| Summary: | 碩士 === 國立中山大學 === 海洋科學系研究所 === 106 === Gene exchange of widespread marine species populations may be easily interrupted
by various conditions in the ocean, which may result in divergences. Previous studies
suggested that complex coastal current system, Changjiang Diluted Water and
Pleistocene Glacial Cycle are possible factors causing divergence of marine
organisms in Coastal China. Tridentiger barbatus is a benthic goby widely spread in
coastal China, Korea and Japan. In this study, we collected 258 individuals of T.
barbatus from 14 sites along the coast of China to explore its genetic structure.
Fragments of cyt b, Rh and RAG1 from all individuals were obtained and analyzed.
Bayesian trees and TCS network revealed two deeply divided lineages (southern
lineage and northern lineage) in T. barbatus, distributions of the two lineages
appeared to match summer coastal current pattern in China. It implied that currents
may have important effect on the phylogeographic pattern of T. barbatus. Cyt b
haplotype distributions and AMOVA showed further divisions within southern
lineage, which may be related to currents and barriers in coastal China. Divergence
time of the two lineages was 1.65 Mya, which may be dated back to Pleistocene
glacial cycles. Tajima’ D and Fu’ Fs statistics were significantly negative in both
southern and northern lineage, suggesting that the two lineages might have undergone
sudden expansions in past. Bayesian skyline plot showed that sudden expansion times
of southern and northern lineage were 0.010 Mya and 0.015 Mya, respectively, which
happened at the end of the last glacial period (about 0.02 Mya). It implied that
Pleistocene glaciation may be important to divergence and population size of T.
barbatus.
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