Ocean barriers and glaciation: evidence for explosive Blackwell Publishing Ltd

• Main Authors: Doris Kerguelenensis (mollusca, Nerida G. Wilson, M. Schrödl, Kenneth M. Halanych
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Drake Passage; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.420.9197; http://gump.auburn.edu/halanych/lab/Pub.pdfs/Wilson2009.pdf

Strong currents and deep passages of water can be barriers for larval dispersal of continental marine animals, but potential effects on direct developers are under-investigated. We examined the genetic structure of Doris kerguelenensis, a directly developing sea slug that occurs across the Drake Passage, the body of water separating Antarctica from South America. We found deep mitochondrial divergences within populations on both sides of the Drake Passage, and South American animals formed multiple sister-group relationships with Antarctic animals. A generalised molecular clock suggested these trans-Drake pairs diverged during the Pliocene–Pleistocene, after the formation of the Drake Passage. Statistical parsimony methods recovered 29 separate haplotype networks (many sympatric) that likely correlate with allopatric events caused by repeated glacial cycles. Data from 16S were congruent but more conserved than COI, and the estimated ancestral 16S haplotype was widespread. The marked difference in the substitution rates between these two mitochondrial genes results in different estimates of connectivity. Demographic analyses on networks revealed some evidence for selection and expanding populations. Contrasting with the