Lukhtanov Vladimir A, Shapoval Nazar A, Anokhin Boris A, Saifitdinova Alsu F, Kuznetsova Valentina G
Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, Universitetskaya nab. 1, 199034, St Petersburg, Russia Department of Entomology, St Petersburg State University, Universitetskaya nab. 7/9, 199034, St Petersburg, Russia
Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, Universitetskaya nab. 1, 199034, St Petersburg, Russia Department of Entomology, St Petersburg State University, Universitetskaya nab. 7/9, 199034, St Petersburg, Russia.
Proc Biol Sci. 2015 May 22;282(1807):20150157. doi: 10.1098/rspb.2015.0157.
Genomes of numerous diploid plant and animal species possess traces of interspecific crosses, and many researches consider them as support for homoploid hybrid speciation (HHS), a process by which a new reproductively isolated species arises through hybridization and combination of parts of the parental genomes, but without an increase in ploidy. However, convincing evidence for a creative role of hybridization in the origin of reproductive isolation between hybrid and parental forms is extremely limited. Here, through studying Agrodiaetus butterflies, we provide proof of a previously unknown mode of HHS based on the formation of post-zygotic reproductive isolation via hybridization of chromosomally divergent parental species and subsequent fixation of a novel combination of chromosome fusions/fissions in hybrid descendants. We show that meiotic segregation, operating in the hybrid lineage, resulted in the formation of a new diploid genome, drastically rearranged in terms of chromosome number. We also demonstrate that during the heterozygous stage of the hybrid species formation, recombination was limited between rearranged chromosomes of different parental origin, representing evidence that the reproductive isolation was a direct consequence of hybridization.
许多二倍体动植物物种的基因组都有物种间杂交的痕迹，许多研究将其视为对同倍体杂交物种形成（HHS）的支持，这是一个新的生殖隔离物种通过杂交和亲本基因组部分的组合而产生，但倍性不增加的过程。然而，关于杂交在杂种和亲本形式之间生殖隔离起源中起创造性作用的令人信服的证据极为有限。在这里，通过对阿格罗迪埃特斯蝴蝶的研究，我们提供了一种以前未知的HHS模式的证据，该模式基于染色体不同的亲本物种杂交形成合子后生殖隔离，并随后在杂种后代中固定新的染色体融合/裂变组合。我们表明，在杂种谱系中起作用的减数分裂分离导致了一个新的二倍体基因组的形成，其染色体数目发生了剧烈重排。我们还证明，在杂交物种形成的杂合阶段，不同亲本来源的重排染色体之间的重组受到限制，这表明生殖隔离是杂交的直接后果。
