Abstract
Abstract Taiwan island locates at the margin of Eurasia plate. Lots of species have dispersed from the mainland of Eurasia to Taiwan after the formation of the island. The main biota of Taiwan has formed consequently. Freshwater fishes dwelling in island-like habitats provide an ideal model for phylogeographical studies. Bagrids are an attractive group because of a great morphological diversity and wide distribution. But only a few studies focused on the phylogenetic relationships of Taiwan bagrids. Based on the comparisons of their morphological characters, this group of fishes can be divide into two groups: (1) Pseudobagrus brevianalis and P. taiwanensis; (2) P. adiposalis . The aim of our present work are to sequence D-loop of thses two groups and then to analyse population genetic structures and the phylogeographical patterns and the relationships of P. brevianalis and P. taiwanensis. No matter the morphological characters or genetic evidence can’t prove that P. brevianalis and P. taiwanensis are both existed . The biogeographical pattern of bagrid catfishes in Taiwan, with a distribution range restricted to western Taiwan, is highly correlated with the topographical isolation by the Central Mountain Range. According to the phylogenetic tree, the populations of the two species demarcated by Miaoli Plateau and fell into two clusters: (1) the northern group; (2) the central group. Genetic variability in the mitochondrial control region of the bagrid catfishes in Taiwan examined was low at both within- and among- population levels. P. brevianalis has ten haplotypes and the genetic distance is from 0.1% to 1.6%, and P. adiposalis has three haplotypes and the genetic distance is from 0.3% to 1.8%. According to the previous studies and this work, the low variability in bagrids should be explainable by some historical biogeographic reason or molecular evolutionary rate . Genetic distance between northern population and middle population is high, although the morphological characters are quiet similar. The results suggest northern population and middle population are possible subspecies.