Lillian Parker

and 9 more

Rapid shifts in environmental variables associated with elevational changes in montane ecosystems provide opportunities to test hypotheses regarding the effects of environmental heterogeneity on gene flow and genetic structure. In tropical mountains, spatial environmental heterogeneity combined with seasonal environmental stability is predicted to result in low dispersal across elevations. Few studies have investigated the genetic consequences of elevational environmental heterogeneity in tropical montane mammals. Here, we use a population genomics approach to test the hypothesis that mountain treeshrews (Tupaia montana) exhibit limited gene flow across elevational gradients and between two neighboring peaks within Kinabalu National Park (KNP) in Borneo. We sampled 83 individuals across elevations on Mt. Tambuyukon (MT) and Mt. Kinabalu (MK) and sequenced mitogenomes and 4,106 ultraconserved elements containing an average of 1.9 single nucleotide polymorphisms per locus. We detected high gene flow across elevations and between peaks. We found greater 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 colonization history combined with restricted upslope gene flow on MT due to unique plant communities associated with its upper montane habitats. Our results serve as a foundation to identify and mitigate future effects of climate change on mountain treeshrews in KNP. Given predictions for 2100 CE, we predict that mountain treeshrews will maintain genetic connectivity in KNP, making it an important conservation stronghold.
Reduced representation genome sequencing has popularized the application of single nucleotide polymorphisms (SNPs) to address evolutionary and conservation questions in non-model organisms. Patterns of genetic structure and diversity based on SNPs often diverge from those obtained with microsatellites to different degrees, but few studies have explicitly compared their performance under similar sampling regimes in a shared analytical framework. We compared range-wide patterns of genetic structure and diversity in two amphibians endemic to the Iberian Peninsula: Hyla molleri and Pelobates cultripes, based on microsatellite (18 and 14 loci) and SNP (15,412 and 33,140 loci) datasets of comparable sample size and spatial extent. Model-based clustering analyses with STRUCTURE revealed minor differences in genetic structure between marker types, but inconsistent values of the optimal number of populations (K) inferred. SNPs yielded more repeatable and less admixed ancestries with increasing K compared to microsatellites. Genetic diversity was weakly correlated between marker types, with SNPs providing a better representation of southern refugia and of gradients of genetic diversity congruent with the demographic history of both species. Our results suggest that the larger number of loci in a SNP dataset can provide more reliable inferences of patterns of genetic structure and diversity than a typical microsatellite dataset, at least at the spatial and temporal scales investigated.