2Overall Theme of Evolution Evolution Requires 3 elements:1. Variety2. Selection3. Time
3VarietyFor evolution to occur, there must be ways for organisms within a species to be different from each otherVariety is generated through mutations and sexual reproduction
4Evolution is now considered a Theory What is the difference between a Theory and a Hypothesis?Theory- a hypothesis that has been confirmed by testing and has much evidence backing it upHypothesis- an educated guess that can be tested
5Charles DarwinCharles Darwin took many years to publish his theory of evolution by natural selection.Many of his ideas were first inspired by his 1831 global voyage on the ship called the Beagle.
6Charles Darwin (1809 – 1882)In l831, when Darwin was only 22 he signed on as the ship’s naturalist aboard the Beagle on a 5-year expedition around the world.Darwin studied and collected many different and unusual specimens which contributed to his theory.
7Darwin’s Voyage to the Galapagos Islands Some of Darwin’s most important observations were made on the Galapagos Islands.
8Animals of the Galapagos Islands Blue Footed Boobies in the GalapagosAnimals of the Galapagos Islands
9Galapagos Islands: Finches Darwin observed organisms with slight differences.Example: Galápagos finches with different beaks
10Assumptions At That Time Species were fixed creations that never changed and they were arranged from least complex to most complex.Earth is only a few thousand years old.
11Darwin’s Book: On the Origin of Species Darwin’s book stated:Species changeSpecies evolved from a common ancestor over time (implying a much older Earth)Natural Selection is the mechanism for change
12The only picture in Darwin’s book shows Common Ancestry
14Jean Baptiste LamarckLamarck proposed that organisms change over time as they adapt to changing environments.
15Jean Baptiste LamarckHe also incorrectly proposed that changes due to use and disuse of a characteristic would be passed on to offspring.Example: A baseball player’s children would inherit strong arm musclesGiraffe’s neck stretchesto reach food
16Charles Lyell Lyell studied fossils and rock layers His work showed that Earth’s history was long enough for species to have evolved gradually.
17Charles Lyell Lyell found evidence of long extinct habitats Example: Fossil sea shells in the Andes Mountains
18Thomas MalthusMalthus observed that human populations were increasing faster than the food supply.Darwin saw that all kinds of organisms tend to produce more offspring than can survive.
19Darwin’s Theory of Natural Selection Overproduction- Organisms produce more offspring than can survive. Leads to competition for resources.Variety- Variation exists within every population.Selection- Having a particular trait can make individuals more or less likely to survive and reproduce offspring4) Adaptation– Over time, the traits that improve survival and reproduction become more common.
20Artificial SelectionA human practice of breeding animals or plants that have desired traitsExample: Pigeon and Dog breeders
22Evidence for Evolutionary Theory Galapagos FinchesTransitional FossilsBiogeographyEmbryologyHomologous StructuresBiochemistry
23Galapagos FinchesAll Galapagos finch species are similar to each other.Beak size and shape are different due to different types of food.
24Transitional Fossils Traces of organisms that lived in the past. Some fossils show a pattern of gradual change from the past to the present
25Transitional Fossils Tiktaalik roseae (Amphibian/Fish) Fossils dated 375 million years old
26Transitional Fossils Archaeopteryx lithographica (Bird/Reptile) Fossils dated 150 million years old
27Transitional Fossils Ambulocetus natans called the “walking whale” Fossils dated ~ 50 million years old
28Transitional FossilsRodhocetus kasrani-extinct whale with mammal characteristicsFossils dated ~ 46 million years old
29Transitional Fossils Basillosaurus cetoides-marine mammal Fossils dated ~ 40 million years old
30Physeter macrocephalus Modern sperm whale Transitional FossilsPhyseter macrocephalus Modern sperm whale
31Fossils: Common Ancestry Darwin found fossils of Giant extinct Armadillos in South America that are related to Modern day Armadillos.
32Biogeography Study of the locations of organisms around the world. Example: The Rhea, Ostrich, and Emu are similar in size, shape, eating habits, and habitat. However each species lives on a separate continent. (Convergent Evolution)
33BiogeographyRhea (South America)Ostrich (Africa)Emu (Australia)
34Study of the first stage of development EmbryologyStudy of the first stage of development
35Homologous Structures Characteristics that are similar in structure but different in functionHomo = SameSame evolutionary history
37Biochemistry Comparison of DNA or amino acid sequences over time This is the most powerful evidence for a common ancestor
38Biochemistry The following is a comparison of genes in Humans and Monkeys
39Common Cell ProcessesCellular Respiration pathways are similar processes in most speciesMitosis process is the same in all eukaryotes
40Vestigial StructuresStructures that have lost all or most of their original function in a species through evolutionExamples: Mole rat eyes, Manatee fingers, Human wisdom teeth, Whale leg bone, Human Appendix
49Adaptations Mimicry- mimics or copies characteristics of others Fly vs Honey Bee Moth vs Bracket Fungi
50AdaptationsKing snake vs coral snake Moth Eye Spot vs Owl Eyes Remember: Red touch Yellow, Kill a Fellow; Red touch Black, Good for Jack
51Does Natural Selection Occur Now? Yes, Bacteria reproduce very quicklyOver decades of antibiotic use, bacteria have developed resistance to antibiotic medicinesMutations for antibiotic resistance arise naturally and often in bacteria
52Antibiotic Resistance Today, nearly all bacteria are becoming resistant to one or more antibioticsAs bacteria become resistant, physicians must switch to using different antibiotics.Example: Staph infections and Tuberculosis are both more difficult to treat
53Misconceptions of Evolution Evolution does not just add complexity, it can take it away as wellExample: A Tapeworm lacks many organ systems
54Misconceptions of Evolution Evolution does not “finish” with a “perfect trait”The human eye has a blind spot due to the Optic Nerve
55Evolution Can Add Complexity Random mutation can lead to more complex changesExample: The icefish is able to withstand the Antarctic freeze because it has an antifreeze protein in its blood that was mutated from the typsinogen protein.
562 Subgroups of Evolution Microevolution- refers to evolution as a change in allele frequency in populationsMacroevolution- refers to the appearance of a new species over timeThe following slides are examples of Macroevolution
57Divergent Convergent Evolution Evolution See Page 383, Figure 8new organismssome similarities begin to develop in same environmentcommon ancestordifferent ancestries
58Adaptive Radiation or Divergent Evolution Adaptive Radiation is a special case of divergent evolution - when many niches are filledNotice that there are 14 species that evolved from the original Finch from South America
59Gradualism vs. Punctuated Equilibrium Slow, even changeLong periods of no change with bursts of rapid change
60CoevolutionPopulations are not isolated, and often evolve in response to each otherCoevolution is when 2 species are competing to “one up” each other with adaptations
61CoevolutionThis moth species and this orchid species have coevolved is a close relationship. The moth feeds exclusively on the orchid, and the orchid’s pollen is spread by the moth.