Genetic Analysis and Life History Consequences of Variation in Larval Behavior in Cactophilic Drosophila

生物学中的一些最基本的问题与理解物种形成有关。物种形成的一个强大推动力是对种群所处的当地环境的适应，这可能导致基因库分裂。如果生活在不同环境中的同一物种的两个种群适应当地的生态条件，两个种群之间的后代可能也不会存活，最终减少种群之间的遗传信息交换。正是这种遗传隔离的形成可能导致种群变成不同的物种。本研究以生活在不同环境中、使用不同仙人掌种类、具有不同幼虫行为的两个仙人掌繁殖蝇种群为研究对象。在一个种群中，幼虫以小的仙人掌垫(刺梨)为食，活动不多，而另一个种群的幼虫以较大的仙人掌(风琴管)为食，活动更多、更快。利用果蝇丰富的遗传“工具箱”，这项研究将确定导致这些差异的基因，并确定基因水平的变化如何导致不同的行为和种群隔离。这项研究的信息将通过出版物和演示文稿与科学界共享。研究人员将通过行为遗传学研究指导学生，并将在以研究为重点的大学课程中使用资助的技术。研究人员还将与当地高中合作，让学生接触大学层面的研究。了解另类幼虫行为的进化和潜在遗传学可能有助于阐明适应当地生态条件如何导致种群、物种形成的差异，以及基因类型如何导致行为表型。生态适应对行为策略的变化有显著影响。在腐生和植食性昆虫中，寄主的性质已经被证明对基因组、代谢组学、生理、生活史和行为变异有很大的影响。正是这种不同的、生态驱动的对宿主特性的适应可以推动宿主种群之间生殖不亲和性的进化，并导致物种的形成。这项研究将集中在嗜食果蝇幼虫活动的变化及其潜在的遗传控制。不同的种群有不同的营养和化学成分的仙人掌寄主，这与不同的幼虫行为有关。这项研究将检验不同行为的生理和生活史后果，并将其与不同仙人掌寄主种群之间的转录和基因组变化联系起来。数量性状基因座分析将检验幼虫行为的遗传基础。CRISPR-Cas9基因敲除和转基因将被产生，以量化候选行为QTL在生态环境中的功能作用，并检查这些基因座变异的生活史后果，并提供从基因型到表型水平的强有力的检查。

Some of the most fundamental questions in biology pertain to understanding speciation. A strong driving force in speciation is adaptation to the local environment a population resides in, which can lead to splitting gene pools apart. If two populations of the same species living in distinct environments are adapted to their local ecological conditions, offspring between the two populations may not survive as well and ultimately reduce the exchange of genetic information between populations. It is the formation of this genetic isolation that can lead populations to become different species. This study focuses on two populations of a cactus-breeding fly, Drosophila mojavensis, which live in different environments, use different cactus species, and have distinct larval behaviors. In one population the larvae feed on small cactus pads (prickly pear) and don't move much, while the other population feeds on larger cactus (organpipe) and move more and faster. Capitalizing on the rich genetic 'toolkit' for Drosophila this study will identify the genes responsible for these differences and determine how changes at the gene level can lead to different behaviors and population isolation. Information from this research will be shared with the science community through publications and presentations. The investigator will mentor students through research in behavioral genetics and will use the funded techniques in research-focused college courses. Also the investigator will partner with local high schools to expose students to research at the university level.Understanding the evolution and underlying genetics of alternative larval behaviors could be instrumental in elucidating how adaptation to local ecological conditions can lead to the divergence of populations, speciation, and how genotypes lead to behavioral phenotypes. Ecological adaptation has a significant influence on the variation seen in behavioral strategies. In saprophytic and phytophagous insects the properties of the plant host have been shown to greatly influence the pattern of genomic, metabolomics, physiological, life history and behavioral variation. It is this divergent, ecologically-driven adaptation to a host's properties that can drive the evolution of reproductive incompatibilities between host populations and lead to the formation of species. This study will focus on the variation of larval activity, and its underlying genetic control, of the cactophilic Drosophila mojavensis. Distinct populations of D. mojavensis have nutritionally and chemically distinct cactus hosts, which are associated with different larval behaviors. The study will examine the physiology and life history consequence of the distinct behaviors and link it to the transcriptional and genomic changes between the distinct cactus host populations of D. mojavensis. A quantitative trait loci analysis will examine the genetic underpinnings of larval behavior. CRISPR-Cas9 knockouts and transgenics will be generated to quantify the functional role of the candidate behavior QTLs in an ecological context and examine the life history consequences of variation at these loci and provide a strong examination of genotype to phenotype level questions.