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EVOLUTIONARY PROCESSES AND PATTERNS

EVOLUTIONARY PROCESSES AND PATTERNS. Theories of species creations and diversity prior to evolutionary theory Theory of Special Creation Species are unchanged through time and are independent of one another

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EVOLUTIONARY PROCESSES AND PATTERNS

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  1. EVOLUTIONARY PROCESSES AND PATTERNS • Theories of species creations and diversity prior to evolutionary theory • Theory of Special Creation • Species are unchanged through time and are independent of one another • All species were created independently by “…the Trinity on the October 26th 4004 B.C. at 9:00 in the morning” Archbishop James Ussher 1664.

  2. EVOLUTIONARY PROCESSES AND PATTERNS • Theories of species creations and diversity prior to evolutionary theory • Theory of Spontaneous Generation • New organisms (species) may suddenly appear wherever conditions are suitable • Some new life-forms arise spontaneously from streams, soils, rotting meat, and other nonliving materials; not all life arises directly from living organisms

  3. EVOLUTIONARY PROCESSES AND PATTERNS • Theories of species creations and diversity prior to evolutionary theory • Prior to Darwin and Wallace - Lamarck • New simple life forms arise by spontaneous generation and change over time into more complex life forms • Individuals change in response to their environment and the changes are passed to the next generation.

  4. EVOLUTIONARY PROCESSES AND PATTERNS • Theories of Evolution • Darwin and Wallace • Species are related to one another, and they change over time, thus species existing today have descended, with modifications, from other preexisting species. • Natural selection acts on individuals; individuals with certain favorable characteristics will produce more offspring.

  5. Evolution • What is evolution? • Microevolution: survival through the inheritance of favorable characteristics • mutations • selection • Macroevolution: progression of biodiversity through geological time • speciation • extinction

  6. Evolution • How does it occur?

  7. Evolution • Species – group of potentially interbreeding natural populations capable of producing viable offspring • Speciation (through reproductive isolation) • division of populations (allopatricspeciation) • barriers to reproduction (sympatricspeciation)

  8. Evolution • Allopatric Speciation

  9. Evolution • Sympatric Speciation ?

  10. Evolution • Parapatric Speciation ?

  11. Evolution • "All life comes from life" • Modification of previously existing structures (homologous) – mammal forelimb structure • Increasing resemblance of organs or organisms serving the same function (analogous) • insect wings vs. bird wings (mimicry) • spurges vs. cacti • aloes vs. agaves • via Convergence

  12. Darwinian Selection • All natural selection results in evolution, but not all evolution is the product of natural selection. • What is evolution? • What is natural selection? • What is an adaptation?

  13. Darwinian Selection • All natural selection results in evolution, but not all evolution is the product of natural selection. • What is evolution? • Evolution is the change in allele frequencies (or traits) over time.

  14. Darwinian Selection • All natural selection results in evolution, but not all evolution is the product of natural selection. • What is evolution? • Evolution is the change in allele frequencies (or traits) over time. • What is natural selection? • What is an adaptation?

  15. Darwinian Selection • All natural selection results in evolution, but not all evolution is the product of natural selection. • What is evolution? • Evolution is the change in allele frequencies (or traits) over time. • What is natural selection? • . • What is an adaptation?

  16. Darwinian Selection • Sum it all up

  17. Seeds Ticks off of iguanas etc. Tools use to get insects Leaves and fruit Insects, spiders, nectar

  18. Darwinian Selection Is there variation about a trait?

  19. Darwinian Selection Is the variation heritable and not the result of maternal effects?

  20. Darwinian Selection Is there an excess of individuals so that only some animals live to reproduce? Are resources limited?

  21. Darwinian Selection Is reproduction nonrandom? The drought of 1977 eliminated seed set by most of the plants producing small soft seeds. Tribulus cistoides seeds are large and hard and became the dominant food item. Only large birds with deep beaks could defend resources and access the resources

  22. Darwinian Selection Is reproduction nonrandom?

  23. Darwinian Selection Did evolution occur? The El Niño of 1983 produced 1359 mm of rain and lavish seed set by the small soft seeded plants. Birds with shallow beaks harvest these seeds more efficiently and thus reproduced better than birds with deep beaks, undoing the selection shown here. Fluctuating environmental conditions maintain both phenotypes.

  24. Types of Selection • Directional Selection • Stabilizing Selection • Disruptive selection

  25. Directional Selection • Phenotype at one extreme of population distribution has selective advantage. • Leave more offspring • Mean for trait shifts which way?

  26. Types of Selection • Directional Selection • Stabilizing Selection • Disruptive selection

  27. Stabilizing Selection • Intermediate phenotypes have selective advantage. • What happens to the distribution for the trait?

  28. Types of Selection • Directional Selection • Stabilizing Selection • Disruptive selection

  29. Disruptive Selection • Intermediate phenotypes selected against

  30. Darwinian Selection • At what level does natural selection work? • Genes • Individual • Group • Population • Species

  31. Darwinian Selection • .

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  37. Darwinian Selection

  38. Darwinian Selection

  39. Darwinian Selection • The consequences of natural selection are expressed at the population level. • Natural selection, like all forms of evolution results in a change in allele frequencies (or frequencies of a trait).

  40. Genetic drift • Genetic drift results in a gradual loss of genetic diversity • Over time an individual locus and gene frequency will drift until one allele becomes fixed

  41. Convergent Evolution

  42. ISOLATION AND CONVERGENT EVOLUTION Convergence • Myrmecophages anteaters, aardvark, aardwolf, numbat, pangolins

  43. ISOLATION AND CONVERGENT EVOLUTION Convergence • Cursorial herbivores pronghorn, capybara, guanaco, kangaroos digestive tract, dentition, elongated limbs

  44. Convergent Evolution • Batesian Mimcry • Benign species resembles a noxious or dangerous species

  45. Convergent Evolution • Mullerian Mimicry • Noxious species resemble each other

  46. Convergent Evolution • Mullerian Mimicry • Noxious species resemble each other • Pitohui birds in New Guinea • homobatrachotoxin in skin and feathers

  47. Convergent Evolution • Aggressive Mimicry • Noxious or dangerous species resembles a benign one • Zone-tailed Hawk

  48. Coevolution

  49. Mutualism

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