Incorporating Developmental Genetic Pathways into Speciation Theory

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

0075451 Johnson & Porter Developmental geneticists have made tremendous progress characterizing molecular mechanisms by which genetic blueprints encode the traits of organisms. Genes often interact in pathways to regulate the final traits, and these interactions usually involve binding between different molecules. Drs. Johnson and Porter, the authors of this proposal, have incorporated these developmental pathways into models of evolutionary change. They started pairs of computer-simulated populations with identical genes and allowed them to evolve under identical conditions of natural selection. As these populations evolved, their hybrids quickly accumulated genetic incompatibilities and thus became drastically less fit. The authors have also developed analytical theory to make quantitative predictions. The simulation results fit the theoretical expectations. Johnson and Porter propose to examine the robustness of their models to different assumptions about binding functions and the relationship between traits and fitness. They will also investigate the extent to which hybrid incompatibilities can evolve despite some exchange of genes between the populations. This study has important implications for the solution to a fundamental evolutionary problem: species formation. Biologists remain interested in how one species become two because, among other things, knowledge of this process is critical for understanding how biodiversity is generated. Hybrid fitness reduction, an important contributor to the speciation process, usually is due to genetic incompatibilities: genes from one species do not interact well with genes of the other. How these incompatibilities evolve is still poorly understood, in large part because mechanistic models of how traits evolve are lacking. The proposed study provides such a plausible mechanism. Moreover, the proposed exploration of the basic evolutionary principles of developmental genetic pathways establishes a theoretical foundation for the ultimate union of population genetics and developmental biology.