What does it mean when one or more assumptions of the Hardy-Weinberg model is violated? Group of answer choices
a. natural selection is strong
b. evolution is occuring
c. evolution is not occuring
d. allele frequencies are at fixation
e. all mechanisms of evolution are acting at the same time
The correct answer and explanation is:
The correct answer is: b. evolution is occurring
Explanation:
The Hardy-Weinberg equilibrium model provides a mathematical framework for studying genetic variation in a population. The model assumes that allele frequencies in a population will remain constant from generation to generation in the absence of evolutionary forces. This equilibrium is maintained under the following five assumptions:
- No mutation occurs.
- Random mating occurs.
- No natural selection occurs.
- The population is large enough to prevent genetic drift.
- No gene flow (migration) occurs.
If one or more of these assumptions is violated, then Hardy-Weinberg equilibrium is not upheld, and evolution is occurring. Here’s how each assumption influences evolutionary processes:
- Mutation: If mutations occur, they introduce new alleles into the population, which can alter allele frequencies and drive evolution.
- Non-random mating: If individuals prefer mates with certain traits, allele frequencies can change based on these preferences, potentially leading to sexual selection.
- Natural selection: If certain individuals have a higher fitness than others, natural selection will cause allele frequencies to shift over generations, leading to evolutionary change.
- Genetic drift: In small populations, random changes in allele frequencies can occur, even without selective pressure, and this can result in evolutionary changes.
- Gene flow: The migration of individuals between populations can introduce new alleles and affect allele frequencies, leading to evolutionary change.
When these assumptions are violated, evolution is taking place because the genetic makeup of the population is changing over time. Evolutionary processes such as natural selection, genetic drift, and gene flow contribute to these changes, and the population is no longer in Hardy-Weinberg equilibrium. Therefore, the violation of one or more assumptions indicates that evolutionary mechanisms are acting on the population.