10.2.2 Microevolution: Continued Flashcards Preview

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Flashcards in 10.2.2 Microevolution: Continued Deck (11)
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1
Q

review

A
  • Review: The five criteria for maintaining Hardy-Weinberg equilibrium in a population are:
    1. large population size
    2. no gene flow in or out of the population
    3. no mutation
    4. random mating
    5. no natural selection
    • Review: When any of the five criteria are broken, microevolution occurs, and the Hardy-Weinberg equilibrium is no longer in effect.
    • With regard to the Hardy-Weinberg theory, natural selection is the only factor that acts as an adaptive force, influencing which individual characteristics are passed on.
2
Q

genetic drift

A
  • changes in the gene pool of a small population because of chance.
3
Q

gene flow

A
  • changes in the gene pool because of migration of fertile individuals or gametes. In the example shown on the left, an event occurs which splits a single population into two separate populations, A and B. Populations A and B begin to accumulate differences in their allelic frequency as they each adapt to their own local environments. The two populations intermingle, resulting in gene flow. If the gene flow between the two populations is extensive, a single genetically homogeneous population will result.
4
Q

mutations

A
  • changes in an organism’s DNA. A mutation can create a new allele, and the immediate effect is very small in the gene pool. If the new allele is selected for, however, microevolution can occur.
5
Q

nonrandom mating

A
  • occurs when an individual chooses a mate based on specific criteria, which can result in microevolution.
  • Plants may undergo self-fertilization, the ultimate form of nonrandom mating! Continued self-fertilization may result in genetically homogenous populations.
  • Many animal species choose mates based on physical and/or cultural similarities.
6
Q

natural selection

A
  • the differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. When selection causes a change in the gene frequency of a population, microevolution occurs.
  • Of the five causes of microevolution, natural selection is the only one that shapes organisms to suit their environment. The other four may, in turn, be acted upon by natural selection.
7
Q

Match the terms and give the correct order of answers.

Gene flow a. source of new alleles in a
population
Genetic drift b. differences in survival and
reproduction in a variant population
Natural selection c. change in a population’s allelic
frequency due to chance alone
Mutation d. a change in allelic frequency from
emigration and immigration

A
  • d, c, b, a
8
Q

True or false?

Macroevolution is a change in a population’s alleles or genotype frequencies over fewer than 10 generations.

A
  • false
9
Q

Why are meaningful mutations very rare?

A
  • Most genes and therefore most mutations are never expressed.
  • Most mutations are never expressed. In fact most loci on the DNA strand are never expressed. The DNA codes mostly for proteins, so unless the mutation is one in which a significant protein is harmed, the mutation has little effect. However, meaningful mutations, the kind in which the mutation enhances the organism’s chance for survival may and do occur. It is the statistical probability that makes them rare. They must be expressed and not repaired by the DNA.
10
Q

Which factor is the most important in reducing the variability that occurs in each generation of a population of tree frogs?

A
  • natural selection
11
Q

Under which of the following conditions would you expect rapid evolution of a butterfly species to occur?

A
  • a population in a diverse environment

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