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Leks • Hotspot • Female preference – Male aggregations – Hotshots • Kin selection • The lek paradox Leks • • • • Swedish for mating arena No male parental care No resource on territory Males aggregate and display at traditional sites Leks occur when females are not defensible Leks -> antelope 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 QuickTime™ and a H.263 decompressor are needed to see this picture. Cock-of-the-rock Manakins Bell birds 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 Best-of-n expectation – No evidence in sage grouse – 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 Std dev units • More efficient comparison of males Number of males 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. 2000 Nature 408:352-353 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
