Plant Hybrid Zones as Focal Points of Insect Biodiversity and Bridges for Host Shifting

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Little is know about how hybrid plants and zones affect herbivore distributions and evolution. Studies of insects on cottonwoods by these investigators demonstrated that hybrids should no longer be treated as anomalies and that fundamentally important interactions occur in these zones of unparalleled genetic variability. The proposed work will continue these studies to address 3 major hypotheses that have far reaching implications for understanding plant-herbivore interactions. First, are natural plant hybrid zones focal points of insects biodiversity? If true the loss of these zones may results in the extinction of many insect species. Because the Endangered Species Act of 1973 does not protect hybrid plants, studies of this issue are important from both basic and applied perspectives. Second, do natural plant hybrid zones act as bridges that facilitate insect and pathogen host shifting? Hybrid intermediates may be used by insects as stepping stones to gradually shift from one plant species to another. If true, this process would represent a fundamentally new view of how insects and pathogens host shift. Third, does the presence of susceptible hybrids affect insect evolution and perhaps even prevent them from becoming adapted to resistant host plants? Here the investigators will examine the implications of mixed resistance and susceptibility in plant populations as it might affect insect evolution. This question has important implications for understanding insect distributions and could affect insect management practices. This research will provide an important contribution to the overall understanding of hybrid zones, potentially extremely important habitats in the evolution and ecology of plants herbivores insects.