quiz nanaman

• Darwin's Theory


  • Existing species descended from ancestral species
  • Natural selection is the mechanism of evolution
• Natural Selection as the Mechanism for Evolution


  • In a population that varies, individuals best suited for a particular environment are more likely to survive and reproduce than those that are less suited to that environment
• Galapagos finches exhibit variation related to food gathering
• Modern research has verified Darwin's selection hypothesis
• Natural selection acts on variation in beak morphology, favoring larger beaked birds during extended droughts and smaller-beaked birds during long periods of heavy rains
• In unpolluted areas, light-colored forms remained predominant
• Experiments suggested that predation by birds was the cause; light colored moths stand out on dark trunks, and vice versa
• In the last 50 years, pollution has decreased in many areas and the frequency of light-colored moths has rebounded
• Laboratory experiments in directional selection have shown that substantial evolutionary change can occur in these controlled populations

  
• Agricultural selection has led to extensive modification of crops and livestock
• Genetic variation


  Genetic differences among individuals within a population
• Hardy-Weinberg equilibrium


  Observed genotype frequencies match the prediction from calculated frequencies, and occurs only when evolutionary processes are not acting to shift the distribution of alleles or genotypes in the population

  
• Mutation


  • Changes alleles and is the ultimate source of genetic variation
• Gene flow


  • Occurs when alleles move between populations, can introduce genetic variation and can homogenize allele frequencies between populations
• Nonrandom mating


  • Shifts genotype frequencies, assortative mating increases homozygosity, disassortative mating increases the frequency of heterozygotes
• Genetic drift


  • May alter allele frequencies in small populations
• Selection


  • Favors some genotypes over others, for evolution by natural selection to occur, genetic variation must exist, it must result in differential reproductive success, and it must be inheritable

  
• Mutation is the ultimate source of variation
• If mutation did not occur, evolution would eventually stop
• Camouflage is a structural adaptation that allows organisms to blend with their surroundings
• Natural selection can result in camouflage adaptations in organisms