Standard Article

Evolution of X-Linked Male-Biased Genes in Drosophila

  1. Danielle K Herrig,
  2. Ana Llopart

Published Online: 15 JUL 2014

DOI: 10.1002/9780470015902.a0025537



How to Cite

Herrig, D. K. and Llopart, A. 2014. Evolution of X-Linked Male-Biased Genes in Drosophila. eLS. .

Author Information

  1. University of Iowa, Iowa City, Iowa, USA

Publication History

  1. Published Online: 15 JUL 2014


Sex chromosomes, particularly the X chromosome, play a unique role in evolution due to several distinct features. In Drosophila, the X chromosome has been proposed to constitute an undesirable environment for genes expressed at higher levels in males than in females (i.e. male-biased genes) and, as a result, is partially demasculinized. However, male-biased genes remaining on the X chromosome do not seem to be at a disadvantage relative to their autosomal counterparts. Population genetic models predict that under certain conditions X-linked genes will experience more bouts of positive selection than autosomal genes, leading to faster-X evolution, particularly for male-biased genes. As theory posits, Drosophila X-linked male-biased genes show evidence of adaptive evolution at both protein and expression levels. This faster-X evolution has broad implications. In speciation, it may contribute to explain why the X chromosome is a hotspot for the genetic factors underlying hybrid male sterility (i.e. the large X-effect).

Key Concepts:

  • Underrepresentation of X-linked male-biased genes due to unfavorable features of the X chromosome.

  • Faster-X evolution of male-biased genes at both the protein and expression levels.

  • Consequences of faster-X evolution include the disproportionally large effect of the X chromosome in hybrid male sterility.


  • X chromosome;
  • sexual antagonism;
  • meiotic sex chromosome inactivation;
  • dosage compensation;
  • faster-X;
  • gene expression;
  • large X-effect;
  • speciation;
  • adaptive evolution;
  • positive selection