Genetic characteristics play an important role in alien species for achieving high adaptation and rapid evolution in a new environment. The American mink (Neovison vison) is one of the best-known and most widespread invasive species that has successfully invaded the Eurasian mainland over quite a short period, including most parts of northeastern China. However, genetic information on farmed and feral American mink populations introduced in China is completely lacking. In this study, we combined mitochondrial DNA sequences and polymorphic microsatellites to examine the genetic divergence and genetic diversity of farmed and feral American mink populations. Our results suggest that there is admixture of individuals of different genetic characteristics between farmed and feral populations of mink. Furthermore, the genetic diversity of both farmed and feral American mink populations was high, and no bottleneck or population expansion was detected in most of the populations. These findings not only highlight the genetic characteristics of American mink in northeastern China but also contribute to the general understanding of the invasiveness of farmed species.

Background: Pleistocene climatic oscillations and historical geological events may both influence current patterns of genetic variation, and the species in southern China that faced unique climatic and topographical events have complex evolutionary histories. However, the relative contributions of climatic oscillations and geographical events to the genetic variation of these species remain undetermined. To investigate patterns of genetic variation and to test the hypotheses about the factors that shaped the distribution of this genetic variation in species of southern China, mitochondrial genes (cytochrome b and NADH dehydrogenase subunit 2) and nine microsatellite loci of the Omei tree frog (Rhacophorus omeimontis) were amplified in this study.Results: The genetic diversity in the populations ofR. omeimontiswas high. The phylogenetic trees reconstructed from the mitochondrial DNA (mtDNA) haplotypes and the Bayesian genetic clustering analysis based on microsatellite data both revealed that all populations were divided into three lineages (SC, HG and YN). The two most recent splitting events among the lineages coincided with recent geological events (including the intense uplift of the Qinghai-Tibet Plateau, QTP and the subsequent movements of the Yun-Gui Plateau, YGP) and the Pleistocene glaciations. Significant expansion signals were not detected in mismatch analyses or neutrality tests. And the effective population size of each lineage was stable during the Pleistocene.Conclusions: Based on the results of this study, complex geological events (the recent dramatic uplift of the QTP and the subsequent movements of the YGP) and the Pleistocene glaciations were apparent drivers of the rapid divergence of theR. omeimontislineages. Each diverged lineages survivedin situwith limited gene exchanges, and the stable demographics of lineages indicate that the Pleistocene climatic oscillations were inconsequential for this species. The analysis of genetic variation in populations ofR. omeimontiscontributes to the understanding of the effects of changes in climate and of geographical events on the dynamic development of contemporary patterns of genetic variation in the species of southern China.

Current genetic variation patterns across different geographic areas are mainly the result of various historical processes, including paleoclimate oscillations and tectonic events. Southern China, characterized by a complex paleoclimate and topography, presents an opportunity to examine such genetic variation patterns. Herein, we selected three species of moustache toads (Leptobrachium boringii, Leptobrachium liui and Leptobrachium leishanense) distributed across southern China to elucidate historical processes that shaped their current phylogeographic patterns based on two mitochondrial genes and eight microsatellite loci. L. boringii and L. liui are estimated to have genetically diverged from the late Miocene to the Pleistocene, which were largely associated with paleoclimate oscillations and geological barriers generated by complex mountain systems in southern China. Within L. liui, a recent split was caused by the rising of the Wuyi Mountains during the early Pleistocene. Demographic analyses revealed that complex topography might play buffering roles in Leptobrachium species during the last glacial maximum. These findings not only highlight the combined effects of climatic oscillations and tectonic events on driving genetic divergences, but also contribute to the general understanding of the phylogeography in this biodiversity hotspot.

The production of foam nests is one of the strategies that has evolved to allow some anuran species to protect their eggs and larvae. Despite considerable knowledge of the biochemical components of and construction behavior leading to anuran foam nests, little is known about the molecular basis of foam nest construction. Rhacophorus omeimontis presents an arboreal foam-nesting strategy during the breeding season. To better understand the molecular mechanism of foam nest production, transcriptome sequencing was performed using the oviduct of female R. omeimontis during the period when foam nest production began and the period when foam nest production was finished. The transcriptomes of six oviduct samples of R. omeimontis were obtained using Illumina sequencing. A total of 84,917 unigenes were obtained, and 433 genes (270 upregulated and 163 downregulated) were differentially expressed between the two periods. These differentially expressed genes (DEGs) were mainly enriched in extracellular space and extracellular region based on Gene Ontology (GO) enrichment analysis and in the pathways of two-component system, cell adhesion molecules, steroid hormone biosynthesis and neuroactive ligand-receptor interaction based on Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Specifically, genes encoding lectins, surfactant proteins and immunity components were highly expressed when the foam nest construction began, indicating that the constituents of foam nests in R. omeimontis were likely a mixture of surfactant, lectins and immune defense proteins. During the period when foam nest production was finished, genes related to lipid metabolism, steroid hormone and immune defense were highly expressed, indicating their important roles in regulating the process of foam nesting. Our study provides a rich list of potential genes involved in the production of foam nests in R. omeimontis. These results provide insights into the molecular mechanisms underlying the process of foam nest construction and will facilitate further studies of R. omeimontis.