Bending the Course of Evolution: How Mutualistic Interactions Affect Macroevolutionary Dynamics of Diversification in Mimetic Ithomiini Butterflies

AbstractDisentangling the relative importance of biotic versus abiotic factors at a macroevolutionary scale is key to our understanding of the processes of diversification. Mutualistic Müllerian mimicry is a compelling example of an ecological interaction that affects population and species ecology and evolution. Here, we test how Müllerian mimicry shapes macroevolutionary patterns of diversification in the Ithomiini butterflies. We show that the age of color patterns is the most important predictor of species richness within mimicry rings but does not predict phylogenetic diversity of mimicry rings. We find pervasive phylogenetic signal in mimicry rings and in color patterns associated within polymorphic species. Only a small set of mimicry rings show high phylogenetic diversity. We identify patterns of saturation in the accumulation of new mimicry rings and in the number of evolutionary convergences toward the most species-rich mimicry rings. We discuss how the time-dependent effects detected in our study illustrate how neutral processes and ecological interactions interact and shape species and phenotypic diversification. Our results show that selection driven by mimetic interaction has not erased the effect of time and phylogenetic signal on the formation of mimicry rings but ecological saturation linked to mimetic interactions affected the dynamics of color pattern evolution and species diversification.