Genetic basis of thermal plasticity variation in Drosophila melanogaster body size.

Elvira Lafuente,David Duneau,Patrícia Beldade,Gregory P Copenhaver

doi:10.1371/journal.pgen.1007686

Abstract

Body size is a quantitative trait that is closely associated to fitness and under the control of both genetic and environmental factors. While developmental plasticity for this and other traits is heritable and under selection, little is known about the genetic basis for variation in plasticity that can provide the raw material for its evolution. We quantified genetic variation for body size plasticity in Drosophila melanogaster by measuring thorax and abdomen length of females reared at two temperatures from a panel representing naturally segregating alleles, the Drosophila Genetic Reference Panel (DGRP). We found variation between genotypes for the levels and direction of thermal plasticity in size of both body parts. We then used a Genome-Wide Association Study (GWAS) approach to unravel the genetic basis of inter-genotype variation in body size plasticity, and used different approaches to validate selected QTLs and to explore potential pleiotropic effects. We found mostly “private QTLs”, with little overlap between the candidate loci underlying variation in plasticity for thorax versus abdomen size, for different properties of the plastic response, and for size versus size plasticity. We also found that the putative functions of plasticity QTLs were diverse and that alleles for higher plasticity were found at lower frequencies in the target population. Importantly, a number of our plasticity QTLs have been targets of selection in other populations. Our data sheds light onto the genetic basis of inter-genotype variation in size plasticity that is necessary for its evolution.

Highlights

Body size has a great impact on the performance of individuals [1, 2], as well as that of species [3]
Using a panel of D. melanogaster flies representing naturally segregating alleles, we identified DNA sequence variants associated to variation in thermal plasticity for body size
We used a Genome-Wide Association Study (GWAS) approach to identify DNA sequence polymorphisms associated with variation in body size plasticity (Fig 3)

Summary

Introduction

Body size has a great impact on the performance of individuals [1, 2], as well as that of species [3]. Body size is a prime example of the environmental regulation of development, or developmental plasticity [19, 20], and it is influenced by different factors, including nutrition and temperature This plasticity can help organisms cope with environmental heterogeneity and, as such, can have major implications for population persistence and adaptation [20,21,22]. The environmental dependency of body size, and other plastic traits, is often studied using reaction norms, in which phenotypic variation is plotted as a function of gradation in the environment [27] The properties of these reaction norms, including their shapes and slopes, can differ between genotypes [28,29,30], and the genes underlying such variation can fuel the evolution of plasticity. It is unclear to what extent the loci contributing to variation in thermal plasticity in size are the same for different body parts, and whether the loci contributing to variation in size plasticity are the same that underlie inter-individual variation in body size at a given temperature

Methods

Results

Discussion

Conclusion