Evolution Continued BIO 152
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This 2 page Class Notes was uploaded by Samuel Croteau on Saturday April 9, 2016. The Class Notes belongs to BIO 152 at Massachusetts College of Pharmacy & Health Sciences taught by Dr. Demasi in Fall 2016. Since its upload, it has received 22 views. For similar materials see Biology of the organism in Biology at Massachusetts College of Pharmacy & Health Sciences.
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Date Created: 04/09/16
Selection • VISTA- Variation, Inheritance, Selection, Time, Adaptation • What drives selection? • Food source • Predators • Pathogens • Climate • “Survival of the fittest” ◦ misleading- implies direct competition among individuals • Reproductive success or Relative fitness ◦ Its all about who can be able to survive and pass along their genes/heritable trait to the next generation • Examples of this is the Finches – Galapagos Islands ◦ 1977 severe drought ◦ Food source changed to only hard nuts ◦ 85% of finches died • Over time the population adapted to the environment. ◦ Population evolve over time Microevolution • Genes- control development in beaks of birds • Alleles-versions of this gene ◦ b= less growth ◦ B= more growth • Possible phenotypes ◦ small beak ◦ average beak ◦ large beak • Before the drought no certain combination had the advantage after the drought the large beak birds did • With no variation in the beak size the population would have not been able to evolve • Microevolution- a change in allele frequencies in populations over time. • Natural election ◦ Three types of selection • Directional selection- favors individuals at one end of phenotypic range (FF) • Disruptive selection- favors extreme (ff,FF) • Stabilizing selection- favors intermediate variants (Ff) • Microevolution-a change in allele frequencies in a population over time • Before drought ◦ 10 B alleles (10/22)=45% ◦ 12 b alleles (12/22)=55% • After drought ◦ 16 B alleles (16/18)=89% ◦ 2 b alleles (2/18)=11% • Apply Hardy-Weinberg principle to see if evolution is occurring • Hardy-Weinberg alleles frequencies and genotype frequencies in a population remain constant from generation to generation
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