Life history evolution: the constraints of sexual plasticity

Congress of the European Society for Evolutionary Biology (ESEB), 19-24 August 2019, Turku, FinlandOne of the main aims of life history theories is to investigate how, given specific trade-offs and constraints, life history traits and strategies can maximise fitness. Let’s consider, for example the extraordinary diversity of animal sexual systems. Among vertebrates, fish show the most variable repertoire of reproductive modes, from unisexual reproduction (gynogenesis and hybridogenesis) to gonochorism, simultaneous hermaphroditism, sequential hermaphroditism (sex-change) and mixed mating system (androdioecy, when males coexist with hermaphrodites). An even larger range is found in crustaceans (with the inclusion of obligate and cyclical parthenogenesis and protandric simultaneous hermaphroditism, when males become hermaphrodites). In the attempt to explain so much variability, we have started studying sex in an evolutionary perspective, as a continuum of plastic traits affecting sex determination and sex differentiation. Here we propose a further switch in perspective. If sex can be so plastic, what are its constraints? Why certain reproductive modes, common in certain taxa are not found in others? Using fish and crustaceans as reference, we propose a multi-taxa approach to explore what limits sexual plasticity. In particular, we will focus on why so few crustacean species are simultaneous hermaphrodites, why no decapods are protogynous and why in fish protandry is not as common as protogyny, based on physiological, developmental and evolutionary constraint