Question

The figure illustrates the soil zinc tolerance of the grass species Anthoxanthum along a transect from inside a mine to the middle of a pasture outside the mine.
\includegraphics[width=0.5\linewidth]{62a.png} 
Which one or more of the following processes explain(s) the observed pattern of zinc tolerance in this grass species?

• A. Genetic drift
• B. Local adaptation
• C. Coevolution
• D. Introgression

Hint:

Local adaptation often leads to marked differences in traits within species across different environments, especially when these environments impose significant selective pressures, such as varying levels of toxins or nutrients.

Answer 1

The Correct Option is B

Analysis of Zinc Tolerance Variation: The significant variation in zinc tolerance from high within the mine to low in the surrounding pasture is indicative of local adaptation. The plants inside the mine likely evolved a high tolerance to zinc due to the heavy metal-rich environment, which is a classic example of local adaptation to extreme environmental conditions. Reasons for Excluding Other Options:
Genetic drift typically impacts small populations and does not usually result in such distinct, adaptive traits that respond directly to environmental pressures.
Coevolution is not applicable as there is no interaction with other species that influences zinc tolerance.
Introgression might influence genetic diversity but there's no indication of hybridization affecting the zinc tolerance trait in this scenario.