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

University Of Alabama In Huntsville, Huntsville AL

Investigators

Abstract

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.