Female dewlap ornaments are evolutionarily labile and associated with increased influence diversification rates in Anolis lizards

The evolution of costly signaling traits has largely focused on male ornaments. However, our understanding of the ornament evolution is necessarily incomplete without investigating the causes and consequences of variation in female ornamentation. Here, we study the Anolis lizard dewlap, a trait extensively studied as a male secondary sexual characteristic but present in females of several species. We characterized female dewlaps for 339 species to test hypotheses about their evolution. Our results did not support the hypothesis that female dewlaps are selected against throughout the anole phylogeny. Rather, we found that female dewlaps were evolutionary labile. We also did not find support for the adaptive hypothesis that interspecific competition drove the evolution of female dewlaps. However, we did find support for the non-adaptive pleiotropy hypothesis as species with larger females and reduced sexual size dimorphism were more likely to possess female dewlaps. Lastly, we found that female dewlap presence influenced diversification rates in anoles, but only secondarily to a hidden state. Our results demonstrate that female ornamentation is widespread in anoles and the traditional hypothesis of divergent selection between the sexes does not fully explain their evolution. Instead, female ornamentation is likely subject to complex adaptive and non-adaptive evolutionary forces.Funding provided by: Division of Environmental BiologyCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000155Award Number: DEB-154253