Phylogeography of the Japanese pipistrelle bat, Pipistrellus abramus, in China: the impact of ancient and recent events on population genetic structure

Effects of Colonization, Geography and Environment on Genetic Divergence in the Intermediate Leaf-Nosed Bat, Hipposideros larvatus

Determining the evolutionary history and population drivers, such as past large-scale climatic oscillations, stochastic processes and ecological adaptations, represents one of the aims of evolutionary biology. Hipposideros larvatus is a common bat species in Southern China, including Hainan Island. We examined genetic variation in H. larvatus using mitochondrial DNA and nuclear microsatellites. We found a population structure on both markers with a geographic pattern that corresponds well with the structure on mainland China and Hainan Island. To understand the contributions of geography, the environment and colonization history to the observed population structure, we tested isolation by distance (IBD), isolation by adaptation (IBA) and isolation by colonization (IBC) using serial Mantel tests and RDA analysis. The results showed significant impacts of IBD, IBA and IBC on neutral genetic variation, suggesting that genetic variation in H. larvatus is greatly affected by neutral processes, environmental adaptation and colonization history. This study enriches our understanding of the complex evolutionary forces that shape the distribution of genetic variation in bats.

The first authenticated record of the pangolin tick Amblyomma javanense (Acari: Ixodidae) in Singapore, with notes on its biology and conservation

The first authenticated record of the co-endangered pangolin tick (Amblyomma javanense) is reported from the Republic of Singapore, based on specimens of males and females collected from the Sunda pangolin (Manis javanica). The biology of the species is reviewed and steps for its conservation are outlined to ensure its continued survival across its range.

Diversification and Demography of the Oriental Garden Lizard (Calotes versicolor) on Hainan Island and the Adjacent Mainland

The Oriental garden lizard (Calotes versicolor) is one of the few non-gekkonid lizards that are geographically widespread in the tropics. We investigated its population dynamics on Hainan Island and the adjacent mainland of China and Vietnam, focusing on the impact of cyclic upheaval and submergence of land bridges during the Pleistocene. Our Bayesian phylogenetic analysis reveals two mitochondrial lineages, A and B, which are estimated to have coalesced about 0.26 million years ago (95% credibility interval: 0.05–0.61 million years ago). Lineage A contains individuals mainly from central and southern Wuzhi Mountain on Hainan Island, whereas lineage B mainly comprises individuals from other sites on the island plus the adjacent mainland. The estimated coalescence times within lineages A (0.05 million years ago) and B (0.13 million years ago) fall within a period of cyclical land-bridge formation and disappearance in the Pleistocene. A spatial analysis of molecular variance identified two distinct population groupings: I, primarily containing lineage A, and II, mainly consisting of lineage B. However, haplotypes from lineages A and B occur sympatrically, suggesting that gene flow is ongoing. Neither Wuzhi Mountain nor Qiongzhou Strait and Gulf of Tonkin act as barriers to gene flow among C. versicolor populations. Analyses of the data using mismatch distributions and extended Bayesian skyline plots provide evidence of a relatively stable population size through time for Group I, and moderate population expansions and contractions during the end of the Pleistocene for Group II. We conclude that the phylogeographical patterns of C. versicolor are the combined product of Pleistocene sea-level oscillations and nonphysical barriers to gene flow.

Historical male-mediated introgression in horseshoe bats revealed by multilocus DNA sequence data

Instances of hybridization between mammalian taxa in the wild are rarely documented. To test for introgression between sibling species of horseshoe bat (Rhinolophus yunanensis and R. pearsoni) and two subspecies of the latter (R. p. pearsoni and R. p. chinensis), we sequenced two mtDNA and two ncDNA markers in individuals sampled from multiple localities within their overlapping ranges. The interspecific mtDNA gene tree corresponded to the expected taxonomic divisions, and coalescent-based analyses suggested divergence occurred around 4 MYA. However, these relationships strongly conflicted with those recovered from two independent nuclear gene trees, in which R. yunanensis clustered with R. p. pearsoni to the exclusion of R. p. chinensis. This geographically widespread discordance is best explained by large-scale historical introgression of ncDNA from R. yunanensis to R. pearsoni by male-mediated exchange in mixed species colonies during Pleistocene glacial periods, when ranges may have contracted and overlapped more than at present. Further species tree-gene tree conflicts were detected between R. p. pearsoni and R. p. chinensis, also indicating past and/or current introgression in their overlapping regions. However, here the patterns point to asymmetric mtDNA introgression without ncDNA introgression. Analyses of coalescence times indicate this exchange has occurred subsequent to the divergence of these subspecies from their common ancestor. Our work highlights the importance of using multiple data sets for reconstructing phylogeographic histories and resolving taxonomic relationships.