Dr. Yost - Exam 1 Lecture Notes - Chapter 18 PDF

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Dr. Robert Yost lecture notes for exam 1 of BIOL-K 103. These notes provide exact details as to what material is present on his exams. The book is unnecessary to purchase. He never changes his exams. ...

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Chapter 18: Introduction to Darwinian Evolution Objectives 1. Define the terms species, population, and evolution (knowledge) 2. Name several historical figures and describe their contribution to views on classification and evolution [Aristotle, daVinci, de Lamarck, Hutton, Cuvier, Malthus, Darwin] (knowledge/comprehension) 3. Compare and contrast the ideas of Darwin, Lamarck, and Wallace (knowledge/comprehension) 4. Name and explain Darwin’s four observations used to support his view of evolution by natural selection (knowledge/comprehension) 5. Compare and contrast the various forms of evidence supporting evolution (e.g. fossil record, homology, homoplasy, vestigial structures, and molecular and development homologies). (knowledge/comprehension) [also covered in chapter 23] Some Key Words Convergent evolution Homologous Homoplasy Macroevolution

organisms evolved similar characteristics as a result of exposure to similar environmental challenges [natural selection]

major evolutionary changes that occur over a long period of time resulting in large phenotypic changes such as the formation of new species Microevolution more minor evolutionary changes that occur over just a few generations Modern synthesis an explanation of evolution that incorporates many aspects of biology such as molecular genetics, phylogeny, natural selection, mutations, etc. Population a group of individuals of the same species Species a group of successfully interbreeding organisms that also produce fertile offspring Vestigial structure remnants of structures that were present and functional in the ancestral organisms

Chapter 18: Introduction to Darwinian Evolution (and Selected Historical Figures) Objective 1: Define the terms species, population, and evolution (knowledge) Slide 24 I. What is evolution? Terminology A. Species  Similar organisms capable of interbreeding and producing fertile (able to reproduce) offspring B. Population  Group of individuals of one species  Live in same geographic area at same time Slide 25 D. Evolution and natural selection:  Accumulation of heritable genetic changes over time.  Two populations may diverge to the point of becoming different species Things to keep in mind with respect to evolution:  Organisms survive as a result of changes that have occurred in gene pool (natural selection)  Do not change to survive (survive because they have met the challenge)  Modification or changes may not result in a more complex or ordered state  Natural selection favors genetic change that supports survival Slide 26 C. Evolutionary time:  Time is relative  Evidence with bacteria and some birds indicate modifications can occur in just a few generations Antibiotic resistance in E.coli

Objective 2: Name several historical figures and describe their contribution to views on classification and evolution [Aristotle, daVinci, de Lamarck, Hutton, Cuvier, Malthus, Darwin] (knowledge/comprehension

Slide 28 I. Pre-Darwinian ideas about evolution A. Aristotle - scale of nature  Viewed organisms as working toward more ordered/perfect state B. Leonardo da Vinci  Recognized fossils as remains of now extinct animals/organisms C. Lamarck 1. Acquired characteristics: traits acquired during parent’s lifetime passed to offspring 2. Use vs disuse 3. First indication of theory of evolution: natural phenomenon involved, and evolutionary change occurs 4. Natural selection o Organisms pass traits acquired during their lifetimes to offspring o Realized natural phenomenon involved & evolutionary chage occurs Slide 29 Geologists E. Hutton  Gradualism – observations led to proposal  Fossils: he could find A, B, C, D and similarities F. Cuvier  Catastrophes produced mass extinctions and new species arose  punctuated equilibrium: Fossils: A, D, G, M (no intermediates) Slide 30 G. Malthus – geometric (exponential) vs arithmetic (linear) growth  clergyman/economist  inherited variations favorable to survival tend to be preserved, while unfavorable ones are eliminated  “its possible than the population could outgrow its food supply” – some plants produce geometrically

I. Combined views of Darwin and Lamarck

Lamarck: use vs disuse; extension of next cause elongation and offspring will have longer neck

Darwin: longer neck reaches higher leaves; longer neck survives; genetic drift toward favorable trait which is a longer neck (natural selection)

II. Views of Darwin and Wallace - Evolution occurs through natural selection  Darwin, On the Origin of Species by Natural Selection, 1859 a. Natural selection  Wallace. Contributions to the Theory of Natural Selection, 1870 I. Darwin proposed that evolution occurs by natural selection based upon 4 observations A. Variation  Individuals in a population exhibit variation in traits  Some improve changes of survival and reproductive success, others don’t B. Overproduction  Each generation can produce more offspring than can survive C. Limits on population growth  Competition from limited resources - not all survive to reproduce D. Differential reproductive success (survival of the fittest)

 Individuals with most favorable combination of characteristics more likely to survive and reproduce Homolog, homoplasy, and molecular homologies read and also see chapter 18. Consider the definitions and examples. Slide 34 I.

What does the fossil record show? A. Relationships/lineage/progression  Connections between living/dead organism  Earliest unicellular organisms to organisms living today B. Genetic relationships  DNA successfully recovered from some  Changing “historical” relationships C. Other fossil evidence  Preserved footprints and embryos

Bias fossil record 1. Fossilization depend upon “rapid” preservation  Favors organisms that die in: o Aquatic/marine environment o Bogs and tar pits  Not favorited organisms that die in: o Dry environments (most land dwellers) o Rain forest o Organisms rapidly decay so rarely fossilized 2. Fossilization influenced by body structure  Hard body parts are more likely to fossilize than soft body parts Slide 36 II. Comparative anatomy A. Homology, homoplasy, analogy See notes from chap 23 discussion B. Vestigial structures  Remnants of past structure  No longer useful; was once useful i. Wiggling ears ii. Appendix  Happens over time as useful structure becomes smaller and/or loses function and/or degenerates  We don’t have the ability to move our ears like other domestic animals. We lost the ability to be able to use it. Slide 37 C. Examples 1. Humans fused tailbones, third molars wisdom teeth, and muscles that move ears 2. Other animals

Raven & Johnson 6th ed pg 441

Slide 38 II. Molecular homologies  Based upon data: o DNA/RNA: base sequences o Proteins: amino acid sequence o Developmental genes: Hox genes (similar structures with different end results) o Dogs closely related to wolves

Slide 39 III. Developmental homologies  How and when genes are switeched on and off during development results in diversity of form in species with similar genes  Mutations in developmental genes also have an impact  Fish, chickens, and humans are vertebrates with strikingly similar genes

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Development of their early embryos is similar but see areas colored orange follow different developmental pathways, resulting in fins, wings, or limbs...