Conservation of social effects (Ψ) between two species of Drosophila despite reversal of sexual dimorphism

Abstract

Indirect genetic effects (IGEs) describe the effect of the genes of social partners on the phenotype of a focal individual. Here, we measure indirect genetic effects using the “coefficient of interaction” (Ψ) to test whether Ψ evolved between Drosophila melanogaster and D. simulans. We compare Ψ for locomotion between ethanol and nonethanol environments in both species, but only D. melanogaster utilizes ethanol ecologically. We find that while sexual dimorphism for locomotion has been reversed in D. simulans, there has been no evolution of social effects between these two species. What did evolve was the interaction between genotype‐specific Ψ and the environment, as D. melanogaster varies unpredictably between environments and D. simulans does not. In this system, this suggests evolutionary lability of sexual dimorphism but a conservation of social effects, which brings forth interesting questions about the role of the social environment in sexual selection.

Dynamic changes in gene expression and alternative splicing mediate the response to acute alcohol exposure in Drosophila melanogaster

“…There are also many differences in the amount of time that Drosophila were exposed to ethanol, and at what concentration, for example in most inebriometer studies the mean time to elution of the flies (when they fall through the contraption and can no longer right themselves) is 6 min. In our assays the flies were still active at 30 min, suggesting a lower dose of ethanol (Signor et al 2017a(Signor et al , 2017b. As many of the targets of these studies will have been partial transcripts, it is possible that many of the detected changes included differences in splicing.…”

“…Lastly, the effect of ethanol may be mediated by its high nutritional value, as many genes which respond to ethanol also have metabolic roles. This latter interpretation is unlikely as we have not observed males engaged in extensive feeding in our behavioral observations of these experiments (Signor et al 2017a(Signor et al , 2017b.…”

“…2a). Control flies were exposed to the same experimental setup, but the food was made entirely with water rather than 15% ethanol, as described in (Signor et al 2017a(Signor et al , 2017b. In general, more than three replicates of each experiment were needed to produce enough material for an RNA library, and these were combined randomly to create three biological replicates for each genotype and six treatment/control types.…”

“…Within each chamber a female fly was included as stimulus, but not as a part of the collections for RNA-seq (Signor et al 2017a(Signor et al , 2017b). The female genotype was an inbred laboratory strain y 1 w 1 (Bloomington stock number 1495).…”

Evolution of Plasticity in Response to Ethanol between Sister Species with Different Ecological Histories (Drosophila melanogasterandD. simulans)

“…Six genotypes were used in these experiments. The genotypes used for male flies from D. simulans were collected from the Zuma Organic Orchard in Zuma Beach, CA in the winter of 2012 and made nearly isogenic by 15 generations of full sib inbreeding [58,59]. In natural conditions flies will not by homozygous at all loci, thus each inbred genotype was crossed to a white eyed 'tester' strain to create the F1 flies used in the ethanol exposure assays (D. simulans, w 501 , Cornell species stock number 14021-0251.011).…”