How does coevolution in mutualistic networks shapes discrete polymorphisms?

Abstract

How the diversity of forms within species (polymorphism) is maintained in natural communities is one of the major questions in evolutionary biology. In these communities, mutualistic interactions is a strong selective pressure that drives the coevolution and may shape the amount of polymorphisms in populations of species. Polymorphisms are expected to be eroded by mutualistic coevolution, yet mutualists in ecological communities displays a wide range of variation in the amount of polymorphisms maintained. Previous theoretical and empirical work showed that when mutualists coevolve in pairs, conflicting selective pressures that comes from geographically, temporally structured or frequency dependent selection can maintain polymorphisms. However, when we proceed from pairs to entire communities of mutualists that forms networks, it is possible that conflicting selective pressures comes from the network itself. In networks, such conflicting selective pressures may emerge from a combination of direct and indirect evolutionary effects - i.e. evolutionary effects that occurs among species that do not directly interact. Understanding whether indirect evolutionary effects contribute to maintain polymorphisms remains an open question. Here, we propose to develop a coevolutionary model in networks to derive theoretical predictions on how indirect evolutionary effects shapes polymorphisms in coevolving mutualistic networks. Using this coevolutionary model we will combine analytical treatments and numerical simulations parameterized with the structure of empirical networks. We expect that our results will directly link how indirect evolutionary effects shapes polymorphisms of mutualistic populations and move us one step further to understanding what maintains the diversity and persistence of forms within species. (AU)