The proliferation of species:

Darwin and Mechanisms of Evolution The theory and why it works

Causes of Evolution:

Fossil Record: Evidence of Evolution Indicates life began 3 byaIndicates life began 3 bya Prokaryotes then Eukaryotes then multicellular EukaryotesProkaryotes then Eukaryotes then multicellular Eukaryotes Fossil record determines:Fossil record determines: When species appearedWhen species appeared The type of environmentThe type of environment When/if species became extinctWhen/if species became extinct

Darwin: Brain Pop Video Darwin: Brain Pop Video

What does the theory say? Theory b/c lots of evidence but not enough to make it a lawTheory b/c lots of evidence but not enough to make it a law States that:States that: Variations in individuals can lead to changes in whole speciesVariations in individuals can lead to changes in whole species

Natural Selection: The Idea Behind the Theory Evolution controlled by NATURAL processesEvolution controlled by NATURAL processes THE PROCESS IS:THE PROCESS IS:LIVE + BREED + PASS ON GENETIC INFO = SURVIVAL OF SPECIES = SURVIVAL OF SPECIES “Survival of Fittest”“Survival of Fittest” Those best ADAPTED will be able to DO THE PROCESSThose best ADAPTED will be able to DO THE PROCESS

Results of Natural Selection Short term result:Short term result: Best fit (adapted) will pass on GOOD genes to offspringBest fit (adapted) will pass on GOOD genes to offspring Long term result:Long term result: Change in frequency (number) of certain traitsChange in frequency (number) of certain traits Which do you think will increase in frequency GOOD OR BAD?Which do you think will increase in frequency GOOD OR BAD? GOOD OF COURSE! As more individuals have good trait, species is evolvingAs more individuals have good trait, species is evolving

What drives evolution? Interactions between individuals and the environment: 1.OVERPRODUCTION 2.STRUGGLE FOR SURVIVAL 3.GENETIC VARIATION 4.SELECTION BY THE ENVIRONMENT

Evolution Cause #1: OVERPRODUCTION POTENTIAL TO PRODUCE MORE OFFSPRING THAN WILL SURVIVEPOTENTIAL TO PRODUCE MORE OFFSPRING THAN WILL SURVIVE This means the best “fit” individuals will survive, grow and reproduce.This means the best “fit” individuals will survive, grow and reproduce. EX: DEER, FISHEX: DEER, FISH

Evolution Cause #2: STRUGGLE FOR SURVIVAL Overproduction leads to STRUGGLE within species: 1.O nly some live to reproduce 2.C ompetition for resources 3.B est competitors will live and breed Must STRUGGLE with environment also (disease, predators, temp changes etc) Those that withstand will survive!

Genetic importance and evidence of evolution

Evolution Cause #3: GENETIC VARIATION Variation must exist within survivorsVariation must exist within survivors Ex: Longer legs, bigger claws, diff. fur colorEx: Longer legs, bigger claws, diff. fur color Favored traits will stay in population and lead to evolutionFavored traits will stay in population and lead to evolution Adaptive Value:Adaptive Value: Describes a trait that helps an individual survive in a particular environmentDescribes a trait that helps an individual survive in a particular environment EX: polar bears have black skin; the black skin has adaptive value b/c it helps them surviveEX: polar bears have black skin; the black skin has adaptive value b/c it helps them survive

Evolution Cause #4: SELECTION BY ENVIRONMENT Traits w/ adaptive value benefit those individuals If reproduce, offspring have traits too Eventually, # of individuals with trait increases, and most all will have it! Therefore, adapting to environment DRIVES EVOLUTION!

Evolutionary Trees: Animals

Comparison of Human and Chimp Chromosomes

Actual Cartoons from Scope’s Trial, 1925