The roles of climate, geography and natural selection as drivers of genetic and phenotypic differentiation in a widespread amphibian Hyla annectans (Anura: Hylidae)

The role of geological events and Pleistocene climatic fluctuations as
drivers of current patterns of genetic variation in extant species has
been a topic of continued interest among evolutionary biologists.
Nevertheless, comprehensive studies of widely distributed species are
still rare, especially from Asia. Using geographically extensive sampling
of many individuals and a large number of nuclear single nucleotide
polymorphisms (SNPs), we studied the phylogeography and historical
demography of Hyla annectans populations in southern China. Thirty-five
sampled populations were grouped into seven clearly defined genetic
clusters that closely match phenotype-based subspecies classification.
These lineages diverged 2.32–5.23 million years ago, a timing that closely
aligns with the rapid and drastic uplifting of the Qinghai-Tibet Plateau
and adjacent southwest China. Demographic analyses and species
distribution models indicate that different populations of this species
have responded differently to past climatic changes. In the Hengduan
Mountains, most populations experienced a bottleneck, whereas the
populations located outside of the Hengduan Mountains have gradually
declined in size since the end of the last glaciation. In addition, the
levels of phenotypic and genetic divergence were strongly correlated
across major clades. These results highlight the combined effects of
geological events and past climatic fluctuations, as well as natural
selection, as drivers of contemporary patterns of genetic and phenotypic
variation in a widely distributed anuran in Asia.