The genetic consequences of range expansion and its influence on diploidization in polyploids.
The genetic consequences of range expansion and its influence on diploidization in polyploids.
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范围扩展的遗传后果及其对多倍体二倍化的影响。
DOI：
10.1101/2023.10.18.562992
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发表时间：
2024
期刊：
影响因子：
--
通讯作者：
Schrider,DanielR
中科院分区：
文献类型：
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作者：
Booker,WilliamW;Schrider,DanielR
尽管新形成的多倍体受到无数适合性后果的影响，但在生命树的当代和祖先分支中，多倍体的相对流行表明，替代优势超过了这些后果。一个被提出的优点是，多倍体可能更容易在新的栖息地定居，比如冰川消融的地区。然而，之前在二倍体中进行的研究表明，范围扩大伴随着适应成本，因为有害突变可能会迅速修复扩大前沿。在这里，我们通过进行空间上显式的时间向前模拟来询问多倍体扩张的潜在后果，以调查倍性和遗传模式如何影响多倍体扩大其范围的相对能力。我们表明，在现实的显性模型下，同源多倍体比二倍体遭受更大的适应度降低，这是由于范围扩大的结果，这是由于固定了隐藏在范围核心中的增加的突变负载。或者，异源多倍体的二体遗传为这种固定提供了一种保护，导致最小的适合度结果。鉴于二体提供的这一优势，我们研究了范围扩大如何通过同源四倍体回复到二体来影响细胞遗传学二倍体。我们表明，在两种二倍化模型所研究的广泛参数范围内，二体在扩张前沿的演化速度往往比在射程核心更快，并且这种动态遗传模型对适应度有额外的影响。总而言之，我们的结果表明，当种群分布在一个地理范围内时，优势、倍性、遗传和重组之间存在着复杂的适合度相互作用。
Despite newly formed polyploids being subjected to myriad fitness consequences, the relative prevalence of polyploidy, both contemporarily and in ancestral branches of the tree of life, suggests alternative advantages that outweigh these consequences. One proposed advantage is that polyploids may more easily colonize novel habitats, such as deglaciated areas. However, previous research conducted in diploids suggests that range expansion comes with a fitness cost, as deleterious mutations may fix rapidly on the expansion front. Here, we interrogate the potential consequences of expansion in polyploids by conducting spatially explicit forward-in-time simulations to investigate how ploidy and inheritance patterns impact the relative ability of polyploids to expand their range. We show that under realistic dominance models, autopolyploids suffer greater fitness reductions than diploids as a result of range expansion due to the fixation of increased mutational load that is masked in the range core. Alternatively, the disomic inheritance of allopolyploids provides a shield to this fixation, resulting in minimal fitness consequences. In light of this advantage provided by disomy, we investigate how range expansion may influence cytogenetic diploidization through the reversion to disomy in autotetraploids. We show that under a wide range of parameters investigated for two models of diploidization, disomy frequently evolves more rapidly on the expansion front than in the range core, and that this dynamic inheritance model has additional effects on fitness. Together our results point to a complex interaction among dominance, ploidy, inheritance, and recombination on fitness as a population spreads across a geographic range.