Evolution Natural Selection and Evidence for Evolution 1

Evolution Natural Selection and Evidence for Evolution 1

Life • How did we come from this? • To this. 2

What is Evolution? • Change in a population over a long time or MANY generations • A population is a group of a single species – Humans…or Lions • Evolution occurs through Natural Selection (“That is the Key!”) 3

What is a Species? • A Species is defined as a group of organisms that share similar characteristics and that are capable of interbreeding and producing fertile offspring 4

Lamarck • French scientist Jean Baptiste de Lamarck (1744 – 1829) • First to propose a unifying hypothesis of species modification • Acquired Traits – trait that is not determined by genes • Lamarck – these were passed on to offspring 5

Charles Darwin • Darwin – – individuals struggle to survive • (competing for food and space, escaping predators, finding mates, locating shelter). – Only some individuals survive the struggle and produce offspring 7

Charles Darwin • Darwin – – Descent with Modification – Modification by Natural Selection 8

Darwin and Natural Selection • Four things that drive N. S. – Fitness • Ability to survive and reproduce – Variation • Differences among species – Adaptation • Variation that improves chances of survival • Adaptations develop over many generations – Competition • Fight for survival (food, shelter) 9

Selection • Artificial Selection – Breeding organisms with specific traits • Natural Selection – Mechanism for change in population – Organisms with certain variations survive, reproduce and pass their traits to offspring • Survival of the Fittest! 10

Variation A variation is an inherited trait that makes an individual different from other members of the species. Some traits are “better” or more favorable than others 11

Adaptation • Adaptation: any variation that aids an organism’s chances of survival in its environment 12

Evidence of Evolution 1. Structural Adaptation: – allow a species to defend against predation. Monarch – Mimicry: • The ability species to resemble another species; two types. Viceroy – Camouflage: • The ability of species to blend in with their surroundings 13

What is this? 14

Structural Adaptations cont • Mimicry 15

Leafhoppers 16

Treehopper 17

Leaf Hopper 18

Ants 19

Warning Coloration 20

Other Evidence 2. Physiological Adaptations: – Develop rapidly…(antibiotic resistance; pesticide resistance) – This is Direct Evidence • 3 – 6. Indirect Evidence 21

3. Fossils • Fossils show evolutionary history 22

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4. Anatomy • Homologous Structures – Common ancestry • Analogous Structures – No Common ancestry • Vestigial Structures – No visible function or use any longer 25

Anatomy Revisited • Homologous Structures – Common Ancestor – Can have similar arrangement and function • Analogous Structures – No common ancestor – Similar function; different anatomy 26

Vestigial Structures • Flightless Cormorant 27

Vestigial Structures • Human Ear Muscles • Baleen Whale Pelvic Bone • Vestigial Video 28

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5. Embryology • Similarities in Embryos – Suggest a common ancestor 30

Embryology and Evolution 31

6. Biochemistry • Comparison of DNA and RNA • Determine evolutionary relationship 32

Evolution and History How Evolution Happens - You. Tube 33

Industrial Melanism • Peppered moths – • Before the Industrial Revolution • After the Industrial Revolution 34

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Mechanisms of Evolution 37

Disruption of Equilibrium shows Evolution • Mutation – change in the DNA of an organism • Genetic Drift – Alleles frequency changes by random events or chance • Non-Random Mating – Assortative Mating – Selection of mate based on similar characteristics • Migration – into or out of population – Gene Flow: genes moving from one pop to another • Natural Selection – See Below 38

Assortative Mating 39

Review Natural Selection • Natural Selection – – The idea that organisms with traits best suited to their environment are more likely to survive and reproduce 40

Types of Natural Selection • Stabilizing Selection – Favors average individuals • Disruptive Selection – Favors both extremes of a variation • Directional Selection – Favors a single extreme variation 41

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Speciation • What is Speciation? – The evolution of new species • Geographic Isolation – Occurs when a small part of the population becomes separated; over generations, different variations become more common • Reproductive Isolation – Members of a species change from one another over time so much that they can no longer reproduce fertile offspring 43

How long does speciation take? • Gradualism – The model that describes evolution as a slow ongoing process • Punctuated Equilibrium – States that rapid evolution comes about when the mutations of a few genes results in the appearance of a new species over a relatively short period of time 44

Patterns of Evolution • Divergent Evolution – Adaptive Radiation – Single species evolves into an array • Convergent Evolution – The acquisition of the same biological trait in unrelated lineages 45