Question

Students in a genetics laboratory began an experiment in an attempt to increase heat tolerance in two strains of Drosophila melanogaster. One strain was trapped from the wild six weeks before the experiment was to begin; the other was obtained from a Drosophila repository at a university laboratory. In which strain would you expect to see the most rapid and extensive response to heat-tolerance selection, and why?

Short answer

Short Answer: The wild-caught strain (strain 1) of Drosophila melanogaster is more likely to show the most rapid and extensive response to heat-tolerance selection due to its higher genetic diversity compared to the laboratory strain (strain 2).

Step-by-step solution

Identify the strains of Drosophila melanogaster in the experiment

The two strains of Drosophila melanogaster in the experiment are: 1. Strain trapped from the wild six weeks before the experiment began. 2. Strain obtained from a Drosophila repository at a university laboratory.

Assess the potential genetic diversity of each strain

The genetic diversity of a population is an essential factor in its ability to adapt to new environmental conditions or selection pressure. Higher genetic diversity means that there are more variations in the genetic traits. This increases the chance of having some individuals with greater heat tolerance in the population. Strain 1 (wild-caught): This strain, being from the wild, is likely to have more genetic diversity since wild populations are exposed to a wide range of environmental conditions and other selection pressures. The wild-caught strain is more likely to have individuals with greater heat tolerance or the potential to develop greater heat tolerance. Strain 2 (university laboratory): This strain is obtained from a repository at a university laboratory. Laboratory populations are often maintained under controlled and stable conditions and might have experienced a genetic bottleneck due to being kept as a small, isolated population for an extended time. This can result in reduced genetic diversity.

Determine the strain likely to have the most rapid and extensive response to heat-tolerance selection

Based on the genetic diversity assessment, the wild-caught strain (strain 1) is more likely to have higher genetic diversity and, therefore, a greater potential for rapid and extensive response to selection pressure for heat tolerance. In contrast, the laboratory strain (strain 2) might have reduced genetic diversity and a limited ability to respond to selection for heat tolerance due to potential genetic bottlenecks and controlled environmental conditions.