Answer Key_ Name: _ Pretest: _____/48 Posttest: ______/48 Pretest Ch 17 & 19.2: Patterns of Evolution Part 1: Matching Vocab. Match the term on the right with the definition on the left by placing the letter on the blank where it best matches. 1. __ 2. __ 3. __ J__ all of the genes and alleles in an entire population A. adaptive radiation B. behavioral isolation one extreme, e.g. feet keep getting smaller and smaller C. bottleneck effect D. coevolution E. convergent evolution to a middle point, e.g. medium sized feet naturally selected F. directional selection G. disruptive selection H. divergent evolution F__ evolution keeps making things more to T__ evolution tends to make organisms more I 4. __ __ when organisms move to a new habitat and start their own population and gene pool I. founder effect J. gene pool K. genetic drift 5. __ L. genetic equilibrium M. geographic isolation S__ the processes where an organism becomes its own species 6. __ 7. __ 8. __ 9. __ B__ members of a population start to act differently and stop breeding together N. Hardy-Weinberg Principle O. macroevolutionary patterns when organisms became different species P. molecular clock Q. punctuated equilibrium and the gene frequency changes R. reproductive isolation S. speciation P__ looking at DNA and rate of mutation to tell K__ a disaster wipes out part of a population O__ all the changes in behavior, structures, functions and ecology that a species undergoes T. stabilizing selection U. temporal isolation 10. __ D__ when organisms live together and evolve together (e.g. coral and algae) 11. __ U__ when populations that live in the same area mate at different times and become separate species 12. __ Q__ when evolution happens quickly in very short time frames, not little by little over very long time frames 13. __ R__ when members of a population stop breeding and become their own species 14. __ G__ evolution tends towards both extremes, not the middle, e.g. big and small feet are good, medium is bad 15. __ A__ when organisms evolve and fit all parts of an ecosystem, e.g. live in the ground, on the ground, in the trees, in the air…. 16. __ M__ populations that get separated physically (e.g. by a river) become different species 17. __ H__ when organisms evolve into many different organisms, but still have similarities (homologous structures) 18. __ L__ when populations do not evolve 19. __ C__ over time, in small population, one allele becomes more common than another but not by natural selection 20. __ E__ when organisms in similar environments evolve to have similar traits (analogous structures) 21. __ N__ says that all allele frequencies in a population should remain the same, and the organisms will not evolve Here is a graph of the range of phenotypes in a population. Explain what each of the following is and draw what the graph would look like after each: Proportion of individuals 22. - 23. Directional selection Evolution tends towards one extreme, e.g. small hands, or tallness only 24. – 25. Stabilizing selection Evolution selects against the extremes, e.g. big/small hands are bad, close to medium is good 26. – 27. Disruptive selection Evolution selects extremes, e.g. tall and short are good, medium is bad Trait value Genetic equilibrium is the idea that allele frequencies in a population do not change over time. In other words, a population in genetic equilibrium does not evolve. There are five things that can disrupt genetic equilibrium and cause evolution to happen. Name and explain them. 28. 29. 30. 31. 32. Non-random mating (artificial selection) … choosing what traits get passed down (e.g. fast horses) Small population size, genetic drift can happen more easily (random accidents do selection instead of nature) e.g. a landslide wipes out an endangered plant Immigration (or Emigration): organisms can join (or leave) the population and bring (or take) alleles. This called gene flow. e.g. black squirrels in Kent Mutations: introduce new alleles into the gene pool e.g. four leaf clovers Natural selection: learned about that in the last unit. As a population of organisms evolves, it eventually reaches a point where some of the members can not breed with the others. They have evolved to become a new species and the process is called speciation. There are 4 ways this can happen. Name and explain them. 33. 34. Reproductive isolation: organisms don’t breed anymore Behavioral isolation: mating rituals change, so no inbreeding 35. 36. Geographic isolation: separated by mountains or islands or a river and can’t inbreed Temporal isolation: mate at different times of the year 37. – 38. What is the difference between a background extinction and a mass extinction? Which happens more frequently? A background extinction is the kind you hear about in the news…one single species goes extinct A mass extinction is when some calamity happens on the planet and large quantities of species go extinct around the same time. This has happened 3 times in the past, the last time 66 my ago when the dinosaurs died out Explain each of these four patterns of evolution (how they happen, what they lead to): Two species look alike through different ancestors (just by adapting the same way to a similar environment). Leads to analogous structures 39. convergent evolution: Two species descend from a common ancestor. Leads to homologous structures 40. divergent evolution: Two species evolve at the same time in the same place in the same way. e.g. coral and algae that gives it color 41. coevolution: When an organisms evolves to fill many niches (roles) in an ecosystem. e.g. dinosaurs in the air, in the water, in the ocean, on the land, in the swamps…. 42. adaptive radiation: 43. – 44. What is the difference between gradualism and punctuated equilibrium?” Explain which picture to the right is which. Gradualism is when changes in a population happen slowly over time, bit by bit. The picture on the left shows this. Punctuated equilibrium is when there are long periods of no change followed by small bursts of sudden change. The picture on the right shows this. Above are pictures 2 identical diagrams called cladograms. They show how closely related organisms are and some of the characteristics that separate one from another. According to the diagram, what is most closely related to: 45. birds lizards 46. lobsters spiders 47. mammals 48. lungfish lizards and birds lizards/birds/mammals