Objectives for Chapter: 22

Transcription

1 Descent With Modification: A Darwinian View of Life Chapter 22 Objectives for Chapter: Understand the following contributions made by the following as they relate to Darwin s Theory of evolution. Aristotle, Plato Linnaeus Cuvier Hutton, Lyell Lamarck, and Malthus Alfred Wallace 2. Know the main observations and related inferences that Darwin suggested to explain natural selection as a mechanism for evolutionary change. 3. Know the main steps that make up Darwin s theory of evolution. 4. Know the main aspects of Darwin s voyage that influenced his theory: including South American flora and fauna, Galapagos Islands, Finches, tortoises What is Evolution? A change in the gene pool of a population in response to various stimuli exhibited by a species over time. 1

2 Geologist Theories Hutton 1795 Gradualism Cuvier 1815 Catastrophism Lyell 1830 Uniformitarianism Catastrophism Naturalist s Theories Carolus Linneaus Thomas Malthus 1798 Principles of populations Alfred Wallace 1858 Theory of Natural Selection 2

3 Jean Baptist Larmark Theory of Inheritance of Acquired Characteristics Change is made by what the organisms wants or need and then is passed down to offspring. WRONG!!! Why????? Charles Darwin English Naturalist At age 22 set sail on H.M.S. Beagle for South America Galapagos Islands. Wrote The Origin of Species Three major findings: Fossils, Geographical Patterns and Similarities among the Oceanic Islands. The Voyage that Changed Everything 3

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6 What leads to the change of organisms? Artificial Selection Man selects the desired traits Dogs Horses Pigeons 6

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8 What leads to the change of organisms? 1. Over reproduction Many organisms produce more than the environment can accommodate. Carrying Capacity the # of individuals a given area will hold. What leads to the change of organisms? 2. Variation among species. Some due to genetic changes called mutations. Most due to genetic diversity! What leads to the change of organisms? 3. Limited resources Food Shelter Territory Mates Water 8

9 What leads to the change of organisms? 4. Competition Fast Strong Smart Hide Bluff Make noise What leads to the change of organisms? 5. Reproductive Success Able to make offspring and pass their genes on to the next generation. The Origin of the Species convinced most biologists that species are the products of evolution. What was missing in Darwin s explanation was an understanding of inheritance that could explain how chance variations arise in a population while also accounting for the precise transmission of these variations from parents to offspring. Although Gregor Mendel and Charles Darwin were contemporaries, Mendel s discoveries were unappreciated at the time, even though his principles of heredity would have given credibility to natural selection 9

10 The finches of the Galapagos Islands diversified after an initial colonization from the mainland to exploit different food sources on different islands. Theory of Natural Selection Those individuals that possess superior physical, behavioral, or other attributes are more likely to survive than those that are not so well endowed. Survival of the Fittest Those best able to reproduce! Biodiversity 10

11 Pocket Mice Biological diversity is something to relish and preserve, but it can also be a bit overwhelming. Evidence of Evolution Fossil Record Earliest 3.5 Billion yrs. Old Cell type? 11

12 Age of the Earth Alternatively, we can view these episodes with a clock analogy. 12

13 Comparative Anatomy Homologous Structures Same origin, close to same structure with a different function. Examples Comparative Anatomy Analogous Structures Same function different structure. 13

14 Comparative Anatomy Vestigial Organs Structures that serve no purpose Often homologous with other organs useful in other species Examples- eye on cave fish 14

15 Molecular Biology *Sequencing of lettering of DNA *Biochemical Cytochrome C Blood Proteins Amino Acids Development Embryological Development Gene Expression Most embryos develop almost identically 15

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