Genomics analysis ofDrosophila sechelliaresponse toMorinda citrifoliafruit diet

Abstract

Drosophila sechellia is an island endemic host specialist that has evolved to consume the toxic fruit of Morinda citrifolia, also known as noni fruit. Recent studies by our group and others have examined genome-wide gene expression responses of fruit flies to individual highly abundant compounds found in noni responsible for the fruit’s unique chemistry and toxicity. In order to relate these reductionist experiments to the gene expression responses to feeding on noni fruit itself, we fed rotten noni fruit to adult female D. sechellia and performed RNA-sequencing. Combining the reductionist and more wholistic approaches, we have identified candidate genes that may contribute to each individual compound and those that play a more general role in response to the fruit as a whole. Using the compound specific and general responses, we used transcription factor prediction analyses to identify the regulatory networks and specific regulators involved in the responses to each compound and the fruit itself. The identified genes and regulators represent the possible genetic mechanisms and biochemical pathways that contribute to toxin resistance and noni specialization in D. sechellia.

Placing human gene families into their evolutionary context

“…, relative to rates of neutral synonymous substitutions) and would likely correspond to an environmental chemical signal or signals relevant to fitness. Evidence for adaptation is prevalent in Drosophila , where behavioral and biochemical assays have repeatedly demonstrated specialization of odorant genes in Drosophila species to ligands of host fruits (e.g., Drosophila sechellia and the host shift to morinda fruit) [ 169 – 173 ]. However, outside of model organisms, interpretations of correlative patterns have emerged but are still inconclusive.…”