Embryology of the Gekkota: Insights into the Evolution an Development of Morphological Diversity
Date of Award
Doctor of Philosophy (PhD)
Petrella, Lisa N.
Schnitzer, Stefan A.
Understanding the patterns and processes which result in morphological diversity is a central goal of evolutionary developmental biology or evo-devo. This diversity encompasses morphologies which have evolved numerous, independent times within a clade (evolutionary convergence) and others which have evolved only once within a clade (i.e. evolutionary novelty). Though many of these diverse morphologies exhibit functional capabilities and are intertwined with the ecology and diversification of the evolutionary lineage in question, their origins are largely unknown. Robust phylogenic analysis, genomic information, and detailed developmental data are critical lines of evidence to explain the evolutionary and ontogenetic origins of morphological novelty and convergence. The central goal of my dissertation is to understand how development has changed over evolutionary time to produce convergence within the morphologically diverse and species-rich clade of gecko lizards (Infraorder Gekkota). To address this goal, I first characterized the embryonic development of the mourning gecko (Lepidodactylus lugubris): a parthenogenetic species which exhibits a unique compliment of derived and ancestral character states. Second, I investigated embryonic pigment development between gecko species with different activity times. Third I investigated the development of morphological novelty, the adhesive pads on the tails of New Caledonian crested geckos (Correlophus ciliatus), which has converged in function with a different gecko structure, the adhesive pads found on the digits of many gecko species. Finally I investigated the developmental processes which result in morphological convergence: repeated independent evolution of interdigital webbing retention in southeast Asian gliding geckos (Gekkonidae). Collectively, these data demonstrate how developmental patterns are altered to produce convergently evolved morphologies.
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