Overdosed
"Grass" said she has a BF
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- Joined
- May 25, 2021
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Many biological researchers raise the question of why """monogamous""" females and males form a pair bond and then females multiply their mates. They postulate three main hypotheses which propose multiple paternities may provide direct or indirect benefits. However, as we review the data of these so called "benefits", we'll find that they're dubious at best on a genetic and social level.
The first and most common hypothesis is that multiple paternities increases 'good', genetic diversity, hereby improving the next generation's probability to survive under natural selection.
Does the data support this?
That's embarrassing.
The next hypothesis suggests that cuckoldry provides social and economic benefits (from extra-pair mates) for females and their offspring.
This is worse than the first hypothesis! These findings should make us question the idea females attempt to confuse paternity as a viable evolutionary tactic. After all, the long-term males had to discover the female's infidelity so to reduce paternal care in both duration of the pairing and as a default of the species.
The third hypothesis proposes that bastard young are more epigenetically suitable for sexual selection and outside pressure.
The issue with this proposal is that it doesn't transfer well to mammals (including humans, as I tried to explain here), since the mothers' offspring epigenetics are dictated by their hormones/factors in the womb, not before laying an egg.
And the epigenetics the patriarch doesn't necessarily benefit the child. E.G. The father's IGF-2 levels can pass on to increase his baby's birth weight, however, the baby's intestines might grow faster than their abdominal wall resulting a rupture, which may reduce the quality of life, and death.
After doing a deep dive of the research, we find that none of the popular models demonstrate any benefits of extra-pair paternity or copulation among "monogamous" females. Rather what we unvailed the activity deleterious to most "monogamous" species (except for the extra-pair males).
The leaves the question open-why is it common for females engage in infidelity and cuckoldry? Because the vulvae are intrinsically promiscuous to short-term males' phalli, fornically upward in the cranium, and have zero propensity for monogamy without reinforcement. (I'll explain why oxytocin doesn't counterdict this in an another thread.)
The first and most common hypothesis is that multiple paternities increases 'good', genetic diversity, hereby improving the next generation's probability to survive under natural selection.
Does the data support this?
https://link.springer.com/article/10.1007/s00265-012-1374-8Mate guarding may inhibit extra-pair behaviour; however, parental arrival date and presence in the colony of wandering albatrosses (Diomedea exulans) prior to laying did not correlate with extra-pair paternity (EPP). There was little support for genetic advantages to producing EPP chicks, but the population is characterised by low genetic variability, which may result in mate incompatibility.
Mates of pairs that failed and pairs producing EPP young tended to be more similar genetically to their partners than mates producing within-pair paternity (WPP) young.
https://onlinelibrary.wiley.com/doi/10.1111/een.12346The horned passalus (Odontotaenius disjunctus) is a socially monogamous beetle with biparental care that breeds in decaying logs.
Extra-pair mating, however, seems unlikely to increase offspring genetic diversity as extra-pair offspring were not more heterozygous than within-pair offspring, and average brood heterozygosity did not increase with higher rates of extra-pair paternity.
https://www.frontiersin.org/articles/10.3389/fevo.2017.00018/fullDespite decades of research, empirical support for the “compatible genes” and “good genes” hypotheses as explanations for adaptive female extra-pair mating remains discordant. One largely untested theoretical prediction that could explain equivocal findings is that mating for compatible genes benefits should reduce selection for good genes.
Females (of Tui) in highly-related pairs did not engage more frequently in extra-pair mating.
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1474-919X.2006.00597.xAlthough there was some evidence for inbreeding avoidance, within-pair and extra-pair chicks showed similar levels of heterozygosity, and the incidence of EPP was independent of age, experience or past reproductive success. Hence, we found no evidence that females benefit from extra-pair copulation (EPC)s.
That's embarrassing.
The next hypothesis suggests that cuckoldry provides social and economic benefits (from extra-pair mates) for females and their offspring.
https://onlinelibrary.wiley.com/doi/full/10.1002/evl3.56Dominant males did not adjust their food provisioning rates in response to extra-pair paternity (EPP).
Although extra-pair males were more strongly related to the dominant female and less heterozygous than the latter’s social mate, this did not result in more inbred extra-pair offspring, likely because identified extra-pair males were not representative of the extra-pair male population.
Polyandry can experience positive direct selection, for example when multiple mating ensures female fertility and/or additional males provide cumulative resources that increase female fecundity However, such effects often appear to be weak or absent, and numerous sources of negative direct selection against polyandry have been demonstrated or hypothesized (e.g., stemming from physical harm, time or energy expenditure and/or predation or disease risk to females).
Further, paternity loss might cause an additional component of negative selection by prompting reduced male care for polyandrous females’ offspring. Explaining the evolution and persistence of polyandry, and resulting extra-pair paternity, consequently remains a core problem in evolutionary ecology.
https://www.researchgate.net/public...een_Divorce_and_Extra-Pair_Paternity_in_BirdsAlthough most bird species are socially monogamous, they show a large variation in both divorce rate and the proportion of extra-pair paternity (EPP). Recently, adaptive explanations of avian monogamy have considered divorce and EPP as related behavioural strategies by which individuals paired with low quality mates can improve their breeding status within ecological and time constraints. It has been suggested that, at both the intra- and inter-specific levels, divorce rate should be associated with the frequency of EPP.
https://www.pnas.org/content/112/44/13603High rates of extra-pair paternity are consistently associated with low parental cooperation [pic below]. To confirm that our predictions also hold when testing the male involvement in care, we also analyzed relative male care, which is a proxy of parental care bias expressed on the scale from female-biased to male-biased care
Specifically, our results are consistent with the prediction that the larger sex (usually the male in birds), which is often under stronger sexual selection than the smaller sex, reduces its care provisioning, translating into lower contribution to care on macroevolutionary time scales. Similarly, our results support the prediction that high rates of extrapair paternity will lead, on a macroevolutionary time scale, to a reduction in male care and consequently to reduced parental cooperation.
Reduction of male parental contribution due to female promiscuity might lead to lower overall parental effort, and eventual breakdown of biparental breeding systems.
This is worse than the first hypothesis! These findings should make us question the idea females attempt to confuse paternity as a viable evolutionary tactic. After all, the long-term males had to discover the female's infidelity so to reduce paternal care in both duration of the pairing and as a default of the species.
The third hypothesis proposes that bastard young are more epigenetically suitable for sexual selection and outside pressure.
https://onlinelibrary.wiley.com/doi/10.1111/jeb.13564In nests that had been exposed to predators, extra-pair offspring (EPO) were larger, longer-winged and heavier than within-pair offspring (WPO). In nonpredator nests, WPO tended to be larger, longer-winged and heavier than EPO, though the effect was nonsignificant. We found no differences in age, morphology or stress physiology between extra-pair and within-pair sires from the same nest, suggesting that additive genetic benefits cannot fully explain the differences in nestling size that we observed. The lack of an effect of predator exposure on survival or glucocorticoid stress physiology of EPO and WPO further suggests that observed size differences do not reflect more general variation in intrinsic genetic quality.
http://repository.upenn.edu/biology_papers/12The meta-analysis shows that extra-pair males are on average larger and older than within-pair males, but not different in terms of secondary sexual traits, condition or relatedness to the female. No difference was found between extra-pair and within-pair young in survival to the next breeding season. We found no significant correlation between pair genetic similarity and extra-pair paternity.
The issue with this proposal is that it doesn't transfer well to mammals (including humans, as I tried to explain here), since the mothers' offspring epigenetics are dictated by their hormones/factors in the womb, not before laying an egg.
And the epigenetics the patriarch doesn't necessarily benefit the child. E.G. The father's IGF-2 levels can pass on to increase his baby's birth weight, however, the baby's intestines might grow faster than their abdominal wall resulting a rupture, which may reduce the quality of life, and death.
After doing a deep dive of the research, we find that none of the popular models demonstrate any benefits of extra-pair paternity or copulation among "monogamous" females. Rather what we unvailed the activity deleterious to most "monogamous" species (except for the extra-pair males).
The leaves the question open-why is it common for females engage in infidelity and cuckoldry? Because the vulvae are intrinsically promiscuous to short-term males' phalli, fornically upward in the cranium, and have zero propensity for monogamy without reinforcement. (I'll explain why oxytocin doesn't counterdict this in an another thread.)