Quantitative Genetic Mapping of Life History Traits in Drosophila melanogaster

Abstract

While it has long been established that populations of animals harbor substantial natural genetic variation for life history traits, an understanding of the location, effect, and frequency of naturally occurring alleles has been elusive. This study uses the elite model system Drosophila melanogaster to perform quantitative genetic mapping on two important life history traits: the morphology of the posterior lobe of the genital arch and the length of time flies resist death due to starvation stress. Experiments on the posterior lobe identify multiple quantitative trait loci (QTL) that influence its shape and reveal a small number of strong candidate genes for future study. Studying starvation stress we identify many small effect QTL that generally act in a sex-specific manner. Using a series of crosses we both identify many new cross-specific QTL while replicating all QTL originally identified among inbred lines in outbred genetic backgrounds. These results indicate that inbreeding depression is likely not playing a major role in genetic mapping results obtained with inbred animals. These studies identify an exceedingly complex genetic architecture for starvation stress resistance in Drosophila that may include additive, dominant, and epistatic alleles acting to influence this important life history trait.