Bogart James P
Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
Genome. 2021 Dec;64(12):1053-1065. doi: 10.1139/gen-2021-0019. Epub 2021 Jun 15.
Unreduced gametes have been implicated in the evolution of polyploid species of plants and animals and are normally produced by female anuran amphibians. Such eggs may initiate the evolution of polyploid species that have arisen independently in several anuran families. Polyploid females could also produce unreduced eggs that might lead to species with higher ploidy levels, or their eggs may develop gynogenetically to reduce the ploidy level. Diploid (2 = 24) and tetraploid (4 = 48) are sibling cryptic species of North American grey treefrogs. Artificial crosses using females and genetically distant diploid males were performed to produce haploid and to assess the production of unreduced eggs in this tetraploid species. Gynogenetic diploid (haploid ), allotriploid, gynogenetic tetraploid, allopentaploid, autohexaploid, and gynogenetic octoploid tadpoles were confirmed using chromosome counts from tadpole tail tip squashes. The transformation and survival of different ploidies varied. Gynogenetic diploids transformed but expressed aspects of haploid syndrome and died before or shortly after transformation.
未减数配子与动植物多倍体物种的进化有关,通常由雌性无尾两栖动物产生。此类卵可能引发了在几个无尾目家族中独立出现的多倍体物种的进化。多倍体雌性也可能产生未减数的卵,这可能导致出现更高倍性水平的物种,或者它们的卵可能通过雌核发育来降低倍性水平。二倍体(2n = 24)和四倍体(4n = 48)是北美灰树蛙的姐妹隐性物种。利用雌性和遗传关系较远的二倍体雄性进行人工杂交,以产生单倍体,并评估该四倍体物种中未减数卵的产生情况。通过对蝌蚪尾尖压片进行染色体计数,确认了雌核发育二倍体(单倍体)、异源三倍体、雌核发育四倍体、异源五倍体、同源六倍体和雌核发育八倍体蝌蚪。不同倍性的转化和存活情况各不相同。雌核发育二倍体发生了转化,但表现出单倍体综合征的特征,并在转化前或转化后不久死亡。