Evolution

http://life.uiuc.edu/animalbiology/105/ID: eee105Password: prAIRie

Lec 14 18Feb02

Plant-animal coevolutionPlant-animal coevolution

Plant-animal coevolutionPlant-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 defensese.g. the flavors of vegetablese.g. the flavors of vegetables

Why aren’t all the plants eaten?

Plants have evolved chemical defenses

Why aren’t all the plants eaten?Why aren’t all the plants eaten?

Plants have evolved chemical defensesPlants have evolved chemical defenses

milkweedmilkweed is toxicis toxic but a few insects have evolved resistancebut a few insects have evolved resistance

Why aren’t all the plants eaten?Why aren’t all the plants eaten?

Plants have evolved chemical defensesPlants have evolved chemical defenses

milkweedmilkweed is toxicis toxic but a few insects have evolved resistancebut a few insects have evolved resistance

milkweed bug is toxicmilkweed bug is toxic

and has evolved warning colorationand has evolved warning coloration

Why aren’t all the plants eaten?Why aren’t all the plants eaten?

Plants have evolved chemical defensesPlants have evolved chemical defenses

milkweedmilkweed is toxicis toxic but a few insects have evolved resistancebut a few insects have evolved resistance

monarch butterflymonarch butterfly caterpillarcaterpillar isis toxictoxic

Why aren’t all the plants eaten?Why aren’t all the plants eaten?

Plants have evolved chemical defensesPlants have evolved chemical defenses

milkweedmilkweed is toxicis toxic but a few insects have evolved resistancebut a few insects have evolved resistance

monarch butterflymonarch butterfly isis toxic tootoxic too

andand has evolved bright warning colorshas evolved bright warning colors

Why aren’t all the plants eaten?Why aren’t all the plants eaten?

Plants have evolved chemical defensesPlants have evolved chemical defenses

milkweedmilkweed is toxicis toxic but a few insects have evolved resistancebut a few insects have evolved resistance

viceroy butterflyviceroy butterfly isis notnot toxictoxic

butbut has evolved bright warning colorshas evolved bright warning colors

a mimica mimic

Why aren’t all the plants eaten?Why aren’t all the plants eaten?

Plants have evolved chemical defensesPlants have evolved chemical defenses

milkweedmilkweed is toxicis toxic but a few insects have evolved resistancebut a few insects have evolved resistance

Plant-animal coevolutionPlant-animal coevolution

plants evolved fruitsplants evolved fruits

Plant-animal coevolutionPlant-animal coevolution

plants evolved fruitsplants evolved fruits to “persuade” animals to disperse seedsto “persuade” animals to disperse seeds

Are humans evolving?

Yes but in surprising waysDarwin’s Descent of Man

and Selection in Relation to SexDarwin’s Darwin’s Descent of ManDescent of Man

and Selection in Relation to Sexand Selection in Relation to Sex

Sexual selectionSexual selection

bizarre, “useless” ornamentationbizarre, “useless” ornamentation bizarre, “useless” ornamentationbizarre, “useless” ornamentation secondary sexual characteristicssecondary sexual characteristics

Sexual selectionSexual selection

bizarre, useless ornamentationbizarre, useless ornamentation bizarre, useless ornamentationbizarre, useless ornamentation secondary sexual characteristicssecondary sexual characteristics

Sexual selectionSexual selection

bizarre, useless ornamentationbizarre, useless ornamentation bizarre, useless ornamentationbizarre, useless ornamentation secondary sexual characteristicssecondary sexual characteristics

Sexual selectionSexual selection

bizarre, useless ornamentationbizarre, useless ornamentation bizarre, useless ornamentationbizarre, useless ornamentation secondary sexual characteristicssecondary sexual characteristics

rainbow darter

Sexual selectionSexual selection

bizarre, useless ornamentationbizarre, useless ornamentation bizarre, useless ornamentationbizarre, useless ornamentation secondary sexual characteristicssecondary sexual characteristics

in humansin humans

female choiceSexual selectionSexual selection

female choiceSexual selectionSexual selection

the naked ape ?

racial differences?

female choiceSexual selectionSexual selection

male combat why mammalian males are larger than females

female choiceSexual selectionSexual selection

male combat male combatmale combat

Sexual selection

female choiceSexual selectionSexual selection

male combat why mammalian males are larger why mammalian males are larger than females than females

in most species females are in most species females are

the larger sex the larger sex

male combat male combat

in most species females arein most species females are

the larger sexthe 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 effecte.g. polydacytyly

Population bottlenecksPopulation bottlenecks

World population of cheetahs is smallWorld population of cheetahs is small

20,00020,000 genetically identicalgenetically 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