© Nico Posnien

Understanding the evolutionary forces shaping the breathtaking morphological diversity present in nature is one prerequisite to describe and maintain this biodiversity. Linking genetic variation to phenotypic differences is a crucial step towards this goal because information about the appearance of an organism is stored in its genome. New sequencing technologies fueled exciting advances in the identification of the genetic architecture of many norganismal traits However a mechanistic understanding of the biological processes affected by these genetic variants remains largely elusive Closing this gap is challenged by the fact that many organismal traits vary continuously in a population, and they are often affected by hundreds or even thousands of mutations spread throughout the genome with each of them having only a minor impact on the phenotype It is therefore of general interest to improve our understanding of genotype phenotype associations In my previous research I predominantly used naturally occurring variation in head morphology in various Drosophila fruit fly species as a model to develop an integrative framework to study the genetic basis of quantitative trait variation As adult morphology is a result of embryonic and post embryonic development I propose that genetic variants associated with differences in adult organ size and shape must affect developmental and cellular processes as intermediate organismal phenotypes Such developmental processes are coordinated by the action of gene products and therefore the integration of multi omics data quantifying the regulation and expression of developmental genes represents a powerful intermediate molecular phenotype In my current research I employ and expand this framework to study the genetic and developmental bases of morphological diversity on different phylogenetic levels. On a micro evolutionary scale I identify genomic loci underlying local adaptation in European Drosophila melanogaster populations I am continuing to study intra and interspecific variation in head morphology in Drosophila and I am identifying genomic loci and developmental processes responsible for the formation of novel head and mandibular horns in the broad horned beetle Gnatocerus cornutus On a macro evolutionary scale I am studying molecular mechanisms underlying the diversification of gene expression and the functional consequences of gene and genome duplications in spiders and insects In summary I employ a multi faceted approach combining morphology genetics development and molecular biology to gain mechanistic insights into the evolution of morphology