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The History of Evolutionary Thought

The History of Evolutionary Thought. Aristotle (384-322 B.C.). Ladder of Life 2 types of animals – those w/ blood & those w/o Animals classified by their way of life Plants by structure Observation of various marine life anatomy was remarkably accurate Distinguished whales from dolphins.

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The History of Evolutionary Thought

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  1. The History of Evolutionary Thought

  2. Aristotle (384-322 B.C.) • Ladder of Life • 2 types of animals – those w/ blood & those w/o • Animals classified by their way of life • Plants by structure • Observation of various marine life anatomy was remarkably accurate • Distinguished whales from dolphins

  3. Carol von Linné (1707 – 1778) “Father of Taxonomy” • Linnaeus was classifying organisms based on what they looked like. • This made it difficult to classify organisms that seemed to share characteristics with both kingdoms that Linnaeus proposed, Plants and Animals. • For example, fungi including mold and mushrooms do not move (or do they?) so they seem to be plants but, unlike plants…..?????

  4. Immutable Species???

  5. Jean-Baptiste Lamarck (1744-1829) • His name is associated merely w/ a discredited theory of heredity – he died in obscurity & poverty • Darwin & Lyell give him great credit • Law of use/disuse • Law of acquired characteristics

  6. LAMARCK’S THEORY

  7. Charles Darwin (1809-1882) • Voyaged around the world 1831-1836 • Wrote On the Origin of Species which reveals his ideas on Evolution by means of Natural Selection

  8. ACCORDING TO DARWIN…

  9. Natural Selection Summarized: Darwin’s theory suggests that in a species: • There is a tendency towards overproduction • Variationexists • Variations are inherited • Individuals survive in their environments with varying degrees of success • Best adapted, survive and pass favorable variation on to next generation • In time, great differences arise, until a new species evolved from an old species

  10. What is biological fitness???

  11. Biological fitness: The contribution an individual makes to the gene pool of the next generation relative to contributions of other individuals Offspring should be fertile

  12. Alfred Wallace (1823-1913) • Studied the way geography limited or facilitated the extension of species range • How ecology influenced the shaping of adaptations • In 1858, shared with Darwin on the Theory of Evolution by means of Natural Selection

  13. Genetic variation exists in sexually reproducing populations • Different alleles are available in the population thus producing • different phenotypes.

  14. The Hardy–Weinberg principle states: • Both allele and genotype frequencies in a population remain constant or are in equilibrium from generation to generation unless… • Disturbing influences happen such as non-random mating, mutations, selection, limited population size, random genetic drift and gene flow. • Genetic equilibrium is a basic principle of population genetics.

  15. The Hardy-Weinberg principle is like a Punnett square for populations, instead of individuals.

  16. p2 + 2pq + q2 = 1; p + q = 1 Hardy-Weinberg Principle

  17. Homologous Structures • Structures that have different mature forms in different organisms but develop from the same embryonic tissues.

  18. Homologous Structures

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