SMILE

Stochastic Models for the Inference of Life Evolution

Some Consequences of demographic stochas- ticity in population genetics.

Parsons, T., Quince, C., Plotkin, J.

Genetics

2010

Much of population genetics is based on the diffusion limit of the Wright-Fisher model, which assumes a fixed population size. This assumption is violated in most natural populations, particularly for microbes. Here we study a more realistic model that decouples birth and death events and allows for a stochastically varying population size. Under this model, classical quantities such as the probability of and time before fixation of a mutant allele can differ dramatically from their Wright-Fisher expectations. Moreover, inferences about natural selection based on Wright-Fisher assumptions can yield erroneous and even contradictory conclusions: at small population densities one allele will appear superior, whereas at large densities the other allele will dominate. Consequently, competition assays in laboratory conditions may not reflect the outcome of long-term evolution in the field. These results highlight the importance of incorporating demographic stochasticity into basic models of population genetics.

Bibtex

@article{parsons_consequences_2010,
Author = {Parsons, TL and Quince, C and Plotkin, JB},
Title = {Some {Consequences} of demographic stochas- ticity in
population genetics.},
Journal = {Genetics},
Volume = {185},
Number = {4},
Pages = {1345--1354},
abstract = {Much of population genetics is based on the diffusion
limit of the Wright-Fisher model, which assumes a fixed
population size. This assumption is violated in most
natural populations, particularly for microbes. Here we
study a more realistic model that decouples birth and
death events and allows for a stochastically varying
population size. Under this model, classical quantities
such as the probability of and time before fixation of
a mutant allele can differ dramatically from their
Wright-Fisher expectations. Moreover, inferences about
natural selection based on Wright-Fisher assumptions
can yield erroneous and even contradictory conclusions:
at small population densities one allele will appear
superior, whereas at large densities the other allele
will dominate. Consequently, competition assays in
laboratory conditions may not reflect the outcome of
long-term evolution in the field. These results
highlight the importance of incorporating demographic
stochasticity into basic models of population genetics.},
doi = {10.1534/genetics.110.115030},
year = 2010
}

Link to the article

Accéder à l'article grâce à son DOI.