Question

DNA fixes substitutions at a roughly constant rate. This graph shows how distantly related pairs of species have a large number of different substitutions in the cytochrome C gene. This regular mutation rate allows scientists to____________________ in order to deduce the divergence time between lineages in a phylogeny.

1) create phylogenies
2) develop a molecular clock
3) identify the last common ancestor
4) analyze morphological similarities

Answer 1

Scientists use the concept of a molecular clock, based on the constant rate of mutations in the cytochrome C gene, to estimate the divergence time between species by comparing protein sequence differences and employing computer algorithms to correct for convergent evolution and random similarities.

Step-by-step explanation:

The use of cytochrome C gene substitutions to estimate the divergence time between lineages relies on the concept of a molecular clock. A molecular clock operates under the premise that mutations accumulate at a constant rate over time in certain genes. By comparing the number of differences in the conserved protein sequences of this gene across different species, scientists can estimate the time of divergence from a common ancestor. It is important to be aware that convergent evolution or random similarity in sequences can misrepresent relatedness, which might require computer algorithms to decipher accurate phylogenies and eliminate analogous traits.

By comparing the number of different substitutions in the cytochrome C gene, scientists can develop a molecular clock to infer the divergence time between lineages in a phylogeny. This allows them to create phylogenies and estimate the time when related species diverged from a common ancestor.