Final answer:
The best region or gene to use as a molecular clock for studying the divergence of monkey species depends on the evolutionary timescale of interest. Poorly conserved genes are suitable for examining recent divergences, while highly conserved regions like mtDNA or certain proteins are better for ancient divergences.
Step-by-step explanation:
To identify the best region, or gene, to use as a molecular clock for studying the divergence of various species of monkey, it is important to select a region of DNA that reflects the evolutionary timescale of interest. For recent divergence events, a poorly conserved gene is appropriate since it undergoes rapid changes, providing a higher resolution for studying closely related species. In contrast, highly conserved regions, such as mitochondrial DNA (mtDNA) or certain proteins, are better candidates for studying more ancient divergences due to their slower mutation rates.
Using molecular clocks involves comparing DNA or protein sequences to estimate the time since species diverged from a common ancestor. The number of DNA sequence differences between species is directly proportional to the time since their divergence. Therefore, to study the evolutionary history of monkeys, scientists can compare sequences from genes that mutate at a rate complimentary to the timescale of divergence. For example, if the interest lies in the divergence of monkey species over millions of years, mitochondrial DNA or conserved proteins could be ideal.