James F. Crow

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IT has sometimes been suggested that the wild-type allele is not a single entity, but rather a population of different isoalleles that are indistinguishable by any ordinary procedure. Withhundreds of nucleotides, each presumably capable of base substitutions and with additional permutations possible through sequence rearrangements, gains, and losses, the(More)
Rates of spontaneous mutation per genome as measured in the laboratory are remarkably similar within broad groups of organisms but differ strikingly among groups. Mutation rates in RNA viruses, whose genomes contain ca. 10(4) bases, are roughly 1 per genome per replication for lytic viruses and roughly 0.1 per genome per replication for retroviruses and a(More)
Spontaneous mutations were allowed to accumulate in a second chromosome that was transmitted only through heterozygous males for 40 generations. At 10-generation intervals the chromosomes were assayed for homozygous effects of the accumulated mutants. From the regression of homozygous viability on the number of generations of mutant accumulation and from(More)
For assessing the degree of population subdivision, and therefore the extent to which group selection might favor an altruistic trait, an appropriate measure is Nei's GST, defined by (F0-F)/(1-F). F0 is the probability that two alleles drawn from the same group are identical in state and F is the probability for two alleles drawn at random from the entire(More)
The germline mutation rate in human males, especially older males, is generally much higher than in females, mainly because in males there are many more germ-cell divisions. However, there are some exceptions and many variations. Base substitutions, insertion-deletions, repeat expansions and chromosomal changes each follow different rules. Evidence from(More)
In a diploid, outbreeding organism like man the deleterious mutants carried by the population are only partly expressed in each generation, being largely concealed by heterozygosis with more favorable alleles. However, the total hidden-mutational damage carried by the population can be estimated indirectly from the detrimental effects of consanguineous(More)
  • James F. Crow
  • Proceedings of the National Academy of Sciences…
  • 1997
The human mutation rate for base substitutions is much higher in males than in females and increases with paternal age. This effect is mainly, if not entirely, due to the large number of cell divisions in the male germ line. The mutation-rate increase is considerably greater than expected if the mutation rate were simply proportional to the number of cell(More)
In this paper, a correction and extension of earlier work, we derive expressions for the inbreeding effective number, NeI , and the variance effective number, NeV , with various models. Diploidy, random mating, and discrete generations are assumed and formulas for NeI are given for six situations: isogamous monoecious populations with self-fertilization(More)