Department of Microbiology, Department of Statistics, University of Manitoba, 45 Chancellor Circle, 213 Buller Building, Winnipeg Manitoba Canada, R3T 2N2, Canada.
Department of Genetics, University of Wisconsin-Madison, 425g Henry Mall, Madison WI 53703, USA.
FEMS Microbiol Rev. 2021 Sep 8;45(5). doi: 10.1093/femsre/fuab006.
Changes in ploidy are a significant type of genetic variation, describing the number of chromosome sets per cell. Ploidy evolves in natural populations, clinical populations, and lab experiments, particularly in unicellular fungi. Predicting how ploidy will evolve has proven difficult, despite a long history of theoretical work on this topic, as it is often unclear why one ploidy state outperforms another. Here, we review what is known about contemporary ploidy evolution in diverse fungal species through the lens of population genetics. As with typical genetic variants, ploidy evolution depends on the rate that new ploidy states arise by mutation, natural selection on alternative ploidy states, and random genetic drift. However, ploidy variation also has unique impacts on evolution, with the potential to alter chromosomal stability, the rate and patterns of point mutation, and the nature of selection on all loci in the genome. We discuss how ploidy evolution depends on these general and unique factors and highlight areas where additional experimental evidence is required to comprehensively explain the ploidy transitions observed in the field, the clinic, and the lab.
倍性变化是一种重要的遗传变异类型，描述了每个细胞中的染色体组数。倍性在自然种群、临床种群和实验室实验中进化，特别是在单细胞真菌中。尽管在这个主题上已经有很长的理论工作，但预测倍性将如何进化一直很困难，因为通常不清楚为什么一种倍性状态优于另一种。在这里，我们通过群体遗传学的视角回顾了不同真菌物种中当代倍性进化的已知情况。与典型的遗传变异一样，倍性进化取决于新倍性状态通过突变出现的速度、不同倍性状态的自然选择以及随机遗传漂变。然而，倍性变异也对进化产生了独特的影响，有可能改变染色体稳定性、点突变的速度和模式，以及基因组中所有基因座的选择性质。我们讨论了倍性进化如何取决于这些一般和独特的因素，并强调了需要额外的实验证据来全面解释在野外、临床和实验室中观察到的倍性转变的领域。
