The Population Genetics of the Origin and Divergence of the Drosophila simulans Complex Species

The origins and divergence of Drosophila simulans and close relatives D. mauritiana and D. sechellia were examined using the patterns of DNA sequence variation found within and between species at 14 different genes. D. sechellia consistently revealed low levels of polymorphism, and genes from D. sec...

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Bibliographic Details
Published in:Genetics (Austin) 2000-12, Vol.156 (4), p.1913-1931
Main Authors: Kliman, Richard M, Andolfatto, Peter, Coyne, Jerry A, Depaulis, Frantz, Kreitman, Martin, Berry, Andrew J, McCarter, James, Wakeley, John, Hey, Jody
Format: Article
Language:English
Subjects:
Animals
Biodiversity
Codon - genetics
Deoxyribonucleic acid
DNA
DNA - genetics
DNA, Mitochondrial - genetics
Drosophila - classification
Drosophila - genetics
Drosophila mauritiana
Drosophila melanogaster - genetics
Drosophila sechellia
Drosophila simulans
Evolution, Molecular
Genes, Insect
Genetics
Genetics, Population
Insect Proteins - genetics
Models, Genetic
Mutation
Phylogeny
Polymorphism, Genetic
Population
Species Specificity
Time Factors
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Summary:The origins and divergence of Drosophila simulans and close relatives D. mauritiana and D. sechellia were examined using the patterns of DNA sequence variation found within and between species at 14 different genes. D. sechellia consistently revealed low levels of polymorphism, and genes from D. sechellia have accumulated mutations at a rate that is approximately 50% higher than the same genes from D. simulans. At synonymous sites, D. sechellia has experienced a significant excess of unpreferred codon substitutions. Together these observations suggest that D. sechellia has had a reduced effective population size for some time, and that it is accumulating slightly deleterious mutations as a result. D. simulans and D. mauritiana are both highly polymorphic and the two species share many polymorphisms, probably since the time of common ancestry. A simple isolation speciation model, with zero gene flow following incipient species separation, was fitted to both the simulans/mauritiana divergence and the simulans/sechellia divergence. In both cases the model fit the data quite well, and the analyses revealed little evidence of gene flow between the species. The exception is one gene copy at one locus in D. sechellia, which closely resembled other D. simulans sequences. The overall picture is of two allopatric speciation events that occurred quite near one another in time.
ISSN:0016-6731
1943-2631
1943-2631
DOI:10.1093/genetics/156.4.1913