Highly variable recombinational landscape modulates efficacy of natural selection in birds.
Bottom Line: We investigated whether a special feature of avian genomes, the highly variable recombinational landscape, modulates the efficacy of natural selection through the effects of Hill-Robertson interference, which predicts that selection should be more effective in removing deleterious mutations and incorporating beneficial mutations in high-recombination regions than in low-recombination regions.Furthermore, more compact genes (i.e., those with fewer/shorter introns or shorter proteins) evolve faster than less compact ones.In sum, our results demonstrate that transcriptome sequencing is a powerful method to answer fundamental questions about genome evolution in nonmodel organisms.
Affiliation: Department of Animal and Plant Sciences, University of Sheffield, United Kingdom email@example.com firstname.lastname@example.org.Show MeSH
Mentions: We have shown that the rate of molecular evolution varies substantially inpasserine birds across the genome. It is, however, unclear whether genes withissue-specific expression also have different ω’s. To answer thisquestion, we extracted tissue-specific genes for the eight tissues included inthe transcriptome sequencing, and compared their ω values (fig. 2). The median ω value forgenes specifically expressed in the brain is 0.051, which is significantly lowerthan the genome-wide median of 0.1 (Mann–Whitney U test[MWU], P = 0.005) and the median value of othertissue-specific genes (MWU, P = 0.021). This could beexplained by the theory put forward by Drummond and Wilke (2008, see Introduction). In contrast,testis/ovary-specific genes have significantly increased evolutionary rates whencompared with other tissue-specific genes (MWU, P =0.027), consistent with the intra- and interspecific arms race theory.Interestingly, genes specifically expressed in the heart had the highest medianω = 0.129, which is comparable to that of the testis/ovary-specificgenes (MWU, P = 0.15). This is different from humanswhose heart-specific genes have significantly lower median ω (0.07) thantestis-specific genes (0.103) (Winter etal. 2004). The cause of this difference is unclear and warrantsinvestigation in future. Fig.2.—
Affiliation: Department of Animal and Plant Sciences, University of Sheffield, United Kingdom email@example.com firstname.lastname@example.org.