PHYLOGEOGRAPHY AND DEMOGRAPHIC HISTORY OF THE DUSKY DOLPHIN, LAGENORHYNCHUS OBSCURUS

LOIZAGA DE CASTRO, ROCÍO; MARTINAZZO, LIZA BEATRIZ; HOELZEL, A. RUS; CRESPO ENRIQUE A.

Puerto Madryn

Congreso; 15a Reunión de Trabajo de Expertos en Mamíferos Acuáticos de América del Sur y 9º Congreso de la Sociedad Latino Americana de Especialistas en Mamíferos Acuáticos (SOLAMAC); 2012

CENPAT-UNPSJB

The dusky dolphin (Lagenorhynchus obscurus) is distributed along temperate, coastal regions of New Zealand, South Africa, Argentina, and Peru, although generally limited to coastal waters, the species shows high potential for dispersal over large distances. Here, we have investigated its genetic diversity, population structure, and demographic history across its worldwide geographic range by analyzing 457 base pairs (bp) of DNAmt control region from 208 individuals. Samples from Argentina (N = 124) (Buenos Aires, Golfo San Matías, Golfo San José, Golfo Nuevo, Golfo San Jorge and Ushuaia) were collected using biopsy techniques and preserved in DMSO 20% saturated NaCl. Sequences from New Zealand (N = 18), South Africa and Argentina (N = 24) and Peru (N = 42) were downloaded from Genebank. Haplotypes genealogy was evaluated building a consensus tree using the Jukes Cantor parameter model. population structure was estimated by Φ st statistics and AMOVA in Arlequin v3.1. The demographic history was performed calculating Tajima?s D and Fu?s F statistic and performing a Mismatch analysis, also we used BEAST to generate Bayesian Skyline plots (BSP), which allow an assessment of historical patterns of change in N over time. Also nucleotide and haplotypic diversity and segregation sites were calculated. Our results indicate that L. obscurus presents high levels of genetic diversity and a phylogeographic pattern that suggests the existence of at least 4 populations worldwide. The AMOVA indicates that 48% of the molecular variance is found within the populations. Nevertheless, 42% of the remaining variance among populations is slightly significant (p 1). The results obtained here provide novel insights on the evolutionary history of this small cetacean. The low genetic structure associated with its geographic distribution is consistent with expectations for populations with a recent evolutionary history, which is characterized by a rapid population growth in the past during the Pleistocene.