Strategies for the evolution of sex

Abstract

We find that the hypothesis made by Jan, Stauffer, and Moseley ͓Theory Biosci. 119, 166 ͑2000͔͒ for the evolution of sex, namely, a strategy devised to escape extinction due to too many deleterious mutations, is sufficient but not necessary for the successful evolution of a steady state population of sexual individuals within a finite population. Simply allowing for a finite probability for conversion to sex in each generation also gives rise to a stable sexual population, in the presence of an upper limit on the number of deleterious mutations per individual. For large values of this probability, we find a phase transition to an intermittent, multistable regime. On the other hand, in the limit of extremely slow drive, another transition takes place to a different steady state distribution, with fewer deleterious mutations within the population.

Evolutionary route to diploidy and sex

“…1) adopted here (8)(9)(10)14) extrapolates for finite temperatures (smaller values of ␤) between highly synergistic (step function) and independent (exponential) survival probabilities (23) as a function of m. A recent study by Peck and Waxman (24) indicates that competition for limited resources can lead to synergy between successive mutations, leading to truncation or step function-like survival probabilities, which they also find favors sexual populations.…”

“…The population of haploid asexuals settles down to a minimally stable (15) steady-state distribution (see Table 1) as shown in Fig. 1, independent of the value of ⌫, for ⌫ Ն 1͞N (9,10).…”

“…Let us briefly summarize our algorithm for conversion to sex, which we also used in our previous study (see Model A in ref. 10).…”

“…1 should be contrasted with the results of ref. 10. (Model A, nonhereditary and hereditary; see above), in which cloning of the sexuals is not allowed, but there is a steady influx of new sexuals from the haploids (see Table 1).…”

Equilibrium correlations in a model for multidimensional epistasis

“…Since Eigen first introduced the quasi-species model [4] bitstring models of genetic evolution have been extensively studied numerically [5,10,11,12]. In this approach, the genotype of an individual is represented by a string of Boolean variables σ i , i = 1, .…”