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Tsang LM, Wu TH, Shih HT, Williams GA, Chu KH, Chan BK. Genetic and morphological differentiation of the Indo-West Pacific intertidal barnacle Chthamalus malayensis. Integr Comp Biol 2012; 52:388-409. [PMID: 22523127 PMCID: PMC3417159 DOI: 10.1093/icb/ics044] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chthamalus malayensis is a common intertidal acorn barnacle widely distributed in the Indo-West Pacific. Analysis of sequences of mitochondrial cytochrome c oxidase subunit I reveals four genetically differentiated clades with almost allopatric distribution in this region. The four clades exhibit morphological differences in arthropodal characters, including the number of conical spines and number of setules of the basal guard setae on the cirri. These characters are, however, highly variable within each clade; such that the absolute range of the number of conical spines and setules overlaps between clades, and therefore, these are not diagnostic characters for taxonomic identification. The geographic distribution of the four clades displays a strong relationship between surface temperatures of the sea and ocean-current realms. The Indo-Malay (IM) clade is widespread in the tropical, equatorial region, including the Indian Ocean, Malay Peninsula, and North Borneo. The South China (SC) and Taiwan (TW) clades are found in tropical to subtropical regions, with the former distributed along the coasts of southern China, Vietnam, Thailand, and the western Philippines under the influence of the South China Warm Current. The TW clade is endemic to Taiwan, while the Christmas Island (CI) clade is confined to CI. There was weak or no population subdivision observed within these clades, suggesting high gene flow within the range of the clades. The clades demonstrate clear signatures of recent demographic expansion that predated the Last Glacial Maximum (LGM), but they have maintained a relatively stable effective population in the past 100,000 years. The persistence of intertidal fauna through the LGM may, therefore, be a common biogeographic pattern. The lack of genetic subdivision in the IM clade across the Indian and Pacific Oceans may be attributed to recent expansion of ranges and the fact that a mutation-drift equilibrium has not been reached, or the relaxed habitat requirements of C. malayensis that facilitates high concurrent gene flow. Further studies are needed to determine between these alternative hypotheses.
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Affiliation(s)
- Ling Ming Tsang
- *Simon F. S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Life Science, National Chung Hsing University, Taichung 402, Taiwan; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong; Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Tsz Huen Wu
- *Simon F. S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Life Science, National Chung Hsing University, Taichung 402, Taiwan; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong; Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Hsi-Te Shih
- *Simon F. S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Life Science, National Chung Hsing University, Taichung 402, Taiwan; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong; Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Gray A. Williams
- *Simon F. S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Life Science, National Chung Hsing University, Taichung 402, Taiwan; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong; Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Ka Hou Chu
- *Simon F. S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Life Science, National Chung Hsing University, Taichung 402, Taiwan; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong; Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Benny K.K. Chan
- *Simon F. S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Life Science, National Chung Hsing University, Taichung 402, Taiwan; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong; Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
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