Global population genetic structure and biogeography of the oceanic copepods Eucalanus hyalinus and E. spinifer

Erica Goetze

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Although theory dictates that limited gene flow between populations is a necessary precursor to speciation under allopatric and parapatric models, it is currently unclear how genetic differentiation between conspecific populations can arise in open-ocean plankton species. I examined two recently distinguished sympatric, circumglobal sister species, Eucalanus hyalinus and Eucalanus spinifer, for population genetic structure throughout their global biogeographic ranges. Here I show that oceanic zooplankton species can be highly genetically structured on macro-geographic spatial scales, despite experiencing extensive gene flow within features of the large-scale ocean circulation. Mitochondrial DNA analyses of 450 and 383 individuals of E. hyalinus and E. spinifer, respectively, revealed that habitat discontinuities at the boundaries of subtropical gyres in the North and South Pacific, as well as continental land masses, acted as effective barriers to gene flow for both species. However, the impact of specific barriers on population genetic structure varied between the sister species, despite their close phylogenetic relationship and similar circumglobal biogeogeographic distributions. The sister species differed in their oceanographic distributions, with E. spinifer dominating oligotrophic waters of the subtropical gyres and E. hyalinus more abundant along central water mass boundaries and in frontal zones and upwelling systems. This species-specific difference in the oceanographic habitat is an important factor determining the historical and contemporary patterns of dispersal of the two species. I suggest that species-specific ecological differences are likely to be a primary determinant of population genetic structure of open-ocean plankton
Original languageEnglish
JournalEvolution
Volume59
Issue number11
Pages (from-to)2378-2398
ISSN0014-3820
DOIs
Publication statusPublished - 2005

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