Genomic evidence for a large-Z effect
2009 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 276, no 1655, 361-366 p.Article in journal (Refereed) Published
The 'large-X effect' suggests that sex chromosomes play a disproportionate role in adaptive evolution. Theoretical work indicates that this effect may be most pronounced in genetic systems with female heterogamety under both good-genes and Fisher's runaway models of sexual selection (males ZZ, females ZW). Here, I use a comparative genomic approach (alignments of several thousands of chicken-zebra finch-human-mouse-opossum orthologues) to show that avian Z-linked genes are highly overrepresented among those bird-mammalian orthologues that show evidence of accelerated rate of functional evolution in birds relative to mammals; the data suggest a twofold excess of such genes on the Z chromosome. A reciprocal analysis of genes accelerated in mammals found no evidence for an excess of X-linkage. This would be compatible with theoretical expectations for differential selection on sex-linked genes under male and female heterogamety, although the power in this case was not sufficient to statistically show that 'large-Z' was more pronounced than 'large-X'. Accelerated Z-linked genes include a variety of functional categories and are characterized by higher non-synonymous to synonymous substitution rate ratios than both accelerated autosomal and non-accelerated genes. This points at a genomic 'large-Z effect', which is widespread and of general significance for adaptive divergence in birds.
Place, publisher, year, edition, pages
2009. Vol. 276, no 1655, 361-366 p.
large-Z, adaptive evolution, sex chromosomes
IdentifiersURN: urn:nbn:se:uu:diva-129268DOI: 10.1098/rspb.2008.1135ISI: 000262005200022OAI: oai:DiVA.org:uu-129268DiVA: diva2:338150