17.4

Macroevolutionlarge scale evol. Patterns

Extinctionmore than 99% of org. that were, are not

Extinction

Mass extinctionfood webs wiped out

cretaceous period- huge asteroidMost mass extinctions

several causes

Adaptive radiation

Several species can evol. From one speciesex: darwin’s finches (13 species from 1)

Convergent evolutionunrelated org. react to similar env. And evolve to look very alike

Ex- many unrelated aquatic species have similar body shapes

Coevolutionorg. that are evolving in response to each other

Flowers and insects (pollinators) Ex- orchid changed to have pollinator

40 cm down the flower--- insect with 40 cm structure to get nectar

Punctuated equilibriumunlike what Darwin thought (slow changes) there is a time with no change and then period with a lot of changes

Changes in dev. genes/body plans One change in one gene can turn on or

off dif. CharacteristicsEx- ancient insects wings on all

segments, modern insects have one segment with wings