A fine-scale comparison of the human and chimpanzee genomes: linkage, linkage disequilibrium and sequence analysis

We have performed a fine-scale comparative study of the human andchimpanzee genomes, using linkage, linkage disequilibrium and sequenceanalyses on microsatellite loci spanning a region of approximately 30 cM onhuman chromosome 4p. Our results extend the findings of previous studiesthat indicated virtually complete conservation between the human andchimpanzee genomes at the chromosomal and sub-chromosomal level and supportthe hypothesis, derived from previous analyses of mitochondrial DNA, thatchimpanzee populations are more diverse than human ones. By sequencingseveral human and chimpanzee alleles of two microsatellites we showed thatbase substitutions that diminish the length of perfect repeats (but do notchange allele sizes) are probably responsible for the low heterozygosity ofthese loci in chimpanzees; our results suggest that the evolutionaryhistory of microsatellites should not be inferred from comparisons of meanallele lengths between populations or species.