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Why would females choose “flashy”?. Gray tree frogs. Do long calls indicate good genes?. Do long calls indicate good genes? yes. Runaway sexual selection?. Fisherian Runaway Selection. The notion that sexual selection is more rapid than natural selection - PowerPoint PPT Presentation
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Why would females choose “flashy”?
Gray tree frogs
Do long calls indicate good genes?
Do long calls indicate good genes? yes
Runaway sexual selection?
Fisherian Runaway Selection
The notion that sexual selection is more rapid than natural selectionand that it can lead to evolution of great extravagances that are detrimental
Male red-collared widow bird
Antlers are secondary sexual characteristics…
Use varies by species:Visual display of dominanceFightingMate attraction
Extinct 11,000 years ago
Irish Elk—extinctCrazy-big antlers, right? “Runaway Sexual Selection”?Or not…
http://eebweb.arizona.edu/animal_behavior/chase/chaseaway2a.htm
˄ Why the Irish Elk went extinct…Not
Note axes = log scale
M = Megaloceros
X axis = 200 mm increase
Y axis = 1000 mm increase
Not a 1:1 ratio of increase!
Irish Elk had antlers exactly the right size for their bodiesRunaway sexual selection could not have been
the cause of their extinction!
Endler ExperimentWithout predator, sexual selection is the driving force
Endler ExperimentWith predator, sexual selection is tempered
Discussion
Why are females often drab?
Why don’t males prefer flashy females?
