IMAT 2015 Q40 [Evolution]

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Which of the following could be the outcome of evolution?

  1. speciation
  2. a change in allele frequency
  3. increased biodiversity

A. 2 and 3 only
B. 1 only
C. 1 and 3 only
D. 1, 2 and 3
E. 1 and 2 only

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The answer to this question is choice D.

Let us define each of the statements and whether or not they are a correct association with the concept of evolution.

  • Speciation: This is the creation of new species as a result of evolution or the accumulation of gradual genetic changes over time, that created organisms that are reproductively isolated. This means that to soldify that it is indeed a new species, there are a lot of factors including environmental, genetic, and even biological, that prevent the organisms of the new species from mating with related species. These “new” species are only able to reproduce via mating within the species. Thus, this is a correct association with evolution.

  • A change in allele frequency: The genetic changes that accompany evolution are ones that favor reproductive success and the overall survival of a certain population. These changes are gradual and heavily depend on the ability of the organisms to adapt to external changes, which in turn, depends on various phenotypes that affords them reproductive success in the long run. This favors the survival of the population that has advantageous phenotypes, which makes sense why the allelic frequency for these phenotypes would increase. At the same time, phenotypes that are detrimental will cause the gradual decline of the population that have these non-advantageous phenotypes, effectively decreasing the frequency of the alleles that express this trait. This then, makes it a correct association with evolution.

  • Increased biodiversity: This is heavily related to the previous 2 concepts that have been mentioned. Biodiversity refers to the variation of life within the different ecosystems present. At the present time, the species that contribute to this biodiversity are the products of evolution, since for them to survive until now, requires genetic change over a long period of time, adapting to the different factors that assist or decrease their survival as a population.

Thus, this makes all statements as correct association with evolution, making D as the correct choice.

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I am a little confused into why statement 2 is correct. I thought that a change in allele frequency is a mechanism for evolution, not a result of it. Do mechanisms and results of evolution go hand in hand?