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Multilocus evidence for globally distributed cryptic species and distinct populations across ocean gyres in a mesopelagic copepod
Author(s) -
Andrews Kimberly R.,
Norton Emily L.,
FernandezSilva Iria,
Portner Elan,
Goetze Erica
Publication year - 2014
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.12950
Subject(s) - biology , allopatric speciation , mesopelagic zone , biological dispersal , ecology , reproductive isolation , pelagic zone , gene flow , population , species complex , copepod , sympatric speciation , evolutionary biology , zoology , genetic variation , genetics , crustacean , gene , demography , sociology , phylogenetic tree
Zooplanktonic taxa have a greater number of distinct populations and species than might be predicted based on their large population sizes and open‐ocean habitat, which lacks obvious physical barriers to dispersal and gene flow. To gain insight into the evolutionary mechanisms driving genetic diversification in zooplankton, we developed eight microsatellite markers to examine the population structure of an abundant, globally distributed mesopelagic copepod, Haloptilus longicornis , at 18 sample sites across the Atlantic and Pacific Oceans ( n = 761). When comparing our microsatellite results with those of a prior study that used a mt DNA marker (mt COII , n = 1059, 43 sample sites), we unexpectedly found evidence for the presence of a cryptic species pair. These species were globally distributed and apparently sympatric, and were separated by relatively weak genetic divergence (reciprocally monophyletic mt COII lineages 1.6% divergent; microsatellite F ST ranging from 0.28 to 0.88 across loci, P < 0.00001). Using both mt DNA and microsatellite data for the most common of the two species ( n = 669 for microsatellites, n = 572 for mt DNA ), we also found evidence for allopatric barriers to gene flow within species, with distinct populations separated by continental landmasses and equatorial waters in both the Atlantic and Pacific Ocean basins. Our study shows that oceanic barriers to gene flow can act as a mechanism promoting allopatric diversification in holoplanktonic taxa, despite the high potential dispersal abilities and pelagic habitat for these species.