Sexual Selection
Why are there ornaments?
Sexual selection history
Batemanís Experiment
Conclusions from Batemanís experiment
In mammals, VLRSmale is usually > VLRSfemale
Intrasexual selection: one sex (typically males) competes for access to and fertilization of the other
Sexual dimorphism reflects the intensity of selection on males
Why are females choosy?
Intersexual (epigamic) selection: female choice
Direct benefits: Females choose resources
Pied flycatcher females prefer dominant males
When males only provide sperm
Hens prefer sperm from dominant males
Fisherís Runaway process
Landeís model of Fisherís runaway
Female preference exhibits a genetic correlation with male trait in sticklebacks
Natural selection opposes sexual selection
Sexual and natural selection on barn swallow tails
Arbitrary traits in zebra finch or sensory bias?
Good genes models
Parasites indicate plumage brightness
Swallow tail feather length indicates ectoparasite resistance
Peahens prefer males with eyespots which have better offspring survival
Email: gw10@umail.umd.edu
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