Human Population Genetics英文电子书.pdf

Human population genetics • Rough outline of human evolution • What makes us human? • Variation in modern humans • Relevance to human health Relationship to other primates Our closest living relative appears to be the chimpanzees. . . Pan troglodytes (chimpanzee) Pan paniscus (bonobo) Humans, chimps, and gorillas Chen Li1 sequenced 53 regions randomly chosen short regions from humans, chimps, and gorillas. They then estimated 53 phylogenetic trees. . . H C G H G C C G H 31 10 12 1Am. J. Hum. Genet. 2001 Gene trees and species trees If species are separated by enough time for gene lineages to “coalesce” within species, then gene trees will reflect species trees. Coalescence times within species depend on pop- ulation sizes, geographic structure, etc. Gene trees and species trees If species are not sepa- rated by enough time for gene lineages to “coalesce” within species, then gene trees will often not reflect species trees. The human-chimp split is borderline: coalescence times within the species seem to lie between 0.5 and 1 Myr; the species may only be sep- arated by 4–5 Myr. A B C Perspective on polymorphism • two human genomes differ from each other about once every 1,000 base pairs • chimps differ from each other once every 200 base pairs • fruit flies differ from each other once every 100 base pairs • Californian intertidal copepods (Suzanne Edmands) may differ from each other every 10 bp • a human and a chimp genome differ from