ANALYSIS OF SELECTION PROCESSES USING THE INCOMPLETELY-PENETRANT MUTANT eu OF TRIBOLIUM CASTANEUM

Abstract

Two genetic markers were followed for ten generations in one hybrid and two control populations of the flour beetle Tribolium castaneum (Herbst). The incompletely-penetrant eu changes the number of terminal appendages in the larva and the pupa (urogomphi) from the normal 2 to 3 or 4, and the semi-dominant b changes the body color from brown to black in adult beetles. Three simultaneous selective processes were discovered. There was strong selection against eu, mainly through lowered eu/eu adult fecundity and zygote mortality. Selection against genes linked to b may have caused its decline from 50 to 40% in ten generations. Egg to adult survival increased considerably in all three populations, apparently due to selection for improved fertility at 25 °C imposed by the experimental regime.