To understand the adaptive nature of phenotypic diversity, I study convergence in animal form and function on a micro- and macro-evolutionary scale. As model system, I mainly focus on the lizard integument, which ranges from skin glands and the pheromones they produce, over skin appendages (e.g. claws, toepads, dewlaps), to the skin surface structure.
My studies require a mixture of research approaches.
- To examine morphology, I make use of a combination of several bio-imaging techniques that visualizes structures on the macro- (e.g. 2D X-ray), micro- (e.g. µCT, gel-based stereo-profilometry), and nanoscale (e.g. SEM, AFM). Using traditional and geometric morphometrics, I quantify form variation.
- To study patterns of trait diversity among species (macro-scale), I take a phylogenetic comparative approach. Advanced comparative statistics and evolutionary models enable me to test how universal (or idiosyncratic) particular design solutions are, to evaluate trends of co-evolution and evolutionary convergence, and to compare rates of morphological evolution among clades or between traits, among others. I use among-island comparisons to study patterns of evolutionary change among populations of the same species (micro-scale).
- By taking an experimental and mechanistic approach, I examine form-function relationships (e.g. using optical and biomechanical tests) and assess the ecological relevance of design diversity (e.g. using behavioral observations). I combine lab- and field-based experiments and conduct in vivo en ex vivo tests to acquire a total understanding of organismal function in nature.
Lizards have been an excellent vertebrate group to answer my research questions, largely because (1) they show great morphological and ecological diversity among (closely-related) species, (2) they are a species-rich vertebrate clade, (3) the phylogenetic relationships among species are well supported, and (4) they are highly abundant on numerous islands.