MEPS 418:165-178 (2010)  -  DOI: https://doi.org/10.3354/meps08829

ABSTRACT: Dosidicus gigas and Sthenoteuthis oualaniensis (Teuthoidea: Ommastrephidae: Ommastrephinae) are abundant, ecologically important squid that co-occur in the eastern tropical Pacific. Little is known about the genetic basis of population structure in either species, although the presence of 2 species within S. oualaniensis has been suggested. We report here on a comparative population genetic study of D. gigas and S. oualaniensis using the mitochondrial marker NADH dehydrogenase subunit 2. Despite the high potential for dispersal in these active swimmers, both species exhibit a distinct biogeographic break at 5 to 6°N. S. oualaniensis contains multiple deeply divergent, geographically segregated clades, whereas D. gigas shows only mild divergence between northern and southern hemisphere populations. We suggest that dispersal and genetic mixing across the eastern tropical Pacific may be impeded by both oceanographic and ecological factors.

KEY WORDS: Biogeographic comparison · Eastern Pacific · Ommastrephid squid · Population genetic structure