In this scenario, the main selective pressure is 3. drought. The drought directly affects the availability of resources (ponds and fish), creating a challenge for the birds. Consequently, it impacts the survival and reproductive success of the long-legged birds more than the short-legged birds, since the long-legged birds rely on fish that are in decline due to the drought. Meanwhile, the short-legged birds, which feed on insects, face less impact because the insect populations remain stable. Therefore, the drought acts as the selective pressure influencing the survival of the two bird groups based on their dietary preferences and adaptations.
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. The drought has little effect on the insect populations. What is the main selective pressure in this scenario?
1. leg length
2. insect population
3. drought
4. fish population
1 answer