Population Divergence of Père David’s Red–backed Vole (Eothenomys melanogaster) in Taiwan

• Main Authors: Yu-Cheng Chang, 張育誠
• Other Authors: Liang-Kong Lin
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/86509085378916262805

碩士 === 東海大學 === 生命科學系 === 95 === Père David’s red–backed vole (Eothenomys melanogaster) inhabits in the middle and high elevations of Taiwan. It is adapted to cold and lives underground in a tunnel system. Cytogenetic studies separate E. melanogaster into two races based on the differently shaped X chromosomes. Populations of E. melanogaster in Taiwan may have deeply diverged genetically. To test the interglacial refugia hypothesis and identify the pattern of phylogeographic differentiation, I investigated variation among the geographical populations of E. melanogaster in Taiwan. Chromosomal analysis, complete mitochondrial cytochrome b sequences (1143 bp), partial nuclear IRBP exon 1 sequences (1260 bp), and complete X chromosome-link gene G6pd intron 1 sequences (579 bp) supported division of E. melanogaster in Taiwan into Northern and Southern groups. The X chromosome of the Northern group was acrocentric, but it was submetacentric in the Southern group. The Cyt b genetic distance (Juke-Cantor model) between Northern and Southern groups was 3.7%. There were 6 diagnostic sites on IRBP and 2 diagnostic sites on G6pd separating Northern and Southern groups. Divergence time between two groups was 0.59 million years ago (Mya) according to mean rate 6.02% per million years (Cyt b). The populations of E. melanogaster in Taiwan were probably restricted to isolated refugia around the Cromerian interglacial period (0.63-0.56 Mya) and then differentiated genetically. The haplotype network indicated Cromerian interglacial refugia around the Alishan area for Southern group and around the Guanwu area for Northern group. Based on the genetic distance, I recommend that the Northern and Southern groups be considered two subspecies. This is because the middle degree of genetic distance and the extremely low gene flow. Since the mean Cyt b genetic distance between E. melanoagaster in Taiwan and Sichuan was greater than the minimal genetic Cyt b distance and almost reached mean Cyt b genetic distance within subgenus. I recommend E. melanogaster in Taiwan and Sichuan be considered two species.