Crossing the species barrier: genomic hotspots of introgression between two highly divergent Ciona intestinalis species.

Details

Serval ID
serval:BIB_4DADC68A91F6
Type
Article: article from journal or magazin.
Collection
Publications
Title
Crossing the species barrier: genomic hotspots of introgression between two highly divergent Ciona intestinalis species.
Journal
Molecular Biology and Evolution
Author(s)
Roux C., Tsagkogeorga G., Bierne N., Galtier N.
ISSN
1537-1719 (Electronic)
ISSN-L
0737-4038
Publication state
Published
Issued date
2013
Volume
30
Number
7
Pages
1574-1587
Language
english
Abstract
Inferring a realistic demographic model from genetic data is an important challenge to gain insights into the historical events during the speciation process and to detect molecular signatures of selection along genomes. Recent advances in divergence population genetics have reported that speciation in face of gene flow occurred more frequently than theoretically expected, but the approaches used did not account for genome-wide heterogeneity (GWH) in introgression rates. Here, we investigate the impact of GWH on the inference of divergence with gene flow between two cryptic species of the marine model Ciona intestinalis by analyzing polymorphism and divergence patterns in 852 protein-coding sequence loci. These morphologically similar entities are highly diverged molecular-wise, but evidence of hybridization has been reported in both laboratory and field studies. We compare various speciation models and test for GWH under the approximate Bayesian computation framework. Our results demonstrate the presence of significant extents of gene flow resulting from a recent secondary contact after >3 My of divergence in isolation. The inferred rates of introgression are relatively low, highly variable across loci and mostly unidirectional, which is consistent with the idea that numerous genetic incompatibilities have accumulated over time throughout the genomes of these highly diverged species. A genomic map of the level of gene flow identified two hotspots of introgression, that is, large genome regions of unidirectional introgression. This study clarifies the history and degree of isolation of two cryptic and partially sympatric model species and provides a methodological framework to investigate GWH at various stages of speciation process.
Keywords
Animals, Bayes Theorem, Ciona intestinalis/genetics, Ciona intestinalis/physiology, Evolution, Molecular, Gene Flow, Genetic Speciation, Hybridization, Genetic, Selection, Genetic, Sequence Analysis, DNA, Species Specificity
Pubmed
Web of science
Open Access
Yes
Create date
20/02/2013 19:48
Last modification date
20/08/2019 15:02
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