Biological species concept (BSC) defines species as ’groups of interbreeding natural populations that share the common gene pool and that are reproductively isolated from other such groups (Mayr, 1963). According this definition, the standard of speciation is based on reproductive isolation (RI) and non-gene flow. Genetic and molecular analyses of speciation in the last decade have suggested that gene, or complexes of genes, are the units of evolution. The process of speciation is a dynamic procedure, base on genes mutation and differentiation, as well as the formation of RI. Based on the recent empirical observation, Wu suggest a review of BSC, which suggest that the process of speciation is differential adaptation to different natural or sexual environment and that RI is the byproduct of this differential adaptation. Granting this premise, there is unnecessary to insist the RI over the whole-genome as the gold standard of the speciation. Two central criteria should be involved in the review of BSC: (1) not losing the differentiation, (2) being able to continue to diverge. This new concept is compatible at certain aspect for those taxa which is asexual. Wu also suggest another new concept as “speciation gene” which refers to genes which serve as the critical element in the process of speciation but the number of those is few.
