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Genetic divergence over small geographic scales and conservation implications for Commerson's dolphins ( Cephalorhynchus commersonii ) in southern Argentina
Author(s) -
Cipriano Frank,
Hevia Marta,
Iñíguez Miguel
Publication year - 2011
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.2010.00434.x
Subject(s) - genetic divergence , bycatch , population , geography , gene flow , biology , genetic structure , fishery , ecology , zoology , genetic variation , genetic diversity , fish <actinopterygii> , demography , sociology
Cephalorhynchus commersonii is distributed in the nearshore coastal waters of South America, and thus is particularly vulnerable to bycatch in coastal nets and trawls. Our study documents genetic structure in presumed Commerson's dolphin subpopulations along the southern Argentina coastline, from the Ría Deseado in the north to Ría Gallegos in the south, and focuses on the potential for depletion in the apparently more heavily impacted Ría Gallegos area. Only two control region (423 bp) haplotypes were shared among all these locations (out of 11 identified), and striking differences in haplotype frequencies between areas are apparent. AMOVA analysis, using mitochondrial sequence data, indicates significant population subdivision (overall F ST = 0.21, P < 0.001) between Ría Deseado ( n = 8), Bahía San Julián ( n = 11), Ría Gallegos ( n = 31), and a small sample of dolphins from the captive colony at San Diego Seaworld ( n = 7) derived from animals originally captured in the Strait of Magellan. Comparisons based on haplotypic distances indicated relatively strong differences between regions (Φ ST = 0.30, P < 0.001). This research provides the first indication of reduced gene flow and genetic differentiation within local subpopulations of Commerson's dolphins, along a relatively small stretch of coastline.