Species:Maximum no. F produced Males Females Seals Elk Humans Gulls D. melanogaster Jacanas Species:Maximum no. F produced Males Females Seals Elk Humans Gulls D. melanogaster Jacanas 10 20

II.Female Choice  Why should females spend time/energy/risk in discriminating among males? 1). Resource-based mating systems: a) NS favors choosy females b/c being choosy returns direct benefits to females in the form of resources (food or protection etc …) 2). Non-resource-based mating systems: a)NS favors choosy females b/c being choosy returns indirect benefits gained by producing better offspring (“Good genes” hypotheses) b) No benefits go to females: i] Females have arbitrary preferences and females within a species vary in their preferences [Fisherian Runaway Selection] ii] Females have pre-existing sensory biases that are exploited by males [Sensory Exploitation hypothesis]

Examples: (Resource-based systems) Red-wing blackbirds and the polygyny threshold model (PTM) males are territorial in cattail marshes females are very choosy about where they decide to make nests and which male they mate with territories vary in quality and some territories have multiple nests whereas others have none Examples: (Resource-based systems) Red-wing blackbirds and the polygyny threshold model (PTM) males are territorial in cattail marshes females are very choosy about where they decide to make nests and which male they mate with territories vary in quality and some territories have multiple nests whereas others have none Non-resource-based systems: do females choose even though there “appears” to be no benefit via NS? What cues do females use to discriminate among males? Barn swallows (Anders Moller et al.) Non-resource-based systems: do females choose even though there “appears” to be no benefit via NS? What cues do females use to discriminate among males? Barn swallows (Anders Moller et al.)

Female choice seen in many species: barn swallows, widow birds, stalk-eyed flies, tree frogs, humans, dragonflies, mites, trees, etc.... WHY? Good Genes hypothesis: Test tree frogs: males vary in length of call  is this a cue to male genetic quality? Welch et al….eggs from one female fertilized by sperm from LC and SC male rear young in low food and high food environments Results  usually offspring from LC males had better larval performance in both environments, resulting in greater fitness for LC males CONCLUSION: LC is a cue to females for greater male genetic quality [why are LC males “better” ---- ??? --- LC males feed vigorously as tadpoles even with predators present…will this trait always be “better”?] [why are LC males “better” ---- ??? --- LC males feed vigorously as tadpoles even with predators present…will this trait always be “better”?]

RUNAWAY SELECTION HYPOTHESIS Stalk eyed flies (Cyrtodiopsis)