Presentation on theme: "Darwin and Mechanisms of Evolution The theory and why it works."— Presentation transcript:
Darwin and Mechanisms of Evolution The theory and why it works
Evidence of Evolution: The Fossil Record 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
What does the theory of evolution say? Theory b/c lots of evidenceTheory b/c lots of evidence Tested and re-tested by many scientistsTested and re-tested by many scientists 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 btw individuals and the environment: 1.OVERPRODUCTION 2.STRUGGLE FOR SURVIVAL 3.GENETIC VARIATION 4.SELECTION BY THE ENVIRONMENT
Evolution Cause #1: B. 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: C. 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!
Evolution Cause #3: D. 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 pop’n and lead to evolutionFavored traits will stay in pop’n 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: E. 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!