Leks Hotspot Female preference –Male aggregations –Hotshots Kin selection The lek paradox

Swedish for mating arena No male parental care No resource on territory Males aggregate and display at traditional sites Leks

Leks -> antelope Leks occur when females are not defensible grouse & ptarmigan

Males defend tiny territories on a lek Bat video

Male mating success on leks Sage grouse video

Lekking and frugivory in birds Lek Exploded lek Territory

New World lekking birds ManakinsBell birds Cock-of-the-rock

Hypotheses for male clustering Hotspot –males aggregate to maximize female encounter rate Female preference –Females prefer to select mates in aggregations –Females prefer central male –Females prefer attractive male (hotshot) and other males aggregate around him Kin selection –Males aggregate around relatives

The hotspot model

Leks of leks suggest hotspots Hermit hummingbird Ochre-bellied flycatcher Red-capped manakin Blue-crowned manakin

Sage grouse leks and hotspots Lek location Female nest density

Possible reasons for female preference to mate at a lek Reduce predation –No evidence in sage grouse More efficient comparison of males –Reduce mate searching costs –But, assuming male quality is normally distributed, advantage of choosing best male is greatest in small, not large, leks –Can copy choice of others Number of males Std dev units Best-of-n expectation

Mate choice copying in sage grouse Green = observed, orange = predicted w/out copying

Mate choice copying simulations

Do leks recruit more females/male in kob? No!

Do leks recruit more females/male in ruff? Sometimes!

Are black grouse hotshots? Yearly shift suggests male attractiveness, not position, is important

Related manakins on leks Shorey et al Nature 408: Also in peacock, black grouse, satin bowerbirds, wild turkeys

The lek paradox In lekking species, males only pass sperm. Therefore, only indirect benefits are possible. If males differ in genetic quality, then females should always prefer the male of highest quality. Over time, such intense selection will deplete and possibly eliminate genetic variation. What then do females gain by choosing?

Solution to the lek paradox Genetic variation must persist for ornamental traits and genetic quality Ornament expression depends on condition. –Only males in good condition are able to fully express ornament –Condition is likely influenced by many genes. Consequently, deleterious mutations constantly replenish genetic variation.

Sage grouse condition and display