| Research Abstract |
In 9 species of all 11 species of the Genus Tetraclita, T. japonicaィイD1*ィエD1, T. formosanaィイD1*ィエD1, T. squamosaィイD1*ィエD1, T. rufotinctaィイD1*ィエD1, T. serrataィイD1*ィエD1, T. rubescensィイD1+ィエD1, T. confinisィイD1+ィエD1, T. stalactiferaィイD1+ィエD1, T. panamensisィイD1+ィエD1 (ィイD1*ィエD1Indo-West Pacific, ィイD1+ィエD1E & W of North America) were analyzed on COI (852bp) and 16SrRNA(470bp) genes in the mtDNA for understanding of phylogeny within the genus Tetraclita.
Phylogeny based on COI (Transversion) is characteristics that 1) formosana is the closest to japonica, 2) rufotincta is the second closest to rubescens and forms a clade, 3) stalactifera, confinis and panamensis divided geographically by the Panama Canal are relative, 4) squamosa is a root of the North American Tetraclita, and rubescens is a root of the Indo-West Pacific Tetraclita. Phylogeny based on 16SrRNA is characteristics that 5) squamosa and rufotincta are containted in a clade of 1), 6) rubescens is contained in a clade of 3), and 7) ge
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ographic distribution of two clades separates to Indo-West Pacific and North America.
The phylogeny of 16SrRNA relates to the geographic distribution of Tetraclita. In tree by NJ, rufotincta is the most primitive, squamosa, serrata, japonica / formosana derived from it in the Indo-West Pacific in ascending order and rubescens, stalactifera, panamensis / confinis also derived in the North America. In tree by MP, order of apperance between squamosa and serrata reversed in comparison with NJ method.
Molecular evolution rate was calculated 1.48 to 1.87% / My in COI by stalactifera, panamensis and confinis that were divided geographically by the Panama Canal. The rate is similar to the 1.4% / My by sister species of shrimp Alphenus (Knowlton et al. 1998). Based on the rate, speciation between panamensis and confinis occurred at the 2.8 to 3.6Ma and speciation between japonica and formosana was 0.38 to 0.49Ma. In 16SrRNA, molecular evolution rate is 0.47 to 0.61% / My. Speciation between serrata and japonica / formosana occrtted 6.3 to 8.1Ma, and speciation between confinis and japonica / formosana occurred 8.2 to 10.6Ma.
Phylogeny of Family Tetraclitidae was analyzed using Austrobalanus imperator, Tetraclitella multicostata, Newmanella radiata, Epopella plicatus, Tesseropora rosea, and Tetraclita squamosa. In 16SrRNA, Austrobalanus is the most primitive, and appeared Tetraclita, Tetraclitella, Newmanella, Epopella, and Tesseropora in ascending order. Less
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