bio phylogeny (main idea 3)

what do molecular clocks help?

track evolutionary time

what does a molecular clock use?

constant rates of evolution genes to estimate the absolute time of evolutionary change

the number of changes in related genes is assumed to be..

proportional to the time since they last shared.a common ancestor

molecular clocks are set by:

plotting the number of genetic changes against the dates of branch points known from the fossil record

what are some potential problems with molecular clock?

— not always accurate if mutations were selectively neutral (no effect) or strongly favored by natural selection

— estimates of evolutionary divergences older than the dossil record have a higher degree of uncertainty

— the use of multiple genes may improve estimates