Which processes and factors drive the evolution of mutation rates? Why do mutation rates vary among species and populations?
- Mutations are the ultimate source of genetic variation and thus play a central role in evolution. However, de novo mutations are mostly deleterious and thus all cellular mechanisms that suppress or repair mutational events in an individual genome are under strong selection. This fine-scale balance between DNA repair systems and de novo mutations evolves to a species-specific rate that is expressed in the magnitude of 10exp-8 to 10exp-11. Measuring the emergence of de novo mutations across generations thus equals searching for the needle in a haystack... We developed a method to directly estimate the spontaneous mutation rate using short term mutation accumulation lines and whole genome sequencing. This method is generally applicable to all organisms that can be cultivated in the laboratory, have a reasonable short to intermediate generation time, and survive the sequential inbreeding for mutation accumulation for about five generations.
- Environmental factors such as the ambient temperature have a great impact on cellular functions, especially in ectothermic organisms (development, metabolism, etc.). We directly estimated spontaneous mutation rates under the impact of different experimental temperatures in our insect model C. riparius. This study reveals the direct temperature-dependence of mutation rates following an optimum curve.
- Ecological factors such as a population's demography define the strength of selection in relation to the effect of genetic drift. Whether population sizes directly influence mutation rates actually depends on the heritability of mutation rates as a quantitative trait. This hypothesis will be tested as part of the Atacama CRC project.