Many modern refrigerators have an internal temperature of 458F. What if refrigerators were set at 558F in the factory? How would this affect our lives?
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