Consider the following scenario: A drought hits the habitat of a semi-aquatic bird population. All ponds dry up, and fish populations decline. There are two groups of birds in the population that differ in leg length and diet. Long-legged birds eat fish, while short-legged birds eat insects. Drought has little effect on insect populations.
What is the main selective pressure in this scenario?
a
drought
b
insect population
c
leg length
d
fish population
d. fish population.
The main selective pressure in this scenario is the drought.
To determine the main selective pressure in this scenario, we need to analyze the factors that are affected by the drought and how they relate to the two groups of birds.
In this scenario, the drought causes all ponds to dry up and leads to a decline in fish populations. However, the insect populations remain unaffected by the drought.
Given this information, we can deduce that the main selective pressure in this scenario is the availability of food resources. Since the long-legged birds primarily rely on fish as their food source, the decline in fish populations due to the drought puts them at a disadvantage. On the other hand, the short-legged birds that feed on insects are not affected by the drought because the insect populations remain stable.
Therefore, the main selective pressure in this scenario is the availability of fish, affecting the long-legged birds. So, the correct answer is "d) fish population."