Abstract:

Speciation is a basic evolutionary process, which plays a fundamental role in the formation of biodiversity. Ecological speciation refers to the process by which barriers to gene flow evolve between populations as a result of ecologically-based divergent selection. In spite of the continual accumulation of experimental and theoretical evidence, our understanding of ecological speciation remains incomplete. In this review, we first briefly introduce the history of research on ecological speciation and focus on its three components: a source of divergent selection, a form of reproductive isolation, and a genetic mechanism linking the two. Sources of divergent selection include differences in environment or niche, certain forms of sexual selection, and the ecological interaction of populations. There are various barriers of reproductive isolation, and we summarize pre-zygotic and post-zygotic isolation mechanisms and their roles in ecological speciation. Pleiotropy and linkage disequilibrium are the two mechanisms to link divergent selection and reproductive isolation. The applications of next generation sequencing technologies have contributed greatly to the research of gene and genome based ecological speciation. In addition, we review the recent advances in ecological speciation understanding, including the genomic basis of parallel evolution and the theories of speciation-with-gene-flow. By comparison of up-down strategy and down-up strategy, we put forward that the combination of these ideas which can provide more powerful and precise methods to find the ecological speciation genes. More detailed phenotypic description and more complete genomic information, as well as more representative species can facilitate greater exploration of ecological speciation.

Key words: ecological speciation, ecological factor, divergence selection, reproductive isolation, genomics, parallel evolution, gene flow