Department of Biology, Terrestrial Ecology Unit, Ghent University, BE-9000 Ghent, Belgium.
Department of Plant Biotechnology and Bioinformatics, Ghent University, BE-9000 Ghent, Belgium.
Proc Biol Sci. 2023 Mar 29;290(1995):20222456. doi: 10.1098/rspb.2022.2456. Epub 2023 Mar 22.
Polyploidy, i.e. the occurrence of multiple sets of chromosomes, is regarded as an important phenomenon in plant ecology and evolution, with all flowering plants likely having a polyploid ancestry. Owing to genome shock, minority cytotype exclusion and reduced fertility, polyploids emerging in diploid populations are expected to face significant challenges to successful establishment. Their establishment and persistence are often explained by possible fitness or niche differences that would relieve the competitive pressure with diploid progenitors. Experimental evidence for such advantages is, however, not unambiguous, and considerable niche overlap exists among most polyploid species and their diploid counterparts. Here, we develop a neutral spatially explicit eco-evolutionary model to understand whether neutral processes can explain the eco-evolutionary patterns of polyploids. We present a general mechanism for polyploid establishment by showing that sexually reproducing organisms assemble in space in an iterative manner, reducing frequency-dependent mating disadvantages and overcoming potential reduced fertility issues. Moreover, we construct a mechanistic theoretical framework that allows us to understand the long-term evolution of mixed-ploidy populations and show that our model is remarkably consistent with recent phylogenomic estimates of species extinctions in the Brassicaceae family.
多倍体，即多套染色体的发生，被认为是植物生态学和进化中的一个重要现象，所有有花植物可能都有一个多倍体的祖先。由于基因组冲击、少数细胞型排斥和生育力降低，在二倍体群体中出现的多倍体预计将面临成功建立的重大挑战。它们的建立和持续存在通常可以通过可能的适应性或生态位差异来解释，这将减轻与二倍体祖先的竞争压力。然而，对于这种优势的实验证据并不明确，而且大多数多倍体物种及其二倍体对应物之间存在相当大的生态位重叠。在这里，我们开发了一个中性的空间显式生态进化模型，以了解中性过程是否可以解释多倍体的生态进化模式。我们通过展示有性繁殖生物以迭代的方式在空间中聚集，减少了频率依赖性交配劣势，并克服了潜在的生育力降低问题，从而提出了一种多倍体建立的一般机制。此外，我们构建了一个机械理论框架，使我们能够理解混合倍性种群的长期进化，并表明我们的模型与最近对 Brassicaceae 科物种灭绝的系统基因组估计非常一致。
