Natural Selection and Evolution!

Why two types of clover? What advantages does the striped clover have? The plain? How does cyanide help/hurt these plants in different habitats?

Organisms have variation Same species (Trifolium repens), different characteristics Variation = differences among individuals of one species; different forms of same trait (ex: eye colors)

Variation helps organisms adapt Adaptation = inherited characteristic, increases an organism’s chance for survival Fitness = ability of an individual to survive and reproduce in its environment Which clover is more “fit?” Why?

Variation allows for Selection Humans and nature “choose” which organisms win and get to procreate Artificial selection = human select most useful variations, allow those to reproduce ex: race horses - what trait would be selected for? ex: broccoli and other veggie friends

The struggle for existence Resources are limited, so only some can survive Natural Selection = individuals better adapted to their environment survive, reproduce, and pass on their genes AKA “survival of the fittest” leads to change over time (EVOLUTION!)

Natural Selection - Ex: Darwin’s Finches Beak size and shape vary - all descended from common ancestor but changed over time

Evolution by Natural Selection Descent with modification = over time, natural selection produces organisms with differences from their ancestors Different food sources, habitats, body parts, behaviors Implies that living things are all related, have a common ancestor (common descent)

Common Descent - one ancestor in the past Phylogenetic tree - distance between organisms is directly related to differences in genes (short distance = few differences, long = many)