Meeting Abstract
Species vary widely in their patterns and magnitudes of sexual dimorphism, yet the proximate mechanisms that regulate these differences remain poorly understood. Sexually dimorphic characters present special challenges to our understanding of anatomical evolution because the sexes share the majority of their genomes yet can diverge in size, shape, and anatomical characters during development. Lizards in the genus Anolis (anoles) are an often-used model for evolutionary studies of sexual dimorphism and are also an emerging model for comparative developmental analyses. An example of a sexually dimorphic trait in Anolis is the dewlap, a colorful throat fan that is usually larger in males than in females and is used frequently by males (but infrequently by females) during courtship and aggression. Located on the throat and extending down the belly, the dewlap is supported by the second ceratobranchial (C2) cartilage in the hyoid system. We investigated the developmental basis of the sexually dimorphic dewlap apparatus in anoles and find that morphogenesis of the C2 skeleton diverges in males and females at a surprisingly early stage of development. Our results suggest that dewlap dimorphism is rooted in sex-specific regulation of early skeletogenesis.
