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5.4 Evolution

5.4 Evolution. 5.4.1 Define evolution. Evolution is. ‘ heritable ’ – changes must be passed on genetically from one generation to the next Implies that evolution doesn’t happen overnight ‘cumulative’ - one change isn’t enough to have major impact on the species

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5.4 Evolution

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  1. 5.4 Evolution

  2. 5.4.1Defineevolution • Evolution is . • ‘heritable’– • changes must be passed on genetically from one • generation to the next • Implies that evolution doesn’t happen overnight • ‘cumulative’- • one change isn’t enough to have major impact on • the species • ‘population’- • changes do not affect just one individual

  3. 5.4.1Defineevolution Five “sub theories” : • Evolution: all life is and has been perpetually changing • Common descent: if traced back far enough,  all life has common ancestor • Gradualism: evol change is slow & gradual • Multiplication of species: speciation leads to diversity of life; pops adapt to locations, become reproductively isolated from other pops • Natural selection: produce genetic variation & select for/against

  4. History of Evolutionary Thoughts

  5. Lamarck’s Theory of Evolution • Jean-Baptiste Lamarck, 1809 • one of first scientists to understand that • stated that changes are adaptations to environment • said acquired changes were passed to offspring

  6. Lamarck’s Theory of Evolution • Idea called • If a body part were used, it got stronger • If body part NOT used, it deteriorated

  7. Lamarck’s Theory of Evolution • Inheritance of Acquired Characteristics • proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime • these traits could then be passed on to their offspring • over time this led to new species

  8. Lamarck’s Theory of Evolution

  9. Lamarck’s Mistakes • Lamarck did not know how traits were inherited(Traits are passed through genes !) • genes are NOT changed by activities in life • change through mutationoccurs before an organism is born

  10. Charles Darwin • 1809-1882 • British naturalist • In 1858, and independently proposed the idea of evolution by

  11. Charles Darwin • Darwin published On theOrigin of Species by Means of Natural Selection the following year

  12. Charles Darwin (1809-1882) http://www.ucmp.berkeley.edu/diapsids/birds/archaeopteryx.html

  13. 5.4.2 Outline evidence for evolution. • Fossil record • transition species • Comparative Anatomy • homologous & vestigial structures • Comparative Embryology • embryonic development • Molecular record • protein & DNA sequence • Artificial selection • human-caused evolution

  14. Fossil record • Layers of contain fossils • new layers cover older ones, creating a record over time • fossils within layers show that a succession of organisms have populated Earth throughout a long period of time PBS: How do we know evolution happen? http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

  15. Fossil record

  16. Fossil record 550 • A record showing us that today’s organisms descended from ancestral species 500 450 Equus 400 350 Body size (kg) 300 250 Merychippus 200 Mesohippus 150 Hyracotherium 100 50 Nannippus 60 55 50 45 40 35 30 25 20 15 10 5 0 Millions of years ago

  17. Fossil record • A record showing us that today’s organisms descended from ancestral species

  18. ? ? ? ? Fossil record Land Mammal Where are thetransitional fossils?

  19. Fossil record • Fossil discovery of early tetrapod in 2006 (Tiktaalik) • “missing link” from sea to land animals http://animal.discovery.com/tv-shows/other/videos/animal-armageddon-tiktaalik.htm(animal planet) Fish out of water: http://videos.howstuffworks.com/university-of-chicago/2162-tiktaalik-fish-out-of-water-video.htm Meet the Tiktaalik: http://tiktaalik.uchicago.edu/meetTik.html

  20. Comparative Anatomy • Similar • Similar • Different • Evidence of close evolutionary relationship • recent • Homologous structures

  21. Comparative Anatomy • Homologous structures • similarities in characteristics resulting from common ancestry • Results of adaptive radiation- • All vertebrates have similar bone structures in their limbs

  22. Comparative Anatomy • Separate evolution of structures • Similar • Similar • different internal structure & development • Different • no evolutionary relationship • Analogous structures Don’t be fooledby their looks!

  23. Comparative Anatomy • Flight evolved in 3 separate animal groups • evolved similar “solution” to similar “problems” • may have developed as a result of convergent evolution– • Analogous structures

  24. Comparative Anatomy Analogous structures • Fish: aquatic vertebrates • Dolphins: aquatic mammals • similar adaptations to life in the sea • not closely related Those fins & tails & sleek bodies areanalogous structures!

  25. Comparative Anatomy • Homologous structures • Analogous structures Remember: Convergent evolution Adaptive radiation • Results from: • Adaptive radiation • Common ancestor • Similar origin • Different functions • Ex. wing of bat, human arm, dolphin flipper • Results from: • Convergent evolution • Different ancestors • Different origin • Similar functions • Ex. wings of bird, wings of insect

  26. Comparative Anatomy • Vestigial structures • Modern animals may have structures that serve little or no function • remnants of structures that were • deleterious mutations accumulate in genes for non-critical structures without reducing fitness • snakes & whales — remains of pelvis & leg bones of walking ancestors • eyes on blind cave fish • human tail bone, appendix

  27. Comparative Anatomy • Vestigial structures PBS: Whales in the Makinghttp://www.pbs.org/wgbh/evolution/library/03/4/quicktime/l_034_05.html

  28. Fish Comparative embryology Salamander Tortoise Chicken Human

  29. Comparative embryology • Similar embryological development in closely related species • all vertebrate embryos have similar structures at different stages of development • gill pouch in fish, frog, snake, birds, human, etc.

  30. Human/kangaroo 100 Human/ cow Dog/ cow 75 Rabbit/ rodent Human/rodent Llama/ cow Horse/ donkey 50 Nucleotide substitutions Horse/cow Sheep/ goat Pig/ cow 25 Goat/cow 0 0 25 50 75 100 125 Millions of years ago Molecular record • DNA & proteins are a molecular record of evolutionary relationships • Closely related species have sequences that are more similar than distantly related species

  31. Molecular record Dog Human Macaque Bird Frog Lamprey 32 45 125 67 20 30 40 50 60 70 80 90 100 110 120 Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans

  32. Artificial selection (selective breeding) • Artificial breeding can use • line of evidence that supports evolution by natural selection • the breeding of domestic plants and animals to produce specific desirable traits (ex. different breeds of dogs) • people are doing the “selecting” rather than the environment

  33. Artificial selection (selective breeding)

  34. 5.4.3 State that populations tend to produce more offspring than the environment can support. Natural populations (a population consists of all the individuals of one species in a particular area) of all organisms have the potential to increase rapidly – organisms produce far more offspring than can possibly survive

  35. 5.4.3 State that populations tend to produce more offspring than the environment can support. • More than needed to keep species around • More than K (carrying capacity) can support, but limited resources • Intraspecific competition • Some have such as traits, behaviors, symbiosis) • More fit (competing for resources, • fighting disease, etc.) = • Frequency of these alleles higher • in next generation

  36. 5.4.4 Explain that the consequence of the potential overproduction of offspring is a struggle for survival.

  37. 5.4.4 Explain that the consequence of the potential overproduction of offspring is a struggle for survival. • Some individuals selected FOR • Some selected AGAINST • Survivors (selected FOR) form new breeding • population • Increases frequency of advantageous alleles

  38. 5.4.5 State that the members of a species show variation. Individual members of a population differ from one another in their ability to obtain resources, withstand environmental extremes, escape predators etc. (Variation)

  39. 5.4.5 State that the members of a species show variation. • At least some of the variation among individuals in traits that affect survival and reproduction is due to genetic differences that can be passed on from parent to offspring – natural selection • Over many generations, differential, or unequal, reproduction among individuals with different genetic makeup changes the overall genetic composition of the population – evolution • Evolution is the result of natural selection

  40. 5.4.6Explainhow sexual reproduction promotes variation in a species.

  41. 5.4.6Explainhow sexual reproduction promotes variation in a species. • MIXING IT UP w/MEIOSIS! • Random assortment of chromosomes in Metaphase I • 2^n combinations of chromosomes in daughter cells (n = haploid number) • 8,388,608 in humans!! • Crossing-over in • Prophase I • New combos of alleles • on a chromosomes • Random fertilization • any gamete can fertilize any • gamete from the other individual

  42. Darwin’s Theory of Natural Selection: Populations produce more offspring than can possibly survive. (overproduction) Individuals in a population vary extensively from each other, mostly due to inheritance. (variation) Struggle to survive: individuals whose inherited characteristics best fit to environment leave more offspring than less fit. (survival of the fittest) Unequal ability of individuals to survive and reproduce leads to gradual change in population. (adaptation) Favorable characteristics accumulate over generations – (descent with modification). PBS: How does evolution really work? http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

  43. 5.4.7Explainhow natural selection leads to evolution.

  44. 5.4.7Explainhow natural selection leads to evolution. • Individuals with genetic characteristics that are WELL-adapted for environment: • Tend to be MORE successful at • And thus have BETTERchance of • Since they survive to adulthood, these successful organisms have a better chance to and to the next generation. • Over many generations, accumulation of changes in the heritable characteristics of a population results in . THE GENE POOL HAS CHANGED!

  45. 5.4.8 Explain 2 examples of evolution in response to environmental change. (one must be antibiotic resistance in bacteria) PBS: Why does evolution matter now? http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

  46. 5.4.8 Explain 2 examples of evolution in response to environmental change. (one must be antibiotic resistance in bacteria) http://www.sumanasinc.com/scienceinfocus/sif_antibiotics.html

  47. 5.4.8 Explain 2 examples of evolution in response to environmental change – peppered moth melanism

  48. 5.4.8 Explain 2 examples of evolution in response to environmental change – peppered moth melanism

  49. 5.4.8 Explain 2 examples of evolution in response to environmental change – insecticide resistance Insecticide Resistance – evolution in action • Insecticide & drug resistance • insecticide didn’t kill all individuals • resistant survivors reproduce • resistance is inherited • insecticide becomes less & less effective

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