| Summary: | 博士 === 中興大學 === 生命科學系所 === 95 === To comprehend the geographical patterns of genetic variation in anurans in Taiwan, the genetic structures of Sylvirana latouchii from 203 individuals, and Rana latouchii from 244 individuals were tested using mitochondrial DNA (mtDNA) cytochrome b sequences. Phylogenetic structures, nested clade analyses, and molecular clock tests were applied to compare the phylogeography of these two species.
In S. latouchii’s study, a neighbor-joining tree of 39 haplotypes revealed three major divergences among Taiwanese individuals: the northern, western, and eastern-and-peninsula clades. Each clade was restricted to single geographical district and showed obvious differentiation. In R. sauteri’s result, 77 haplotypes from 5 distant lineages, including northern lineage (NL), eastern lineage (EL), southern hill lineage (SHL), northern mountain lineage (NML), had been identified from phylogenetic analyses. The lineages of these two frogs show congruence on both biogeographic history and phylogenetic structures as follows: (1) The routes into Taiwan in the first beginning of migration events were located near Miaoli Plateau. (2) Both northern lineages migrated into Taiwan most recently, and limited in northern part of this island. (3) The first divergence events within this island were occurred by the formation of Central Mountain Rang. Phylogenetic results of both species exposed the possibility of multiple invasions hypothesis to the formation of Taiwanese fauna.
Another contribution of this study is to summarize the biogeography of terrestrial vertebrates into five districts as follows: Northern District, Eastern District, Northern part of Western District, Southern part of Western District, and Hengchun Peninsula District. This biogeographic pattern is corresponsive to the landscape characters of Taiwan.
There are some disagreements on the comparative phylogeny between these two species. The first colonization of S. latouchii failed to establish stable populations in northern Taiwan, but two lineages from different invasion events of R. sauteri occupied northern Taiwan sympatrically. Furthermore, a divergent lineage of R. sauteri in western-southern Taiwan had been identified and which was potentially occurred by reproduction isolation.
The patterns of geographical divergence in these species reflect common historical events experienced by other native animals distributed in Taiwan such as freshwater fishes. The orders of divergence times between lineages were inferred using a molecular clock tests. Hypotheses of within-island differentiation models and multiple incursion models are proposed to depict the possible colonization history of S. latouchii and R. sauteri in Taiwan. The population relationships of S. latouchii between Taiwan and mainland China were also discussed.
|
|---|
