Département de biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, 1030 Avenue de la Médecine, G1V 0A6, Quebec, Canada.
Institut de Systématique, Evolution et Biodiversité (UMR 7205 CNRS/MNHN/SU/EPHE), Museum National d'Histoire Naturelle, CP50, 57 rue Cuvier, 75005, Paris, France.
Nat Commun. 2020 Feb 3;11(1):670. doi: 10.1038/s41467-020-14479-7.
How natural diversity is maintained is an evolutionary puzzle. Genetic variation can be eroded by drift and directional selection but some polymorphisms persist for long time periods, implicating a role for balancing selection. Here, we investigate the maintenance of a chromosomal inversion polymorphism in the seaweed fly Coelopa frigida. Using experimental evolution and quantifying fitness, we show that the inversion underlies a life-history trade-off, whereby each haplotype has opposing effects on larval survival and adult reproduction. Numerical simulations confirm that such antagonistic pleiotropy can maintain polymorphism. Our results also highlight the importance of sex-specific effects, dominance and environmental heterogeneity, whose interaction enhances the maintenance of polymorphism through antagonistic pleiotropy. Overall, our findings directly demonstrate how overdominance and sexual antagonism can emerge from a life-history trade-off, inviting reconsideration of antagonistic pleiotropy as a key part of multi-headed balancing selection processes that enable the persistence of genetic variation.
自然多样性是如何维持的是一个进化谜题。遗传变异可能会被漂变和定向选择所侵蚀，但某些多态性会持续很长时间，这暗示了平衡选择的作用。在这里，我们研究了海藻蝇 Coelopa frigida 中染色体倒位多态性的维持机制。通过实验进化和量化适应度，我们表明该倒位存在一个生活史权衡，即每个单倍型对幼虫存活率和成虫繁殖力有相反的影响。数值模拟证实了这种拮抗多效性可以维持多态性。我们的研究结果还强调了性别的特异性效应、显性和环境异质性的重要性，它们的相互作用通过拮抗多效性增强了多态性的维持。总的来说，我们的研究结果直接证明了超显性和性拮抗如何从生活史权衡中产生，并促使人们重新考虑拮抗多效性作为多因素平衡选择过程的关键部分，这些过程使遗传变异得以持续存在。
