Title
Phylogeographic analysis reveals a deep lineage split within North Atlantic Littorina Saxatilis
Advisor(s)
Geoffrey C. Trussell
Contributor(s)
Steven V. Vollmer, Matthew E.S. Bracken
Date of Award
2010
Date Accepted
12-2010
Degree Grantor
Northeastern University
Degree Level
M.S.
Degree Name
Master of Science
Department or Academic Unit
College of Arts and Sciences. Department of Biology.
Keywords
ecology, biology, cryptic diversity, glacial refugia, mtDNA, phylogeography, speciation, trans-Arctic interchange
Subject Categories
Littorina saxatilis--Evolution
Disciplines
Biology
Abstract
Phylogeographic studies provide critical insight into the evolutionary histories of model organisms; yet, to date, range-wide data are lacking for the rough periwinkle Littorina saxatilis, a classic example of marine sympatric speciation. I utilized mitochondrial DNA (mtDNA) sequence data to demonstrate that L. saxatilis is not monophyletic, but is comprised of two mtDNA lineages (I and II) that are shared with its sister-species L. arcana and L. compressa. Bayesian coalescent dating and phylogeographic patterns indicate that both L. saxatilis lineages (I and II) originated in the northeastern Atlantic, around the British Isles, approximately 0.64 Ma. Both lineages are now distributed broadly across the eastern, central, and western North Atlantic, and show strong phylogeographic structure among regions. The Iberian Peninsula is genetically distinct, suggesting prolonged isolation from northeastern Atlantic populations. Western Atlantic populations of L. saxatilis Lineages I and II both predate the last glacial maximum and have been isolated from eastern Atlantic populations since that time. The existence of two broadly distributed cryptic mtDNA lineages further complicate observed patterns of repeated incipient ecological speciation in L. saxatilis, because the sympatric origins of distinct ecotype pairs on northeastern Atlantic shores may be confounded by admixture of divergent lineages.
Document Type
Master's Thesis
Rights Holder
Meredith M. Doellman
Permanent URL
Recommended Citation
Doellman, Meredith M., "Phylogeographic analysis reveals a deep lineage split within North Atlantic Littorina Saxatilis" (2010). Biology Master's Theses. Paper 12. http://hdl.handle.net/2047/d20000804
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