This problem is from A-Level and IB, and it is not in the NEET syllabus…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
This problem is from A-Level and IB, and it is not in the NEET syllabus. In a model of a pest, the resistance allele is recessive and has a frequency . Susceptible insects on the toxin plants lose a fraction of their fitness. With no refuge, . One generation of selection gives mean fitness , and a new frequency .
- What is with no refuge?
- What is with no refuge?
- A refuge that is half of the area cuts the effective to . What is now?
Need a reminder? The key ideaShow
The manipulation of living organisms needs rules. GM organisms could have unpredictable results when they are introduced into the ecosystem. The Indian Government set up the Genetic Engineering Approval Committee (GEAC), which decides on the validity of GM research and on the safety of introducing GM organisms for public services. A model of gene flow says that the share of pollen from a GM field falls with distance. A model of resistance says that a refuge, where the pest is not selected, slows the rise of a resistance allele.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. , so . with no refuge.
Plan. Find the mean fitness, then the new frequency, for each value of .
Step 1. Mean fitness. .
Step 2. New frequency. The top is . So .
Step 3. With the refuge. : . The top is . So .
Answer: ; ; .
Check. The frequency rises from to without a refuge, and only to with it. The refuge slows the rise a great deal.
Watch out. This is a model. Real resistance depends on the number of genes, the dominance and the movement of the pests.
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