Kerry L. Shaw, IOS-0818862: The genetics of female acoustic preference behavior.
New species may be formed by changes in the signals that precede mating. In several well known clusters of species, divergent mating signals appear to be a primary reason why closely related species remain distinct. This sort of evolutionary change is poorly understood. One hypothesis is that the genes for male mating signals are the same as those for female response (or preference). This study focuses on Laupala, a group of closely related cricket species that has diverged very rapidly. Like most crickets, Laupala communicate acoustically, and acoustic differences contribute to mating incompatibility between species. However, some species can be hybridized in the laboratory, enabling a genetic study of these differences. Two closely related species that differ markedly in male song and female preference will be hybridized. Hybrid offspring will be mated with one of these species for several generations to move preference and song genes from one species into the other. Molecular markers will be used to produce a genome map of the location of genes underlying song and preference. With this map, it will be possible to ascertain whether song and preference genes map to the same location and how much each gene contributes to differences between species. The number of molecular markers on this map will subsequently be increased to facilitate the eventual cloning of genes underlying song and preference.
Research and education are integrated by training undergraduate, graduate and postdoctoral students. Kamehameha Schools students will be involved by establishing a web-based science lab analyzing the genetics of song and preference inheritance. The P. I. will visit the school to provide context through lecture and informal interaction with students.
Intellectual merit: In all organisms with males and females, functional coordination is required for successful reproduction of offspring. However, distinct mating signals are a primary reason why closely related species remain separate. The widespread differences between species, in lieu of maintained coordination within species, are poorly understood. One hypothesis is that the genes for male mating signals are the same as those for female response (or preference). This study uses closely related insect species as a comparative model system to understand the functional coordination required for reproduction and the role that changes in behavior play in the diversification of species. Insects, such as Drosophila (the genetic workhorse) are useful models in science because they can be studied genetically in the laboratory. In the cricket genus Laupala, males and females use many signals to coordinate reproduction. In particular, we studied acoustic communication in Laupala. Acoustic similarities are important for successful reproduction, and acoustic differences also contribute to mating incompatibility between species. Fortunately, some species can be hybridized in lab, enabling a genetic study of acoustic behavioral differences. Two closely related species that differ markedly in song and preference were hybridized. Hybrid offspring were mated with one of these species for several generations to move preference and song genes from one species into the other. Molecular markers were used to produce a genome map of the location of genes underlying song and preference. With the genome map, we determined whether song and preference genes occur at the same location and how much each gene contributes to acoustical differences between species. The number of molecular markers on this map was subsequently increased in order to measure the distance, in DNA base pairs, between markers. The major findings include extensive evidence for genetic associations between song and preference and a genetic basis to the functional coordination of reproduction, a finding that has never before been demonstrated to this extent. The long term goal is to identify the genes involved in these acoustic behavioral differences. The benefit of identifying these genes will be to better understand the genetic basis of how species differ, to identify genes that regulate temporal behaviors (acoustic behavior is analogous to other rhythmic behaviors such as heart beat rhythm), and to understand the genetic coordination between males and females that underlies successful reproduction. Broader impacts: The project provided professional training to 2 postdoctoral, 1 graduate and 4 undergraduate students. The post docs and graduate student have trained extensively in animal breeding, behavioral quantification, molecular genetics, genome mapping and bioinformatics. The undergraduates have trained in behavioral quantification and animal breeding techniques. As part of this work, the P.I. has developed several science outreach activities. The P.I. worked with the Museum of the Earth in Ithaca, NY to put together an exhibit on the acoustic diversity of cricket species and the role that behavior plays in the generation of species diversity. The museum is visited by school children from across the county as well as families and other individuals. The P.I. worked with the curator to produce text for the exhibit and supplied the exhibit with live crickets and expertise on maintaining them in the exhibit. The P.I. gave 2 public seminars in the University of Hawaii system where multiple Hawaii State and management employees attended, helped to identify cricket contents eaten by the invasive coqui frog in Hawaii, and educated members of the Haleakala National Park about endemic cricket diversity within the national park boundaries in 2011. In fall 2010, the P.I. provided microscopes and insect specimens at a local Ithaca school and developed an art-science project to introduce concepts of insect form and function. The P.I. recently (2011) spoke to the Tropical Conservation Biology and Environmental Science program at University of Hawaii, Hilo and advised student projects, and worked with staff at the Nature Conservancy at Kaiholena and Honomalino Preserves, assisting with their biodiversity cataloging of native crickets. Most recently, the P.I. has developed a science outreach program for grade schools using acoustic behavior as a mechanism for teaching children about mathematical concepts such as rate (events per unit time). Mating songs have mathematical components imbedded within them (such as rate), and children are very excited to experience these components as animals do in nature, and are eager to participate in acoustic games. We have built a "sound tunnel" and children play a game whereby they enter the tunnel and listen to cricket songs of different rates, and must choose either the faster or slower song. We vary the level of difficulty of the acoustic task in order to challenge the children in their mathematical discrimination. Accompanying this game, we make an age-appropriate presentation about how animals "talk" to each other in a variety of sensory modalities, allowing us to discuss concepts of species diversity, animal behavior and communication.
