|
Vol. 45 No. 3, 2006
The Phylogeography and Population Demographics of Selected Freshwater Fishes in Taiwan
Chyng-Shyan Tzeng1,*, Yeong-Shin Lin1,2, Si-Min Lin1,3, Tzi-Yuan Wang1,4, and Feng-Yung Wang1
1Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 300
2Present address: Institute of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan 300
3Present address: Department of Life Science, Chinese Culture University, Taipei, Taiwan 111
4Present address: Genomics Research Center, Academia Sinica, Taipei, Taiwan 115
Chyng-Shyan Tzeng, Yeong-Shin Lin, Si-Min Lin, Tzi-Yuan Wang, and Feng-Yung Wang (2006)
Unlike most fluvial species, which are usually isolated by geographical
barriers, low-elevation wetland fishes have more opportunities to
exchange migrants (i.e., higher gene flow). Our phylogeographic
analyses revealed that Taiwanese populations of the ricefish (Oryzias latipes), paradise fish (Macropodus opercularis), and a species of the landlocked freshwater goby (Rhinogobius giurinus)
are all paraphyletic and clustered with Chinese populations. The 3
ricefish populations known from Taiwan may have been derived from
multiple invasion events. We hypothesized that the original ricefish
populations distributed throughout northwestern Taiwan significantly
declined from their overall range, and the surviving inhabitants were
restricted to Shuanglien Pond. This population thereby exhibited high
genetic diversity. Alternatively, humans probably unintentionally
introduced the other 2 populations. We also found that the abundant
freshwater goby and the endangered paradise fish populations in Taiwan
had both recently expanded from China. The separation time is
insufficient for the Taiwanese populations to have diverged and
developed elevated genetic diversity. In other words, the actual
genetic homogeneity of paradise fish in Taiwan is not necessarily
derived from a recent extinction. The other example of shallow
differentiation among Taiwanese fishes is the Formosan masu salmon, Oncorhynchus masou
formosanus. Its low genetic diversity may partly have been the result
of a founder effect when initial masu salmon populations colonized
Taiwan during the last glaciation.
Key words: Biogeography, Evolution, Mutation rate, Mitochondrial control region, Conservation.
*Correspondence: Tel and Fax: 886-3-5742765. E-mail:cstzeng@life.nthu.edu.tw
|
