Cryptic female choice

Cryptic female choice is a form of mate choice which occurs both in pre- and post-copulatory circumstances in which females of certain species use physical or chemical mechanisms to control a male's success of fertilizing their ova or ovum; i.e. by selecting whether sperm are successful in fertilizing their eggs or not.

The present understanding of cryptic female choice is largely thanks to the extensive research and analysis done by William G. Eberhard.

The term ‘cryptic’ according to Eberhard is meant to describe an internal and thereby hidden choice some female organisms are able to make following insemination with regards to sperm selection.

Cryptic female choice reduces these costs by allowing them to also benefit from and select for favorable matings.

[2] The assumption above can be made because there is an energetic cost for a male to continue to court a female following insemination because he has to invest energy to do so.

[1]: 3–7  As discussed below, female species that are able to use cryptic choice have developed various mechanisms to manipulate male reproductive success.

Pre-Copulation – female cryptic choice can include physical, anatomical, and chemical barriers that can promote or hinder a male's success in the mating process.

[1]: 143 After insemination, male sperm are relatively slow and inert in the reproductive tracts or storage areas of the female and are only activated by calcium ionophores in vitro.

Two species of Echinometra sea urchins produce eggs that prefer sperm with a similar bindin genotype as their own.

Mouse egg glycoproteins also have preferences when it comes to sperm surface proteins; a mismatch causes reduced litter sizes.

In addition, mice, salmon, and guppies also produce eggs that have specific major histocompatibility complex protein preferences.

In the Cassadine Plant Beetle, Chelymorpha alternans, the female has a complexly coiled spermathecal duct that frequently reverses in direction.

[1] The Sand Lizard, Lacerta agilis, provides us an example of cryptic female choice during the insemination phase of mating.

These results suggest that the timing of the spermatophore removal is determined partly by genotype and is independent of the quality of a female's mate.

[11] The Japanese pygmy squid, Idiosepius paradoxus, is yet another example of a species which exhibits cryptic female choice.

Females continue to mate with different males until finding one with a large nuptial gift, upon which she enters a period of sexual non-receptivity and begins laying eggs.

Copulatory plug
Theropithecus gelada