Climbing mount probable: mutation as a cause of nonrandomness in evolution

Area of Science:

• Evolutionary biology
• Genomics
• Molecular evolution

Background:

• The Modern Synthesis views evolution as modulating existing genetic variation.
• An alternative perspective considers evolution as a two-step process: mutation origin followed by selection or drift.
• The role of mutation as a cause of nonrandomness in evolution is often misunderstood.

Purpose of the Study:

• To review theoretical results on mutation's role in evolutionary causation.
• To demonstrate how mutational biases can impose predictable directionality on evolution.
• To analyze the contribution of mutation to amino acid replacement rates in human-chimpanzee divergence.

Main Methods:

• Review of theoretical evolutionary models.
• Partitioning variance in amino acid replacement rates.
• Analysis of codon mutation and amino acid exchangeability.

Main Results:

• Mutation can act as a cause of nonrandomness in evolution, independent of neutrality.
• Mutational biases can lead to predictable evolutionary trajectories.
• Mutational effects explain the majority of variance in amino acid replacement rates between humans and chimpanzees.

Conclusions:

• Mutation is a significant causal factor in evolution, not just a source of random variation.
• Comparative genomics must incorporate mutational effects for accurate evolutionary analyses.
• Understanding mutation's role is crucial for deciphering evolutionary propensities and developing new analytical methods.