Genetic divergence among sympatric populations of three species of oyster drills (Urosalpinx) in Cedar Key, Florida

• Autores: John D. Robinson, Robert T. Dillon
• Localización: Bulletin of Marine Science, ISSN 0007-4977, Vol. 82, Nº. 1, 2008, págs. 19-31
• Idioma: inglés
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• Resumen

  • Three gastropod species of the genus Urosalpinx inhabit intertidal and subtidal regions of the southeastern United States. Urosalpinx cinerea (Say, 1822) is native to the Atlantic coast from Newfoundland to northeast Florida, while Urosalpinx perrugata (Conrad, 1846) and Urosalpinx tampaensis (Conrad, 1846) are largely restricted to the Gulf of Mexico. The morphological similarity of U. cinerea and U. perrugata is so striking that they have been suggested to be subspecies. We used a combination of molecular and morphological methods to examine divergence among populations of these three nominal species in a newly discovered area of sympatry: Cedar Key, Florida. Significant shell morphological differences were detected among the three species, but overlapping ranges prevented unambiguous discrimination of U. cinerea and U. perrugata. A survey of gene frequencies at nine allozyme-encoding loci in the three Cedar Key populations (together with two allopatric controls) revealed multiple fixed differences between the species, confirming their reproductive isolation. Interspecific mtDNA sequence divergence was extensive (10.3%-17.3%), but well within the range of previously reported congeneric divergences. A neighbor-joining phylogeny grouped U. cinerea with U. perrugata, while U. tampaensis was found to be slightly more divergent. We suggest that the Florida peninsula may have served as a barrier to gene flow, promoting the allopatric speciation of U. cinerea and U. perrugata sometime after the divergence of U. tampaensis.