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 insect populations.
What is the main selective pressure in this scenario?
A)fish population
B)leg length
C)insect population
D)drought
Help? PLeaSe
In this scenario, the main selective pressure is D) drought. The drought has caused the ponds to dry up and led to a decline in fish populations, which is the main food source for long-legged birds. The drought does not have a significant impact on insect populations, so it is not the main selective pressure in this scenario.
To determine the main selective pressure in this scenario, we need to understand which factor is driving the changes in the bird population. Selective pressure refers to the influence of environmental factors that affect the survival or reproduction of specific traits in a population.
In this scenario, we can eliminate options A (fish population) and C (insect population) as potential main selective pressures. Although the drought has caused a decline in fish populations, it states that the drought has little effect on insect populations. Therefore, the changes in the bird population may not be primarily driven by the availability of fish or insects.
We are left with options B (leg length) and D (drought). Based on the information provided, it is evident that all ponds have dried up due to the drought, resulting in a scarcity of aquatic resources such as fish. Since long-legged birds eat fish, their primary food source has dramatically decreased, placing them at a disadvantage compared to short-legged birds that primarily consume insects.
Therefore, the main selective pressure in this scenario is likely option B (leg length), as the drought-induced decline in the availability of fish has caused a disadvantage for long-legged birds.