Evolutionary genetics of a cosmopolitan generalist herbivore

为了抵抗动物食草动物的放牧，植物使用大量的防御措施，包括产生有毒化合物。反过来，食草动物利用不同的策略来克服这些植物防御。由于食草动物对自然植物群落有着深远的影响，并且是农业作物损失的主要来源之一，因此了解食草动物如何适应以植物宿主为食的遗传基础和策略具有生态和农业意义。本研究的目的是描述两点叶螨草食动物和不同的植物宿主之间的相互作用的遗传基础。这种螨是众所周知的多面手食草动物，这意味着它可以以许多植物物种为食，包括100多种农作物。这项研究将进一步加深我们的理解，在何种程度上给定的菌株的通才草食动物可以坚持同样好的不同植物宿主，或者也可以专门为更具体的植物物种的子集。此外，这项研究将描述哪些基因和等位基因，包括那些影响基因表达调控变化的基因和等位基因，对这种通才食草动物的生活史很重要。研究成果将包括对影响与人类福祉相关的通才食草动物遗传变异的力量的具体见解，这项工作将更广泛地为旨在阐明适应不断变化的环境的遗传基础的各种生物体的研究提供信息。本研究还将培训K-12、本科生和研究生。为了完成研究目标，将收集来自不同地理位置和宿主植物的螨株。使用高通量DNA测序，随后将确定菌株的基因组以描述遗传变异。然后将评估与例如植物毒素代谢相关的基因的选择的分子特征。作为对这些DNA变异研究的补充，还将进行高通量转录组测序，以评估这些基因调控的变异在不同宿主上建立的可能性。最后，将进行遗传杂交，然后对在不同植物宿主上选择的种群进行测序，以确定宿主植物适应的特定基因和等位基因。

To counteract grazing by animal herbivores, plants use a large array of defenses that include the production of toxic compounds. In turn, herbivores exploit diverse strategies to overcome these plant defenses. As herbivores have profound impacts on natural plant communities, and are one of the major sources of crop loss in agriculture, understanding the genetic basis and strategies for how herbivores adapt to feed on plant hosts is of ecological and agricultural relevance. The objective of this research is to characterize the genetic underpinnings of the interaction between the two-spotted spider mite herbivore and different plant hosts. This mite species is well known as a generalist herbivore, meaning that it can feed on many plant species, including more than a hundred crop plants. The research will further our understanding of the extent to which given strains of generalist herbivores can persist equally well on diverse plant hosts, or alternatively may be specialized to more specific subsets of plant species. Furthermore, the research will characterize which genes and alleles, including ones that impact variation in gene expression regulation, are important for the life history of this generalist herbivore. Outcomes of the research will include specific insights into forces shaping genetic variation in generalist herbivores relevant to human welfare, and the work will more broadly inform studies in diverse organisms that aim to elucidate the genetic basis of adaptation to changing environments. The research will also train K-12, undergraduate, and graduate students.To accomplish the research objectives, mite strains from diverse geographical locations and host plants will be collected. Using high-throughput DNA sequencing, the genomes of the strains will subsequently be determined to describe genetic variation. Molecular signatures of selection will then be assessed for genes associated with, for example, the metabolism of plant toxins. Complementing these studies of DNA variation, high-throughput transcriptome sequencing will also be performed to assess the possibility that variation in the regulation of these genes underlies establishment on different hosts. Finally, genetic crosses, followed by sequencing of resulting populations selected on different plant hosts, will be carried out to identify specific genes and alleles underlying host-plant adaptation.