Mitochondrial evolution and phylogeography in the hydrozoan Obelia geniculata (Cnidaria)

The distribution and genetic structure of many marine invertebrates in the North Atlantic have been influenced by the Pleistocene glaciation, which caused local extinctions followed by recolonization in warmer periods. Mitochondrial DNA markers are typically used to reconstruct species histories. He...

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Bibliographic Details
Published in:Marine biology 2005-01, Vol.146 (2), p.213-222
Main Authors: GOVINDARAJAN, A. F, HALANYCH, K. M, CUNNINGHAM, C. W
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Aquatic life
Biological and medical sciences
Cryptic species
Deoxyribonucleic acid
DNA
Evolution
Fundamental and applied biological sciences. Psychology
Genetic structure
Glaciation
Haplotypes
Life history
Marine
Marine biology
Marine invertebrates
Mitochondrial DNA
Obelia geniculata
Pleistocene
Recolonization
Refugia
Sea water ecosystems
Synecology
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Summary:The distribution and genetic structure of many marine invertebrates in the North Atlantic have been influenced by the Pleistocene glaciation, which caused local extinctions followed by recolonization in warmer periods. Mitochondrial DNA markers are typically used to reconstruct species histories. Here, two mitochondrial markers [16S rDNA and cytochrome c oxidase I (COI)] were used to study the evolution of the widely distributed hydrozoan Obelia geniculata (Linnaeus, 1758) from the North Atlantic and the Pacific and, more specifically, in the context of North Atlantic phylogeography. Samples were collected from six geographic localities between 1998 and 2002. Hydroids from the North Atlantic, North Pacific (Japan), and South Pacific (New Zealand) are reciprocally monophyletic and may represent cryptic species. Using portions of the 16S rDNA and COI genes and the date of the last trans-Arctic interchange (3.1-4.1 million years ago), the first calibrated rate of nucleotide substitutions in hydrozoans is presented. Whereas extremely low substitution rates have been reported in other cnidarians, mainly based on anthozoans, substitution rates in O. geniculata are comparable to other invertebrates. Despite a life history that ostensibly permits substantial dispersal, there is apparently considerable genetic differentiation in O. geniculata. Divergence estimates and the presence of unique haplotypes provide evidence for glacial refugia in Iceland and New Brunswick, Canada. A population in Massachusetts, USA, appears to represent a relatively recent colonization event.[PUBLICATION ABSTRACT]
ISSN:0025-3162
1432-1793
DOI:10.1007/s00227-004-1434-3