Unisexual hybrids break through an evolutionary dead end by two‐way backcrossing
Unisexual hybrids break through an evolutionary dead end by two‐way backcrossing
复制标题
单性杂交通过双向回交突破了进化的死胡同
DOI：
10.1111/evo.13903
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发表时间：
2020
期刊：
影响因子：
3.3
通讯作者：
Munehara Hiroyuki
中科院分区：
文献类型：
--
作者：
Suzuki Shota;Miyake Shota;Arai Katsutoshi;Munehara Hiroyuki
单性脊椎动物（即，通过克隆或半克隆繁殖产生的那些）通常不能清除有害的突变，因此，在进化方面被认为是短命的。在半克隆生殖（杂交发生）中，一个亲本基因组在卵子发生过程中被消除，产生含有单个亲本基因组的单倍体卵子。半无性系杂种通常是由半无性系杂种与父本物种的雄性回交产生的。当半克隆杂交种从一个属的绿（Hellammos）与男性的母体物种杂交，后代是表型相似的母体物种，并产生重组配子的规则减数分裂。本研究的目的是确定半克隆基因组是否返回到野生母体物种的基因库中。利用一种特异的细胞遗传学标记来区分这种后代和母系物种，我们观察到，哈什拉莫西杂种与母系和父系祖先以相同的频率交配。这种双向回交，其中克隆基因组返回到基因库中，在那里它们可以进行重组，在增加半克隆基因组的遗传变异性和降低灭绝风险方面起着重要作用。通过这种方式，杂交谱系通过偶尔的重组世代存活的时间可能比预期的更长。
Unisexual vertebrates (i.e., those produced through clonal or hemiclonal reproduction) are typically incapable of purging deleterious mutations, and, as a result, are considered short-lived in evolutionary terms. In hemiclonal reproduction (hybridogenesis), one parental genome is eliminated during oogenesis, producing haploid eggs containing the genome of a single parent. Hemiclonal hybrids are usually produced by backcrossing hemiclonal hybrids with males of the paternal species. When hemiclonal hybrids from a genus of greenlings (Hexagrammos) are crossed with males of the maternal species, the progeny are phenotypically similar to the maternal species and produce recombinant gametes by regular meiosis. The present study was conducted to determine if the hemiclonal genome is returned to the gene pool of the maternal species in the wild. Using a specific cytogenetic marker to discriminate between such progeny and the maternal species, we observed thatHexagrammoshybrids mated with maternal and paternal ancestors at the same frequency. This two-way backcrossing in which clonal genomes are returned to the gene pool where they can undergo recombination plays an important role in increasing the genetic variability of the hemiclonal genome and reducing the extinction risk. In this way, hybrid lineages may have survived longer than predicted through occasional recombinant generation.