The population genetics of the origin and divergence of the Drosophila simulans complex species

Citation
Rm. Kliman et al., The population genetics of the origin and divergence of the Drosophila simulans complex species, GENETICS, 156(4), 2000, pp. 1913-1931
Citations number
89
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology,"Molecular Biology & Genetics
Journal title
GENETICS
ISSN journal
0016-6731 → ACNP
Volume
156
Issue
4
Year of publication
2000
Pages
1913 - 1931
Database
ISI
SICI code
0016-6731(200012)156:4<1913:TPGOTO>2.0.ZU;2-J
Abstract
The origins and divergence of Drosophila simulans and close relatives D. ma uritiana and D. sechellia were examined using the patterns of DNA sequence variation found within and between species at 14 different genes. D. sechel lia consistently revealed low levels of polymorphism, and genes from D. sec hellia have accumulated mutations at a rate that is similar to 50% higher t han the same genes from D. simulans. At synonymous sites, D. sechellia has experienced a significant excess of unpreferred codon substitutions. Togeth er these observations suggest that D. sechellia has had a reduced effective population size for some time, and that it is accumulating slightly delete rious mutations as a result. D. simulans and D. mauritiana are both highly polymorphic and the two species share many polymorphisms, probably since th e time of common ancestry. A simple isolation speciation model, with zero g ene flow following incipient species separation, was fitted to both the sim ulans/mauritiana divergence and the simulans/sechellia divergence. In both cases the model fit the data quite well, and the analyses revealed little e vidence of gene flow between the species. The exception is one gene copy at one locus in D. sechellia, which closely resembled other D. simulans seque nces. The overall picture is of two allopatric speciation events that occur red quite near one another in time.