[C05] Evolution and Genetics

[C05-03] Multiple Copy Effect of Somatic Mutations Enhances Mutant Establishment by Overcoming Loss by Genetic Drift

*Sou Tomimoto¹, Akiko Satake¹, Sarah P Otto² (1. Kyushu University (Japan), 2. University of British Columbia (Canada))

Keywords:

Branching processes,Overlapping generation,Germline mutation,Modular organism,Tree,Coral

Newly arising mutations are mostly lost due to random genetic drift because of their low frequencies within a population. Mutations that overcome such loss are critical to evolution. Recent advancements in next-generation sequencing technologies have verified the transmission of somatic mutations to offspring in modular organisms, such as trees and corals. Once somatic mutations emerge during growth, they are passed on to subsequently formed modules and, consequently, to all gametes produced by those modules. Somatic mutations are thus repeatedly supplied to the gene pool of the population, in contrast to gametic mutations that occur during gametogenesis and are supplied in a one-shot manner. This "Multiple Copy Effect" may help somatic mutations overcome random genetic drift and establish within the population. To test this hypothesis, we calculated the establishment probability for both somatic and gametic mutations using branching processes, simplifying the life histories of modular organisms. Our results show that somatic mutations are more likely to establish than gametic mutations for a single event of mutation. This highlights the importance of somatic mutations in the evolution of modular organisms.