Mating frequency in male chickens: long-term selection.

Twenty-three generations of bidirectional selection in male chickens (Gallus domesticus) for number of completed matings resulted in widely diverse mating behavior in the high and low lines. Selection caused a steady increase in cumulative number of completed matings (CNCMs) of the high line with a realized heritability of 0.18±0.02. In contrast, selection for decreased CNCMs caused many males to pass a threshold below which they would not mate naturally. Changes in male mating behavior were not accompanied by changes in mating behavior of females.