The 'molecular clock' hypothesis assumes a constant rate of mutation over time. The greater the number of differences in nucleotide sequences, the longer ago those individuals shared a common ancestor.

A family tree of different species represents the evolutionary relationships between these species. It shows which species had a common ancestor and how they are related to each other.

Mitochondrial DNA mutates faster than nuclear DNA, so differences in mitochondrial DNA sequences can provide evidence for the origin of species and their subsequent migrations.

DNA sequence data can be compared between species.

Species that are more closely related (have a more recent common ancestor) will have more similar DNA sequences, while those that are distantly related will have fewer similarities.

Cytochrome c and ribosomal RNA are commonly studied molecules in comparative biochemistry because they are highly conserved among species, and slight changes can help identify evolutionary links.

DNA molecules, messenger RNA, and amino acid sequences can also be used to identify evolutionary relationships between organisms.

The DNA molecules may be nuclear, mitochondrial, or from chloroplasts.

Both Darwin and Wallace independently proposed the theory of evolution by natural selection.

They suggested that organisms best suited to their environment are more likely to survive, reproduce, and pass on their advantageous characteristics to their offspring.

Comparing amino acid sequences reveals genetic diversity and evolutionary relationships, as amino acid sequences are determined by mRNA and DNA.

By comparing the base sequences of mRNA, which are complementary to DNA, we can assess DNA diversity.

If they are closely related evolutionarily, two species have fewer differences in their proteins' amino acid sequences.