Molecular Phylogenetics and Host Transfer Among Genera and Species in the Leafhopper Tribe Deltocephalini

9306436黑叶蝉是一种通过穿刺和吸吮口器从植物中吸取营养物质的昆虫。叶蝉出现在各种各样的树木、灌木、草本植物和草上，并能传播一些重要的植物疾病。人们认为，叶蝉物种是通过寄主植物专门化的变化而产生的。以几种密切相关的植物为食的物种可能会专门以一种植物为食，或者以一种植物为食的叶蝉可能会扩大其活动范围。寄主植物专门化的转变被认为发生在Deltocephalini部落的叶蝉中。这个部落中的一些属在世界范围内分布，出现在乔木和灌木上，或在木本和草本植物之间交替生长。其他属主要与草本植物有关。一种主要生活在北美洲、中美洲和南美洲的草地上。从这些物种中产生了一个几乎完全局限于北美和墨西哥草类的种群。这表明，从广泛分布在许多木本和草本植物科上的物种到只发生在草上的北美和墨西哥物种的发展。寄主植物转移在叶蝉物种起源中的重要性尚不清楚，因为叶蝉只有少数形态特征可以用来区分物种和确定它们之间的遗传关系。该项目的研究将利用DNA序列来估计叶蝉物种之间的遗传关系。目标是为叶蝉发展一个客观的系统发育，以检验新物种通过宿主转移和特化而产生的假设。叶蝉是一种具有重要经济意义的昆虫，因为其中一些叶蝉会将植物疾病传播给作物、树木、灌木等。更好地了解这些昆虫之间的关系将有助于解释宿主植物关联的变化，这可能对疾病控制有潜在的影响。该项目的结果也将作为其他昆虫类群的一般模型，其中寄主植物转移和专门化被怀疑。* * *

9306436 Black Leafhoppers are insects that extract nutrients from plants through piercing and sucking mouthparts. Leafhoppers occur on a wide variety of trees, shrubs, herbaceous plants and grasses and can transmit a number of important plant diseases. It is believed that leafhopper species arose through changes in host plant specialization. A species that feeds on several closely related plant species may have come to specialize on one or a leafhopper that fed on one plant species may have broadened its range. Shifts in host plant specialization are believed to have occurred among leafhoppers in the tribe Deltocephalini. Some genera in this tribe have a worldwide distribution and occur on trees and shrubs or alternate between woody and herbaceous plants. Other genera are largely associated with herbaceous plants. One group inhabits primarily grasses in North, Central and South America. From these arose a group that are almost entirely limited to grasses in North America and Mexico. This suggests a progression from widely distributed species that occur on many families of woody and herbaceous plants towards North American and Mexican species that occur exclusively on grasses. The importance of host plant transfer in the origin of leafhopper species is poorly understood because leafhoppers have only a few morphological characters that can be used to separate species and determine the genetic relationships among them. The research of this project will use DNA sequences to estimate genetic relationships among leafhopper species. The goal is to develop an objective phylogeny for leafhoppers that will test the hypothesis that new species arise through host transfer and specialization. %%% The leafhoppers are a group of insects that have economic importance because several members transmit plant diseases to crops, trees, shrubs, etc.. Developing a better understanding of relationships among these insects will serve to explain changes in host pl ant associations which may have potential implications for disease control. The results of this project will also serve as a general model for other insect groups where host plant transfer and specialization is suspected. ***