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Evolution: Change Over Time

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Presentation on theme: "Evolution: Change Over Time"— Presentation transcript:

1 Evolution: Change Over Time
The Evidence The Evidence Evolution: Change Over Time Evolution: Change Over Time The Evidence The Evidence

2 Fossil Record Defined: Collection of every known fossil
Most fossils found in sedimentary rock Age determined by depth Law of Superposition: new rock forms on top of older rock A.k.a. Relative Dating Evidence Conclusions: 1) Newer fossils are more complex 2) Common ancestors: similarities between ancient & modern life

3 Missing Link Fossils AKA: Transition Fossils
Whale Evidence Long spine Found in dried up oceans Reptile Evidence Teeth Bony tail Fish evidence Scales Fins Found in dried-up oceans Amphibian evidence Eyes on top of head Wrist bones Land Evidence Wolf-like teeth Hind legs Bird Evidence Wishbone Feathers AKA: Transition Fossils Archaeopteryx: shares both bird & reptile features Basilosaurus: shares whale & land mammal features Tiktaalik: shares fish & amphibian features Evidence Conclusion : Indicates common ancestry


5 Comparing old fossils to modern life shows change
Ancient Kelp Modern Kelp

6 Radiometric Dating Helps determine age of fossils. More accurate than relative dating. Isotopes: atoms of the same element with differing neutrons Ex: 12C and 14C 12C = 6 protons + 6 neutrons 14C = 6 protons + 8 neutrons Organisms collect carbon throughout their lifetime. When organism dies: 14C starts to decay into 14 N at a known rate (half-life) Fossil age determined by comparing ratio of C to N Wider ratio = older sample Both are Carbon


8 Dating Fossils

9 The study of geography provides evidence of evolution.
island species most closely resemble nearest mainland species populations can show variation from one island to another

10 Embryo Development Different species show similar development patterns
Different body plans become noticeable later in development Evidence Conclusion : Indicates common ancestry Embryo Development

11 flipper arm leg wing Homologous Structures walking grasping swimming
flight Defined: similar body structures with very different functions Different environments lead to adaptations Ex: The forelimbs of animals Evidence Conclusion : Indicates common ancestry

12 Homologous structures are different than analogous structures
Analogous structures have similar functions but different structures. Human hand Bat wing Mole foot Fly wing Analogous structures are not evidence of a common ancestor.

13 Vestigial Structures Defined: Organs or structures which have lost most or all their original function Vestigial Human Parts: Gill slits = once used to breath oxygen in water Yolk sac = once used to nourish developing embryo Tailbone = once used for balance Appendix = once used to digest plants Wisdom teeth = once used to grind plant tissue Evidence Conclusion : Indicates common ancestry

14 Human Embryo w/ Vestigial Structures

15 Pythons have tiny femurs (leg bone)

16 Biochemical Evidence DNA, RNA, proteins compared
Genetic code same for most life More related species have more similar biochemistry Evidence Conclusion : Indicates common ancestry

17 Constant creation of chemicals for human use is eliminating the “unfit” (invading)organisms
Ex: Antibiotics eliminating unfit bacteria Ex: Pesticides eliminating unfit pests Ex: Antivirals… Ex: Fungicides… Allows resistant to survive and reproduce Resistant Organisms

18 Most bacteria killed Strong Survive Bacterial Resistance Strong Reproduce

19 Antibiotic Resistance
penicillin vancomycin ampicillin Amoxycillin tetracyclin Which antibiotics would successfully treat this infection?



22 Review How does antibiotic and pesticide resistance show natural selection? How do the following lines of evidence show change over time? Fossils Homologous structures Vestigial structures Resistant organisms Embryo development Biochemical (molecular) evidence Fossil age can be determined two ways. What are they? Which type of anatomical structures do not show evidence of common ancestry?

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