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R H Flake

Publications and source records attributed to R H Flake.

4 recordsLinked to original sources
PubMed1974

Solutions to the cost-of-selection dilemma.

There are various biologically realistic ways around the cost-of-selection restriction on rapid multiple-gene substitution. Some of these ways depend upon particular forms of interaction or linkage in the genes undergoing substitution; other ways depend on particular conditions of population size and structure. The special genotypic and populational conditions required for rapid evolutionary change in genetically complex characters are not unusual in higher organisms.

Alleles↗
PubMed1974

Population structure in relation to cost of selection.

The opposing requirements in an evolving population for a rapid rate of multiple gene substitution and for the maintenance of normal population size can be reconciled in a variety of ways. The ways out of the impasse suggested here invoke deviations from the usual assumption of a large continuous population with constant numbers. In a colonial population system there may be significant random fluctuations in the accidental mortality rate between different colonies; and those colonies with reduced numbers of accidental deaths could tolerate the larger number of selective deaths that go hand in hand with rapid evolution. In new daughter colonies founded by one or a few colonizing individuals from a large polymorphic ancestral population, some genes may reach complete fixation in one or a few generations, without the usual concomitant selective cost. Or, in the same setup, the favored alleles may change by chance from rare to moderately common, but not to complete fixation, during the founding of some daughter colonies; and this raises the allele frequencies above the low range, where the cost of selection is greatest, so that the cost of further selective changes is bearable.

Alleles↗
PubMed1974

An analysis of the cost-of-selection concept.

It is shown for a continuous haploid model that the common standard assumptions used in calculating the cost of gene substitution, namely, large constant population size and small constant selective value, are unnecessary. Population size may fluctuate during the course of substitution without affecting the calculated total cost. The selective intensity does not need to be small and constant to give the standard result for substitution cost. Diploid models with multiple alleles are analyzed and contrasted with standard two-allele models in respect to calculation of substitution cost. The influence of population structure on the probability of occurrence of complete gene substitution is discussed on the basis of a numerical example. The robust nature of the cost-of-selection concept is examined in the light of a conservation principle.

Alleles↗