Question

Why are polyandrous mating systems more rare than polygynous matings?

a. Only males are capable of multiple rounds of reproduction within a single breeding season.

b. Only females care for the young.

c. Females usually experience more intrasexual selection pressure than males.

d. Females usually devote more energy to offspring production and development.

Short answer

The females spend more time and energy on the growth and development of an offspring as compared to males. Therefore, polyandrous matings are rare as compared to polygynous matings.

Step-by-step solution

Step 1. Introduction

In polyandrous type of mating system, one female mates with multiple male partners. The polyandrous mating system is far less common as compared to monogamous and polygynous mating systems.

Step 2. Only males are capable of multiple rounds of reproduction within a single breeding season. 

Option a is incorrect because males and females both are capable of multiple rounds of reproduction during a single breeding season.

Step 3.  Only females care for the young.  

Option b is incorrect because males and females both can take care of young ones.

Step 4. Females usually experience more intrasexual selection pressure than males.  

Option c is incorrect because females does not experience higher intrasexual pressure as compared to males. But males usually experience higher inter and intrasexual pressure as compared to females.

Step 5. Females usually devote more energy to offspring production and development. 

Option d is correct because polyandrous matings are usually rare and males generally does not devote time in the protection and development of the offsprings. Only females are more devoted towards their offsprings while males compete with others for their territories and for the best resources. Therefore, option d is the correct option. Other options does not explain why the polyandrous matings are rare.