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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?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 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
male combat why mammalian males are larger than females
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
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
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