Regulatory control of phenotypic plasticity

This project aims to understand how the environment interacts with and shapes genomes, and how genome regulation and variation are linked to phenotypic plasticity and phenotypic evolution. It focuses specifically on the stage-dependent, tissue-specific and reversible morphological development of traits that are induced, in the new genomics model organism, Daphnia pulex, by chemical signals from their environment. So far, our understanding of the mechanistic basis of common morphological variation such as phenotypic plasticity is only fragmentary as there has been relatively little success at identifying empirical patterns of cellular control mechanisms governing phenotypic variation. This is predominantly due to the fact that determining the genetic architecture of complex traits is challenging since plastic development typically does not rely on a few plasticity or robustness genes but rather arises from interactions between multiple environmentally sensitive components and pathways that might be controlled by many loci. To elucidate the cellular machineries that drive the expression of plastic responses at the molecular level, we employed a complex gene expression study using the model organism Daphnia pulex. In response to chemical cues released by predators (i.e., kairomones) this species exhibits an astonishing repertoire of inducible defences including developmental, stage dependent, tissue-specific and reversible de novo morphological formations. By conducting functional genomic assays across genotypes and developmental stages that differ in expression of the adaptive and plastic traits, the overarching goal of the proposed project is to provide novel insights into how organisms can and do respond to environmental challenges. In particular, this study emphasizes on a real-world scenario by investigating how anthropogenic influences (here additional metal exposure) can interfere with the cellular stress responses that facilitate the predator induced morphological defences in question. Because Daphnia is a keystone species of ponds and lakes, this study will ultimately transform our current understanding of the buffering capacity of populations and ecosystems to environmental changes.