Mate choice and gene expression signatures associated with nutritional adaptation in the medfly (Ceratitis capitata)

Will Nash,Irina Mohorianu,Tracey Chapman

doi:10.1038/s41598-019-42610-2

Will Nash, Irina Mohorianu + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-42610-2

Copy DOI

Abstract

Evolutionary responses to nutrition are key to understanding host shifts and the resulting potential for reproductive isolation. Experimental evolution has previously been used to describe the responses of the medfly (Ceratitis capitata) to larval diets with different nutritional properties. Within 30 generations this led to divergence in larval development time, egg to adult survival and adaptation in adult body size. Here we used mRNA-seq to identify differences in gene expression patterns in these same populations, using males from the 60th generation of nutritional selection. We validated differential expression by using qRT-PCR and found that genes linked to metabolism, oxidative phosphorylation and proteolysis were significantly over-represented among the differentially expressed genes. The results provide the first genome-wide survey of the putative mechanisms underpinning evolved responses to nutritional adaptation. In addition, we tested the hypothesis that nutritional adaptation can alter mating patterns. We found evidence for assortative mating by diet at generation 60, but not 90. Hence, the pattern was variable across generations and there was no evidence overall for any isolating mating divergence between the lines. Overall, the results provide insight into the mechanisms underpinning dietary adaptation and extend our knowledge of which traits represent core responses to nutritional selection.

Highlights

Adaptation to different nutritional ecologies can underpin successful expansion into new habitats and reproductive divergence associated with host shifts with the potential to result in reproductive isolation (RI)[1,2,3]
The variation in complexities observed between replicates, derived primarily from variation in sequencing depth, suggested that a subsampling normalization would be appropriate[57,58]
We observed evolved differences in the expression patterns of genes involved in metabolism, development and oxidative phosphorylation (OXPHOS) in adult males from experimentally evolved populations subjected to divergent nutritional selection

Summary

Introduction

Adaptation to different nutritional ecologies can underpin successful expansion into new habitats and reproductive divergence associated with host shifts with the potential to result in reproductive isolation (RI)[1,2,3]. Www.nature.com/scientificreports medfly Ceratitis capitata, is an extreme generalist and exhibits wide plasticity in host selection, utilization[32,33] and oviposition[33,34]. We used mRNA sequencing (mRNA-seq) to identify the responses of protein-coding gene expression to selection under two divergent larval dietary treatments in the medfly (Ceratitis capitata), a global agricultural pest. We tested for evolved differences in gene expression and conducted separate tests for evidence of divergent mating preferences, in these same populations. DE was observed in a suite of genes involved in nutrient metabolism, oxidative phosphorylation (OXPHOS) and proteolysis These differences may underpin the previously reported divergence in developmental survival and adult body mass. Mating patterns across generations 60 and 90 were variable, providing no evidence for assortative mating by diet

Objectives

Methods

Results

Conclusion