Person:

Sherratt, Emma

Studies integrating evolutionary and developmental analyses of morphological variation are of growing interest to biologists as they promise to shed fresh light on the mechanisms of morphological diversification. Sexually dimorphic traits tend to be incredibly divergent across taxa. Such diversification must arise through evolutionary modifications to sex differences during development. Nevertheless, few studies of dimorphism have attempted to synthesize evolutionary and developmental perspectives. Using geometric morphometric analysis of head shape for 50 Anolis species, we show that two clades have converged on extreme levels of sexual dimorphism through similar, male-specific changes in facial morphology. In both clades, males have evolved highly elongate faces whereas females retain faces of more moderate proportion. This convergence is accomplished using distinct developmental mechanisms; one clade evolved extreme dimorphism through the exaggeration of a widely shared, potentially ancestral, developmental strategy whereas the other clade evolved a novel developmental strategy not observed elsewhere in the genus. Together, our analyses indicate that both shared and derived features of development contribute to macroevolutionary patterns of morphological diversity among Anolis lizards.

Anoles are well known example of adaptive radiation and convergent evolution. their phylogenetic relationships have been intensely studied, but their fossil record remains fairly poor, limiting understanding of their evolutionary history. We present new data on Anolis electrum, the first discovered fossil anole and sole vertebrate described from Mexican amber, using xray Computd Tomography. We inferred the phylogenetic relationships of a electrum and comment on its use in estimating the age of Anolis origins, Anolis electrum us represented by two pieces of amber containing parts of the same individual. Partial squamation and skeleton details are well preserved, though only ten characters commonly used in phylogenetic analyses could be scored. the lack of informative characters resulted in a electrum being inferred in 14 different places within four recognized subclades. Dactyloa cristatellus series, darlingtoni series, and Norops one of which corresponds to previously suggested close relationships. Results fail to support a suggested age estimation of 130 Myr of Anolis; consequently, the hypothesis of overwater dispersal as the explanation for the occurence of anoles on Caribbean islands remains the most robust hypothesis.

A new species of siphonopid caecilian, Microcaecilia dermatophaga sp. nov., is described based on nine specimens from French Guiana. The new species is the first new caecilian to be described from French Guiana for more than 150 years. It differs from all other Microcaecilia in having fewer secondary annular grooves and/or in lacking a transverse groove on the dorsum of the first collar. Observations of oviparity and of extended parental care in M. dermatophaga are the first reproductive mode data for any species of the genus. Microcaecilia dermatophaga is the third species, and represents the third genus, for which there has been direct observation of young animals feeding on the skin of their attending mother. The species is named for this maternal dermatophagy, which is hypothesised to be characteristic of the Siphonopidae.