Why are really old Fossils are hard to come by? -The remains decay. -Special circumstance embed bones into rocks or images of animals like the Trilobites I recommend visiting the Museum of Science and Industry. How would you date fossils from rocks?
What is an example of a homologous Structure? Birds wing to mans arm, or horse leg
Analagous- similar to the word analogy: A comparison between two different situations that have something in common
Does anyone have any examples of selective breeding? Tell the class about Cats I am waiting until they breed cats they have less of a chemical that causes allergic reactions because I love cats, but allergic to them
Unit 8 evolution for moodle
Unit 8 Evolution
What is Evolution? A well-supported scientific theory stating that organisms change over time
Evidence in stone Preserved remains of a once living organism is called a FOSSIL Fossil evidence supported that organisms changed gradually
Anatomical Evidence Comparative Anatomy: study of similarities and differences between organisms Homologous Structures Analogous Structures Vestigial Organs
Homologous StructuresAs similar organisms adapt to differentenvironments, the function of their appendageschanged A bird’s arms became wings to flap A human’s arm is used to pick-up, carry, grasp, etc… A horse’s arm became a fore-leg to run on
Analogous Structures Different organisms began living in similar environments, their appendages evolved to perform the same function A butterfly has wings to fly that are made from an exoskeleton A sparrow has wings to fly that have an endoskeleton Butterfly Bird
Vestigial Structures Structures which remain in organisms but have no obvious function Leg bones in snakes and whales Appendix in humans ** Ear muscles in humans
Comparative EmbryologyExamining theembryos oforganismsOrganisms withsimilar embryos arethought to be moreclosely related
Biochemical Evidence(aka Molecular Biology)Comparison of the amino acid and DNAsequences Chimp and human hemoglobin are VERY similar
Genetic Evidence DNA passes on traits When mutations occur the genes and chromosomes can change Humans have imposed change through selective breeding The higher the percentage of similarities the closer the relationship between two organisms
Jean Baptiste de Lamark First to recognize that organisms change Published his hypotheses in 1809 Theory was disproved!
Jean Baptiste de Lamark3 Key Assumptions: Desire to Change: organisms have an inborn urge to better themselves Law of Use and Disuse: body parts that are used will develop; those not used will become smaller/disappear Inheritance of Acquired Characteristics: organisms pass on traits acquired during their lifetime
Charles DarwinCredited for the theory of evolutionHMS Beagle sailed in 1831 – Galapagos IslandsPublished Origin of Species in 1858
Darwin’s Observations Observed tortoises, iguanas, and finches The islands had different climates and vegetation The animals were similar… but had noticeable differences WHY?
Darwin’s AssumptionsVariations Differences among members of the same speciesStruggle for Existence Predation and competitionOverproduction More offspring are produced than will surviveSurvival of the Fittest (Natural Selection) Individuals best suited for the environment will survive, reproduce, and pass on traits to their offspringDescent with Modification Principle that species change but descend from common ancestors
Darwin’s Theory of Natural Selection Variations help members of a species to survive in a given environment The environment selects the beneficial adaptation and over time this trait will become more prevelant
Fossil FormationWater carries small Dead organisms are buried The preserved remainsrock particles to lakes by layers of sediment, may later be discoveredand seas which forms new rock and studied.
Fossil RecordPreserved remains of a once livingorganism is called a FOSSIL IE: amber, sedimentary rock, tar, and iceFossil record is incomplete
Relative Dating Used to ESTIMATE the age of fossils Older fossils are in deeper layers of rock
Genes and EvolutionIn terms of genetics, evolution is the change infrequency of alleles in a population’s genepoolNatural selection leads to change in gene frequencyMolecular clocks use mutation rates to estimatehow recent a common ancestor was
Hox GenesGenes which control an organism’s basic body plan Anterior/posterior ends Limbs, wings
Genetic DriftChanges in the genepool of a smallpopulation due torandom chance ex: small group colonizes a new habitat – founder effect
SpeciationGradualism – change in speciesis slow and steadyPunctuated Equilibrium – longperiods of stability followed byshort periods of rapid change
Hominine Evolution Ardipithecus ramedus “Ardi”, 4.4 mya Australopithecus afarensis “Lucy”, 3.2 mya Homo habilis “handy man”, ≈ 2 mya Used tools, first of the genus Homo Homo erectus, “Java Man”, ≈ 1.6 mya 1st to use fire Homo neanderthalensis ≈ 200,000 years ago Homo sapien Modern Human ≈ 100,000 years ago