Little genetic structure in a Bornean endemic small mammal across a steep ecological gradient.

Janzen's influential "mountain passes are higher in the tropics" hypothesis predicts restricted gene flow and genetic isolation among populations spanning elevational gradients in the tropics. Few studies have tested this prediction, and studies that focus on population genetic structure in Southeast Asia are particularly underrepresented in the literature. Here, we test the hypothesis that mountain treeshrews (Tupaia montana) exhibit limited dispersal across their broad elevational range which spans ~2,300 m on two peaks in Kinabalu National Park (KNP) in Borneo: Mt Tambuyukon (MT) and Mt Kinabalu (MK). We sampled 83 individuals across elevations on both peaks and performed population genomics analyses on mitogenomes and single nucleotide polymorphisms from 4,106 ultraconserved element loci. We detected weak genetic structure and infer gene flow both across elevations and between peaks. We found higher genetic differentiation on MT than MK despite its lower elevation and associated environmental variation. This implies that, contrary to our hypothesis, genetic structure in this system is not primarily shaped by elevation. We propose that this pattern may instead be the result of historical processes and limited upslope gene flow on MT. Importantly, our results serve as a foundational estimate of genetic diversity and population structure from which to track potential future effects of climate change on mountain treeshrews in KNP, an important conservation stronghold for the mountain treeshrew and other montane species.

An efficient method for simultaneous species, individual, and sex identification via in-solution single nucleotide polymorphism capture from low-quality scat samples.

Understanding predator population dynamics is important for conservation management because of the critical roles predators play within ecosystems. Noninvasive genetic sampling methods are useful for the study of predators like canids that can be difficult to capture or directly observe. Here, we introduce the FAECES* method (Fast and Accurate Enrichment of Canid Excrement for Species* and other analyses) which expands the toolbox for canid researchers and conservationists by using in-solution hybridization sequence capture to produce single nucleotide polymorphism (SNP) genotypes for multiple canid species from scat-derived DNA using a single enrichment. We designed a set of hybridization probes to genotype both coyotes (Canis latrans) and kit foxes (Vulpes macrotis) at hundreds of polymorphic SNP loci and we tested the probes on both tissues and field-collected scat samples. We enriched and genotyped by sequencing 52 coyote and 70 kit fox scats collected in and around a conservation easement in the Nevada Mojave Desert. We demonstrate that the FAECES* method produces genotypes capable of differentiating coyotes and kit foxes, identifying individuals and their sex, and estimating genetic diversity and effective population sizes, even using highly degraded, low-quantity DNA extracted from scat. We found that the study area harbours a large and diverse population of kit foxes and a relatively smaller population of coyotes. By replicating our methods in the future, conservationists can assess the impacts of management decisions on canid populations. The method can also be adapted and applied more broadly to enrich and sequence multiple loci from any species of interest using scat or other noninvasive genetic samples.

Cryptic diversity in Black rats Rattus rattus of the Galápagos Islands, Ecuador.

Human activity has facilitated the introduction of a number of alien mammal species to the Galápagos Archipelago. Understanding the phylogeographic history and population genetics of invasive species on the Archipelago is an important step in predicting future spread and designing effective management strategies. In this study, we describe the invasion pathway of Rattus rattus across the Galápagos using microsatellite data, coupled with historical knowledge. Microsatellite genotypes were generated for 581 R. rattus sampled from 15 islands in the archipelago. The genetic data suggest that there are at least three genetic lineages of R. rattus present on the Galápagos Islands. The spatial distributions of these lineages correspond to the main centers of human settlement in the archipelago. There was limited admixture among these three lineages, and these finding coupled with low rates of gene flow among island populations suggests that interisland movement of R. rattus is rare. The low migration among islands recorded for the species will have a positive impact on future eradication efforts.