Molecular Mechanisms and Evolutionary Processes Contributing to Accelerated Divergence of Gene Expression on the Drosophila X Chromosome
Year: 2015
Type: article
Abstract: In species with a heterogametic sex, population genetics theory predicts that DNA sequences on the X chromosome can evolve faster than comparable sequences on autosomes. Both neutral and nonneutral evolutionary processes can generate this pattern. Complex traits like gene expression are not predicted to have accelerated evolution by these theories, yet a "faster-X" pattern of gene expression divergence has recently been reported for both Drosophila and mammals. Here, we test the hypothesis that accelerated adaptive evolution of cis-regulatory sequences on the X chromosome is responsible for this pattern by comparing the relative contributions of cis- and trans-regulatory changes to patterns of faster-X expression divergence observed between strains and species of Drosophila with a range of divergence times. We find support for this hypothesis, especially among male-biased genes, when comparing different species. However, we also find evidence that trans-regulatory differences contribute to a faster-X pattern of expression divergence both within and between species. This contribution is surprising because trans-acting regulators of X-linked genes are generally assumed to be randomly distributed throughout the genome. We found, however, that X-linked transcription factors appear to preferentially regulate expression of X-linked genes, providing a potential mechanistic explanation for this result. The contribution of trans-regulatory variation to faster-X expression divergence was larger within than between species, suggesting that it is more likely to result from neutral processes than positive selection. These data show how accelerated evolution of both coding and noncoding sequences on the X chromosome can lead to accelerated expression divergence on the X chromosome relative to autosomes.
Source: Molecular Biology and Evolution
Institutions: University of Michigan, Carnegie Mellon University, UConn Health
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: bronze
Awards: Evolution of Gene Expression in Yeast, Using next-generation sequencing to understand the evolution of gene regulation, The Evolution of Gene Expression: Molecular Mechanisms and Inheritance Patterns Revealed on a Genomic Scale With Next-Generation Sequencing, Trans-Splicing in Drosophila, IGERT: Open Data: Graduate Training for Data Sharing and Reuse in E-Science
OpenAlex ID: W2099485194