{"id":39069,"date":"2019-10-31T22:27:41","date_gmt":"2019-10-31T19:27:41","guid":{"rendered":"https:\/\/prohoster.info\/blog\/genetika-lyubvi-mezhpolovoj-konflikt-kak-osnova-sotrudnichestva-v-parah-monogamnyh-ptits\/"},"modified":"2019-10-31T22:27:41","modified_gmt":"2019-10-31T19:27:41","slug":"genetika-lyubvi-mezhpolovoj-konflikt-kak-osnova-sotrudnichestva-v-parah-monogamnyh-ptits","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/news\/genetika-lyubvi-mezhpolovoj-konflikt-kak-osnova-sotrudnichestva-v-parah-monogamnyh-ptits","title":{"rendered":"The Genetics of Love: Intersexual Conflict as the Basis for Cooperation in Monogamous Bird Pairs","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"The
\n
\nRelationships between partners filled with care, attention, and empathy are called love by poets, while biologists refer to them as intersexual relationships aimed at survival and procreation. Some species prefer quantity\u2014reproducing with as many partners as possible to increase offspring, thus enhancing the chances of survival for the entire species. Others form monogamous pairs that can only cease to exist upon the death of one partner. For many years, scientists believed that the first option was significantly more beneficial, but this is not entirely true. Monogamous pairs typically raise their offspring together, protecting them from predators, finding food, and teaching essential skills, while in polygamous relationships, this responsibility often falls on the fragile shoulders of the females. Of course, there are exceptions, but today we will not focus on them. Biologists have long been interested in another intriguing point\u2014males continue to show attention to females even after their pair has formed and existed for several years. What causes this behavior, what are the benefits, and what evolutionary aspects are related to it? We will find answers to these questions in the report by the research group. Let's go.<\/a><\/noindex><\/p>\n

The foundation of the research<\/h3>\n

\nConsidering the theme of the study, we will not focus on polygamous bird species but will concentrate on feathered romantics who fall in love once and for all. <\/p>\n

When discussing monogamy, it is worth noting that there are several types depending on duration: one season, multiple years, and for life.<\/p>\n

Among birds, seasonal monogamy is the most common. A striking example can be wild geese. Females take care of the nest and incubate the eggs, while the male protects the territory. On the second day after hatching, the family heads to the nearest water body, where the goslings learn to find food for themselves. In case of danger in the water, the female fiercely defends the offspring, while the male, perhaps remembering important matters, usually escapes. Not the most ideal relationship, to say the least.<\/p>\n

\"The
\nFamily of wild geese.<\/i><\/p>\n

When it comes to relationships based on permanence, storks are the best in this regard. They form a monogamous pair for life and even their place of residence doesn't change without a good reason. One stork nest, which can weigh up to 250 kg and reach 1.5 m in diameter, serves them for many years unless destroyed by natural disasters or human intervention. In the Czech Republic, there is a nest that was built back in 1864. <\/p>\n

\"The
\nThe building skills of storks need no evaluation when you see such structures.<\/i><\/p>\n

Unlike wild geese, storks share their duties equally: both partners incubate the eggs, search for food, teach their offspring to fly, and protect them from dangers. Various rituals play an important role in stork relationships: singing, dancing, etc. Interestingly, these rituals are performed not only during the pair formation period (on the first date) but throughout their entire life together (even when a male replaces the female during incubation, he performs a small dance). To us, it seems very cute, romantic, and completely illogical, as from a biological standpoint, this behavior offers no benefits. Right? This leads us smoothly into examining the research that aimed to answer this question.<\/p>\n

Ethologists*<\/i> believe that the constant display of feelings by males is linked to maintaining the reproductive state of females.<\/p>\n

Ethology*<\/b> is the science that studies genetically determined behavior, i.e., instincts. <\/p><\/blockquote>\n

At the same time, it remains unclear why such behavior continues not only during the initial mating period but throughout life, as it would be more logical for males to invest more time and energy in offspring rather than in showing affection to females. To date, many researchers have believed that the intensity of affection directed towards females directly affects the quality of mating and, consequently, offspring (i.e., the number of eggs laid). <\/p>\n

\"The
\nA male from one of the species of birds of paradise dances in front of a female. As we see, the male looks much brighter than the female. <\/i><\/p>\n

This theory is supported by observations. A female whose partner is an unremarkable male and the first flier in the area puts more effort into her offspring than if the male were average. It sounds amusing and funny, but the rituals that males perform in front of females are aimed at demonstrating not only beauty but also strength. It turns out that bright plumage, beautiful singing, and other displays of attention from males are merely cognitive signals that the female decodes into information about the male. <\/p>\n

Scientists from the universities of North Carolina and Chicago, whose work we are reviewing today, believe that such male behavior is aimed at optimizing female behavior regarding the process of offspring production.<\/p>\n

The model proposed by the researchers is based on numerous experiments that have shown that enhancing these signals from males increases females' contributions to reproduction. It is suggested that the source of such stimulating effects lies in the perceptual responses arising from the properties of the environment, signals, and the nervous system itself. Currently, about 100 examples of such 'deviations' from the normal sensory systems (hearing, sight, and smell) are known.<\/p>\n

When a male repeatedly demonstrates his advantages over other males, it can positively affect the male himself (the female will definitely choose him). However, for the female, this can be a disadvantage, as it may reduce her future reproductive success. In other words, we have a situation of 'exceeding expectations.' A male who is significantly better than other males and consistently shows signs of interest in the female will achieve his goal\u2014mating and the continuation of his lineage. The female, however, who expects similar behavior from other males but does not receive it may find herself in a dire situation. This situation is referred to by scientists as intersexual conflict: the display of beauty by males increases within the population, while among females, resistance to this tactic grows.<\/p>\n

This conflict was modeled using a computational approach (neural networks). In the obtained models, the signaler (the source of the signal \u2014 the male) utilizes the perceptual reception of the receiver (the signal receiver \u2014 the female), which stimulates the signals at the expense of perception. At a certain point, there is a change in the reception of signals within the population of females (a sort of mutation), which will significantly decrease the strength of the source signals (the male). A gradual increase in such changes will lead to certain types of signals becoming completely ineffective. As these changes progress, some signals disappear, losing their strength, but new ones emerge, and the process begins anew.<\/p>\n

This rather convoluted system is quite simple in practice. Imagine a male with a bright feather (just one), which stands out against the others, and females prefer him. Then another male appears with two bright feathers, then three, and so on. But the strength of such a signal, due to its increase and spread, begins to fall proportionally. Suddenly, a male appears who can sing beautifully and build nests. As a result, beautiful plumage as a signal ceases to be effective and starts to degenerate. <\/p>\n

However, there is always an exception to the rule \u2014 some inter-sex conflicts can evolve into full-blown and quite effective inter-sex cooperation. <\/p>\n

\"The
\nThe scheme of inter-sex conflict and inter-sex cooperation emergence.<\/i><\/p>\n

The essence is that a male with a more pronounced signal compels the female to lay not three eggs, but four. For the male, this is beneficial \u2014 he will have more offspring carrying his genetic material. For the female, however, it is not so beneficial, as she will need to expend more energy ensuring all offspring survive to independence. Consequently, females start developing in parallel with males to be more resilient to their signals. As a result, there can be two pathways: conflict or cooperation. <\/p>\n

In cooperative situations, females evolve to lay three eggs, as they did before stronger signals from males appeared, while still responding to these signals. This showcases the female strategies in nature. Thus, not just a pair is formed, but a pair that supports each other at an optimal level for reproduction in terms of signal-response interaction. <\/p>\n

Males, however, cannot evolve back, so to speak. Their intensified signals toward females yield a result of three eggs, which is not as expected. However, reducing the signal back to the previous level would also be ineffective, as it would lead to a decrease in the number of eggs laid to two. This creates a closed loop \u2014 males cannot reduce the signal strength and cannot increase it either, as in the first case, females would produce fewer offspring, and in the second, they would not respond.<\/p>\n

Naturally, neither males nor females have any malicious intent or desire to dominate each other. This entire process unfolds at a genetic level and is aimed solely at the benefit of the offspring of a given pair and the welfare of the species as a whole. <\/p>\n

Research Results<\/h3>\n

\nBy using mathematical modeling, scientists assessed the conditions under which intersexual cooperation can arise. The quantitative characteristic with the average value zf<\/i> describes the main contribution of the female to her offspring. Initially, the average value is allowed to develop to its optimal value zopt<\/i>, which depends on two variables: the benefit from the contribution (the number of surviving offspring) and the cost of the contribution for females (cf<\/i>). The latter variable is assessed after reproduction, implying that some females survive and can produce offspring again next year, leading to an increase in the number of generations.<\/p>\n

In this study, several terms will often be used that deserve a brief explanation:<\/p>\n