Emergence of Evolutionary Thought Evolution: Change in populations of organisms over time Early...
-
Upload
sherilyn-obrien -
Category
Documents
-
view
218 -
download
1
Transcript of Emergence of Evolutionary Thought Evolution: Change in populations of organisms over time Early...
Emergence of Evolutionary ThoughtEmergence of Evolutionary Thought
Evolution:Evolution: Change in populations of organisms over time Change in populations of organisms over time
Early Explanation of life’s diversityEarly Explanation of life’s diversitySpecies individually created at one time and one placeSpecies individually created at one time and one place
Questions arising from such thoughtsQuestions arising from such thoughtsWhy were organisms different in different regions of earth?Why were organisms different in different regions of earth?Why are current organisms different from ancient organisms?Why are current organisms different from ancient organisms?If each species is different, why are there the same fundamental If each species is different, why are there the same fundamental structures (bone plans) that do different things in animals?structures (bone plans) that do different things in animals?
New IdeasNew IdeasScientists thought that species changed over timeScientists thought that species changed over time
Both animals, though very different, Both animals, though very different, exhibit similar wing structuresexhibit similar wing structures
Extinction, fossil record, and Carbon-14 dating Extinction, fossil record, and Carbon-14 dating suggest that organisms arose (and became suggest that organisms arose (and became
extinct) at different time periods extinct) at different time periods
Chimps- Arose on earth ~6 million years ago
Dinosaurs- Arise ~ 200 mya- Dinosaurs- Arise ~ 200 mya-
Extinct 65 myaExtinct 65 mya
Woolly Mammoth- Extinct Woolly Mammoth- Extinct 4500 years ago4500 years ago
Different regions of planet have animals Different regions of planet have animals with unique traits that help them survivewith unique traits that help them survive
New IdeasNew Ideas
Scientists thought that species changed over timeScientists thought that species changed over time
Lamarck’s Disproven Theory of EvolutionLamarck’s Disproven Theory of Evolution
Jean Baptiste LamarckJean Baptiste Lamarck
Believed that an animal’s physical Believed that an animal’s physical
needs determine its development and genesneeds determine its development and genes
Exp. GiraffeExp. Giraffe
Early Giraffes stretched their necks to feedEarly Giraffes stretched their necks to feed
Long neck was then passed off to offspringLong neck was then passed off to offspring
WRONG!!!WRONG!!!
Charles Darwin 1809-1882Charles Darwin 1809-1882Putting the Picture TogetherPutting the Picture Together
Darwin Travels to the Galapagos IslandsDarwin Travels to the Galapagos Islands
Witnessed tremendous diversity of animal lifeWitnessed tremendous diversity of animal life
Fascinated by differences among beaks on finchesFascinated by differences among beaks on finches
Becomes convinced that species change over timeBecomes convinced that species change over time
Young bull
Old bull
Thomas Malthus & Charles DarwinThomas Malthus & Charles Darwin
Malthus Malthus
Populations tend to grow faster than the Populations tend to grow faster than the food supply needed to feed itfood supply needed to feed it
Charles Lyell & Charles DarwinCharles Lyell & Charles Darwin
LyellLyell
Changes occur over time in geology; land Changes occur over time in geology; land formations move and topography changesformations move and topography changes
Darwn’s Descent with ModificationDarwn’s Descent with ModificationEvolutionary pathway resembled a branched treeEvolutionary pathway resembled a branched tree
NOT a ladder from lower forms to higher formsNOT a ladder from lower forms to higher forms
No species that exists today was an ancestor to another living speciesNo species that exists today was an ancestor to another living species
Darwin’s ObservationsDarwin’s Observations•Individuals in a population vary, some of these variations are Individuals in a population vary, some of these variations are inheritableinheritable•Populations produce more offspring than the environment’s food, Populations produce more offspring than the environment’s food, space, and other assets.space, and other assets.•Therefore, species compete for resourcesTherefore, species compete for resources
Lions and cheetahs compete for foodLions and cheetahs compete for food
Dolphins compete for baitfishDolphins compete for baitfish
The Mechanism of Natural SelectionThe Mechanism of Natural SelectionNatural Selection Natural Selection greater reproductive success displayed by greater reproductive success displayed by individuals with favorable traitsindividuals with favorable traits
Nature selects that are passed on to the next generationNature selects that are passed on to the next generation
VariationVariation differences within a population differences within a population
AdaptationsAdaptations traits that are selected for because they help an traits that are selected for because they help an organism survive and reproduceorganism survive and reproduce
Evolution occurs when genes in a population change shift to enhance Evolution occurs when genes in a population change shift to enhance survival and reproductionsurvival and reproduction
Exp. GiraffeExp. Giraffe
How Do Variations Arise?How Do Variations Arise?•Natural selection IS NOT the cause of variationNatural selection IS NOT the cause of variation
•Mutation-> Random changes in DNA sequences in the parents genomeMutation-> Random changes in DNA sequences in the parents genome
•Gene ShufflingGene Shuffling mixing of parental chromosomes can create new mixing of parental chromosomes can create new genetic combinationsgenetic combinations
•Variation arises randomly. Variations are then selected on by nature. Variation arises randomly. Variations are then selected on by nature.
•Variations which are selected for are called adaptationsVariations which are selected for are called adaptations
Adaptations and SpeciationAdaptations and SpeciationTypes of Adaptations Types of Adaptations
Structural Adaptations Structural Adaptations Involve structure or anatomy Involve structure or anatomy
Bird’s beak, Anteaters sticky tongueBird’s beak, Anteaters sticky tongue
Physiological Adaptations Physiological Adaptations Functions in organisms Functions in organisms
Poison Venom in a snake, ink of an octopusPoison Venom in a snake, ink of an octopus
Behavioral Adaptations Behavioral Adaptations Behavior aids in survival and reproduction Behavior aids in survival and reproduction
Wildabeasts/ Caribou/ Bird MigrationWildabeasts/ Caribou/ Bird Migration
Wolves Hunt in Packs Wolves Hunt in Packs
Fish swim in schoolsFish swim in schools
Species & SpeciationSpecies & SpeciationSpecies Species group of organisms that can interbreed and produce fertile group of organisms that can interbreed and produce fertile offspringoffspring
Horses + Donkey = Mule…Not the same species Horses + Donkey = Mule…Not the same species
Human male + human female = human baby…same species!Human male + human female = human baby…same species!
HorseHorse DonkeyDonkey MuleMule
Speciation Speciation Organisms which are separated by distance + gene pool Organisms which are separated by distance + gene pool will no longer interbreed. Each group becomes new specieswill no longer interbreed. Each group becomes new species
Types of Natural SelectionTypes of Natural Selection
Directional Selection Directional Selection shifts a population toward one extreme form of shifts a population toward one extreme form of a traita trait
Example: 4 million years ago; heavy cheetahsExample: 4 million years ago; heavy cheetahs
Over time, light, fast animals reproduced more successfullyOver time, light, fast animals reproduced more successfully
Natural selection favored the genes that pushed the cheetah’s weight in Natural selection favored the genes that pushed the cheetah’s weight in one direction…lighterone direction…lighter
Types of Natural SelectionTypes of Natural SelectionStabilizing SelectionStabilizing Selection shifts a population toward intermediate shifts a population toward intermediate (medium) traits(medium) traits
Example: Most human babies weight ~ 7poundsExample: Most human babies weight ~ 7pounds
Disruptive Selection Disruptive Selection Extreme phenotypes are more common Extreme phenotypes are more common
Example: African butterflies appear as either bright orange or bright Example: African butterflies appear as either bright orange or bright blueblue
These colors mimic other butterflies that are foul-tasting; less likely to These colors mimic other butterflies that are foul-tasting; less likely to be eatenbe eaten
Intermediate butterflies look like neither, and are more likely to be eatenIntermediate butterflies look like neither, and are more likely to be eaten
Patterns of EvolutionPatterns of EvolutionSpecies become dissimilar or more alike over timeSpecies become dissimilar or more alike over time
Gradual Change Gradual Change Genetic changes occur slowly over many Genetic changes occur slowly over many generationsgenerations
Divergent Evolution Divergent Evolution Single population is split into 2 or more Single population is split into 2 or more populations.populations.
Exp. Ground squirrels in the Grand Canyon were split into 2 Exp. Ground squirrels in the Grand Canyon were split into 2 populations after canyon widenedpopulations after canyon widened
Patterns of EvolutionPatterns of Evolution
Adaptive Radiation Adaptive Radiation Organisms occupy different niches in an Organisms occupy different niches in an environment and diverge from one anotherenvironment and diverge from one another
Exp. Darwin’s FinchesExp. Darwin’s Finches
Convergent Evolution Convergent Evolution 2 dissimilar species evolve in ways to make 2 dissimilar species evolve in ways to make them LOOK more similarthem LOOK more similar
Exp. Sugar GlidersExp. Sugar Gliders winged marsupials in Australia winged marsupials in Australia
Flying Squirrels Flying Squirrels Winged squirrels in Northern Hemisphere Winged squirrels in Northern Hemisphere
Sugar GliderSugar Glider Flying SquirrelFlying Squirrel
Pace of EvolutionPace of EvolutionGradualism Gradualism Over time, new species arise as environment change Over time, new species arise as environment change
If true, we should see intermediate species in fossil record…not always If true, we should see intermediate species in fossil record…not always truetrue
Punctuated Equilibrium Punctuated Equilibrium Species exist for long periods of time Species exist for long periods of time without changes, then large changes occur over short periods of timewithout changes, then large changes occur over short periods of time
Populations & Evolution• Larger populations tend to have more genetic variation• Smaller populations tend to have less genetic variation• Genetic Drift/Founder Effect Loss of genetic variation
due small population sizes. Extinction more likely• 10,000 years ago, almost all cheetahs go extinct due to
climate changes. Resulting cheetahs have little genetic diversity
Evidence for EvolutionEvidence for EvolutionFossil Fossil trail of animal that is preserved in rock trail of animal that is preserved in rock
Found in Sedimentary RockFound in Sedimentary Rock
Fossils show overall structural scheme of how living things evolvedFossils show overall structural scheme of how living things evolved
Body schemeBody scheme
Feeding behaviorFeeding behavior
MobilityMobility
Society?Society?
New fossils in upper layers, older fossils in lower layersNew fossils in upper layers, older fossils in lower layers
ExamplesExamplesBurgess ShaleBurgess Shale
Location : British Columbia, CanadaLocation : British Columbia, Canada
Development: Foot of continental shelfDevelopment: Foot of continental shelf
Organisms: Early Marine worms (Hallucigenia)Organisms: Early Marine worms (Hallucigenia)
Badlands, SDBadlands, SD
Development: Shallow oceanDevelopment: Shallow ocean
Organisms: Early Squid, octopusOrganisms: Early Squid, octopus
BadlandsBadlands
ImportanceImportanceLand masses moveLand masses move
Were once covered under oceanic waterWere once covered under oceanic water
Species adapt and go extinct Species adapt and go extinct
Comparative AnatomyComparative AnatomyHomologous structuresHomologous structures Similar structures in related organisms Similar structures in related organisms
Suggests that organism arose from a common ancestorSuggests that organism arose from a common ancestor
Exp. Cheetah forelimb = human handExp. Cheetah forelimb = human hand
Wing = Whale flipperWing = Whale flipper
Vestigial OrgansVestigial OrgansOrgans with no apparent use, but resemble functional structures in Organs with no apparent use, but resemble functional structures in ancestorsancestors
Whale PelvisWhale Pelvis
Whale femurWhale femur
Wisdom TeethWisdom Teeth
AppendixAppendix
Comparative EmbryologyComparative EmbryologyOrganisms with common descent have similar organsOrganisms with common descent have similar organs
Vertebrates breathe though lungsVertebrates breathe though lungs
As embryos, vertebrates have gills (turns into Eustachian tube)As embryos, vertebrates have gills (turns into Eustachian tube)
BiochemistryBiochemistryCommon ancestors have similar fundamental body chemistryCommon ancestors have similar fundamental body chemistry
Most organisms have:Most organisms have:
Same 4 bases in DNASame 4 bases in DNA
Same 20 AASame 20 AA
BiogeographyBiogeographyStudy of species distribution on Galapagos Islands look similar to Study of species distribution on Galapagos Islands look similar to South American speciesSouth American species
Each island would have to had it own special creation event for each Each island would have to had it own special creation event for each species; more likely migrated from South Americaspecies; more likely migrated from South America
Direct EvidenceDirect EvidenceBacteria & AntibioticsBacteria & Antibiotics
Fruit Flies (Drosophila)Fruit Flies (Drosophila)
Artificial SelectionArtificial selection (or selective breeding) describes intentional breeding for certain traits, or combination of traits
Dogs are a prime example.
Bulldogs selectively bred for increasingly large heads. Most bulldogs delivered via Caesarian Section. Trait not favored in nature, but selected for by humans