Evolutionary dynamics of sex-biased genes expressed in cricket brains and gonads.
Carrie A WhittleArpita KulkarniCassandra G ExtavourPublished in: Journal of evolutionary biology (2021)
Sex-biased gene expression, particularly sex-biased expression in the gonad, has been linked to rates of protein sequence evolution (nonsynonymous to synonymous substitutions, dN/dS) in animals. However, in insects, sex-biased expression studies remain centred on a few holometabolous species. Moreover, other major tissue types such as the brain remain underexplored. Here, we studied sex-biased gene expression and protein evolution in a hemimetabolous insect, the cricket Gryllus bimaculatus. We generated novel male and female RNA-seq data for two sexual tissue types, the gonad and somatic reproductive system, and for two core components of the nervous system, the brain and ventral nerve cord. From a genome-wide analysis, we report several core findings. Firstly, testis-biased genes had accelerated evolution, as compared to ovary-biased and unbiased genes, which was associated with positive selection events. Secondly, although sex-biased brain genes were much less common than for the gonad, they exhibited a striking tendency for rapid protein sequence evolution, an effect that was stronger for the female than male brain. Further, some sex-biased brain genes were linked to sexual functions and mating behaviours, which we suggest may have accelerated their evolution via sexual selection. Thirdly, a tendency for narrow cross-tissue expression breadth, suggesting low pleiotropy, was observed for sex-biased brain genes, suggesting relaxed purifying selection, which we speculate may allow enhanced freedom to evolve adaptive protein functional changes. The findings of rapid evolution of testis-biased genes and male and female-biased brain genes are discussed with respect to pleiotropy, positive selection and the mating biology of this cricket.
Keyphrases
- genome wide
- genome wide analysis
- gene expression
- resting state
- white matter
- dna methylation
- bioinformatics analysis
- functional connectivity
- rna seq
- genome wide identification
- poor prognosis
- cerebral ischemia
- binding protein
- amino acid
- mental health
- multiple sclerosis
- single cell
- copy number
- protein protein
- machine learning
- zika virus
- small molecule
- long non coding rna
- electronic health record
- deep brain stimulation
- sensitive detection