Post-glacial habitat release and incipient speciation in the genus Delphinus

The role of ecological and changing environmental factors in the radiation of species diversity is a fundamental question in evolutionary biology. Of particular interest is the potential for these factors to determine the boundary between what we would consider differentiation among populations and...

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Bibliographic Details
Published in:Heredity 2016-12, Vol.117 (6), p.400-407
Main Authors: Segura-García, I, Gallo, J P, Chivers, S, Díaz-Gamboa, R, Hoelzel, A R
Format: Article
Language:English
Subjects:
Animals
Aquatic mammals
Body size
California
Cetacea
Common Dolphins - classification
Common Dolphins - genetics
Delphinus
DNA, Mitochondrial - genetics
Dolphins & porpoises
Ecology
Ecosystem
Environment
Environmental changes
Environmental factors
Evolutionary biology
Gene Flow
Genetic Markers
Genetic Speciation
Geographical distribution
Habitats
Haplotypes
Holocene
Mexico
Microsatellite Repeats
Mitochondrial DNA
Original
Pacific Ocean
Phylogeny
Population Dynamics
Reproductive Isolation
Sequence Analysis, DNA
Speciation
Species diversity
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Summary:The role of ecological and changing environmental factors in the radiation of species diversity is a fundamental question in evolutionary biology. Of particular interest is the potential for these factors to determine the boundary between what we would consider differentiation among populations and incipient speciation. Dolphins in the genus Delphinus provide a useful test case, exhibiting morphological variation in beak length, coloration and body size across their wide geographic distribution, and in particular among coastal and more pelagic habitats. Two species have been proposed, D. delphis and D. capensis, but morphologically similar allopatric populations are not monophyletic, indicating that the mostly coastal 'long-beaked' D. capensis form is not a single globally distributed species. However, the sympatric populations in the Eastern North Pacific currently designated as these two species are both morphologically and genetically differentiated. Here we use microsatellite DNA and mitochondrial DNA markers to investigate the evolutionary mechanisms that led to this incipient speciation event. We used coalescent and assignment methods to investigate the timing and extent of reproductive isolation. Our data indicate that although there is some level of on-going gene flow, the putative species found in the Eastern North Pacific are reciprocally monophyletic. The timing of isolation appears to be associated with regional changes in paleoceanographic conditions within the Holocene timeframe.
ISSN:0018-067X
1365-2540
DOI:10.1038/hdy.2016.66