Institution: | aConway Institute, University College Dublin, Belfield, Dublin 4, Ireland bWellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK, CB10 1SA cBox 357730, Department of Genome Sciences, University Washington School of Medicine, Seattle, WA 98145, USA dFaculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, UK, M13 9PT ePlant Genome Mapping Laboratory, University of Georgia, 111 Riverbend Road Rm 228, Athens, GA 30602, USA fCold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA |
Abstract: | In eukaryotes, chromosomal rearrangements, such as inversions, translocations and duplications, are common and range from part of a gene to hundreds of genes. Lineage-specific patterns are also seen: translocations are rare in dipteran flies, and angiosperm genomes seem prone to polyploidization. In most eukaryotes, there is a strong association between rearrangement breakpoints and repeat sequences. Current data suggest that some repeats promoted rearrangements via non-allelic homologous recombination, for others the association might not be causal but reflects the instability of particular genomic regions. Rearrangement polymorphisms in eukaryotes are correlated with phenotypic differences, so are thought to confer varying fitness in different habitats. Some seem to be under positive selection because they either trap favorable allele combinations together or alter the expression of nearby genes. There is little evidence that chromosomal rearrangements cause speciation, but they probably intensify reproductive isolation between species that have formed by another route. |