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Evolution. Fixed Species Concept u The creator had designed each and every species for a particular purpose.

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Presentation on theme: "Evolution. Fixed Species Concept u The creator had designed each and every species for a particular purpose."— Presentation transcript:

1 Evolution

2 Fixed Species Concept u The creator had designed each and every species for a particular purpose.

3 Result u No evolution. u Created the viewpoint that all species could be identified and named (Taxonomy). A major factor in the Linnaeus classification system.

4 Theory u Fossils were the remains of species lost due to catastrophe. u No new species originated; species could only be lost over time. u Result - No evolution.

5 James Hutton u 1795 - Gradualism u Profound change is the cumulative product of slow, but continuous processes.

6 Result u Changes on the earth were gradual, not catastrophic.

7 Charles Lyell u 1797 - 1875. u Incorporated Hutton’s gradualism into a theory called Uniformitarianism.

8 Uniformitarianism u Geological processes have operated at the same rate over the Earth’s history.


10 Result u The Earth must be VERY old. (much older than 6000 years of the fixed species concept). u Idea that slow and subtle processes can cause substantial change.

11 Jean Baptiste Lamarck u Published theory in 1809. u Theory - Life changed from simple to complex over time.

12 Lamarck u Fossils were the remains of past life forms. u Evolution did occur.

13 Lamarck’s Mechanisms 1. Use and Disuse - u Body parts used to survive become larger and stronger. u Body parts not used to survive deteriorate.

14 Lamarck’s Mechanisms 2. Acquired Characteristics u Modifications acquired by use/disuse were passed on to offspring.

15 Lamarck’s Mechanisms 3. Natural Transformation of Species ….species changed with every generation… extinction never occurred, organisms simply changed overtime.

16 Problems with Lamarck’s Theory u No knowledge of genetics. u Acquired traits are not transmitted offspring.

17 To Lamarck’s Credits u Did suggest correctly the role of fossils in evolution. u Did suggest that adaptation to the environment is a primary product of evolution.

18 Charles Darwin u Father of the modern theory of evolution. u Theory - Descent with Modification.

19 Darwin's Background u Trained as a Naturalist (after trying religion and medicine).

20 Voyage of the Beagle

21 Result u Darwin's training and travel opportunities allowed him to formulate and support his ideas on Natural Selection.

22 Galapagos Finches

23 Galapagos Islands

24 Unique animals Marine IguanaTortise

25 Alfred Wallace - 1858 u Paper on Natural Selection identical to Darwin's ideas.

26 Result - July 1, 1858 u Dual presentation of the Wallace-Darwin ideas to the Linnaean Society of London.

27 Darwin - 1859 u Publication of "The Origin of Species”

28 Comment u Darwin best remembered for the theory because of his overwhelming evidence and because he published.

29 Darwinian View u History of life is like a tree with branches over time from a common source. u Current diversity of life is caused by the forks from common ancestors.

30 Example

31 “The Origin of Species” u Documented the occurrence of evolution. u Suggested that the mechanism for evolution was Natural Selection.

32 The Facts: Fact 1 - All species reproduce themselves exponentially.

33 Fact 2 - Most populations are normally stable in size. Fact 3 - Natural Resources are limited (finite).

34 Inference 1 u The large number of offspring must compete for the finite resources. u Result - Most offspring die.

35 More Facts Fact 4 - No two individuals in a population are exactly alike. Fact 5 - Variation is inheritable.

36 Inference 2 u Those individuals whose inherited characteristics fit them best to their environment survive and reproduce.

37 Inference 3 u Offspring inherit the favorable characteristics. Populations shift over time as the favorable characteristics accumulate.

38 Nature u Determines which characteristics are favorable. u Determines who survives. u Result - “Natural Selection”

39 Natural Selection in action

40 Artificial Selection u When man determines the characteristics that survive and reproduce. u Result - the various breeds of animals and plants we’ve developed.

41 Ex - Mustard Plant OriginalCultivars


43 Evolution Success Measured By u Survival u Reproduction u Whoever lives long enough and has kids is the “winner” in evolution.

44 Requirements u In order for Natural Selection to work, you must have: u Long periods of time. u Variations within a population.

45 Subtleties of Natural Selection 1. Populations are the units of Evolution. 2. Only inherited characteristics can evolve.

46 Comment u Acquired characteristics may allow a species to evolve "outside" of Natural Selection. u Ex: culture, learning

47 Evidences of Evolution 1. Biogeography 2. Fossils 3. Taxonomy 4. Comparative Anatomy 5. Comparative Embryology 6. Molecular Biology

48 Biogeography u The geographical distribution of species. u Problem: u Species mixtures on islands u Marsupials in Australia



51 Evolution Viewpoint u Biogeographical patterns reflect descent from the ancestors that colonized that area.

52 Fossils u Relics or impressions of organisms from the past. u Problem: u Show changes over time from simple to complex. u Many fossils don't have descendants.

53 Evolution Viewpoint u Life has changed over time. u Many species failed to survive and became extinct.

54 Comments 1. Fossilization is a rare event. 2. Only hard parts fossilize well. 3. Problem in finding fossils. 4. Interpretation. 5. Missing Links.

55 Taxonomy u Science of Classification.

56 Main Categories u Kingdom u Phylum or Division u Class u Order u Family u Genus u Species

57 Comparative Anatomy Problems 1. Homologous Structures - Common "building plan” with divergent functions. Mammal forelimbs

58 Comparative Anatomy Problems 2. Vestigial Organs - Rudimentary structures of marginal, if any, use. Whale Legs

59 Human Example

60 Evolution Viewpoint u Remodeling of ancestral structures as their functions or adaptations changed.

61 Comparative Embryology u Problem - closely related organisms go through similar stages in their embryonic development. u Ex: Gill pouches in vertebrates

62 Evolution Viewpoint u Ontogeny is a replay of Phylogeny. (Development reflects descent)

63 Molecular Biology u Study of Evolution at the DNA or protein levels. u Problem - related species have similar DNA sequences.


65 Evolution Viewpoint u Related species share a common ancestrial DNA. The closer the relationship, the more similar the DNA sequences should be.

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