Charles Darwin first analyzed the evolution of mating behavior in his 1871 theory of sexual selection. Darwin explained powerful male features, such as elaborate physical traits and behavioral displays, resulting from female preferences for these traits. Without explaining where the female preference comes from, Darwin pointed out that any trait that increases the likelihood of mating will increase reproductive success and thus be favored by natural selection. Darwin called this process sexual selection to distinguish it from natural selection.
Ronald Fisher developed these ideas theoretically in 1930; they suggested how a runaway process might promote such traits even if they had no particular function. If a mainly male trait is attractive to females, and both the trait and the female preference are heritable, over many generations, the proportion of males with that trait will increase.
Though the runaway process explains how sexual selection can occur even if the preferred trait has no function, sexual selection can occur jointly with natural selection. The traits used in mate choice might be related to other qualities promoting survival or reproductive success.
A game model of female mate choice and paternal care from multiple males Is presented to study the evolution of female polygamy, extrapair copulation, and the pattern of paternal care. Females choose their mates (or multiple mates) in a mating season. In the following breeding season, males invest their paternal care (or damaging care harassment) based on the likelihood of their paternity. Studies show that the preference of females for monogamy or polyandry depends on how the cost increases with paternal care.
The possibility of harassment (e.g., infanticide) by males with a low probability of paternity may force the females to engage in extrapair copulation. Mate guarding by a dominant male can evolve to be imperfect because paternity sharing solicits paternal care or reduces harassment by subordinate males. Females should attempt to mate with a subordinate male within the constraints posed by the dominant male's guarding.
The structural helplessness hypothesis is an alternate explanation to the evolutionary psychology theory for women's desires for resourceful men. According to this viewpoint, women want partners with power, prestige, and earning potential since women are often barred from authority and access to resources controlled mainly by men. Women want to marry up in socioeconomic positions since it is their principal means of acquiring access to resources. Males do not place as much emphasis on economic resources in a spouse as women do since men already have control over these resources and women have fewer resources in general.
The Bakweri community from Cameroon, West Africa, calls this notion into question by demonstrating what occurs when women have genuine influence. Bakweri women wield more personal and economic influence than males since they have more resources and are in shorter supply. Women obtain resources not just via their labor on plantations but also through casual sex, which is a good source of revenue. There are around 236 males for every hundred women, owing to the constant migration of men from other parts of the nation to work on the plantations. Due to the enormous gender imbalance, women have much leeway when choosing a spouse.
As a result, women have more money than males and a larger pool of possible mates to select from. However, Bakweri women continue to favor mates with riches. Women frequently complain about their husbands' lack of assistance. Indeed, the most often mentioned cause for divorce by women is a lack of adequate financial providing. Bakweri women change marriages if they meet a man who can pay a higher bride price and provide them with more money. Women satisfy their developed desire for a guy with resources when they are in a position to do so. Having dominating control over economic resources does not undermine this mate choice.
Ovarian changes in mate preference represent a strategic shift in preference for high genetic quality ancestral markers (i.e., ancestral markers are promising gene) during the peak reproductive period. Previous research has documented such ovulatory changes in mate selection across various traits associated with matched ancestral genes, including symmetry.
The delayed Ovulation Hypothesis makes three predictions −
First, it is hypothesized that during peak fertility, women are more attracted to men with high genetics.
Second, it predicts that women primarily experience cyclical changes when evaluating men as short-term sexual partners. Thus, during peak fertility, changes in ovulation were non-existent or occurred to a lesser extent when assessing men as long-term sexual partners.
Finally, it predicts that changes in ovulation will not persist when measuring mate preference about long-term mate quality (e.g., kindness, fidelity, financial prospects) good, etc.).
According to the ovulatory variation in good genes (GGOSH), women's preferences for certain behaviors, which are thought to indicate male genetic form, will differ depending on their fertility. Women perceive or rate each man as slightly more attractive when fertile than during other cycle phases. Studies have shown that men who act more competitively and exhibit more desirable behavior (e.g., flirting) are rated as more attractive for short-term sex but less attractive. for long-term relationships, regardless of cycle stage or hormone levels.
Changes in women's marital preferences as ovulation approaches should be related to assessing genetic advantage rather than aspects related to long-term relationships, such as women's investment. Women also change their attractiveness to men throughout the menstrual cycle, and several detectable signs of ovulation in women have been documented by researchers challenging traditional views. The ovulation cycle causes changes in a woman's physical characteristics, such as changes in the face, smell, or voice, to which men are susceptible.
The evolution of female mate choice, broadly defined as any female behavior or morphology which biases matings towards specific male phenotypes, is traditionally thought to result from direct or indirect benefits that females acquire when mating with preferred males. In contrast, new models have shown that female mate choice can be generated by the sexual conflict, where preferred males may cause fitness depression in females. Several studies have shown that female Drosophila melanogaster bias matings towards large males.
Studies show that females housed with large males have reduced lifespans and age at an accelerated rate compared with females housed with petite males, and increased male density depressed female fitness further. These fitness differences were due to effects on several different fitness components. Female fitness covaries negatively with the male courtship rate, which suggests a cost of courtship. The mating rate increases with male size, whereas female fitness peaks at an intermediate mating rate.
A study aiming to explore how variation in male mating behaviors and female mate choice influences male investment in reproductive traits that enhance sperm competition, a form of postcopulatory male–male competition in marine fishes, showed that female mate choice is associated with uneven sperm competition risk between male reproductive tactics as well as among males using the same reproductive tactic. Larger guarder males attracted more females and experienced higher rates of attempted cuckoldry than smaller guards.
In turn, larger guarder males appear adapted to this increased sperm competition risk, producing faster sperm than smaller guarder males. Sneaker males (the minor males) had faster swimming sperm, with larger sperm midpieces and smaller sperm heads than guarder males. These results suggest that female choice can amplify the selection gradient acting on males both between and within reproductive tactics.
Direct benefits are gained when immediate effects on fitness occur, such as by providing resources to offspring or improved fertilization success. Indirect benefits enhance offspring fitness by increasing their viability or attractiveness by inheriting good or attractive genes. In nature, individuals gain a combination of both and multiple kinds.
However, the costs and benefits of mate choice vary between individuals and populations, contexts, and over time. Direct benefits are resources females gain directly from the male, such as gifts of food or care for the offspring. In these, the amount or quality of resources a male provides is related to the extravagance of his trait: the more extravagant the male, the better the resource he brings.
In contrast, with indirect benefits, the extravagance of a male's trait indicates the quality of his genes. Females mating with an extravagant male will therefore produce offspring carrying better genes. So these offspring will have a greater chance of surviving or reproducing (they will have higher fitness). Theoretical models show that direct benefits can easily explain the evolution of female preferences for extravagant males where they exist.
However, in many systems, there appears to be no direct benefit; instead, indirect benefit is assumed in these cases. However, the meaning of the indirect benefit is controversial. For example, indirect benefits are projected to be minor, making it unlikely that indirect benefits outweigh the costs to women of expressing preferences.
The structural helplessness hypothesis suggests that women want partners with power, prestige, and earning potential due to their limited access to resources. Temporal context is also important, as women prefer attributes in long-term marital situations over short-term sexual contexts. Ovarian changes in mate preference are a strategic shift in preference for high genetic quality ancestral markers during the peak reproductive period.
The delayed Ovulation Hypothesis makes three predictions: during peak fertility, women are more attracted to men with high genetics, cyclical changes when evaluating men as short-term sexual partners, and changes in ovulation will not persist when measuring mate preference about long-term mate quality. According to the ovulatory variation in good genes (GGOSH), women's preferences for certain behaviors, which are thought to indicate male genetic form, will differ depending on their fertility.
The evolution of female mate choice is traditionally thought to result from direct or indirect benefits that females acquire when mating with preferred males, but new models have shown that female mate choice can be generated by the sexual conflict, where preferred males may cause fitness depression in females.
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