Abstract
BackgroundThe evolution of multi-cellular animals has produced a conspicuous trend toward increased body size. This trend has introduced at least two novel problems: an expected elevated risk of somatic disorders, such as cancer, and declining evolvability due to generally reduced population size, lower reproduction rate and extended generation time. Low population size is widely recognized to explain the high mutation rates in animals by limiting the presumed universally negative selection acting on mutation rates.ResultsHere, we present evidence from stochastic modeling that the direction and strength of selection acting on mutation rates is highly dependent on the evolution of somatic maintenance, and thus longevity, which modulates the cost of somatic mutations.ConclusionsWe argue that the impact of the evolution of longevity on mutation rates may have been critical in facilitating animal evolution.
Highlights
The evolution of multi-cellular animals has produced a conspicuous trend toward increased body size
The evolution of body size, somatic maintenance and germline mutation rate was tracked under various regimens of selection
We did not simulate the processes of allelic segregation by recombination in order to reconstruct a sexual population, but modeled the distribution of mutation rate that was independently inherited from other traits and was not directly subjected to selection in the model (Fig. 2d)
Summary
The evolution of multi-cellular animals has produced a conspicuous trend toward increased body size. This trend has introduced at least two novel problems: an expected elevated risk of somatic disorders, such as cancer, and declining evolvability due to generally reduced population size, lower reproduction rate and extended generation time. Large animals generally demonstrate lower numbers of progeny per time period, longer generation times, and more advanced ages of first reproduction [3, 4] In aggregate, such changes weaken selection that can act on a population and should negatively affect evolvability, defined as “an organism’s capacity to generate heritable phenotypic variation” [5]. This general reduction in evolvability should, be at least partially alleviated by diversity facilitated by sexual reproduction
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