Question

Selection for traits that are sensitive to population density and are favoured at high densities is known as:

• A. Semelparity
• B. k-selection
• C. Natural selection
• D. r-selection

Hint:

Remember:
• \(r\)-selection \(\rightarrow\) Rapid reproduction, many offspring, unstable environment
• \(K\)-selection \(\rightarrow\) Competitive ability, fewer offspring, stable environment \[ K \rightarrow \text{Carrying Capacity of environment} \]

Answer 1

The Correct Option is B

Concept: In population ecology, organisms show different reproductive strategies depending on environmental conditions and population density. Two important strategies are:
• \(r\)-selection
• \(K\)-selection \(K\)-selection occurs in stable environments where population density is high and resources are limited. Traits favored under \(K\)-selection include:
• Slow growth
• Larger body size
• Longer lifespan
• Fewer offspring with greater parental care

Step 1: Understanding density-dependent selection. The question refers to: \[ \text{Traits sensitive to population density and favoured at high densities} \] This is characteristic of: \[ \boxed{K\text{-selection}} \] The term \(K\) comes from the carrying capacity of the environment.

Step 2: Eliminating the incorrect options.
• Option (A): Semelparity refers to organisms reproducing only once in their lifetime.
• Option (C): Natural selection is a broad evolutionary mechanism, not specifically related to high-density population traits.
• Option (D): \(r\)-selection occurs in unstable environments with low population density and favors rapid reproduction and many offspring. Hence, the correct answer is \(K\)-selection. \[ \boxed{\text{High population density} \Rightarrow K\text{-selection}} \]