SAT II Biology E : Types of Evolution and Speciation
Study concepts, example questions & explanations for SAT II Biology E
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Example Questions
Example Question #141 : Sat Subject Test In Biology
Which of the following is not an assumption made by Hardy-Weinberg equilibrium?
Population size is infinitely large
No migration
Random mating
No natural selection
Mutations are non-lethal
Mutations are non-lethal
All of the given are assumptions made for Hardy-Weinberg equilibrium except "mutations are non-lethal." In the Hardy-Weinberg model, there is an assumption of no mutations, as mutations would introduce new alleles that would distort the ratios predicted for a population in Hardy-Weinberg equilibrium.
Example Question #142 : Sat Subject Test In Biology
In which type of speciation does a new species evolve from an ancestral species while inhabiting the same area as the ancestral species?
Sympatric
Parapatric
Peripatric
Convergent
Allopatric
Sympatric
The correct answer is "sympatric." Speciation often occurs after a group of individuals becomes geographically isolated from its original population, as occurs in allopatric and peripatric specition. In parapatric speciation, there is a very small overlap in the area of the diverging population during and after speciation. In sympatric speciation, a new species evolves without the individuals ever leaving the area of the ancestral species. "Convergent" is a type of evolution where two different species adapt similar phenotypes.
Example Question #3 : Types Of Evolution And Speciation
Species X has lived in the forest for many years. One day, some individuals in the Species X forest population moved to the mountains, away from the native habitat in which they had lived for so long. A large river then developed between the mountains and the forest, separating the two environments. None of the Species X individuals in the forest could travel to the mountains and none in the mountains could come back to the forest. Gradually, over time, the individuals that had moved to the mountains became increasingly different from the animals that remained in the forest. Eventually, the Species X individuals that moved to the mountains became so different from those in the forest that they could no longer breed with one another.
Which of the following best describes this type of speciation?
Artificial speciation
Sympatric speciation
Allopatric speciation
Peripatric speciation
Parapatric speciation
Allopatric speciation
The definition of species states that once two groups of animals are no longer able to breed with one another, they are considered members of different species. Allopatric speciation describes speciation that happens when two groups of organisms become separated by a geographic barrier that prevents interbreeding. In this question, the river is the geographic barrier separating the organisms in the mountains from those in the forest. Over time, these two groups of organisms acquire differences. Once these differences are enough to prevent the members of these two groups from being able to mate with one another, they are considered different species and allopatric speciation has occurred.
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