The maintenance of polymorphism in an ancient social supergene
The maintenance of polymorphism in an ancient social supergene
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DOI：
10.1111/mec.16196
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发表时间：
2021-10-08
影响因子：
4.9
通讯作者：
Brelsford, Alan
中科院分区：
文献类型：
--
作者：
Purcell, Jessica;Lagunas-Robles, German;Brelsford, Alan
超基因是基因组中功能突变组之间重组受到抑制的区域，有助于不同系统中复杂表型的进化。除了性染色体之外，迄今为止发现的大多数超基因似乎都很年轻，只存在于一个物种或几个密切相关的物种中。在这里，我们调查如何携带一个古老的超基因的染色体已经进化了大约3000万年（Ma）。蚁属的表基因在至少五个物种中的群体女王数量的变化。我们扩大了以前的分析，这个染色体上的序列分歧，包括约90个物种跨越Formica crossogeny。在nonrecombining区域内，基因敲除包含22个单核苷酸多态性（SNP），始终区分两个替代的超基因单倍型在不同的欧洲福米卡物种，我们发现，这些相同的SNP存在于大多数福米卡分支。在这些分支中，包括一个早期分化的新北蚁分支，在敲除时具有替代基因型的个体在该染色体的其他部分也具有较高的分化。我们确定热点单核苷酸多态性沿着这条染色体是存在于多个Formica分支检测基因，可能有助于出现和维持的遗传多态性。最后，我们推断一个单倍型上的三个基因重复，根据这些基因在单倍体男性基因组中的表观杂合性。这项研究加强了证据表明，这一超基因起源于早期的进化Formica，只有少数位点在这个大区域的抑制重组保留强烈分化的等位基因在当代Formica血统。
Supergenes, regions of the genome with suppressed recombination between sets of functional mutations, contribute to the evolution of complex phenotypes in diverse systems. Excluding sex chromosomes, most supergenes discovered so far appear to be young, being found in one species or a few closely related species. Here, we investigate how a chromosome harbouring an ancient supergene has evolved over about 30 million years (Ma). The Formica supergene underlies variation in colony queen number in at least five species. We expand previous analyses of sequence divergence on this chromosome to encompass about 90 species spanning the Formica phylogeny. Within the nonrecombining region, the gene knockout contains 22 single nucleotide polymorphisms (SNPs) that are consistently differentiated between two alternative supergene haplotypes in divergent European Formica species, and we show that these same SNPs are present in most Formica clades. In these clades, including an early diverging Nearctic Formica clade, individuals with alternative genotypes at knockout also have higher differentiation in other portions of this chromosome. We identify hotspots of SNPs along this chromosome that are present in multiple Formica clades to detect genes that may have contributed to the emergence and maintenance of the genetic polymorphism. Finally, we infer three gene duplications on one haplotype, based on apparent heterozygosity within these genes in the genomes of haploid males. This study strengthens the evidence that this supergene originated early in the evolution of Formica and that just a few loci in this large region of suppressed recombination retain strongly differentiated alleles across contemporary Formica lineages.