Affiliations: 1) UC Davis Plant Sciences, Davis, CA; 2) UC Davis Evolution and Ecology, Davis, CA
Keywords: Complex traits
Traits rarely evolve through changes in a single gene. Often a network of genes must evolve in concert to give rise to a new complex trait. During this process a change in one gene will often influence changes in other genes. A unique model to study complex trait evolution is C4 photosynthesis. This pathway has evolved independently more than sixty times and confers an important adaptive benefit in certain environmental conditions, notably including hot dry climates. The evolution of C4 photosynthesis involves changes in many genes that each have a function in the ancestral C3 photosynthetic pathway, so the trait is not driven by evolution of any one novel gene. We compare protein and gene interactions in C4 plants and their non-C4 relatives in a network model to study the process of complex trait evolution while accounting for the trait architecture. Analysis of the network model allows us to study whether genes that have been exapted, or co-opted from ancestral networks for use in the C4 pathway, tend to have specific placements within the network architecture. We also use the model to compare rates of molecular evolution with gene connectivity in the network, which represents a non-sequence based measurement of gene copy redundancy. By comparing the gene networks of pairs of species on either side of independent C4 evolution events in the grasses, we hope to better understand the process of complex trait evolution.