Question

The variance in male mating success is \(V_m\) and that of females is \(V_f\). Assuming that the sex ratio is 1:1, in which one of the following mating systems is \(V_m/V_f\) expected to be the greatest?

• A. Monogamy
• B. Random mating
• C. Polyandry
• D. Polygyny

Hint:

To assess variance in mating success:
1. Monogamy results in low variance for both sexes.
2. Polygyny greatly increases male variance (\(V_m\)) as only a few males achieve most matings.
3. Polyandry increases female variance (\(V_f\)), reducing the \(V_m/V_f\) ratio.

Answer 1

The Correct Option is D

Step 1: Understand variance in mating success. The variance in mating success (\(V_m\) and \(V_f\)) describes how unequally individuals of a sex contribute to reproduction. The ratio \(V_m/V_f\) indicates how much more variable male reproductive success is compared to females. Step 2: Analyze mating systems. Monogamy (Option A): In monogamous systems, both males and females typically have one mate, leading to low variance in mating success for both sexes. Thus, \(V_m/V_f\) is small.
Random mating (Option B): In random mating, individuals mate without preference, leading to moderate variance in reproductive success for both males and females. \(V_m/V_f\) is not expected to be very large.
Polyandry (Option C): In polyandry, females mate with multiple males. This increases \(V_f\) (female variance in mating success) relative to \(V_m\), leading to a small \(V_m/V_f\) ratio.
Polygyny (Option D): In polygyny, some males mate with many females while others mate with none. This creates a high \(V_m\) (male variance in mating success) compared to \(V_f\), leading to the highest \(V_m/V_f\) ratio among the options.