A scientist attempts to maintain a population of pea plants in a “non-evolving state” by trying to simulate the conditions required for Hardy-Weinberg equilibrium. He places the plants in a contained area under controlled conditions (no factors limiting) and makes certain that all crosses conducted are completely random. Which conditions for Hardy-Weinberg equilibrium have NOT been met?
I. no gene flow
II. no net mutations
III. random mating
IV. no natural selection
A.
I and II
B.
II and IV
C. *****
II only
D.
IV only
A.
I and II
The conditions that have NOT been met for Hardy-Weinberg equilibrium are I. no gene flow and IV. no natural selection. Therefore, the correct answer is C. II only.
To determine which conditions for Hardy-Weinberg equilibrium have not been met, let's review the conditions required for it to be achieved. Hardy-Weinberg equilibrium describes a population in which allele frequencies remain constant from generation to generation. The conditions required for Hardy-Weinberg equilibrium are:
I. No gene flow: This means that there should be no movement of individuals in or out of the population, which ensures that gene frequencies remain unchanged.
II. No net mutations: This condition specifies that there should be no new alleles introduced into the population due to mutations.
III. Random mating: This condition implies that individuals within the population mate randomly, with no preferences or selective breeding.
IV. No natural selection: This condition indicates that the environment does not favor individuals with specific traits over others, allowing all genotypes to have equal fitness.
Now, let's analyze the given scenario. The scientist has placed the pea plants in a contained area under controlled conditions, which eliminates gene flow from outside sources (condition I). The scientist also ensures that all crosses conducted are completely random, which satisfies the condition of random mating (condition III).
However, it is worth noting that conditions II and IV have not been met. While the scientist tries to maintain a non-evolving state by simulating the conditions required for Hardy-Weinberg equilibrium, they cannot completely prevent net mutations (condition II) or influence natural selection (condition IV). Therefore, the correct answer is option C. II only, indicating that condition II (no net mutations) has not been met.
D. IV only
Explanation: In order to meet the conditions of Hardy-Weinberg equilibrium, all of the following conditions must be met: no gene flow, no net mutations, random mating, no natural selection, and large population size. In this scenario, the conditions of no gene flow, no net mutations, and random mating are being met. However, the condition of no natural selection has not been met since the scientist is selecting which plants to place in the contained area, which implies an element of artificial selection.