Expression profiles of Drosophila melanogaster males with DX mothers and X-chromosomes that were subjected to male-limited evolution

Intralocus sexual conflict, where males and females have different fitness optima for the same trait, has been suggested to potentially be resolved by genomic imprinting, whereby expression in offspring is altered according to parent-of-origin. However, this idea has not yet been empirically tested. Here, we designed an experimental evolution protocol in Drosophila melanogaster which enabled us to look for imprinting effects on the X-chromosome. We enforced father-to-son transmission of the X-chromosome for many generations, and compared fitness and gene expression levels between control males, males with a control X-chromosome that had undergone one generation of father-son transmission (CDX), and males with an X-chromosome that had undergone many generations of father-son transmission (MLX). Although fitness differences were consistent with lowered fitness of males with a paternally inherited X-chromosome, expression differences suggested that this was due to deleterious maternal effects rather than imprinting. We conclude that imprinting is unlikely to resolve intralocus sexual conflict in Drosophila melanogaster.

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Abbott JK, Innocenti P, Chippindale AK, Morrow EH