Collaborative Research: Admixture mapping of a hybrid zone to test Tinbergen's emancipation hypothesis

University Of California-Riverside, Riverside CA

Investigators

Abstract

Understanding how genes cause the behavioral traits of different species to be different is a major goal of evolutionary biology. This project seeks to test the emancipation hypothesis proposed by Tinbergen 60 years ago to understand how a novel behavior arises by using a hybrid zone between two species of hummingbirds. The novel behavior is a courtship display that is performed by one species, Allen's Hummingbird, and not the other, Rufous Hummingbird. In this stereotyped display, called the 'pendulum display', the male flies back and forth over a female while producing distinctive sounds with his wings. The investigators will record displays from 400 birds from within a hybrid zone between these two species, and then search for genes associated with individual components of the behavior, by sequencing the genomes of these 400 birds. Understanding how one behavior splits into two will reveal a fundamental mechanism of how behavior evolves. Additionally, this grant will train of students of diverse backgrounds, and enable outreach to the California School for the Deaf, Riverside by funding purchase of an 'acoustic camera', allowing deaf children to learn more about sound through this newly invented way of visualizing it. As the genetic underpinnings of how one behavior splits into two 'paramorphs', alternate forms of a previously unitary character, have not been demonstrated for any behavior, the analyses presented here aim to do so for the first time. This 3-year study has three objectives: (1) Hybrid zone mapping and cline analysis: phenotype, genotype, and selection (2): Sequence analysis of complex display behavior, and (3): Admixture mapping of behavior and morphology. Together these objectives will provide information about selection on the display traits of interest, and test the paramorph hypothesis directly, using phenotypic and genotypic data respectively. Current data indicate no fixed genetic differences between the species within coding regions of the genome, hinting that the paramorphic behavior could be driven by differences in gene regulation between the two species, rather than as the result of a paralogous gene. Just as the modern view of morphological diversity was transformed by the study of its genetic basis, a direct assessment of the genes underlying a behavior that varies across a hybrid zone will allow one of the first tests of how a complex motor pattern has evolved. This project will build infrastructure through addition of sound, video, and specimens to the Macaulay Library at Cornell University, San Diego Natural History Museum and the SDSU Museum of Biodiversity.