Evolutionary Patterns of Sex-Biased Genes in Three Species of Haplodiploid Insects.

Yujun Wang ,Hua-Ling Wang,Xiaowei Wang ,Shu‐Sheng Liu

doi:10.3390/insects11060326

Abstract

Females and males often differ obviously in morphology and behavior, and the differences between sexes are the result of natural selection and/or sexual selection. To a great extent, the differences between the two sexes are the result of differential gene expression. In haplodiploid insects, this phenomenon is obvious, since males develop from unfertilized zygotes and females develop from fertilized zygotes. Whiteflies of the Bemisia tabaci species complex are typical haplodiploid insects, and some species of this complex are important pests of many crops worldwide. Here, we report the transcriptome profiles of males and females in three species of this whitefly complex. Between-species comparisons revealed that non-sex-biased genes display higher variation than male-biased or female-biased genes. Sex-biased genes evolve at a slow rate in protein coding sequences and gene expression and have a pattern of evolution that differs from those of social haplodiploid insects and diploid animals. Genes with high evolutionary rates are more related to non-sex-biased traits—such as nutrition, immune system, and detoxification—than to sex-biased traits, indicating that the evolution of protein coding sequences and gene expression has been mainly driven by non-sex-biased traits.

Highlights

Females and males often differ obviously in morphology and behavior, and most of the differences between sexes are the result of natural selection and/or sexual selection [1]
We focus on a group of non-social haplodiploid insects, i.e., whiteflies of the Bemisia tabaci cryptic species complex that contains > 35 morphologically indistinguishable but genetically divergent species [14,15,16,17,18]
The distance trees of gene expression across species and sexes and the principal component analysis show that variation in gene expression between the three Bemisia species is clustered preferentially by species but not by sex, suggesting that females and males of whiteflies share the same genomes, they differ in expression patterns

Summary

Introduction

Females and males often differ obviously in morphology and behavior, and most of the differences between sexes are the result of natural selection and/or sexual selection [1]. While females and males exhibit different phenotypes, they are roughly the same at the genetic level, indicating that the differences between sexes are largely the result of differences in gene expression. These genes are subject to natural selection and sexual selection pressures from both sexes and are sometimes even subject to conflicting selection pressures [2]. Sex-biased genes contain genes that only express in one sex (sex-specific expression) or show higher expression in one sex than in the other (sex-enriched expression). The evolution of the expression of sex-biased genes may display a positive correlation with that of protein sequences [7]

Methods

Results

Conclusion