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

Manakins Bell birds

Cock-of-the-rock

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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 hummingbirdOchre-bellied flycatcherRed-capped manakinBlue-crowned manakin

Sage grouse leks and hotspots

Lek locationFemale 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 othersNumber of males

Std

dev

uni

ts

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. 2000 Nature 408:352-353

Also in peacock, black grouse, satinbowerbirds, 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