Phylogeography of horseshoe crab, Tachypleus tridentatus in the Indo-West Pacific

• Main Authors: Ming-Che Yang, 楊明哲
• Other Authors: Chang-po Chen
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/72431005475068381073

碩士 === 國立臺灣大學 === 漁業科學研究所 === 92 === The Indo-West-Pacific region (IWP) hosts the highest marine biodiversity on earth. The concordance among different species can be used to deduct the common mechanism that forms the IWP marine biodiversity. Genetic variation of mitochondrial AT- rich region in the “living-fossil” horseshoe crab, Tachypleus tridentatus, were revealed for 82 individuals collected from 5 populations in 3 regions, including southern Burma coast of Andaman Sea (AB), Angsila in Gulf of Thailand (GT), and Kinmen (TK), Donwei (TD), Tehsiwei (TT) in Taiwan. Haplotype phylogeny constructed by neighbour-joining algorithm, the network derived from the minimum spanning network, and dating by fossil records demonstrated that a significantly deep divergence between the populations in Indian and Pacific Ocean, suggesting a pattern of Indian-Pacific tectonic plate divergence from late Oligocene to early Miocene (21-27 Ma). In addition, it also indicated that Taiwan population formed a significantly different clade from Gulf of Thailand divergence time indicates that South China Sea Basin might play an important role in retarding gene flow of between the T. tridentatus populations of southern and northern South China Sea from early Miocene to middle Miocene (17-21 Ma). The demography parameter and unimodal mismatch distribution indicates the sudden range expansion of T. tridentatus population in Gulf of Thailand and affected by sea level and habitat fluctuation during glaciations. The mismatch distribution indicated the bottleneck effect on Donwei population due to recent population size decline and inbreeding in this close bay. The implications of phylogeography and demography towards the T. tridentatus conservation in the IWP are also highlighted.