current_projects

With the exception of Anolis, lizards in the Caribbean are surprisingly understudied. Ground-dwelling lizards (Ameiva and Leiocephalus) are conspicuous members of the Greater Antillean fauna, yet little work has been done to date. My research with lizards in these genera will help to broaden the scope of studies in this region and test hypotheses regarding geographic genetic structure. Hispaniola is a topographically diverse island. The extreme topography presents multiple opportunities for vicariance, enhanced by a turbulent geological history of marine inundation. The topography also results in extreme environmental variation likely responsible for diversification of lizard traits. This work is multidisciplinary and integrates data from molecular genetics, natural history, and GIS technology.

Gifford, M.E., R. Powell, A. Larson, and R.L. Gutberlet, Jr. 2004. Population structure and history of a phenotypically variable teiid lizard (Ameiva chrysolaema) from Hispaniola: The influence of a geologically complex island. Mol. Phylogenet. Evol. 32:735-748.

Gifford, M.E., A. Larson. (In Review) In situ genetic differentiation in a Hispaniolan lizard (Ameiva chrysolaema): A multilocus perspective. Mol. Ecol.

In a previous study (Gifford et al. 2004) we identified a region in the Dominican Republic where two divergent mitochondrial lineages of A. chrysolaema make secondary contact. This region is marked by a steep gradient in precipitation which may influence the distribution of characters across this zone. The consequences of secondary contact, in terms of the fate of lineages and the characters they carry, is of broad interest and have important implications for studies of speciation, local adaptation, and conservation. I am using nuclear and mitochondrial DNA along with morphological and meristic characters to characterize this contact zone and assess implications for species limits in the complex.

Gifford, M.E. 2008. Divergent character clines across a recent secondary contact zone in a Hispaniolan lizard. J. Zool. 274:292-300.

This project examines insular patterns of morphology in Hispaniolan Leiocephalus lizards. Hispaniola is home to nine species of Leiocephalus lizards. Most species have populations inhabiting offshore satellite islands. These satellites differ in size, topography, community structure, and slightly in climatic environment. I am gathering data (adding to those collected by Albert Schwartz in the 60s) to examine morphological trends of these island populations in relation to their putative ancestral populations on the nearby main island. Data collected so far suggest a mixed pattern where some species tend to get larger on the satellite islands and others remain similar in size. An interesting finding in that patterns of sexual dimorphism also vary.

In collaboration with Bob Powell (Avila University), I am examining patterns of sexual dimorphism and reproductive characteristics in five species of Leiocephalus and two species of Ameiva from the Dominican Republic. Although some data regarding sexual size dimorphism in Leiocephalus have been reported, few data are available dealing with head shape dimorphism. Head shape dimorphism may result from sexual selection or intersexual niche divergence. Data to date suggest that dietary divergence plays little role in head shape dimorphism. Therefore we examined scaling relationships of head dimensions to attempt to assess the relative roles of selection and differential growth to the observed dimorphisms. We are also examined reproductive characteristics in these species, as few life history data exist for the genus. Virtually no data are available regarding life history and sexual dimorphism in West Indian Ameiva (save two species from Puerto Rico).

Gifford, M.E., R. Powell. 2007. Sexual dimorphism and reproductive characteristics in five species of Leiocephalus from the Dominican Republic. J. Herpetol. 41:521-527.

In collaboration with Anthony Herrel (University of Antwerp) and Luke Mahler (Losos Lab, Harvard), I am studying the evolution of sprinting performance in populations of Leiocephalus in the Dominican Republic. We are also examining the functional consequences of cranial and tail color polymorphisms in different habitats. One publication and one submitted manuscript has resulted from this work.

Gifford, M.E., A. Herrel, D.L. Mahler. 2008. The evolution of locomotor morphology, performance, and antipredator behaviour among populations of Leiocephlaus lizards from the Dominican Republic. Biol. J. Linn. Soc. 93:445-456.

Gifford, M.E., A. Herrel, D.L. Mahler. Intra-populational variation in the relationship between signal structure and performance in a Hispaniolan lizard. (In Review: Functional Ecology)

This research represents a collaboration with Brian Langerhans (Losos lab, Harvard). We are compiling the most complete phylogeny for the genus using mtDNA (ND2). We will use this phylogeny to examine the historical and ecological processes responsible for species diversification as well as the evolution of other characters in a phylogenetic context. One project from this work (examining mechanisms of speciation in G. hubbsi from the Bahamas) was recently published in Evolution. Check out Brian's website for more information on this work. (Photo copyright, R.B. Langerhans).

Langerhans, R.B., M.E. Gifford, E. Joseph. 2007. Ecological speciation in Gambusia fishes. Evolution 61:2056-2074. (Featured as Editor's Choice in Science, Oct. 5, 2007)