Department of Biology, University of Iowa, 143 Biology Building, Iowa City, IA 52242, U.S.A.
Biology Department, Mount Allison University, Sackville, NB E4L 1G7, Canada.
Biol Rev Camb Philos Soc. 2017 Feb;92(1):234-247. doi: 10.1111/brv.12226. Epub 2015 Oct 14.
Endopolyploidy - the existence of higher-ploidy cells within organisms that are otherwise of a lower ploidy level (generally diploid) - was discovered decades ago, but remains poorly studied relative to other genomic phenomena, especially in animals. Our synthetic review suggests that endopolyploidy is more common in animals than often recognized and probably influences a number of fitness-related and ecologically important traits. In particular, we argue that endopolyploidy is likely to play a central role in key traits such as gene expression, body and cell size, and growth rate, and in a variety of cell types, including those responsible for tissue regeneration, nutrient storage, and inducible anti-predator defences. We also summarize evidence for intraspecific genetic variation in endopolyploid levels and make the case that the existence of this variation suggests that endopolyploid levels are likely to be heritable and thus a potential target for natural selection. We then discuss why, in light of evident benefits of endopolyploidy, animals remain primarily diploid. We conclude by highlighting key areas for future research such as comprehensive evaluation of the heritability of endopolyploidy and the adaptive scope of endopolyploid-related traits, the extent to which endopolyploid induction incurs costs, and characterization of the relationships between environmental variability and endopolyploid levels.
内多倍体 - 生物体中存在高于原始倍性的细胞，而这些细胞原本的倍性水平较低（通常为二倍体） - 几十年前就已被发现，但相对于其他基因组现象，内多倍体的研究仍相对较少，尤其是在动物中。我们的综合综述表明，内多倍体在动物中比通常认为的更为普遍，并且可能影响许多与适应性和生态重要性相关的特征。特别是，我们认为内多倍体可能在关键特征中发挥核心作用，如基因表达、身体和细胞大小以及生长速度，并且在多种细胞类型中发挥作用，包括那些负责组织再生、营养储存和诱导性抗捕食防御的细胞。我们还总结了内多倍体水平的种内遗传变异的证据，并提出了这样的观点，即这种变异的存在表明内多倍体水平可能是可遗传的，因此可能成为自然选择的潜在目标。然后，我们讨论了为什么尽管内多倍体具有明显的益处，动物仍然主要是二倍体。最后，我们强调了未来研究的关键领域，如对内多倍体的遗传性的全面评估和与内多倍体相关的特征的适应性范围，内多倍体诱导所产生的成本的程度，以及环境变异性与内多倍体水平之间关系的特征。
