S2-1.7 Jan. 4 Linking the Evolution of Genes with the Evolution of Morphological Characters WAGNER, G. P. ; Yale University email@example.com
There are two types of questions implied by the title of our symposium: “Linking Genes and Morphology.” At the one hand there is the question what role a certain gene plays in the development of a morphological feature. This is the question of developmental genetics and there is a well developed paradigm of how to answer this question. On the other hand there is the question, what genetic changes led to specific morphological changes in evolution. The paradigm of how to address the latter issue is much less mature than that of developmental genetics. The challenge of elucidating how the evolution of genes have caused the evolution of morphological phenotypes has many levels. In this contribution I want to focus on one specific problem, namely the difficulty to identify which changes have caused the morphological change of interest and which are incidental. I will be discussing a strategy which consists of combining a careful analysis of the molecular evolution of genes involved in the development of a derived morphological character with experimental validation of candidate genetic changes. The objective is to associate un-expected patterns of sequence evolution with the inferred morphological change. This approach assumes that relevant genetic changes happened under directional selection. It also requires sufficient knowledge of the developmental biology of the derived morphology and a hypothesis about what genetic elements are likely to have caused the morphological change (coding sequence evolution of transcription factors, cis-regulatory elements, mi-RNA). Finally it needs an experimental handle on testing the functional consequences of the inferred genetic changes. I will propose a set of minimal set of evidential criteria to validate a specific hypothesis about a link between a genetic and a morphological change in evolution.