Abstract
Sexual antagonism, or conflict, can occur when males and females harbor opposing reproductive strategies. The large fraction of sex-biased genes in genomes present considerable opportunities for conflict to occur, suggesting that sexual antagonism may potentially be a general phenomenon at the molecular level. Here, we employ a novel strategy to identify potential nodes of sexual conflict in Drosophila melanogaster by coupling male, female, and sex-unbiased networks derived from genome-wide expression data with available genetic and protein interaction data. We find that sex-biased networks comprise a large fraction (~1/3) of the total interaction network with the male network possessing nearly twice the number of nodes (genes) relative to the female network. However, there are far less edges or interaction partners among male relative to female subnetworks as seen in their power law distributions. We further identified 598 sex-unbiased genes that can act as indirect nodes of interlocus sexual conflict as well as 271 direct nodal pairs of potential conflict between male- and female-biased genes. The pervasiveness of such potentially conflicting nodes may explain the rapid evolution of sex-biased as well as non-sex-biased genes via this molecular mechanism of sexual selection even among taxa such as Drosophila that are nominally sexually dimorphic.
Highlights
E cooccurrence of distinct morphs—male and female—in sexually reproducing taxa continues to fascinate and perplex developmental and evolutionary biologists alike
Recent genome-wide analyses have demonstrated that sexual dimorphism is prevalent at the level of the genome with the majority of genes expressing a male- or female-bias across a range of developmental stages [3,4,5,6,7]. is emerging molecular view reveals that a large fraction of the genome can be expressed in either male or female states
A gene that is expressed in males may provide an important and critical role in his reproductive success while the same gene, when expressed in females, may impart a important but different role in her survival. us, tness effects from the same locus, under different context-dependent states, may be in con ict. is particular type of antagonism, in which a single gene is expressed differently depending on the sex, has been termed, intralocus sexual con ict
Summary
E cooccurrence of distinct morphs—male and female—in sexually reproducing taxa continues to fascinate and perplex developmental and evolutionary biologists alike. E extent of interlocus sexual con ict across a genome largely depends on how extensive is the linkage between male- and female-speci c gene networks. We generate male and female networks using transcriptome and interactome data from D. melanogaster to characterize network differences among male-, female-biased, and sex-unbiased genes so that we can identify potential nodes of interlocus sexual con ict, across the genome. We describe and characterize two types of sexual con ict at the molecular level: (1) indirect con ict, which refers to sex-unbiased genes that interact with both male and female genes, and (2) direct con ict, which refers to male and female nodes that directly interact with each other. Our ndings provide a rst step in understanding antagonistic con ict at the molecular level, genome-wide
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