Will gene flow save endangered Arabis floodplain species from extinction?

点击翻译按钮获取中文摘要

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 combine experimental genetics with theoretical population genomics approaches to determine the evolutionary significance of gene flow 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. To determine whether gene flow is advantageous and promote resilience in A. nemorensis, we will disentangle the effects of positive and negative selection on the rate of gene flow in each of the two hybridizing species. Specifically, we will 1) conduct a population genomics analysis to reconstruct the history of introgressions, 2) map loci controlling phenotypes of ecological relevance (e.g. flooding tolerance, drought tolerance, viability, incompatibility), 3) perform a transcriptome analysis to better understand the genetic function important for flooding tolerance, 4) develop theoretical tools to infer the rates of adaptive introgression while accounting for the effects of seed banking, and 5) quantify the type and strength of selection at the involved introgressed genes. Through the design and validation of novel approaches to infer the evolutionary significance of gene flow in seed banking species, this project will contribute to support global efforts aiming at preserving plant biodiversity.