Pleistocene speciation of sister taxa in a North Pacific clade of brooding sea stars (<Emphasis Type="Italic">Leptasterias</Emphasis>) |
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Authors: | D W Foltz A T Nguyen J R Kiger C L Mah |
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Institution: | (1) Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA;(2) Molecular Genetics, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA;(3) Department of Invertebrate Zoology, National Museum of Natural History, MRC-163, P.O. Box 37012, Smithsonian Institution, Washington, DC 20007, USA |
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Abstract: | Although numerous coastal marine species show intra-specific lineage splitting and population divergence times that date to
the period of glacial cycles during the Pleistocene epoch, reported instances of recent speciation in the coastal marine environment
are relatively rare. Marine organisms with brood-protection and other reproductive modes with limited dispersal potential
have been suggested to experience more frequent speciation and extinction events than related species with higher dispersal
rates, but few studies have actually estimated divergence times of sister species in these organisms. Here, two mitochondrial
gene regions (cytochrome oxidase subunit I, putative control region and upstream tRNAs) and a nuclear gene region (Elongation
factor 1α subunit intron 4) provide evidence of recent (0.5–1.2 Mya) cladogenetic events in four pairs of putative sister
taxa in a predominantly North Pacific brooding subgenus of sea stars (Leptasterias subgenus Hexasterias). Calibration is obtained from a trans-arctic migration in a related clade of sea stars (Leptasterias subgenera Hexasterias and Nesasterias) that is timed to the opening of the Bering Strait at 3.5 ± 0.25 Mya, and uncertainty in the calibration point is accommodated
with a normally-distributed Bayesian prior probability. Similar estimates of population splitting times for two of the pairs
of putative sister taxa were obtained by a multilocus coalescent analysis. Estimates of mitochondrial mutation rates (0.01/My)
were approximately 50% of the values calibrated for sister species pairs in tropical sea stars and sea urchins.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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