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| The main requisite for morphological evolution is the existence of variation.
Available phenotypic variation sets the limits of further
evolution. The factors determining which directions are actually
explored by phenotypes are thus central for understanding morphological evolution. In populations, individuals differ among each other because of their genes, because of the environmental conditions they experienced and because of stochastic variation in development. The effects of theses sources of variation are modulated by three developmental processes: (1) Canalization, or robustness, tends to limit genetic and environmental effects and is usually estimated by the variance among individuals; (2) developmental stability buffers random developmental noise and is usually estimated by fluctuating asymmetry. (3) phenotypic plasticity is the ability to produce different phenotypes depending on the environment. Plasticity thus tends to increase variation while canalization and stability tend to decrease it. The developmental and molecular mechanisms underlying these processes remain poorly understood. I apply geometric morphometrics (landmarks-based and outline analysis) to diverse living and fossil models to understand the effects of canalization, plasticity and stability on evolutionary rates and evolvability. Latelly I've been involved in several projects coupling geometric morphometrics and quantitative genetics of insects' wings, particularly focusing on the effects of varrying developmental temperature. Drosophila wing is a very convenient model to investigate the link between the patterns of phenotypic variation and molecular developmental processes. |  |
