Life history determinants of Drosophila melanogaster
Year: 2010
Type: article
Abstract: The progression from embryo to reproductive adult to death describes the fundamental life history of an organism. From the perspective of evolutionary biology, life histories are important because they predict the fitness of an individual or a population. As such, life history components are expected to be subject to strong natural selection. One prediction from this expectation is that life history components will have reduced genetic variation relative to other types of traits. In general, this prediction is met. However, it is often the case that life history components have more genetic variation than expected from null models of genetic variation. This observation has led researchers to conclude that other forces such as genotype-environment interactions, balancing selection, tradeoffs, and so on, may act to maintain genetic variation for life history traits in the face of persistent natural selection. The goal of this dissertation is to identify some of the forces that act to maintain genetic variation in Drosophila melanogaster fecundity, a central parameter of this insect's life history. First, I have demonstrated that genetic variation in fecundity and morphological determinants of fecundity exists in natural populations. Second, I have demonstrated that one key ecological parameter, larval nutrition, affects fecundity and provide evidence to suggest that genotype-environment interactions may act to maintain genetic variation in morphological determinants of fecundity. Third, I have inferred the scale of variation in larval nutrition. Indirect evidence suggests that larval nutrition is a fine grained environmental variable; thus, selection on the plastic response to larval nutrition will be efficient. Finally, I have identified one gene underlying variation in fecundity. This gene, Drip, shows evidence that it is undergoing a selective sweep. This observation has led me to suggest that mutations increasing fitness may arise frequently. Thus, any given estimate of genetic variation in life history traits may be larger than expected because alleles affecting fitness could be segregating at relatively high frequencies while they are in the process of going to fixation.
DOI: 10.7301/z0rr1wgw
Author: Bergland, Alan Olav
Language: English
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2257750387