Variation in hybridogenetic hybrid emergence between populations of water frogs from the Pelophylax esculentus complex
Variation in hybridogenetic hybrid emergence between populations of water frogs from the Pelophylax esculentus complex
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Pelophylax esculentus 复合体中水蛙种群之间杂交发生的变化
DOI：
10.1371/journal.pone.0224759
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发表时间：
2019-11-01
期刊：
影响因子：
3.7
通讯作者：
Krasikova, Alla
中科院分区：
文献类型：
--
作者：
Dedukh, Dmitrij;Litvinchuk, Julia;Krasikova, Alla
许多密切相关的物种能够交配产生杂交后代，通常是不育的。然而，改变杂种后代的配子发生可以通过使无性生殖能够将杂种从不育中拯救出来。杂交发生是最复杂的无性生殖模式之一，它包括仅在种系中的剧烈基因组重组;这是通过消除一个亲本基因组并复制剩余的一个来恢复二倍体染色体组并克服减数分裂进程中的障碍来实现的。我们调查了一个模型的杂交，即水蛙从Pelophylax esculentus复杂，出现无性繁殖。此外，我们评估了其无性繁殖的影响，从两个种群的维持种间杂种的P. esculentus范围的西部边缘，其中杂种与两个亲本物种或只有一个亲本物种共存。在分析蝌蚪核型后，我们得出结论，在这两个研究群体中，大多数二倍体杂交雄性产生的单倍体配子与P. ridibundus基因组后消除P. lessonae基因组。杂交雌性表现出基因组消除和复制的问题;它们通常产生单价体的卵母细胞，但也有观察到个别卵母细胞具有13个二价体，甚至26个二价体。在一些杂交蝌蚪，特别是F1杂交，我们观察到失败的生殖细胞发育，而在蝌蚪回交，生殖细胞正常分布，并含有微核。通过鉴定微核中存在的染色体，我们估计所有杂交的大多数蝌蚪都能够选择性地消除P. lessonae染色体。根据我们的研究结果，杂种的杂种发生既可以出现在亲本种的杂交中，也可以出现在有性种与杂种个体的杂交中。消除基因组和进行核内复制以确保配子形成的能力在所研究群体的雄性和雌性杂交种之间是不同的。有些二倍体杂种雌虫不仅能产生单倍体配子，而且还能产生二倍体配子，这是形成三倍体杂种的关键步骤。
Many closely related species are capable of mating to produce hybrid offspring, which are usually sterile. Nevertheless, altering the gametogenesis of hybrid offspring can rescue hybrids from sterility by enabling asexual reproduction. Hybridogenesis is one of the most complicated asexual reproductive modes, and it includes drastic genome reorganization only in the germline; this is achieved through elimination of one parental genome and duplication of the remaining one to restore diploid chromosomal set and overcome blocks in meiotic progression. We investigated a model of hybridogenesis, namely, water frogs from the Pelophylax esculentus complex, for the emergence of asexual reproduction. Further, we assessed the impact of its asexual reproduction on the maintenance of interspecies hybrids from two populations on the western edge of the P. esculentus range, in which hybrids coexist with either both parental species or with only one parental species. After analysing tadpole karyotypes, we conclude that in both studied populations, the majority of diploid hybrid males produced haploid gametes with the P. ridibundus genome after elimination of the P. lessonae genome. Hybrid females exhibited problems with genome elimination and duplication; they usually produced oocytes with univalents, but there were observations of individual oocytes with 13 bivalents and even 26 bivalents. In some hybrid tadpoles, especially F1 crosses, we observed failed germ cell development, while in tadpoles from backcrosses, germ cells were normally distributed and contained micronuclei. By identifying chromosomes present in micronuclei, we estimated that the majority of tadpoles from all crosses were able to selectively eliminate the P. lessonae chromosomes. According to our results, hybridogenesis in hybrids can appear both from crosses of parental species and crosses between sexual species with hybrid individuals. The ability to eliminate a genome and perform endoreplication to ensure gamete formation differed between male and female hybrids from the studied populations. Some diploid hybrid females can rarely produce not only haploid gametes but also diploid gametes, which is a crucial step in the formation of triploid hybrids.