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Introduction to Darwinian Evolution

Introduction to Darwinian Evolution. Terminology Evolution Accumulation of inherited changes within populations over time Population Group of individuals of one species that live in the same geographic area at the same time Species

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Introduction to Darwinian Evolution

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  1. Introduction to Darwinian Evolution

  2. Terminology • Evolution • Accumulation of inherited changes within populations over time • Population • Group of individuals of one species that live in the same geographic area at the same time • Species • Group of organisms with similar structure, function, and behavior capable of interbreeding

  3. Pre-Darwinian ideas • Aristotle (384–322 B.C.E.) • Saw evidence of natural affinities • Leonardo da Vinci (1452–1519) • Correctly interpreted fossil rocks • Jean Baptiste de Lamarck (1744–1829) • First to propose that organisms undergo change as a result of natural phenomenon • Lamarck ideas discredited when Mendel’s theories rediscovered around 1900

  4. Darwinand evolution

  5. Voyage of the H.M.S. Beagle • 1831 • Basis for Darwin’s theory of evolution • Darwin observed similarities between animals and plants • Arid Galapagos Islands • Humid South American mainland

  6. Voyage of the H.M.S. Beagle

  7. Influences on Darwin • Principles of Geology by Lyell • Artificial selection • Breeders developing many varieties of domesticated animals in a few generations • Plant varieties, such as kale and broccoli, developed from wild cabbage • Ideas of Thomas Malthus • Population growth not always desirable • Population increases geometrically; food supply increases arithmetically

  8. Artificial selection in chickens: “Big Bird”

  9. Artificial selection in Brassicaoleracea

  10. Evolution occurs by natural selection • Adaptation • Inherited variations favorable to survival persevere • Unfavorable variations are eliminated

  11. Genetic variation in emerald tree boas

  12. Theory of evolution by natural selection • Proposed by both Darwin and Wallace • Based on four observations • Genetic variation exists among individuals • Reproductive ability of species causes its populations to geometrically increase • Organisms compete for resources • Offspring with most favorable characteristics is most likely to survive

  13. Synthetic theory of evolution • Began in 1930s and 1940s • Combines principles of Mendelian inheritance and natural selection • Mutation provides genetic variability on which natural selection acts • Incorporates expanding knowledge in genetic, systematics, and other scientific fields

  14. Wing size in female fruit flies

  15. Evidence for evolution from fossil records • Direct evidence of evolution comes from fossils • Evidence shows progression from earliest unicellular organisms to organisms of today • Shows life has evolved through time

  16. Exposed layers ofsedimentaryrock

  17. Fossils developin differentways

  18. Fossilintermediatesin whale evolution

  19. Determiningthe ageof fossils:radioisotopedecay

  20. Evidence for evolution from comparative anatomy • Homologous features • Derive from same structure in common ancestor • Homoplastic features • Similar functions in distantly related organisms demonstrates convergent evolution • Vestigial structures • Remnants of structures indicating adaptation

  21. Homology in animals

  22. Homology in plants

  23. Homoplasy

  24. Convergent evolution: mammals who eat ants and termites

  25. Vestigial structures

  26. Biogeography • Study of past and present geographic distribution of organisms • Continental drift has played a major role in evolution

  27. Continental drift

  28. Evidence for evolution from developmental biology • Proteins and DNA contain record of evolutionary change • Phylogeny • Evolutionary history of group of related species • Phylogenetic trees • Diagrams showing lines of descent based on molecular data

  29. Phylogenetictree ofwhales andtheir closestliving relatives

  30. Evolutionary hypotheses tested experimentally • Reznick and Endler • Differences in predation correlated with differences in guppies • Male coloration and behavior • Life history traits

  31. Experimentalevidenceofnaturalselectionin guppies

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