The X chromosome is a hot spot for sexually antagonistic fitness variation

Proc Biol Sci. 2002 Mar 7;269(1490):499-505. doi: 10.1098/rspb.2001.1863.


Sexually antagonistic alleles are selected discordantly between the sexes. Experimental evidence indicates that sexually antagonistic fitness variation is abundant in the genome of Drosophila melanogaster. Theory predicts that the X chromosome will be enriched with this type of variation. To test this prediction in D. melanogaster, we sampled, and cytogenetically cloned, 20 X chromosomes and compared their fitness variation to genome-wide levels. At the juvenile stage, in which gender roles are most similar, the X chromosome made no detectable contribution to genome-wide fitness variation. At the adult stage, in which gender roles diverge, the X chromosome was estimated to harbour 45% of the genome-wide fitness variation and 97% of the genome-wide sexually antagonistic variation. This genomic structure has important implications for the process of sexual selection because X-linked sexually antagonistic variation contributes to negative intersexual heritability for fitness, i.e. high-fitness males (females) produce, on average, low-fitness daughters (sons).

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alleles
  • Animals
  • Biological Evolution*
  • Drosophila melanogaster / genetics*
  • Genetic Linkage / genetics*
  • Genetic Variation / genetics*
  • Genotype
  • Polymorphism, Genetic / genetics
  • Reproduction / genetics
  • Selection, Genetic
  • Sex Characteristics*
  • X Chromosome / genetics*