On the other hand, moderate and strong selection caused a quick reduction of the MSE from youngest mutations to mutations arising in generations 920 to 939, thus resulting in a progressive increase for older mutations.
Based on early estimates of the mutation rate in humans and the size of the human genome, simple calculations done decades ago showed that only a small fraction of it could be constrained at the sequence level, otherwise there would be too many deleterious mutations in every generation for the species to survive (Ohno 1972).
To focus on the role of ALMS1 mutations in the generation and maintenance of this pathological fibrosis, we performed gene expression analysis, ultrastructural characterization and functional assays in 4 dermal fibroblast cultures from ALMS patients.
In the model presented here, we took into account the possibility of several mutations in one generation.
However, in order to achieve appreciable sequence evolution on a laboratory time scale, we used a mutation rate that sometimes produced multiple mutations in a generation.
While here we have invoked deleterious mutations in the generation of fitness variation, beneficial mutations can similarly contribute to inherited variation in fitness (Birky and Walsh, 1988; Barton, 1995).
Allowing for several mutations in one generation highlights an indirect pressure that limits genome growth but that is not necessarily likely to be observed in a sample of the population.
With individuals accumulating appreciable numbers of germline mutations in each generation (for humans, for example this number is estimated to be ∼74 56), each individual genome can be considered as a natural 'perturbation'perturbation
This seems a short time lag for adaptation to have arisen from new mutations (i.e. the best situation to detect the signature of selection), although high fecundities and the large size of oyster populations would allow an appreciable influx of new mutations in each generation.
We will also use Chebyshev's inequality to show that the number of mutations in one generation is indeed sufficient to shrink below \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\tilde{s}$$\end{document} s ~.
