Historical Processes and Genetic Implications of Limb Reduction and Loss in an Island Skink Lineage
Species-level diversity of the genus Brachymeles is concentrated in the Philippines, with species exhibiting a full range of limb development, including fully-limbed, intermediate, and limbless forms. Specimens and genetic samples will be collected for all recognized species, with supplemental material obtained via inter-museum loans. Both mitochondrial and nuclear DNA will be sequenced and morphological and osteological characters will be measured. The molecular data will be used to construct hypotheses of relationships within the genus under parsimony, maximum likelihood, and Bayesian methods. The study will investigate the level of cryptic diversity and will test the monophyly of hypothesized species complexes. Morphological measurements will be used to test the hypothesized morphological changes associated with limb reduction and loss. Correlated patterns of population genetic and biogeographic diversity will be studied using multi-locus approaches. Through the integration of morphology, ecology, molecular phylogenetics, population genetics, and biogeography, the results of this study will provide a basis for testable hypotheses in studies of limb loss. Analyses of three mitochondrial genes (ND2, ATP6, and ATP8) and four nuclear genes (GapD, MyH, R35, and BDNF), for 60% of the recognized species, indicate a high degree of cryptic diversity and unexpected evolutionar transitions between body forms.
