Variation In Speciation Time For Different Parts Of The Genome?

After alignment of thousands of genes across vertebrate genomes, we use the number of substitutions to estimate the relative time back to a common ancestor for different parts of the genome.

The expected variation between loci will be affected by the ancestral population size; hence it is possible to use the data to estimate the ancestral population size. For the human chimp ancestor, the average ancestral coalescence time is of the same order as the time back to human-chimp speciation; we ask if that estimate is plausible.

Estimates for individual chromosomes vary much more than would be predicted. Did some chromosomes undergo earlier speciation than the rest of the genome? We argue that this pattern is better explained by the effects of gene conversion among members of multi-gene families.