, generalized insectivores to a wide array of body sizes and ecological specializations. Many studies have used global- or continental-scale taxonomic databases to analyze this event on coarse temporal scales, but few studies have documented morphological diversity of mammalian paleocommunities on fine spatiotemporal scales in order to examine ecomorphological selectivity and ecospace filling across this critical transition. Focusing on well-sampled and temporally well-constrained mammalian faunas across the K/Pg boundary in northeastern Montana, I quantified dental-shape disparity and morphospace occupancy via landmark- and semilandmark-based geometric morphometrics and mean body size, body-size disparity, and body-size structure via body-mass estimates. My results reveal several key findings: (1) latest Cretaceous mammals, particularly metatherians and multituberculates, had a greater ecomorphological diversity than is generally appreciated, occupying regions of the morphospace that are interpreted as strict carnivory, plant-dominated omnivory, and herbivory; (2) the decline in dental-shape disparity and body-size disparity across the K/Pg boundary shows a pattern of constructive extinction selectivity against larger-bodied dietary specialists, particularly strict carnivores and taxa with plant-based diets, that suggests the kill mechanism was related to depressed primary productivity rather than a globally instantaneous event; (3) the ecomorphological recovery in the earliest Paleocene was fueled by immigrants, namely three multituberculate families (taeniolabidids, microcosmodontids, eucosmodontids) and to a lesser extent archaic ungulates; and (4) despite immediate increases in the taxonomic richness of eutherians, their much-celebrated post-K/Pg ecomorphological expansion had a slower start than is generally perceived and most likely only began 400,000 to 1 million years after the extinction event.

Data from: Decreased small mammal and on-host tick abundance in association with invasive red imported fire ants (Solenopsis invicta)

Invasive species may impact pathogen transmission by altering the distributions and interactions among native vertebrate reservoir hosts and arthropod vectors. Here, we examined the direct and indirect effects of the red imported fire ant (Solenopsis invicta) on the native tick, small mammal and pathogen community in southeast Texas. Using a replicated large-scale field manipulation study, we show that small mammals were more abundant on treatment plots where S. invicta populations were experimentally reduced. Our analysis of ticks on small mammal hosts demonstrated a threefold increase in the ticks caught per unit effort on treatment relative to control plots, and elevated tick loads (a 27-fold increase) on one common rodent species. We detected only one known human pathogen (Rickettsia parkeri), present in 1.4% of larvae and 6.7% of nymph on-host Amblyomma maculatum samples but with no significant difference between treatment and control plots. Given that host and vector population dynamics are key drivers of pathogen transmission, the reduced small mammal and tick abundance associated with S. invicta may alter pathogen transmission dynamics over broader spatial scales.