Question

In a species, the weight of newborn ranges from 2 to 5 kg 97% of the newborn with an average weight between 3 to 3.3 kg survive whereas 99% of the infants born with weights from 2 to 2.5 kg or 1.5 to 5 kg die Which type of selection process is taking place ?

• A. Disruptive Selection
• B. Cyclical Selection
• C. Directional Selection
• D. Stabilizing Selection

Answer 1

The Correct Option is D

The question pertains to the concept of natural selection in biology and asks us to identify the type of selection process described in the scenario.

Let's break down the information given in the question:

1. The weight range for newborns is between 2 to 5 kg.
2. Newborns with an average weight range of 3 to 3.3 kg have a high survival rate of 97%.
3. Newborns with weights from 2 to 2.5 kg or 1.5 to 5 kg have a high mortality rate of 99%.

These details are crucial for understanding the type of selection process:

• Disruptive Selection favours individuals at both extremes of the phenotypic range, which is not supported by the data given as there's high mortality at the extremes.
• Cyclical Selection suggests changes in the selection pressures over time, which is unrelated to the scenario provided.
• Directional Selection favours one extreme phenotype over the other, which again is not what we observe here.
• Stabilizing Selection favours intermediate variants and acts against extreme phenotypes. Given that newborns with an average weight (3 to 3.3 kg) have a high survival rate compared to those at the tails of the weight spectrum, this perfectly describes a stabilizing selection.

Thus, the correct answer here is Stabilizing Selection as it best fits the scenario of favouring a middle range of phenotypes (3 to 3.3 kg), ensuring higher survival of individuals with average weights.

Conclusion: The process taking place is Stabilizing Selection because it reduces variation by favouring the average phenotypic trait values and reducing the extremes.