Christian Braendle is interested in understanding how environmental variation and genotype-environment interactions contribute to phenotypic variation. He is using the C. elegans model as well as closely related species to study how environmental variation modulates developmental processes and their phenotypic outcomes, including fitness consequences.
Environmental sensitivity and evolution of the Caenorhabditis germline
How does an organism adjust its reproduction and underlying developmental processes in response to environmental variation? How do such environmental responses evolve, given that populations and species have adapted to contrasted ecological niches? We address these questions by studying how molecular and cellular processes of the Caenorhabditis germline respond to environmental variation and how such responses evolve. We study how molecular and cellular processes underlying the reproductive system adjust their functioning in response to environmental variation, and how such environmental responses evolve. The overall project objective is to conduct an integrative and quantitative analysis of such germline plasticity and its evolution by characterizing the key processes of germ cell proliferation, gamete differentiation, and maturation, which ultimately define the reproductive output of the organism.
We therefore aim (1) to quantify plasticity and genotype-by-environment interactions for molecular and life history phenotypes in multiple experimental environments in different Caenorhabditis species and isolates; (2) to determine the mechanisms underlying plastic phenotypic responses to ecologically relevant environmental variation; (3) to identify molecular genetic and developmental changes underlying genotype-by-environment interactions, using QTL mapping approaches and by performing developmental genetic analyses in different species and genotypes; (4) to track the process of plasticity evolution in variable environments using experimental evolution; (5) to search for ecological correlates of the observed plasticity and genotype-by-environment interactions by studying natural Caenorhabditis populations and defining their ecological context.
Precision and environmental sensitivity of the C. elegans vulval signalling network
Development may be insensitive to variation in the environment, so that a given developmental process produces an invariant outcome across different environments. Such robustness is a fundamental biological property required to maintain phenotypic stability in a wide range of ecological conditions. To examine how the environment impacts a developmental system, we study the precision and environmental sensitivity of C. elegans vulval development – an intercellular patterning process relying on a network of Ras, Notch and Wnt pathways. We could establish that this process is very robust across various environmental conditions; however, the underlying signalling network and cellular mechanisms show extensive environmental sensitivity. We have identified specific environmental signals, which modulate the constellation and dynamics of the vulval signalling network. We currently address how the signalling network integrates environmental signals via the sensory system and metabolism. These experiments aim to shed light on the environmental modification of conserved molecular signalling cascades important in development and disease.
Natural genetic variation, diversity and ecology of Caenorhabditis nematodes
Although C. elegans and related species are increasingly being used in evolutionary studies, there is still very little information on the ecology and genetic structure of natural populations. We therefore contribute to current sampling efforts to place the model organism C. elegans into a more comprehensive evolutionary ecological context.
Our previous research in the Amazonian rain forest of French Guiana has revealed surprisingly high species diversity and population densities, allowing us to characterize patterns of genetic diversity at multiple spatial scales. We are currently extending sampling of natural populations, followed by genomic analyses to assess how variation in ecological parameters and breeding system relate to species-specific patterns of genetic diversity.
• 2003 : Ph. D. in Ecology and Evolutionary Biology, Princeton University, USA, David Stern's lab
• 2004-2007 : Post-doctoral fellow, Jacques Monod Institute, Paris, France, Marie-Anne Felix' lab
• 2008 : Post-doctoral fellow, Centre d'Immunologie Marseille-Luminy, Marseille, France, Jonathan Ewbank's lab
• Fellow at the Institute for Advanced Study (Wissenschaftskolleg), Berlin, 2012
• ATIP CNRS, 2008
Jan 2013, BMC Evolutionary Biology
Nov 2011, BMC Evolutionary Biology
Mar 2010, PLoS Genetics
Nov 2008, Developmental Cell