Interspecific competition is an integral force in animal communities, shaping the distributions, ecology, and behavior of sympatric species. We evaluated breadth and overlap of diets and space-use within a sympatric carnivore guild, including bobcats (Lynx rufus), cougars (Puma concolor), coyotes (Canis latrans), grey foxes (Urocyon cinereoargenteus), and Pacific martens (Martes caurina) in Yosemite National Park, CA using two approaches. We used DNA metabarcoding of scats to evaluate composition and overlap among diets and scat locations and remote camera detections to estimate the space-use of carnivores. From 1,176 scat samples, we identified 68 vertebrate prey species from 57 genera, 36 families, 16 orders, and five classes. Composition and body size of prey items varied among consumers. Space-use varied among carnivores with some (e.g., cougars, coyotes) occurring throughout Yosemite, while others predominantly occurred in lower (e.g., grey foxes) or higher (e.g., martens) elevations. Vegetation structure, topography, and precipitation correlated with both foraging patterns and space-use patterns within the carnivore guild. Our results suggest that changes in heterospecific occurrence and habitat could affect competition for space and resources in systems affected by continued climate and landscape change.

Nutria (Myocastor coypus) is an invasive, semi-aquatic rodent that recently re-emerged in California’s Central Valley, threatening ecologically vital wetland habitats. To understand invasion dynamics, we aimed to identify the source of contemporary California nutria, assess genetic structure, estimate kinship to infer colonization social dynamics, and identify dispersal corridors. We sampled contemporary California nutria (n = 267), six other invasive populations across North America (n = 40), and historical samples from California fur farms (n = 10). We sequenced the cytochrome-b locus and used RADSeq to discover 6,809 SNP loci. Consistent with recent invasion, we found a single cytochrome-b haplotype among contemporary California nutria, while historical samples had several haplotypes no longer present. Nuclear and mitochondrial data revealed contemporary California nutria have close genetic affiliation with Oregon and Washington populations. SNP-based estimates of kinship indicated closely related individuals occupy the northern and southern leading edges of the invasion, while more central areas displayed low kinship and minimal genetic structure. Landscape genetic analyses identified dispersal corridors facilitating southern range expansion. We provide the first assessment of genetic relationships among nutria invaded regions in the United States, including insights into landscape connectivity and colonization dynamics that will ultimately aid eradication strategies.

Invasive predators can have negative impacts on biological communities through top-down predation, but the ecological processes that shape the consumption of prey in novel communities are less understood. The “Enemy release hypotheses” and “Naïve prey hypothesis” are two explanations for why invasive species succeed in novel environments and, under these hypotheses, diets of invasive predators are expected to initially expand and then contract throughout the invasion process. Furthermore, differing invader densities, and fluctuations in climactic and biogeographic conditions that shape prey community composition are likely to influence prey availability and selection, but the relative importance of these factors has yet to be tested. Here we used DNA metabarcoding on intestinal samples to determine diet composition and diversity of Barred Owls (Strix varia) within their native and invasive ranges. Dietary diversity was greater in the invasive range across all taxonomic levels. Within the native range mice were the most consumed vertebrate (frequency of occurrence = 71%) but were a small component of invasive diet (26%). Non-mammalian prey items had higher importance within the invasive range. We provide preliminary evidence that expansion in hunting opportunities facilitates successful invasions.

White-nose syndrome (WNS) has decimated numerous bat populations in North America. Given the rapid spread of WNS, identifying resistance is critical for mitigating further loss. Yet, detecting genomic signatures of WNS resistance in bat populations has proven challenging. Rapid innovations in sequencing and genome assembly technologies now provide unprecedented opportunity to characterize genomic variation in virtually any species and, in turn, resolve the underpinnings of wildlife disease resistance. We have assembled a near-chromosome-level for the little brown bat (Myotis lucifugus) reference genome using Omni-C and PacBio sequencing, resulting in a mean depth of coverage of 37.7X, a scaffold N50 of 99.0 Mb, and a BUSCO completeness score of 98.5%. We optimized gene annotation by combining ab initio gene predictions, orthology inferences, and transcriptomic evidence. Additionally, we conducted whole-genome resequencing on M. lucifugus samples predating, and 10 years following, WNS exposure. Individuals were sequenced from sites in New York and Pennsylvania (N ≈ 15 per sampling) at a mean depth of 25.7X resulting in >40 million SNPs. To date, this study has produced the highest-quality genomic resources available for M. lucifugus for determining the genomic architecture of WNS resistance. These findings will in turn provide insight into naïve population susceptibility during future spread of WNS.

The blunt‐nosed leopard lizard (BNLL; Gambelia sila) is an endangered species endemic to the San Joaquin Desert of California. Understanding its diet is fundamental to the conservation of the species and its habitat. A number of populations, including that of the Panoche Plateau, have undergone or are in the process of becoming extinct, which underscores the urgency of obtaining fundamental ecological data. DNA metabarcoding leverages the power of high-throughput DNA sequencing to provide both higher taxonomic resolution and prey-detection capacity over traditional fecal diet analyses. We collected fecal samples from across the range during 2013-2021 and used DNA metabarcoding to recover arthropod diet sequences. Based on data from >700 fecal samples we identified >100 invertebrate diet items. Orthopterans (grasshoppers etc.), Hemipterans (true bugs), and Coleopterans (beetles) were the most abundant orders in the BNLL diet across sites. However, the abundance of individual diet species varied widely even among contemporaneous samples. The Panoche Plateau population appeared to have the lowest diet diversity across all sites examined. This population was considered functionally extinct by 2022. The highly resolved arthropod diet data from this study will also improve our ability to assess sites for BNLL suitability.

Bighorn sheep (Ovis canadensis) recovery throughout North America over the last century has been accomplished primarily through translocations from relict herds to unoccupied historical range. Yet the genomic consequences of reintroductions, including founder events, inbreeding depression, and genetic drift remain uninvestigated. This includes evaluating the risk of subsequent demographic/genetic rescue using stock from large, genetically diverse populations, as such individuals could introduce new deleterious recessive alleles. To characterize the effects of a founder event followed by complete isolation, we sequenced 12 whole genomes from a 45-year-old population of bighorn sheep, established from as few as 20 animals, in Sespe Wilderness, California. Size of runs of homozygosity suggested inbreeding was intense at the time of introduction but has been minimal in the last < 20 years. Compared to the source population (n = 12), and a genetically diverse reference population (n = 12), the Sespe individuals had a higher proportion of homozygous and fixed missense and loss-of-function mutations, which may reflect increased expression of deleterious alleles. Simulations of various augmentation scenarios are planned to evaluate extinction risk associated with introducing stock from various sized populations with differing genetic load. This study will guide future reintroductions and demographic/genetic rescue efforts for bighorn sheep throughout North America.