Research | Antoine Kremer

My main research interest relates to the evolution of genetic diversity and differentiation between natural populations, at various hierarchical levels where diversity is expressed (from genes to phenotypic traits). The main emphasis of my research activities is the understanding of evolutionary forces that contribute to the distribution of diversity and differentiation. While focusing at the beginning on the past history of tree populations, my current interest addresses future evolution in the context of environmental changes. I am therefore using microevolutionary approaches by linking genetics, genomics and ecology, along six major research areas.

1. Experimental and theoretical approaches

My research combines theoretical and experimental approaches. An important goal is to gather population data at various spatial and geographic scales to describe and dissect population differentiation, and to depict general distribution patterns. These data are then compared to theoretical predictions obtained by analytical derivations or simulations, where various different evolutionary scenarios are tested.

2. Study species

I am working on long lived temperate tree species, as European white oaks, mainly Quercus petraea (sessile oak) and Quercus robur (pedunculate oak)) and other related Fagaceae species. Extensive diversity assessments were conducted at various spatial scales at the molecular and phenotypic level. We have recently concentrated our monitoring efforts along geographic gradients that mimic spatially temporal variation expected under climate change. These data sets are further completed by genomic and genetic resources (genetic maps, EST libraries, QTLs …) and made available to the scientific community via an electronic portal.

3. Monolocus vs multilocus differentiation

A major difference between phenotypic and molecular differentiation is related to the different architecture of traits. Phenotypic traits are multilocus traits and markers are most generally single locus traits. These differences result in different expectations for differentiation, as linkage disequilibrium may largely inflate differentiation for phenotypic traits (Qst) in comparison to single locus markers or genes (Fst). I am exploring the mechanistic and evolutionary causes of the decoupling of diversity between traits and genes.

4. Adaptive vs neutral differentiation

During recent years we conducted several gene expression studies in European oaks to identify genes controlling traits of important ecological and adaptive significance (bud burst and tolerance to anoxia). We are currently assessing diversity in these genes in natural populations of white oak species that exhibit contrasting adaptive responses, in comparison to earlier differentiation obtained with neutral markers, with the aim to identify molecular footprints of natural selection.

5. Genomic distribution of genetic differentiation

Locating genomic regions responding to natural selection is being investigated by scanning the dense genetic maps for differentiation. These investigations are being conducted by two complementary ways: mapping QTLs of adaptive traits and scanning Fst values of markers along linkage groups of genetic maps of Q. petraea and Q. robur.

6. Population and species differentiation

We are monitoring differentiation between populations within different oak species, but also among two closely related white oak species (Q. petraea Q. robur Q.pubescens and Q.pyrenaica). Differentiation is seen as a common footprint of multilocus selection responsible for species divergence is this oak complex.