PERSPECTIVE: SPONTANEOUS DELETERIOUS MUTATION.

Area of Science:

• Evolutionary genetics
• Molecular evolution

Background:

• Mildly deleterious mutations are a key explanation for evolutionary genetics and molecular evolution observations.
• Evidence for deleterious mutation processes primarily comes from Drosophila melanogaster studies, though some findings are debated.

Purpose of the Study:

• To review empirical data supporting the hypothesis of mildly deleterious mutations.
• To investigate mutation rates across diverse species and factors influencing them.
• To clarify controversies surrounding spontaneous mutation properties and their impact on genetic integrity.

Main Methods:

• Review of existing empirical data on mutation rates and effects.
• Comparative analysis of mutation rates across different species (microbes, plants, animals).
• Consideration of factors like germline cell divisions, generation length, and genome size.

Main Results:

• Deleterious mutations arise in flies at about one per individual per generation, with minor fitness reduction (2% in heterozygotes).
• Evidence from microbes, plants, and other animals supports the prevalence of mildly deleterious mutations.
• Some organisms exhibit significantly lower genomic mutation rates than Drosophila, potentially linked to germline cell divisions.

Conclusions:

• The prevalence of mildly deleterious mutations is supported across various species.
• Factors like germline cell divisions, generation length, and genome size influence interspecific mutation rate differences.
• Further clarification on mutation effect distributions and environmental/genetic modifications is crucial for understanding long-term impacts on human populations under relaxed selection.