2 Scientific TheoryAn explanation of natural phenomenon supported by a large body of scientific evidence obtained from many different investigations and observations.
3 EvolutionA gradual change in a species (populations) through adaptations over time.Adaptation = some phenotypic feature or trait that improves an organism’s likelihood of survival and reproduction.In Georgia, there is a popular hunting area of forest called the Poopycack forest, where the Poopy Deer lives. This species of deer has 6 ears.How might this adaptation have occurred and how is it beneficial?What would you expect to happen to the Poopy Deer population in the next 1000 years?
4 Charles Darwin “Theory of Evolution by Natural Selection” Proposed that new species could develop through a process called Natural SelectionDuring his travels aboard HMS Beagle, made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time
5 Darwin’s VoyageDarwin studied animal species in the Galapagos Islands and found they each had unique adaptations
6 Darwin’s StudiesGalapagos finches demonstrate different adaptations to eat different kinds of foodsGalapagos tortoises are the biggest in the world
7 Natural Selection Acts on Phenotype rather than Genotype Those better suited for their environment will surviveThose least suited to their environment will die faster, leaving fewer offspring
8 Genetic variation is essential! Mutations_________ promote genetic variation, which helps ensure a species survivalLike crossing over!
9 How does a great number of species ensure that at least some organisms survive major changes in the environment?Those who are better at adapting will survive major changes in the environment
10 Natural Selection A mechanism for change in a population Natural Selection (NS) is responsible for most evolutionary change by selectively changing genetic variation through differentiated survival and reproduction.Goal - To be fit enough to survive and reproduceThree types of NS
11 Stabilizing Selection Favors average individuals in a populationThose individuals have a “selective advantage”.Reduces variation in a population
12 Directional Selection Favors one of the extreme variations of a traitCan lead to rapid evolution of a population
13 Disruptive Selection Favors both extreme variations of a trait Leads to evolution of two new species
14 Speciation A process of producing two individual species from one Members of the population no longer interbreed within their natural environment
15 Evidence for Evolution: 1. Fossil recordA piece of organism or imprint left behind.Fossils show that species have changed over time.2. Vestigial structuresBody structures that have shrunken and are not used anymore.3. Homologous structuresStructures that share a common ancestry and look/behave similarly.4. Embryology5. DNA homology, Amino Acid homology, Mitochondrial DNA, Photosynthetic Plant cells
16 Evidence For Evolution FossilsProvide a record of early life and evolutionary history
17 Geologic Strata (sedimentary layers) and Carbon Dating Defining age of fossils!Geologic Strata (sedimentary layers) and Carbon DatingCarbon-14 (remember isotopes?)Used to date any object composed of carbonRadioactive carbon decays over timecheck amount of C14 left in sample, enabling you to tell age of object
18 Did you know that whales have feet? Well, sort of….
19 Fossils help us determine whale evolution 60 millionyears ago50 millionyears ago40 millionyears agoYesterday
20 Vestigial StructuresHuman tail-bone, wisdom teeth, appendix (they have no purpose)Snake feet,Whale feet
21 Homologous Structures (derived from a common ancestral feature) Limb adapted to functionmeans the same!
22 Analogous Structures-similar in function but not structure
23 Evidence For Evolution EmbryologySimilarities among the young embryos suggest evolution from a distant, common ancestorBiochemistryComparing DNA and RNA
24 How do we know what happened when? Radiometric dating relies on half-life decay of radioactive elements to allow scientists to date rocks and materials directlyStratiography provides a sequence of events from which relative dates can be extrapolatedMolecular Clocks allow scientists to use the amount of genetic divergence between organisms to extrapolate backwards to estimate dates.
25 DNA/Amino Acid Homology (Means the same!)DNA/Amino Acid HomologyHuman ’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A-A-C-T-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’Whale ’A-C-C-T-T-A-C-C-A-A-T-C-A-T-T-C-C-C-T-A-A-C-T-T-A-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’Frog ’A-C-C-A-T-G-C-G-T-G-T-C-A-T-C-C-C-C-G-A-G-C-T-T-C-G-G-T-A-T-T-A-C-G-C-A-A-G-C-3’Gorilla ’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A-A-C-A-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’Can you create a cladogram from the information above?