Selection Experiments Performance and Physiology Chapter 12 Focus: Review selection experiments that have targeted organismal performance traits (esp. locomotion & metabolism) Behavior: anything an animal does Performance: ability to do something when maximally motivated Most experiments involve artificial selection and rodents –Whole-organism performance measurements easier with rodents than insects or microorganisms –Laboratory natural selection unethical with rodents

Mice in Different Thermal Environments Multigenerational cold exposure resulted in: –Increased body mass –Increased fertility –Shorter tails –Higher fat and protein content of milk Wind Tunnel Flight in Drosophila –Mean flight speed increased dramatically (2 to 170 cm/sec) –Maximum flight speed did not increase

Endurance Running in Rats and Mice Both mean and maximal voluntary speeds increased significantly for mice Voluntary model more useful because stress tends to actually reduce performance (esp. in mice) Mass decreased for both mice and rats with increased speeds

Sexual Selection Effects of Ornaments on Performance Guppies –Bright coloration preferred by females –More conspicuous to predators –Natural vs. Sexual Selection Stalk-Eyed Flies –Increased eye-span preferred by females –Possible interference with flight abilities –Selected lines for extremes in eye-span currently being tested

Informal Selection “Experiments” Racing Horses and Dogs Examining various breeds of dogs and horses us a good idea of the genetic variation present in each species Greyhounds are getting faster while horses are steady b/c of differences in amount of time each has been breed for racing