7 And then their babies have long necks, too! Lamarck’s theoryAnd then their babies have long necks, too!
8 Darwin’s theoryAt first, there are some long-necked giraffes and some short-necked giraffes. Only the long necked can reach the leaves.
9 The short-necked giraffes are more likely to die of hunger. Darwin’s theoryThe short-necked giraffes are more likely to die of hunger.
10 Darwin’s theoryThe long necked giraffes have babies that will also have long necks when they grow up.
11 Write/Pair/Share What is another possible reason for giraffe necks to have evolved for length? Write at least 2 lines!
12 Natural SelectionCharles Darwin & Alfred Wallace both suggested the theory of natural selectionNatural Selection – organisms best suited for the environment reproduce more successfully than othersThe favorable trait increases in a populationMaking a population the smallest unit able to evolve
13 Charles Darwin H.M.S. Beagle Read books by Charles Lyell (geologist) placing an emphasis on uniformitarianismDarwin observed various habitats and considered that these changes of earth played a part in the adaptation of organisms
14 Darwin’s Data Traveled all over the world Galapagos Islands Collected species of all types of animalsCompared animals from each destinationGalapagos IslandsCollected beetles and finches13 species of finchesObserved tortoises
15 Darwin’s FinchesBased theories on the 13 species of finches collected in the GalapagosHypothesized that the finches all evolved from a common ancestor (originating in South America)The environments of each island produced different challengesThe finches would have to overcome these different environments to survive.
17 Darwin’s Theories Descent with Modification Newer forms in the fossil record are modified descendants of older speciesReproduction allows species to change over timeProposed that ALL organisms descended from a few ancestors with changes
18 Natural Selection HOW descent with modification occurs Influenced by Thomas MalthusPopulations can double and redoubleHuman population is limited by adverse conditionsTheorized that the environment was the limiting factor for populationsSome organisms have traits that make them better fit to respond to certain environmental pressuresOrganisms better fit reproduce more and pass on the favorable traitsIndividuals in a population would respond to environmental changes differently because they are not identicalA population adapts BECAUSE the favorable trait from a few individuals is passed down
19 REMEMBER Natural selection is not an ACTIVE process Meaning that you can’t MAKE yourself changeTraits (ALLELES) MUST be present in a population for evolution to occurVariation exists among individuals in a species.Individuals of species will compete for resourcesSome competition would lead to the death of some individuals while others would surviveIndividuals that had advantageous variations are more likely to survive and reproduce.
20 Evidence of Evolution The Fossil Record What is a fossil? A fossil is the remnants of an organismFound in sedimentary rockTypes of fossils:Mold – imprint in rock in the shape of the organismCast – a rock-like model of the organism
21 Distribution of Fossils Nicholas Steno – Law of SuperpositionSuccessive layers of rock or soil were deposited on top of one anotherLowest strata (stratum) is the oldestObserving these strata allows them to determine the relative age of a fossil and the absolute age
22 Studying FossilsThe fossil record tells us that organisms appeared for awhile and then died offMass ExtinctionsEvidence in fossils shows us that there are periods where large numbers of species disappearedCaused by environmental changes
23 Transitional SpeciesOrganisms that have features that are intermediate between hypothesized ancestors and current species.Hypothesis that whales descended from land mammals based on a sequence of transitional forms.
25 This is what Darwin did with the finches, turtles and beetles!!! BiogeographyScientists study the distribution of fossils and living relatives to help determine how organisms have changedSimilarities between fossils and living organisms allows us to make connections with our ancestorsThis is what Darwin did with the finches, turtles and beetles!!!
26 Comparative Anatomy & Physiology Examining the structure & function of organismsHomologous StructuresSame structure but has a different functionEvolved from a common ancestor
27 Analogous Structure Same function but different structure Evolved from a different ancestor but faced similar pressures
28 Vestigial StructuresOrgan or structure that was useful to an ancestor but now has no use to the current organismExamplesAppendix in humansPelvic and limb bones in snakesLeg bones in whales
29 Macromolecules Genetic Evidence Embryology Examination of major macromolecules in organisms (specifically proteins)Genetic EvidenceDNA and RNA - Similarities in these molecules are evidence that organisms evolve from common ancestorsEmbryologyEarly stages of development are strikingly similar in organismsThe more closely the development, the more closely they are related
30 Fish, salamander, tortoise, chick, hog, calf, rabbit and human
31 Evolution in ActionInteractions between species and environmental pressures continue to drive evolution
32 Types of EvolutionCo evolution – Change of two or more species in close association with each otherPredators and prey, parasites and hostsFlowers and pollinators
34 Convergent Evolution– unrelated species evolve due to similar environmental pressures Shark and porpoise, bird and bee
35 Divergent Evolution – two or more related species evolve from a common ancestor Species DIVERGE (separate)Adaptive radiation – many species evolve from a common ancestorArtificial selection – divergence is sped up by choosing the parents of offspring (found in dogs)
36 Parallel EvolutionSimilar to convergent but this happens in SAME environmentWhen two different species in the same type of environment develop the same adaptations for survival, it is considered parallel evolution