Adaptation to competition in river floodplains

Supervision: The project will be supervised by Juliette de Meaux at the University of Cologne.

Abstract: Increased ecosystem degradation and global climate change place an increasing number of species in danger of extinction. They also reshuffle species boundaries, favoring the emergence of novel patterns of gene flow. Gene flow can enhance adaptation and rescue endangered species, but it can also accelerate their extinction. Determining whether gene flow is beneficial is therefore fundamental for the preservation of biodiversity.

The goal of this study is to characterize the ecological consequences of exchange of flowering time alleles between Arabis nemorensis, an endangered stenoecious species of Central European floodplains, and its sympatric relative A. sagittata. A. nemorensis is confined to river floodplains, where it resists the massive fluctuations imposed by regular flooding and persists via seed banks, a life history trait that has been shown to have manifold consequences on population genetics processes. A. sagittata is an equally endangered drought-adapted species that was so far not reported in floodplain environments. First genetic analyses have shown that A. sagittata has begun to colonize floodplain habitats and that it naturally hybridizes with A. nemorensis, resulting in fertile offspring and thus enabling interspecific gene-flow.

We have identified genetic differences in two important functional traits with potential impact on plant survival to stress and competition, namely flowering time and root/shoot allocation. The aim of this PhD project is to fine map the genetic basis of these differences and determine their ecological relevance. For this, an F3 population will be selected and phenotyped. The gene(s) will be fine mapped and the QTL validated with a transgenic approach. To determine whether one of the flowering time alleles is locally advantageous, we will monitor flowering time, fitness and genotypes in the field. We will extend this work by testing whether early flowering is more advantageous in competitive conditions than in flooding conditions.

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