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Chapter 13.17- 13.22

Chapter 13.17- 13.22. 13.17 Endangered species often have reduced in variation. Endangered species have low genetic variability and the diversity in their gene pool makes them less successful Example: Cheetahs suffered severe bottleneck (possibly two)

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Chapter 13.17- 13.22

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  1. Chapter 13.17- 13.22

  2. 13.17 Endangered species often have reduced in variation • Endangered species have low genetic variability and the diversity in their gene pool makes them less successful • Example: Cheetahs suffered severe bottleneck (possibly two) • Why might low genetic variability decrease survival of a population?

  3. 13.18 The perpetuation of genes defines evolutionary fitness • Survival of the fittest is not necessarily violent • More offspring • Plants: attract pollinators, shape, color, fragrance • Darwinian Fitness: is the contribution of an individual makes to the gene pool of the next generation relative to the contribution of others • Evolutionary fitness has to do with genes

  4. 13.19 There are three general outcomes of natural selection Stabilizing Selection: Average is favored Diversifying Selection: Both extremes are favored Directional Selection: One extreme is favored

  5. 13.20 Sexual selection may produce sexual dimorphism • Sexual dimorphism: differences in sexes not directly associated with reproduction • Size, coloration, manes, antlers • Intrasexual Selection: Secondary sex characteristics used to compete with members of the same sex (males fighting for mating rights) • Intersexual selection: more common, mate choice, individual of one sex (usually female) chooses mate

  6. 13.21 Natural selection cannot fashion perfect organisms • 1) Organisms are locked in historical constraints • Organisms come from ancestors, not from scratch • 2) Adaptations are often compromises • Blue footed booby • 3)Not all evolution is adaptive • Chance affects populations • Not all alleles fixed by genetic drift in the gene pool of a small population are better than those lost • 4) Selection can only edit existing variations • New alleles do not arise on demand

  7. 13.22 The evolution of antibiotic resistance in bacteria is serious public health concern • Antibiotics: most are naturally occurring • Penicillin-isolated from mold • R-plasmids carry resistance to antibiotics and pass it on to others • Ways we contribute to the evolutionary arms race • Antibiotic animal feed • Overprescribing antibiotics • Misuse of antibiotics

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