ABSTRACT

Microevolutionary changes occur primarily from some individuals having more viable offspring than others, so that the genes of the successful parents come to make up a larger proportion of the gene pool of the population in the next generation. When the rate of microevolution is measured by demographic performance rather than from measures of the frequency distributions of alleles, it represents a ceiling, a maximum rate of speed of change in gene frequencies. The chapter shows that knowing something of the demographic parameters of a population allows us to spell out in some detail the concrete mechanics of the genetic transmission process from generation to generation on issues such as the number of children ever born to cohorts, the expected numbers of descendents in successive generations, the degree of opportunity for natural selection and drift for the two sexes, and so on.