Neutrality & The Molecular Clock

Question 1

Synonymous vs. Nonsynonymous site substitutions

Answer 1

• Synonymous: encode “degenerate” positions, which do not affect protein production (supports neutral theory, that most mutations do not affect fitness)
• Nonsynonymous: new amino acid is produced, which may or may not result in a change in fitness

Question 2

Relative rate test

Answer 2

Theory: there is a constant rate of change for specific proteins in all species, which would support the existence of a universal molecular clock

Question 3

Generation-time effect

Answer 3

Synonymous site substitutions are proportional to the rate of DNA replication for the next gen., not an absolute time (longer gen. time = slower clock)

Question 4

Metabolic rate

Answer 4

Higher metabolic rate -> increased rate of mutations due to production of oxygen radicals (usually correlated with smaller bodies)