Condition-dependence of the sexually dimorphic transcriptome in Drosophila melanogaster.
Sexually dimorphic traits are by definition exaggerated in one sex, which may arise from a history of sex-specific selection-in males, females, or both. If this exaggeration comes at a cost, exaggeration is expected to be greater in higher condition individuals (condition-dependent). Although studies using small numbers of morphological traits are generally supportive, this prediction has not been examined at a larger scale. We test this prediction across the transcriptome by determining the condition-dependence of sex-biased (dimorphic) gene expression. We find that high-condition populations are more sexually dimorphic in transcription than low-condition populations. High-condition populations have more male-biased genes and more female-biased genes, and a greater degree of sexually dimorphic expression in these genes. Also, condition-dependence in male-biased genes was greater than in a set of unbiased genes. Interestingly, male-biased genes expressed in the testes were not more condition-dependent than those in the soma. By contrast, increased female-biased expression under high condition may have occurred because of the greater contribution of the ovary-specific transcripts to the entire mRNA pool. We did not find any genomic signatures distinguishing the condition-dependent sex-biased genes. The degree of condition-dependent sexual dimorphism (CDSD) did not differ between the autosomes and the X chromosome. There was only weak evidence that rates of evolution correlated with CDSD. We suggest that the sensitivity of both female-biased genes and male-biased genes to condition may be akin to the overall heightened sensitivity to condition that life-history and sexually selected traits tend to exhibit. Our results demonstrate that through condition-dependence, early life experience has dramatic effects on sexual dimorphism in the adult transcriptome.
Wyman
Minyoung J
MJ
Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada. minyoung.yi@utoronto.ca
Agrawal
Aneil F
AF
Rowe
Locke
L
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D010053:Ovary / Q000378:metabolism; D012727:Sex Characteristics; D013737:Testis / Q000378:metabolism