POPULATION GENETIC STRUCTURE OF THE AMPHIDROMOUS GOBY Sicyopterus japonicus IN THE NORTHWESTERN PACIFIC
Date Issued
2009
Date
2009
Author(s)
Leander, Nico Jose Sarmiento
Abstract
The goby Sicyopterus japonicus is an amphidromous species that spawns in freshwater and has a long marine pelagic larval duration which may diminish population genetic differentiation. To prove this hypothesis, a total of 465 base pairs in the control region of the mitochondrial DNA in S. japonicus were analyzed from 119 specimens collected from 3 different river systems in Fulong, Nan-ao and Hualien in eastern Taiwan during 2007 to 2009. Additional 74 mtDNA sequences from Japan were also included in the analysis to have a general view of its population genetic structure in the northwestern Pacific. Neighbor-joining tree and AMOVA analyses indicated that the eight populations has no significant differentiation (ΦST = 0.00401, P>0.05). The number of migrants per generation (Nm), on the other hand, ranges from 9.25787 (between HW-AUT and KOC) up to infinity. Infinite value of Nm indicates that an extremely high gene flow has occurred between the Taiwan and Japan populations particularly during spring. Significant genetic differences however were observed for specimens collected in Taiwan during autumn and winter seasons in the Pairwise ΦST test, indicating that unfavorable environmental condition (e.g. cold water temperature) might have restricted dispersal of the goby larvae during these seasons and affected the survival and the recruitment of the goby larvae in Japan. On the other hand, the absence of population genetic differentiation found in spring is probably due to gene flow that occurs during the dispersal and transport of the larvae from the south to the north. Meanwhile, the difference in mean pelagic larval duration (PLD) between Japan (208 + 22 days) and Taiwan (163.72 + 12.79 days) is approximately 45 days, which allows the larvae of this species to disperse from Taiwan to Japan by the Kuroshio Current. Although the adults of this species are distributed among isolated freshwater systems, gene flow and larval dispersal can take place to restrict population genetic differentiation. Accordingly, it is no doubt that long marine PLD and oceanic current seem to play an important role in determining the larval dispersal and subsequently, the population structuring of this goby species.
Subjects
goby
mitochondrial DNA
pelagic larval duration
Sicydiinae
larval dispersal
SDGs
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