The origin, genomics and evolution of female-limited polymorphisms

There is a growing interest in the genomic and developmental basis of discrete or multimodal phenotypes governed by genetic polymorphisms. Recent research has uncovered the genomic basis of such polymorphisms and their maintenance through balancing selection such as negative frequency-dependent selection (NFDS). Such polymorphisms often originate through structural genomic changes or through mutations in regulatory genes. Historically, researchers focused on male-limited polymorphisms and intrasexual competition as drivers of NFDS. However, an increasing number of female-limited polymorphisms are being discovered, with sexual conflict, social selection or natural selection maintaining such polymorphisms. Still, significant gaps in our understanding of female-limited polymorphisms linger, partly as a historical legacy of a male-centric research focus on conspicuous male phenotypes. We review and synthesize female-limited polymorphisms, their maintenance, genetic architecture, genomic basis, developmental origin, microevolutionary dynamics and macroevolutionary diversification. Animals with female-limited polymorphisms include invertebrates (e.g. bedbugs, butterflies, damselflies and fruit flies) but also vertebrates (e.g. birds, mammals and reptiles). By highlighting female-limited polymorphisms, we draw attention to the unique sex-specific selection pressures on females distinguishing them from male-limited polymorphisms. Finally, wee present a conceptual model aimed to explain the origin and evolution of female-limited polymorphisms and outline future research avenues in this emerging field.