Reduced rates of genetic recombination are often associated with reduced genetic variability and levels of adaptation. Several different evolutionary processes, collectively known as Hill-Robertson (HR) effects, have been proposed as causes of these correlates of recombination. Here, we use DNA sequence polymorphism and divergence data from the non-crossing over dot chromosome of Drosophila to discriminate between two of the major forms of HR effects: selective sweeps and background selection. This chromosome shows reduced levels of silent variability and reduced effectiveness of selection. We show that neither model fits the data on variability. We propose that, in large genomic regions with restricted recombination, HR effects among non-synonymous mutations undermine the effective strength of selection, so that their background selection effects are weakened. This modified model fits the data on variability, and also explains why variability in very large non-recombining genomes is not completely wiped out. We also show that HR effects of this type can produce an individual selection advantage to recombination.
|Title of host publication||Cold Spring Harbor Symp. Quant. Biol.|
|Place of Publication||Cold Spring Harbor, New York, USA|
|Publisher||Cold Spring Harbor Laboratory Press|
|Number of pages||5|
|Publication status||Published - 1 Jan 2010|