The Link Between Female Parental Care and Mating Systems

Species in which females invest heavily in parental care—feeding, protecting, and nurturing their young—often display specific patterns in their reproductive strategies:

• Male Polygamy: When females are busy with offspring, males may compete for access to multiple mates, leading to polygamous systems.

• Sexual Dimorphism: Differences in appearance, such as size or coloration, often arise when one sex (usually males) competes for mates, while the other (usually females) invests more in care.

• Body Size Differences: Physical differences between males and females are common, especially where sexual selection is strong.

However, one pattern is notably rare: females showing extensive parental care but making no investment in mate selection.

Why Females Invest in Mate Selection

When females bear the greater burden of parental care, their reproductive success depends heavily on the quality of their mates. This leads to strong female mate choice:

• Selecting for Good Genes: Females may choose males with traits indicating health, vigor, or superior genetics, increasing offspring survival and fitness.

• Direct Benefits: In some cases, females select mates who provide resources, protection, or help with offspring.

• Indirect Benefits: Choosing attractive or dominant males can result in offspring who inherit these successful traits.

Because the cost of raising offspring is high, females are under strong evolutionary pressure to be selective about their mates, ensuring their investment pays off in terms of offspring survival and reproductive success.

What Is Least Likely: No Female Investment in Mate Selection

Given these evolutionary pressures, the least likely scenario among animals where females show extensive parental care is that females would make no investment in mate selection. In such systems, mate choice is almost always present and often highly developed. Females may assess males through courtship displays, territory quality, physical attributes, or even the ability to provide resources.

Why the Other Options Are Common

• Male Polygamy: Common where females are preoccupied with care, freeing males to seek additional mates.

• Sexual Dimorphism: Arises from sexual selection, especially where males compete for access to choosy females.

• Body Size Differences: Often a result of sexual selection and competition for mates.

Why No Female Investment in Mate Selection Is Rare

• Evolutionary Cost: Females investing heavily in offspring cannot afford to mate indiscriminately, as poor mate choice can reduce offspring viability.

• Observed Patterns: Across birds, mammals, and many other groups, female mate choice is a hallmark of species with extensive female parental care.

• Empirical Evidence: Studies show that even when females manipulate male behavior or resource allocation, mate choice remains a critical part of their reproductive strategy.

Conclusion

Among animals where females show extensive parental care, it is least likely to observe no investment in mate selection by females. Instead, these females are typically highly selective, ensuring that their substantial investment in offspring translates into maximum reproductive success. This selectivity shapes the evolution of sexual dimorphism, body size differences, and mating systems across the animal kingdom.