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?
leg length
drought
insect population
fish population
1 answer
The main selective pressure in this scenario is the drought. The drying up of the ponds and decline in fish populations are forcing the birds to adapt their feeding habits in order to survive. Those with longer legs, who are able to wade in deeper water to catch fish, may have an advantage over those with shorter legs who primarily rely on insects for food. This environmental change is putting selective pressure on the bird population to adapt to the changing conditions in order to survive.
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