2 Survival of the Fittest? Is this what Darwin meant?
3 Natural SelectionThe process by which organisms with favorable traits survive and reproduce at a higher rate than organisms without the favorable trait
4 Natural Selection Organisms - Better able to survive and reproduce in an environmentMore likely to pass their traits on to future generationsTraits improve chances of survival or reproductionLikely to accumulate in a population after several generationsTraits are “selected”
5 Natural Selection in Four Steps OverproductionGenetic VariationStruggle to SurviveSuccessful Reproduction
6 More individuals are born than will become adults. OverproductionMore individuals are born than will become adults.
7 Genetic Variation Individuals Not exactly the same Have own set of traits (size, color and the ability to find food)Some traits more likely to survive and reproduceOther traits less likely for survival and reproduction
8 Struggle to Survive Environment Individuals Not able to support all of the individuals bornIndividualsKilled by other organismsDo not find matesOnly some will become adults and reproduce
9 Successful Reproduction Individuals and Their EnvironmentWell AdaptedMore likely to surviveMore likely to reproduceTraits likely to be selectedNot Well AdaptedMore likely to die earlyHave few offspringTraits less likely to be selected
10 Survival of the Fittest Key to Natural Selection – HeredityTraits passed from one generation to the nextNo reproduction – genes will not be passed onCharacteristicsSurvival vs. ReproductionPeacock’s bright feathersFlower’s colorEasily spotted by predators/dull and dark colors will not find mateFlowers ultraviolet light – pollination
11 Natural Selection in Action PopulationChanges in response to its environmentTends to be well adapted to its environmentEnvironment changes too quicklySome organisms may not surviveOnly organisms with certain traits are able to survive and reproduce in the new environment
12 Natural Selection in Action ExamplesInsecticide ResistanceAdaptation to HuntingIndustrial MelanismButterfly Story
14 Adaptation to Hunting Tusks of Male African Elephant 1930 – 99% born with tusksPresent – as few as 85% have tusksMales with tusks killed therefore could not reproduceMales without tusks able to reproduceIf this trend continues tuskless elephants will outnumber elephants with tusksMales did not lose tusks, tuskless elephants were able to pass on their traits
16 How has predation influenced evolution? Adaptations to avoid being eaten:Spines (cactii, porcupines)Hard shells (clams, turtles)Toxins (milkweeds, dart frogs)Bad taste (monarchs)CamouflageMimicryAposematic colors
17 Quiz Adaptation and Survival Stripes on a tiger – Song of a bird – How does this characteristic help with survival or successful reproductionStripes on a tiger –Song of a bird –Ears of an elephant –Poison of a rattle snake –Glow of a firefly –Antler of a male deer –Bright flowers of a rose –
18 Quiz Adaptation and Survival Stripes on a tiger - How does this characteristic help with survival or successful reproductionStripes on a tiger -Camouflage for huntingSong of a bird –Attracts mate/defends territory
19 Quiz Ears of an elephant – Prevent overheating Poison of a rattle snake –Capture of prey, protectionfrom predators
20 Quiz Glow of a firefly – Attracts mate Antler of a male deer – Defends right to mate
21 QuizBright flowers of a rose –Attract pollinators
22 VOCABULARY REVIEW EVOLUTION – CHANGE OVER TIME NATURAL SELECTION - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE.A.K.A. “SURVIVAL OF THE FITTEST”
28 3 ISOLATING MECHANISMS…….. BEHAVIORAL ISOLATION- CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS)GEOGRAPHICAL ISOLATION – SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL)TEMPORAL ISOLATION – 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES.
32 5. Geologists: Hutton and Lyell Fundamentalists said that the earth was around 6000 years oldHutton and Lyell argued that the earth is many millions of years old b/clayers of rock take time to formprocesses such as volcanoes and earthquakes shaped the earth and still occur today
33 Lamark Theory of acquired characteristics Lamark said organisms acquired traits by using their bodies in new waysThese new characteristics were passed to offspringLamark was totally wrong!
40 11. Natural Selection and Species Fitness Overtime, natural selection results in changes in the inherited characteristics of a population.These changes increase a species fitness (survival rate)
41 Descent with Modification Each living species has descended with changes from other species over time
42 Summary of Darwin’s Theory 1. Organisms differ; variation is inherited2. Organisms produce more offspring than survive3. Organisms compete for resources4. Organisms with advantages survive to pass those advantages to their children5. Species alive today are descended with modifications from common ancestors
43 13. Evidence of Evolution Fossil Record Geographic Distribution of Living SpeciesHomologous Body structuresSimilarities in Embryology
44 Evidence of EvolutionFossil Record provides evidence that living things have evolvedFossils show the history of life on earth and how different groups of organisms have changed over time
46 Relative Dating Can determine a fossil’s relative age Performed by estimating fossil age compared with that of other fossilsDrawbacks – provides no info about age in years
47 Absolute dating Can determine the absolute age in numbers Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remainDrawbacks - part of the fossil is destroyed during the test
48 13. Evidence of Evolution Geographic Distribution of Living Species Similar animals in different locations were the product of different lines of descent
50 13. Evidence of Evolution Homologous Body Structures TurtleHomologous Body StructuresStructures that have different mature forms but develop from the same embryonic tissuese.g. Wing of bat, human arm, leg of turtleAlligatorBird