Systematics, biogeography, and evolution of the earthworms in the Metaphire formosae species group inferred from morphology and mitochondrial DNA sequences

• Main Authors: Chih-Han Chang, 張智涵
• Other Authors: 陳俊宏
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/87896774736330136072

碩士 === 國立臺灣大學 === 動物學研究研究所 === 93 === A new Metaphire formosae species group in the genus Metaphire of the pheretimoid earthworms (Pheretima auct.) is proposed in this study, and the systematics, biogeography, and evolution of this species group are also concerned. The species abundance of this species group was increased from 6 to 12. Among these species, 11 are endemic to Taiwan, including three new species described in this study. The results suggested that the ancestor of the Taiwanese species arrived Taiwan during the late Miocene, and then dispersed throughout this island. During the rapid uplift of Taiwan between 5.0~2.5 MYA, different populations of the ancestor species were rapidly and continuously isolated by the mountains and rivers that formed due to orogenesis in this period. The isolation initiated genetic differentiation and finally caused speciation of the M. formosae species group. In addition, the uplift of Taiwan after 2.5 MYA caused intraspecific genetic differentiation among geographically isolated populations of the M. formosae species group. For instance, in M. yuhsii, a member of this species group, two populations started to differentiate genetically about 2.5 MYA due to the formation of the Tamsui River, which served as a geographical barrier between the two populations. On the other hand, the results suggested that holandry derives from protandry in the M. formosae species group. Therefore, the use of testis conditions in intrageneric grouping in pheretimoid earthworms is not appropriate. The revision of the pheretimoid systematics needs further investigation using molecular phylogenetic approaches.