The structure of molecular interactions affects evolutionary processes across biological levels of organization: from genomes, to species, to populations and ecosystems. Theory predicts that adaptive evolution may be constrained by the structure of molecular networks, e.g. due to pleiotropy in gene interaction networks. In particular, regulatory evolution is likely a major mechanism of adaptation, which may be biased toward certain positions in regulatory networks. However, results to date have been idiosyncratic, with no clear pattern. In our previous meeting, we investigated the network topology of genes putatively involved in local adaptation to two abiotic stressors: drought and cold in Arabidopsis thaliana. Our findings suggest that these topologies are non-random, with drought response genes being significantly more peripheral and cold response genes being significantly more central than genes not involved in either response. Therefore, we concluded that the constraints associated with the genetic pathways involved in the phenotypic responses predict variation in network topology — essentially, biology constrains evolution. With these results, we began constructing a broader theory of how molecular networks shape evolution across multiple levels of biological organization.
This meeting will advance the research begun during the SFI working group “Molecular Networks and Local Adaptation.” Prior to the start of our follow-on working group, a manuscript presenting the results described above will be in review at Molecular Biology and Evolution. During our meeting in October, we will disambiguate the theoretical and empirical challenges facing our emerging theory of how molecular networks shape evolution across biological Scales. Using this framework, we will prepare a grant for competitive funding to support laboratory, field, and theoretical work. We plan to: 1) expand the number of taxa considered in our laboratory analysis to include Brachypodium distachyon; 2) perform reciprocal transplant experiments in the native range of Brachypodium and Arabidopsis; 3) construct and apply novel network analytic methods to study the dynamics of gene networks during local adaption.