Mining expressed sequence tag (EST) microsatellite markers to assess the genetic differentiation of five Hynobius species endemic to Taiwan

Taiwan harbors five endemic species of salamanders (Hynobius spp.) that inhabit distinct alpine regions, contributing to population fragmentation across isolated "sky islands". With an evolutionary history spanning multiple glacial-interglacial cycles, these species represent an exceptional paradigm for exploring biogeography and speciation. However, a lack of suitable genetic markers applicable across species has limited research efforts. Thus, developing cross-amplifying markers is imperative. Expressed sequence-tag simple-sequence repeats (EST-SSRs) that amplify across divergent lineages are ideal for species identification in instances where phenotypic differentiation is challenging. Here, we report a suite of cross-amplifying EST-SSRs from the transcriptomes of the five Hynobius species that exhibit an interspecies transferability rate of 67.67%. To identify individual markers exhibiting cross-species polymorphism and to assess interspecies genetic diversity, we assayed 140 individuals from the five species across 84 sampling sites. A set of EST-SSRs with a high interspecies polymorphic information content (PIC = 0.63) effectively classified these individuals into five distinct clusters, as supported by discriminant analysis of principal components (DAPC), STRUCTURE assignment tests, and Neighbor-joining trees. Moreover, pair-wise FST values > 0.15 indicate notable between-cluster genetic divergence. Our set of 20 polymorphic EST-SSRs is suitable for assessing population structure within and among Hynobius species, as well as for long-term monitoring of their genetic composition.

Acoustic clue: bringing echolocation call data into the distribution dilemma of Pteronotus (Chiroptera: Mormoopidae) complexes in Central America

In Central America, the distributional limits and the contact zones of some Pteronotus species, such as the naked-backed bats and the lesser mustached bats, are unclear. To elucidate the distributional dilemma of the species groups Pteronotus fulvus + Pteronotus davyi and Pteronotus psilotis + Pteronotus personatus in Central America, we studied the acoustic variation of their echolocation calls along the range of possible contact zones and the existence of distinct phonic groups. We performed hierarchical k-means clustering on principal components (HCPC) using acoustic samples from Mexico, Honduras, El Salvador, Nicaragua and Costa Rica to describe the global acoustic diversity, possibly overlooking differences between species groups. We assessed whether those acoustic differences were related to the geographical distance and geographical location. We found evidence of sympatry for three phonic groups within each species complex, without a clear correspondence to the known distribution of species. The changes in frequency of their echolocation calls seem to follow a similar pattern to the geographical variation in body size of the species. Future studies in Central America should include an integrative sampling of individually captured, tagged and recorded bats to help in resolution of the distribution dilemma raised here.