The main selective pressure in this scenario would be the availability of food resources, specifically fish. During the drought, the ponds dry up, causing a decline in fish populations. As a result, the availability of fish as a food source decreases for the long-legged birds that primarily eat fish. With fewer fish available, the long-legged birds may struggle to find enough food to survive and reproduce.
On the other hand, the short-legged birds, which primarily eat insects, are less affected by the drought since the insect populations remain relatively stable. This gives the short-legged birds an advantage over the long-legged birds in terms of food availability. As a result, the main selective pressure in this scenario is the availability of fish as a food resource, favoring the short-legged birds.
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 insect populations.
What is the main selective pressure in this scenario?
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