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NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION Chapter 15.1.

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Presentation on theme: "NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION Chapter 15.1."— Presentation transcript:

1 NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION Chapter 15.1

2 I. CHARLES DARWIN AND NATURAL SELECTION Evolution: a series of adaptations “over time” Charles Darwin developed this theory of evolution

3 I. CHARLES DARWIN AND NATURAL SELECTION A. Fossils Shape and Ideas About Evolution Fossils form base of evolutionary thoughts

4 I. CHARLES DARWIN AND NATURAL SELECTION B. Darwin on HMS Beagle Took this ship (HMS Beagle) on a 5 year scientific journey around the world Collected fossils at every port along route Compared each to determine evolutionary relationships Studies provided the foundation for evolution by natural selection: ▫Organisms with most favorable traits survive and pass those traits on to their offspring.

5 I. CHARLES DARWIN AND NATURAL SELECTION C. Darwin in the Galapagos Galapagos are a group of small islands near the equator He studied organisms there that are unique to the island, but similar to those elsewhere Led Darwin to believe that species can “change over time”

6 I. CHARLES DARWIN AND NATURAL SELECTION D. Darwin Continues his Studies Darwin observed that the traits of individuals vary in populations. Variations are then inherited. Breeding organisms with specific traits in order to produce offspring with identical traits is called artificial selection. Darwin hypothesized that there was a force in nature that worked like artificial selection.

7 I. CHARLES DARWIN AND NATURAL SELECTION D. Darwin Continues his Studies Natural selection is a mechanism for change in populations. ▫ occurs when organisms with favorable variations survive, reproduce, and pass their variations to the next generation. ▫ Organisms without these traits are less likely to survive

8 I. CHARLES DARWIN AND NATURAL SELECTION E. Darwin Explains Natural Selection In nature, more offspring than can survive are produced In any population, individuals have variations Over time, those with favorable variations survive and pass those traits on to their offspring Over time, individuals with variations look entirely different from their ancestors and make up a large portion of the population

9 I. CHARLES DARWIN AND NATURAL SELECTION F. Interpreting Evidence After Darwin After much investigation, a majority of scientists have accepted Darwin’s theory of Evolution by natural selection

10 II. ADAPTATIONS: EVIDENCE FOR EVOLUTION Adaptation: any variation that aids an organisms chance of survival in its environment Darwin’s theory explains how some of these adaptations may occur

11 II. ADAPTATIONS: EVIDENCE FOR EVOLUTION A. Structural Adaptations Occur Over Time adaptations in species develop over many generations

12 II. ADAPTATIONS: EVIDENCE FOR EVOLUTION A. Structural Adaptations Occur Over Time Mimicry is a structural adaptation that enables one species to resemble another species ▫ a harmless species has adaptations that result in a physical resemblance to a harmful species ▫ Predators that avoid the harmful looking species also avoid the similar-looking harmless species

13 Syphrid Fly

14 II. ADAPTATIONS: EVIDENCE FOR EVOLUTION Camouflage: an adaptation that enables species to blend with their surroundings. ▫ Because well-camouflaged organisms are not easily found by predators, they survive to reproduce.

15 Camouflage

16 II. ADAPTATIONS: EVIDENCE FOR EVOLUTION B. Physiological Adaptations Can Develop Rapidly Physiological adaptations are changes in an organism’s metabolic processes ▫Example is penicillin resistant bacteria ▫Can also be seen in some species of insects and weeds that are pests ▫Some things develop an “immunity”

17 III. OTHER EVIDENCE FOR EVOLUTION A. Fossils Even though fossil record is incomplete, it still gives scientists a good idea of how organisms evolved For example, the evolution of the camel

18 Camel Evolution

19 III. OTHER EVIDENCE FOR EVOLUTION B. Anatomy Homologous structures: structures with common evolutionary origin ▫same structure, same function, or same in both cases

20 Homologous Structures Whale forelimb Crocodile forelimb Bird wing

21 III. OTHER EVIDENCE FOR EVOLUTION B. Anatomy Analogous structures: structures that have NO COMMON ORIGIN, but are similar in function ▫Ex: insect wings and bird wings

22 III. OTHER EVIDENCE FOR EVOLUTION B. Anatomy Vestigial structures: a body structure in a present-day organism that no longer serves its original purpose, but was useful to an ancestor ▫ex: eyes of blind mole rats, forelimbs of an ostrich, pelvic bone in a baleen whale

23 III. OTHER EVIDENCE FOR EVOLUTION C. Embryology Embryo: the earliest stage of growth and development of both plants and animals There are several similarities between fish, reptile, bird, and mammal embryos ▫Both have pharyngeal pouches and a tail This leads people to believe that all have a distant common ancestor

24 Embryology Similarities

25 III. OTHER EVIDENCE FOR EVOLUTION D. Biochemistry Nearly all organisms share DNA, ATP, and many enzymes among their biochemical molecules Scientists compare a specific amino acid sequence, “Cytochrome c” that is present in animals all the way from bacteria to bison (a mammal)

26 Comparison of Cytochrome c Biochemical Similarities of Organisms Comparison of Organisms Percent Substitutions of Amino Acids in Cytochrome c Residues Two orders of mammals Birds vs. mammals Amphibians vs. birds Fish vs. land vertebrates Insects vs. vertebrates Algae vs. animals 5 and 10 8-12 14-18 18-22 27-34 57

27 III. OTHER EVIDENCE FOR EVOLUTION D. Biochemistry If organisms are biochemically similar, then they have fewer differences in amino acid sequences If organisms are biochemically different, then they have more differences in their amino acid sequences

28 DON’T FORGET Today scientists combine all of the following to determine evidence of evolution ▫Fossils ▫Anatomy  Homologous, analogous, vestigial structures ▫Embryology ▫Biochemical Similarities

29 Question 1 ________ is considered to be the fundamental concept of biology. A.Genetics B.The Modern Theory of Evolution C.Artificial selection D.Structural adaptation

30 Question 1 ________ is considered to be the fundamental concept of biology. A.Genetics B.The Modern Theory of Evolution C.Artificial selection D.Structural adaptation

31 Question 2 Breeding organisms with specific traits in order to produce offspring with identical traits is called _________ A.Natural selection B.Adaptation C.Mutation D.Artificial selection

32 Question 2 Breeding organisms with specific traits in order to produce offspring with identical traits is called _________ A.Natural selection B.Adaptation C.Mutation D.Artificial selection

33 Question 3 Mimicry and camouflage are NOT examples of _________. A.Adaptation B.Natural selection C.Evolution D.Artificial selection

34 Question 3 Mimicry and camouflage are NOT examples of _________. A.Adaptation B.Natural selection C.Evolution D.Artificial selection


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