Somatic mutations in organisms with complex life histories

Area of Science:

• Evolutionary biology
• Theoretical biology
• Genetics

Background:

• Organisms with indeterminate growth and clonal reproduction present unique challenges for understanding mutation dynamics.
• Distinguishing the fate of somatic mutations (arising during mitotic division) versus meiotic mutations (arising during meiotic division) is crucial.

Purpose of the Study:

• To develop a theoretical model for the fate of mutations in organisms with indeterminate growth and clonal reproduction.
• To compare the relative strengths of somatic and meiotic mutation under varying conditions.
• To investigate the impact of within-organism selection on somatic mutations.

Main Methods:

• Development of a theoretical model focusing on allele frequencies at gamete production.
• Analysis of mutation fate based on whether mutations arise during mitotic or meiotic cell division.
• Incorporation of empirical mutation rates and demographic data from clonal corals.

Main Results:

• Somatic mutation can alter allele frequencies rapidly, often exceeding meiotic mutation effects with few cell divisions.
• Strong negative selection against somatic mutations within an individual can effectively counteract their impact.
• Within-organism selection can purge significant mutation loads that would otherwise arise from somatic mutations.

Conclusions:

• The fate of mutations in clonal, indeterminately growing organisms is heavily influenced by the type of cell division (somatic vs. meiotic) and the presence of selection.
• Selection acting within an organism plays a critical role in managing the load of somatic mutations.
• Theoretical models are essential for predicting mutation dynamics in complex life-history strategies.