Predicting patterns of long‐term adaptation and extinction with population genetics

  title={Predicting patterns of long‐term adaptation and extinction with population genetics},
  author={Jason Bertram and Kevin Gomez and Joanna Masel},
Population genetics struggles to model extinction; standard models track the relative rather than absolute fitness of genotypes, while the exceptions describe only the short‐term transition from imminent doom to evolutionary rescue. But extinction can result from failure to adapt not only to catastrophes, but also to a backlog of environmental challenges. We model long‐term adaptation to long series of small challenges, where fitter populations reach higher population sizes. The population's… 
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It is demonstrated that even after 50,000 generations over 20 years, gains in fitness show no evidence of leveling off, and mean fitness appears to increase without bound, consistent with a power law.
Demographic and Genetic Constraints on Evolution
This work model the demography and evolution of populations subject to optimizing selection that experience either a single shift or a constant change in the optimum, and derives formulas for critical levels of genetic variability that define demography‐caused absolute constraints.
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The past decade of research in life-history theory has done away with this conveniently simple relation between population viability and evolution, and provided us with a picture today that is considerably more subtle.
On the Fixation Process of a Beneficial Mutation in a Variable Environment
This work presents a framework to describe the fixation process of a single beneficial allele under these conditions, and derives compact analytical approximations for the fixation probability and the distribution of passage times for the beneficial allele to reach a given intermediate frequency.
Dynamic Mutation–Selection Balance as an Evolutionary Attractor
It is found that a surprisingly low fraction of beneficial mutations suffices to achieve stability, even in small populations in the face of high mutation rates and weak selection, maintaining a well-adapted population in spite of Muller’s ratchet.
Limits to the Rate of Adaptive Substitution in Sexual Populations
The results indicate that for some organisms the rate of adaptive substitution may be primarily recombination-limited, depending only weakly on the mutation supply and the strength of selection.
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  • D. Raup
  • Environmental Science
    Proceedings of the National Academy of Sciences of the United States of America
  • 1994
The extinction of species is not normally considered an important element of neodarwinian theory, but the largest mass extinctions produce major restructuring of the biosphere wherein some successful groups are eliminated, allowing previously minor groups to expand and diversify.
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It is found that an asexual model with the strength of selection tuned to that of the linkage block provides an excellent description of genetic diversity and the site frequency spectra compared with computer simulations and allows us to characterize coalescence, genetic diversity, and the speed of adaptation in the infinitesimal model of quantitative genetics.
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Rates of extinction are so high for Neogene pectinaceans and nonsiphonate burrowers that without enjoying high rates of speciation these groups could not exist at the diversities they have maintained during the Neogene Period, and geographic range is not of first-order importance in influencing species longevity.