Meeting Abstract
Tetrapod digits are often characterized by sexually dimorphic digit proportions. For example, in male humans and mice, the second digit is generally shorter than the fourth digit, and, as such, the second to fourth digit length ratio (2D:4D) is generally <1. In females, by contrast, the second and fourth digits are of similar length, giving them a 2D:4D ratio >1. In previous work, our lab demonstrated that differences in the relative levels of androgen and estrogen signaling during limb development underlie the sexually dimorphic 2D:4D ratios in mice. Sexually dimorphic digit ratios have been described in a number of mammals and in a few non-mammalian species, including frogs, lizards and birds; however, the developmental basis of these patterns has not been examined outside of mice. In this study, we investigated digit development in the iguanid lizard Anolis sagrei to determine whether sexually dimorphic digit development is conserved between mammals and squamates. We show that A. sagrei develops sexually dimorphic digit proportions, but the timing and pattern of dimorphic skeletal growth are strikingly different from development of digit dimorphisms in mammals.
