Monogamy in animals

[1][11] Paternal care in monogamous species is commonly displayed through carrying, feeding, defending, and socializing offspring.

It has been shown that female prairie voles live longer when paired with males in a social monogamous relationship.

The proposed conflict is derived from the conflict-centric differential allocation hypothesis, which states that there is a tradeoff between investment and attractiveness.

[16] Female voles have shown no difference in fecundity with genetic monogamy, but it may be enforced by males in some instances.

Anisogamy is thought to have evolved from isogamy, the fusion of similar gametes, multiple times in many different species.

Several behaviors and ecological concerns may have led to the evolution of monogamy as a relevant mating strategy.

Partner and resource availability, enforcement, mate assistance, and territory defense may be some of the most prevalent factors affecting animal behavior.

The end result is that the mate choice is more random than in a more dense population, which has a number of effects including limiting dimorphism and sexual selection.

Any males that do not exhibit parental care would not be accepted as a sexual partner for socially monogamous females in an enforcement pattern.

This theory assumes that without biparental care fitness level of offspring would be greatly reduced.

[20][21] This theory has not garnered much support, however, critiqued by several authors including Lukas and Clutton-Brock and Dixson.

[16] Monogamy as a mating system in animals has been thought to lower levels of some pre and post copulatory competition methods.

[17] A similar feedback loop is thought to occur for the sperm quality in genetically monogamous pairs.

[24] In genetically monogamous species it can be expected that sperm competition is absent or otherwise severely limited.

Large males have an advantage in the competition for access to females, and they consequently pass their genes along to a greater number of offspring.

In monogamous species, on the other hand, females and males have more equal access to mates, so there is little or no sexual dimorphism in body size.

Several studies have reported a large amount of sexual dimorphism in Australopithecus, an evolutionary ancestor of human beings that lived between 2 and 5 million years ago.

Studies suggest sexual dimorphism reached modern human levels around the time of Homo erectus 0.5 to 2 million years ago.

In polygynous species, where one male controls sexual access to females, the testes tend to be small.

[43][44][45] [obsolete source] Chimpanzees, which have a promiscuous mating system, have large testes compared to other primates.

[citation needed] In species where the young are particularly vulnerable and may benefit from protection by both parents, monogamy may be an optimal strategy.

It is thought that this may be due to the fact that too many bears close to one another may deplete the food available to the relatively small but growing cubs.

Due to this hormone's rewarding effects, the male experiences a positive feeling when they maintain a monogamous relationship.

After the chick no longer needs their care, approximately 85% of parents will part ways and typically find a new partner every breeding season.

The males are willing to work to support himself, his mate, and his offspring in order for survival; however, unlike the emperor penguin, the hornbills do not find new partners each season.

[54] It is relatively uncommon to find monogamous relationships in fish, amphibians and reptiles; however, the red-backed salamander as well as the Caribbean cleaner goby practice monogamy as well.

However, the male Caribbean cleaner goby fish has been found to separate from the female suddenly, leaving her abandoned.

Because monogamy is often referred to as "placing all your eggs in one basket" the male wants to ensure his young survive, and thus pass on his genes.

This beaver is particularly interesting, as it is practicing monogamy in its reintroduction to certain parts of Europe; however, its American counterpart is not monogamous at all and often partakes in promiscuous behavior.

In this instance, the scarcity of the European beavers' population could drive its monogamous behavior; moreover, it lowers the risk of parasite transmission which is correlated with biological fitness.