Evolution Natural Selection Charles Darwin proposed Theory of

Evolution

Natural Selection • Charles Darwin proposed Theory of Evolution in 1869 • Observed that single organisms in a population were different • They must be different for a reason

Natural Selection • Some traits made survival easier; some didn’t • Traits passed on to offspring–heredity • Those who died did not have the right adaptation and couldn’t pass on their unsuccessful traits. • After many generations, organisms in the population may develop the same trait— evolution

Coevolution • Two different species evolving because of their relationship • Plants these butterflies use have no smell and the butterfly can’t smell well.

Coevolution • Flies are attracted to the smell of rot. The flower of this plant smells like rot to attract the fly and beetles.

Coevolution • Bees don’t see the color red, but are attracted to purples and yellows

Coevolution • Some animals have few natural defenses, so their adaptation is to look like the environment

Coevolution • Poisonous passionflower leaves are edible to a certain butterfly larvae, protecting the eggs from predators • The leaves got eaten, but now the plant produces little nectarines to look like butterfly eggs, slowing the egg laying

Artificial Selection • Pets are breed for a specific reason: cute, tough, fierce, light, etc. . . • Crops are breed for sweetness, toughness, temperature tolerance, health, pest resistance, etc. . .

Evolution of Resistance • We develop things with traits that may become unwanted later • Organisms have different traits to provide a variety of ways to survive • Take away those differences and one thing can kill all in that population

• The insects naturally select the best trait so they can survive.