Payne Robert B. Sexual selection, lek and arena behavior, and sexual size dimorphism in birds

Washington: American Ornithologists' Union, 1984. — 59 p. ISBN13: 978-0943610405.Charles Darwin (1871) introduced the concept of sexual selection with illustrations of birds that display in leks. He viewed sexual selection as a process of evolutionary change that is distinct from natural selection insofar as it explains the evolution of characters useful in attracting females for sex, rather than in simply surviving. As Darwin and others (Selander 1972; Williams 1975; Maynard Smith 1978; Andersson 1982a) have noted, sexual selection may work in two ways. The first is by means of direct social competition among males for positions in a mating area or a social unit, and the second involves active female choice of one male over another, independent of the competitive interactions among the males. The first is called intrasexual selection; the second is intersexual selection.
Darwin drew attention to the elaborate male plumages and songs of birds as an effect of sexual selection, and wondered whether the sexual dimorphism of birds was the result of males fighting or of females perceiving "beauty" in the plumage of the males. The bright plumages of the male birds of paradise and the large size of male grouse may well be evolutionary results of sexual selection.
As Darwin's concept of sexual selection was developed from considering the lekking birds, it seems appropriate to examine the process and consequences of
sexual selection by contrasting birds that lek with birds that have other mating systems. We can compare birds with lekking and arena behavior with birds
with territorial-polygynous mating systems, and with monogamous birds. If sexual selection is prominent in lekking birds, then we should be able to evaluate the intensity of sexual selection in various birds and to find a more intense level of sexual selection in the birds that lek. We should also account for the mechanisms and consequences of behavior and morphology of the sexes by the sexual selection model.
Sexual selection theory can be tested by comparing the variance among individuals in mating and breeding success in species groups that have different mating systems. I test the following questions here. Are males in lekking and other arena species subject to more intense sexual selection than are males in monogamous species? Are males in lekking and polygynous species under more intense sexual selection than are females? Do males in the lekking and arena species compete among themselves by direct fighting, including both physical combat and aggressive displays, rather than by alternative mating strategies? Does male competition explain the success of males in attracting females? Are the evolutionary results of sexual selection in sexual size dimorphism more pronounced in lekking birds than in their nonlekking relatives? The prediction of sexual selection theory (in particular the concept of competitive interactions among males) in each case is "yes." This study is a test of these predictions of sexual selection.