Evolution ID: eee105 Password: prAIRie Lec 14 18Feb02
Plant-animal coevolution
Why aren’t all the plants eaten?
Plants have evolved chemical defenses
Why aren’t all the plants eaten? Plants have evolved chemical defenses e.g. the flavors of vegetables
Why aren’t all the plants eaten? Plants have evolved chemical defenses
Why aren’t all the plants eaten? Plants have evolved chemical defenses milkweed is toxic but a few insects have evolved resistance
Why aren’t all the plants eaten? Plants have evolved chemical defenses milkweed is toxic but a few insects have evolved resistance milkweed bug is toxic and has evolved warning coloration
Why aren’t all the plants eaten? Plants have evolved chemical defenses milkweed is toxic but a few insects have evolved resistance monarch butterfly caterpillar is toxic
Why aren’t all the plants eaten? Plants have evolved chemical defenses milkweed is toxic but a few insects have evolved resistance monarch butterfly istoxic too is toxic too andhas evolved bright warning colors and has evolved bright warning colors
Why aren’t all the plants eaten? Plants have evolved chemical defenses milkweed is toxic but a few insects have evolved resistance viceroy butterfly isnottoxic is not toxic buthas evolved bright warning colors but has evolved bright warning colors a mimic
Why aren’t all the plants eaten? Plants have evolved chemical defenses milkweed is toxic but a few insects have evolved resistance
Plant-animal coevolution plants evolved fruits
Plant-animal coevolution plants evolved fruits to “persuade” animals to disperse seeds
Are humans evolving? Yes but in surprising ways Darwin’s Descent of Man and Selection in Relation to Sex Darwin’s Descent of Man and Selection in Relation to Sex and Selection in Relation to Sex
Sexual selection bizarre, “useless” ornamentation secondary sexual characteristics
Sexual selection bizarre, useless ornamentation secondary sexual characteristics
Sexual selection bizarre, useless ornamentation secondary sexual characteristics
Sexual selection bizarre, useless ornamentation secondary sexual characteristics rainbow darter
Sexual selection bizarre, useless ornamentation secondary sexual characteristics in humans
female choice Sexual selection
female choice Sexual selection the naked ape ? racial differences?
female choice Sexual selection male combat why mammalian males are larger than females
female choice Sexual selection male combat Sexual selection
female choice Sexual selection male combat why mammalian males are larger than females in most species females are the larger sex male combat
in most species females are the larger sex
Sexual selection is a type of natural selection but there is another mechanism of evolution Genetic drift random changes in gene frequencies (1) gene flow by immigration humans are exceptional migrators
Gene flow by immigration e.g. Asian invasions of Europe % B bloodtype
Sexual selection is a type of natural selection but there is another mechanism of evolution Genetic drift random changes in gene frequencies (1) gene flow by immigration humans are exceptional migrators (2) population bottlenecks
Population bottlenecks In small populations random changes in gene frequencies change the population e.g. small, inbred human populations the founder effect e.g. polydacytyly
Population bottlenecks World population of cheetahs is small 20,000 20,000 genetically identical
Are humans evolving? Yes sexual selection genetic drift natural selection e.g. lactose intolerance
Most adult humans are lactose intolerant Only cattle-herding peoples digest milk easily
Are humans evolving? Yes sexual selection genetic drift natural selection But humans vigorously oppose natural selection Civilization