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Descent with Modification: A Darwinian View of Life.

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Presentation on theme: "Descent with Modification: A Darwinian View of Life."— Presentation transcript:

1 Descent with Modification: A Darwinian View of Life


3 Dance

4 A. Charles Darwin ( ) Charles Darwin Charles Darwin 1. Occupation: Naturalist 2. Most Famous For: Origin of Species (1 st book) 3. Contribution to Evolutionary Biology: Essay - “Theory of Natural Selection” - the mechanism of change in evolution I. THE PLAYER B. Alfred Russel Wallace ( )Alfred Russel Wallace -Essay title: “On the Tendency of Varieties to Depart Indefinitely from the Original Type”

5 Darwin Pictures Darwin focused on adaptations – inherited characteristics of organisms that enhance their survival and reproduction to a specific environment

6 II. Darwin’s (Wallace) Theory of Natural Selection Observations From NatureInferences 1. Members of a population often vary in their inherited traitsvary 2. All species can produce more offspring than their environment can support, and many of these offspring fail to survive and reproduce. survive and reproduce 1. Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring. 2. Unequal ability to survive and reproduce leads to accumulation of favorable traits in a population over generations not Note: Darwin did not introduce the concept of mutations producing new varieties. Darwin believed the variety was always in the genes. Mutation is a post-Darwinian concept.

7 A. Natural Selection in Response to Introduced Species 1. Soapberry bugs use mouth-like part to feed on seeds inside fruits III. Evidence for Evolution a. Southern FL – feeds on native balloon vine vs. central FL goldenrain tree (new tree from Asia) 2. The Evolution of Drug-Resistant Bacteria - MRSA a. MRSA – methicillin-resistant Staphylococcus aureus b. feed best when mouthpart matches depth of seeds in fruit c. Natural selection selected for shorter beaks in central FLNatural selection b. Penicillin in 1943  bacterial resistance  production of antibiotic methicillin 1959  bacterial resistance…bacterial resistance… 3. Take-away from examples a. Natural selection is a process of editing what already existsNatural selection b. Natural selection acts on what characteristics are favorable at the time in a particular environment

8 Older fossils are found in older and deeper strata (layers) 2. Older fossils are found in older and deeper strata (layers) 1. Implication: organism were different than now B. Fossils: Preserved remains of ancient organisms

9 C. Homology– Similarities resulting from common ancestry 1. Anatomical similarities a. Must separate homology (related structures) from homology analogy (similar functions) analogy (similar functions)analogy b.Analogy leads to convergent evolution (organisms similar due to similar yet VERY DISTANT environments; they aren’t related) similar due to similar yet VERY DISTANT environments; they aren’t related) c. May explain vestigial organs - organs of no apparent function; (appendix) appendix 2. Molecular similarities a. All life shares same genetic code and amino acids in proteins b. Organisms have homologous genes (genes in common) ex. 18S ribosomal RNA gene ex. 18S ribosomal RNA genegene

10 D. Biogeography: The geographic distribution of species 1. Species diversity is due to natural selection found in different areas 2. Diversity may reflect divergent evolution 3. Diversity may reflect convergent evolution Divergence (Fruit fly)Convergence (Flying squirrel)

11 Mammalian forelimbs: homologous structures Slide 17

12 Analogous structures Slide 101

13 Human Vestigial Structures Slide 16

14 E. Molecular Genetics 1. Definition: Compares the composition of molecules in different organisms 2. Types a. Comparison of DNA sequences of different organisms b. Compares amino acid sequences in different organisms

15 What if all the spores of this puffball actually germinated? Slide 11

16 Asian Ladybird Beetles Slide 11

17 What do these plants have in common? We artificially selected traits of the wild mustard Slide 11

18 Slide 15

19 Clone USA300 – causes lethal infections to skin, lungs, and bloods MRSA infection proliferation Slide 15

20 COMPARISON of 18S rRNA gene sequences Slide 7

21 Slide 11

22 Slide 3 The Origins of Evolutionary Thought

23 Elephant Evolution “Tree” Slide 7


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