| Summary: | 碩士 === 國立臺灣師範大學 === 生命科學研究所 === 93 === Abstract
Farmland green tree frog, Rhacophorus arvalis is an endemic species of Taiwan. Its main habitats include rice fields, bamboo plantations, and orchards. These environments are frequently disturbed through various types of human activities. Currently it is found only in limited farmlands in Yunlin, Chiayi, and Tainan counties. Apparently this species is greatly threatened by habitat fragmentations and other human activities. Farmland green tree frogs have limited dispersal capabilities due to low mobility and site fidelity. It is one of the best candidate animals to study the impacts of habitat fragmentations on wildlife. Based on their current distribution, farmland green tree frogs can be separate into four populations: north bank of Peikang stream、south bank of Peikang stream、Potz stream and Madou. A total of 120 individuals were used to analyze with partial mitochondrial COX1, cyto b and D-loop gene fragments. Haplotypes, nucleotide diversity, FST, Nm, AMOVA (analysis of molecular variance), minimum spanning network and NCA (Nested clade analysis) methods were applied. The Farmland green tree frog’s maximum intra-specific genetic variance is 0.004, which is the lowest among amphibian being investigated in Taiwan. Even the genetic variance of Madou population is 0. Molecular data showed that four populations all derived from small effective breeding populations. We suspected that the historical stochastic factors and human disturbance might play important roles in this aspect. The north and south bank of Peikang stream populations both were rapid growing. Nevertheless, Potz and Madou population have experienced a period of bottleneck. The phylogeographic evidences indicate that Potz population might come from Peikang population. Data also revealed a consistent phylogeographic pattern, and indicated the results of “past fragmentation”. This leads to low gene flow among populations and bottleneck effect. Genetic variations were lost greatly among population and formed four significantly different populations. We suggest madou population given the higher priority for species conservation in short term. Population of Peikang stream is the genetic hotspot for conservation.
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