Collaborative Research -- Mating Signals and Demographic Divergence: Species Comparisons and an Experimental Test

交配信号可能在物种形成的早期就出现分歧，但目前尚不清楚信号分歧是在物种形成中起直接作用，还是生态专门化等其他过程的副产品。我们的目标是确定交配信号在一组植食性昆虫多样化中的作用。跳树虫的Enchenopa binotata物种复合体由9个物种组成，它们是北美各种树木和灌木的专家。大量证据表明，这一群体的物种形成是一系列向新寄主植物转移的结果。宿主的转移改变了生命史的时间，这与高宿主保真度相结合，允许在新宿主上提高性能的特征差异。我们的研究将通过减少祖先和新寄主植物种群之间的基因流动来验证交配信号的差异在物种形成中很重要的假设。我们的项目将整合(1)对现存的9种双象鼻虫的振动交配信号进行比较研究；(2)种内、种间信号变异模式与DNA序列分化模式的比较；(3)确定信号和生活史特征是否在实验宿主转移种群中发生了分化。这项研究将为完全分化物种的交配信号与分化之间的关系，以及寄主植物种族形成早期的谱系之间的关系提供一个补充的图景。这一研究结果将增强我们对物种形成的基本认识，并可能提供实际的好处，如提高对农业害虫如何在新寄主物种上建立的理解。

Lay SummaryCocroft, Hunt and WoodMating signals can diverge early in the process of speciation, but it is unclear whether signal divergence plays a direct role in speciation or is a byproduct of other processes such as ecological specialization. Our goal is to determine the role of mating signals in the diversification of a group of plant-feeding insects. The Enchenopa binotata species complex of treehoppers consists of nine species that are specialists on various trees and shrubs in North America. Considerable evidence suggests that speciation in this group occurred as a result of a series of shifts to novel host plants. A host shift alters life history timing, which, in combination with high host fidelity, allows divergence in traits that enhance performance on a novel host. Our research will test the hypothesis that divergence in mating signals is important in speciation by reducing gene flow between populations on ancestral and novel host plants. Our project will integrate (1) a comparative study of vibrational mating signals in the nine extant Enchenopa binotata species; (2) comparison of patterns of signal variation within and among species with patterns of DNA sequence divergence; and (3) determination of whether divergence in signals and life history traits has occurred in experimentally host-shifted populations. This research will provide a complementary picture of the relationship between mating signals and divergence not only in fully differentiated species, but also in lineages in the early stages of host plant race formation. Results of this research will enhance our basic understanding of speciation, and may provide practical benefits such as an improved understanding of how agricultural pests become established on novel host species.