chapter 17-4: patterns of evolution essential question: what are 5 important patterns of...

Chapter 17-4: Patterns of Chapter 17-4: Patterns of EvolutionEvolution

Essential Question:Essential Question:What are 5 important patterns of What are 5 important patterns of macroevolution?macroevolution?

Mass extinctionsMass extinctions Several mass extinctions shown in fossil Several mass extinctions shown in fossil

recordrecord Effect is to leave many habitats open for Effect is to leave many habitats open for

surviving speciessurviving speciesOften a burst of evolution follows mass extinctionsOften a burst of evolution follows mass extinctions

Adaptive radiationAdaptive radiation Single species evolves into several different Single species evolves into several different

forms that live in different waysforms that live in different ways

Convergent evolutionConvergent evolution UnrelatedUnrelated organisms that look remarkable organisms that look remarkable

similar to each othersimilar to each other Cause is both species are evolving in similar Cause is both species are evolving in similar

environmentsenvironmentsSelection pressures are similar on traitsSelection pressures are similar on traits

Ex: sharks and dolphinsEx: sharks and dolphins

CoevolutionCoevolution 2 species evolve in response to changes in 2 species evolve in response to changes in

each other over timeeach other over time Ex: Ex:

flowers & pollinating animalsflowers & pollinating animalsPoisonous plants & resistent insectsPoisonous plants & resistent insects

Punctuated equilibriumPunctuated equilibrium Modification of Darwin – he was a Modification of Darwin – he was a ““gradualistgradualist”” Fossil record indicates long periods of little Fossil record indicates long periods of little

evolution evolution ““punctuatedpunctuated”” with periods of rapid with periods of rapid change in specieschange in species