Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download presentation
Document related concepts
Transcript
Evolution Lec 14 18Feb02 http://life.uiuc.edu/animalbiology/105/ ID: eee105 Password: prAIRie Plant-animal coevolution Plant-animal coevolution Why aren’t all the plants eaten? 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 bug is toxic and has evolved warning coloration milkweed is toxic but a few insects have evolved resistance Why aren’t all the plants eaten? Plants have evolved chemical defenses monarch butterfly caterpillar is toxic milkweed is toxic but a few insects have evolved resistance Why aren’t all the plants eaten? Plants have evolved chemical defenses monarch butterfly is toxic too and has evolved bright warning colors milkweed is toxic but a few insects have evolved resistance Why aren’t all the plants eaten? Plants have evolved chemical defenses a mimic viceroy butterfly is not toxic but has evolved bright warning colors 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 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 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 rainbow darter bizarre, useless ornamentation secondary sexual characteristics Sexual selection in humans bizarre, useless ornamentation secondary sexual characteristics Sexual selection female choice Sexual selection female choice the naked ape ? racial differences? Sexual selection female choice male combat why mammalian males are larger than females Sexual Sexual selection selection female choice male combat Sexual selection female choice male combat why mammalian males are larger than females in most species females are the larger sex 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 % B bloodtype Gene flow by immigration e.g. Asian invasions of Europe 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 e.g. polydacytyly the founder effect Population bottlenecks World population of cheetahs is small 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
