The Role of Acoustic Behavioral Changes in Speciation

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Shaw 9729325 Communication signals often change quickly and can be the first to distinguish closely related species in animals. This study examines the historical relationships of populations of Laupala cerasina, a Hawaiian cricket species that shows variation in male singing behavior and female acoustic attraction, two important communication signals. Acoustic behaviors such as these mediate reproductive coordination between males and females in crickets. It is hypothesized that these changes in acoustic signals are a prerequisite to the formation of new species. Prior investigations have suggested that different geographic populations of L. cerasina differ significantly in male song and in female acoustic preference but nonetheless share a similar acoustic rank in their respective communities and are members of the same species. Preliminary data also suggests that these different geographic populations can interbreed. These observations lead to the prediction that the different geographic populations of L. cerasina are closely related. However, from previous work with mtDNA sequences, L. cerasina populations appear to be relatively distantly related. DNA sequences from additional genes will allow this contradiction to be resolved. The goal of this project is to test the hypothesis that populations of L. cerasina are closely related as predicted by the taxonomy, and that changing acoustic signals indicate that new species are in the process of forming. To address this question, nuclear DNA sequences will be collected from one gene from each of 10 populations of L. cerasina and several closely related species. This will ascertain whether the different geographic populations of L. cerasina exhibiting a similar acoustic rank in their respective communities represent products of a common history or a striking example of similarity by other processes. A better understanding of the striking diversity of form, behavior and function in the biological world is vital for projecting the importance of that diversity in stable ecosystems, conservation efforts and human welfare. Tremendous strides have been made toward an understanding of developmental and behavioral diversity in animals and plants. But how does the process begin? We know relatively little about how and why new species arise. The efficacy of communication signaling in animal courtship is a prerequisite to the continued flow of genes within and between populations. The hypothesis that changes in communication signals occur rapidly is gaining support; such changes may provide the early catalyst for the remarkable diversification that follows. Recovering a system where communication signals are actively changing is rare, perhaps because this process occurs so rapidly. Establishing the historical relationships among the component populations that differ in communication signals (such as Laupala cerasina) is a critical first step.