Evidence for a slightly deleterious effect of intron polymorphisms at the EF1α gene in the deep-sea hydrothermal vent bivalve <i>Bathymodiolus</i>

作     者：Faure, B. Bierne, N. Tanguy, A. Bonhomme, F. Jollivet, D. 

作者机构：UPMC CNRS Biol Stn UMR 7144 F-29682 Roscoff France Univ Montpellier 2 CNRS UM2 Inst Sci EvolutUMR5554 Dept Integrat Biol F-34095 Montpellier France 

出 版 物：《GENE》 (基因)

年 卷 期：2007年第406卷第1-2期

页      面：99-107页

核心收录：

学科分类：0710[理学-生物学] 07[理学] 09[农学] 

基　　金：French national programme GIS 

主　　题：deleterious mutations selective sweep gene genealogies non-coding DNA vent species 

摘      要：A multilocus analysis was initiated in order to infer the general effect of demography and the indirect effect of positive selection on some chromosome segments in Bathymodiolus. Mussels of the genus Bathymodiolus inhabit the very hostile, fragmented and variable environment of deep-sea hydrothermal vents which is thought to cause recurrent population bottlenecks via extinction/colonisation processes and adaptation to new environmental conditions. In the course of this work we discovered that the assumption of neutrality of non-coding polymorphisms usually made in genome scan experiments was likely to be violated at one of the loci we analysed. The direct effect of slight purifying selection on non-coding polymorphisms shares many resemblances with the indirect effect of positive selection through genetic hitchhiking. Combining polymorphism with divergence data for several closely related species allowed us to obtain different expectations for the direct effect of negative selection and the indirect effect of positive selection. We observed a strong excess of rare non-coding polymorphisms at the second intron of the EF1 alpha gene in the two species Bathymodiolus azoricus and Bathymodiolus thermophilus, while two other loci, the mitochondrial COI gene and an intron of the Lysozyme gene, did not exhibit such a deviation. In addition, the divergence rate of the EF1 alpha intron was estimated to be unexpectedly low when calibrated using the closure of the Panama Isthmus that interrupted gene flow between the two species. The polymorphism to divergence ratio was similar to the one observed for the other two loci, in accordance to the hypothesis of purifying selection. We conclude that slight purifying selection is likely to act on polymorphic intronic mutations of the EF1 alpha second intron and discuss the possible relationship with the specific biology of Bathymodiolus mussels. (C) 2007 Elsevier B.V. All rights reserved.