The role of sex in evolution: Sexual conflict and Sexual selection
Authors: Sheng-Kai Hsu 1,2; Wei-Yun Lai 1,2; Johannes Novak 3; Felix Lehner 2; Ana Marija Jakšić 1,2,4; Elisabetta Versace 5; Christian Schlötterer 2
Affiliations: 1) Vienna Graduate School of Population Genetics, Vetmeduni Vienna, Vienna, Austria; 2) Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria; 3) Institute of Animal Nutrition and Functional Plant Compounds, Vetmeduni Vienna, Vienna, Austria; 4) École polytechnique fédérale de Lausanne, Lausanne, Switzerland; 5) Department of Biological and Experimental Psychology, Queen Mary University of London, London, UK
Keywords: Experimental evolution
Since the evolution of sex, sexually reproducing organisms have managed to occupy a wider range of habitats and thrived in greater environmental fluctuation owing that recombination increases genetic variation for adaptation. In addition, the distinct roles of males and females in sexual reproductive system brings novel forms of evolutionary dynamics, namely sex-specific fitness requirements and the sexual selection imposed by one sex to the other. On one hand, despite decades of investigation on the resolution of sexual conflict, it is not yet clear whether and how the two sexes are able to respond differently to a sudden environmental shift. On the other hand, how sexual selection interplays with the ecological and mutation-order factors in affecting the evolution of reproductive isolation has long been a popular research question. Nevertheless, empirical studies, particularly on the mutation-order process, are limited. In this work, we decide to take the approach of experimental evolution with the aim to identify demonstrative insights into these open questions. Within 100 generations of experimental thermal adaptation, we demonstrate rapid sex-specific changes in transcriptional, metabolic and behavioral phenotypes. We propose that the standing genetic variation on the sex-specific genetic architecture due to the historical resolution of sexual conflict is the key factor that allows the uncoupled evolution in males and females of the same population. This model is further illustrated with our forward computer simulations. Further, utilizing the high replication level of the same experimental evolution framework, we empirically investigate both the deterministic and stochastic mechanisms behind the evolution of reproductive isolation during the experimental thermal adaptation. Particularly, we reveal the importance of the intersexual epistatic dependency due to sexual selection on the operation of mutation-order process. This not only resounds the theoretical prediction but also highlights the potential incompatibilities among standing genetic variation. This study advances the knowledge on the sex-related aspects of local adaptation and associated ecological/mutation-order speciation with unprecedented experimental evidences.