Petrie et al. 1991 Lekking •Black Grouse •Yearly variation in lek sites 120 years after Darwin suggested female From Scandinavian word ‘lek’ for “play” choice could maintain elaborate plumage: Evidence in support of Hot Spot: Males defend small territories of no resource value •Multiple species lekking near river confluences First demonstration of female preference •Typically clumped in a small display area for elaborate plumage in males. Females arrive there solely for finding mates Evidence against female preference hypothesis: •Uganda kob (an antelope that leks) Underlying Theory: Why do this? Bradbury’s hypothesis •Operational Sex Ratio across leks is fairly •Intersexual Selection •Should be favored in species with wide-ranging constant Specific Hypotheses foraging ecology 1. Female mate choice depends on male plumage •Unpredictable, temporally variable food However, as with all things ecological: train characteristics (intersexual sel’n hyp.) versus sources (tropical fruits ripening at different Depends heavily on the species. 2. Certain plumage train characteristics confer a times on different trees) •Ruffs (type of sandpiper) exhibit competitive advantage to males (intrasexual sel’n behavior supporting all three hypothesis) Big Question: Why do males congregate in small areas? hypotheses Not mutually exclusive hypotheses •Three Hypotheses: •Located near small ponds on elevated ground •“Hot Spot” hypothesis •Females prefer groups with at least 5 displayers Previous Studies (Two) •“Hot Shot” hypothesis •Low-ranking males choose to display near •Experimental manipulations •Female preference hypothesis dominant males •Demo’d increased mating success but didn’t clearly document the mechanism Evidence for “Hot Shot” •Great snipes (European sandpipers) Observational Study •Removal of dominant males caused desertion •One lek at Whipsnade Zoological Park (England) by nearby subordinates •Removal of subordinates created rapidly-filled vacancies Back to Peacocks...

Lekking is one example of various Petrie et al. Observations Monogamy Mating Systems •Morphological measurements on males Inquiry into evolution of patterns of mating Why would males ever be monogamous? •Train features systems started fairly recently. •Other body features 1. Mate Guarding Hypothesis •Females may remain receptive after mating Definitions: •Behavior at one lek •Females may be hard to locate -gyny --> females •Female visits •Clown Shrimp •Male courtship attempts (hoot-dash) -andry --> males -gamy --> both sexes •Male interference and intrusion 2. Mate-Assistance Hypothesis Monogamy, Polygyny, Polyandry, etc. •Improvement in offspring survival with paternal Polybrachygyny --> male “serial monogamy” •Results care may be dramatic •High variance in male mating success •Seahorses Defined in different ways: •Displaying males •Male brood pouches •Peripheral displaying males Pair bonds versus ability to monopolize access to •Floating males mates 3. Female-Enforced Monogamy •Males did attempt to interfere with copulation •American Burying Beetle attempts of other males •But interference did not seem to alter mating Mammals and others: Polygamy far more common--- success interesting cases are monogamy •Successful matings correlated with train morphology •Train size and eye-spot number Birds: Monogamy quite common---interesting cases are •Not correlated with other body measurements or polygyny and polyandry lekking position •Data on 11 female visit sequences Mechanisms of Paternity Infidelity in Monogamous Matings Polygyny and Polyandry Rationale for extra-pair matings Assurance/Remating Prevention Monogamy is the norm in birds Male perspective Examples: •Potential for male reproductive care (mate-assistance •Costs: cuckoldry while he’s gallivanting about hypothesis) seems dominant reason •Risks of searching for extra-pair copulations and Dragonfly hitchhikers: •Most theory about polygyny and polyandry contending with other mates •Fly around on top of developed in the context of bird studies •Clear benefits the female he’s fertilized until eggs are Resource-Defense Polygyny Female Perspective laid •Polygyny Threshhold (Gordon Orians) •Possible Genetic benefits •At some point it benefits females to become a •Sufficient sperm quantity Calopteryx spp. Plugs and cementious semen second mate of a male with a large territory •Sperm competition (fitter sons if heritable) •Lenington with red-winged blackbirds •Genetic variety Chemically noxious odorizing •Males arrive first and establish territories •Sibs less likely to compete ecologically? •Females appear later and choose males •Material benefits Infanticide •Initial choice of unmated males •Resources on extra male territories •“Recently promoted” dominant primate males •Eventually polygyny was chosen over •Parental care •Female fetus resorption mating with males on poorer territories •Two territory variables Male Response on Evolutionary Time Scale: The job of paternity assurance is more difficult in species • Cattail density Paternity Assurance where the female stores semen from previous males • Food density* •Solution in Calopteryx maculata---the hoooked penis

Female defense polygyny: •Pre-existing female clusters •Some bat species females forage together and roost together at night a single site in their cave •Single male defends these clumps •DNA studies: 60 to 90% of matings •Up to 50 pups per male!

•Some males form their own female clusters •Marine amphipod---constructs “mobile apartment buildings” with up to three females

Male dominance polygyny •See lekking