Age‐Distribution and Abundance in Populations of Flour Beetles. I. Experimental Studies

Changes in Group-Selected Traits That Occur When Group Selection Is Relaxed

“…1) and then decline as is typical for Tribolium populations established with small groups of adults (Park, 1954;Lloyd, 1968;Mertz, 1969). The mean productivity of the A populations at every census was comparable to or exceeded that of the most productive ofthe "Park" laboratory strains (Park et al, 1964 strain c-I, Fig.…”

“…Despite the presence of Nosema, there were never fewer than 100 breeding adults in the A populations nor fewer than 50 in the B populations. Furthermore, the maximum period ofinfection, 120 days, is less than the expected lifetime of an adult (Mertz, 1975). Thus it is unlikely that significant selection occurred within the populations.…”

“…However, the recruitment and turnover rates ofthe adult populations, the numbers of cycles exhibited by the age-structures, and estimates from similar Tribolium husbandry regimes by other researchers (Mertz, 1975) indicate that the period of relaxation ofinterdemic selection was equivalent to at least eight and possibly as many as 12 generations. The effective size of a population over this entire period which determines the amount of divergence owing to random genetic drift is equal to the harmonic mean of effective size at each generation.…”

THE PRIMARY CHARACTERISTICS OF TRIBOLIUM POPULATIONS GROUP SELECTED FOR INCREASED AND DECREASED POPULATION SIZE

“…The next paragraph explains the relationship between development and cannibalism. This description of the biology of Tribolium populations when husbanded in discrete generations is synthesized from Strawbridge (1953), Park et al (1965), Park et al (1968), Lloyd (1968), Mertz and Davies (1968), Mertz (1969), Mertz and Robertson (1970), Mertz and Cawthon (1973), Cawthon (1975), andMcCauley (1978). Shortly following their introduction into acclimatized medium, adult females begin laying about 15 eggs per female per day (d. Table 2).…”

“…King and Dawson, 1972;Mertz, 1972;Sokoloff, 1974; for detailed and comprehensive reviews). The characteristics assayed from populations of each of the four treatments were as follows: 1) fecundity, the number of eggs laid per female.…”