Biodiversity Research Center, Academia Sinica Taipei, Taipei, Taiwan (Republic of China)
Understanding the history of diversification and applying integrative methods are keys to objective species delimitation that the results are evolutionarily relevant. We studied the speciation history and species delimitation in an endemic stag beetle of Taiwan, Lucanus miwai, where two geographic populations constrained in isolated mountain ranges have been previously recognized. We showed that there were two mitochondrial CO1 lineages and the pairwise sequence divergence was > 3.2 %; however, one of the geographic taxa was not monophyletic. Our bpp result using four nuclear loci strongly supported the hypothesis that the geographic populations are two evolutionary independent lineages; the genealogical divergence index calculated from our bpp result corresponded to strong support for species level divergence. Using an approximate Bayesian computation approach, we further showed that the northern population was likely founded by the southern population generations ago. Currently, the two geographic populations can be diagnosed by male mandible characters and their morphological variation did not overlap in the PC space based on results from a geometric morphometric analysis. Our results suggest that the divergence between the two geographic taxa of L. miwai merit species-level divergence and demonstrate the power of integrative species delimitation, while cautioning against barcoding practices, to make evolutionary arguments for recognized new species.
