New research from the University of Chicago and The University of North Carolina shows how bird species make long-term commitments to raise their young more efficiently.
Males of species that, like many birds, develop long-lasting pair bonds often continue to show elaborate plumage. Colors and dances after mating with a woman. While their time and energy could be better spent caring for their offspring, these demonstrations also encourage females to invest more energy in the brood. But why all this attention between mates, when the mates could increase their probability of reproduction by looking for as many mates as possible? A new study by biologists from the University of Chicago and the University of North Carolina, published today (October 1
Contrary to theories of sexual selection that men predict The evolutionary explanations for the opposing behaviors – loyalty to a partner, teamwork, and private viewing between couples – were more difficult to explain than finding the greatest possible number of partners the case was. The new work shows how these behaviors often develop inevitably in species that undergo pair bonds.
Sticking Around and Showing Off
Many attempts at birds and some at fish have now shown that a stronger male makes a sweeter song or a more attractive color encourages his partner to invest more in his brood. For example, in the 1980s, Nancy Burley showed that applying red ribbons to the legs of a male zebra finch causes his buddy to work harder for the brood and consequently raise more of his kittens.
"A strong couple, connected and emotional ties between a man and a woman are obviously not just a feature of man.
– Prof. Trevor Price
Such findings are commonplace. They may seem strange, but are easily explained when the additional stimulation by the man takes advantage of the clues a woman already uses in other contexts. For example, zebra finches already have red beaks; Perhaps the more red color you see, the greater the excitement, as it increases the female hormone levels. While the appearance of the eye-catching display that stimulates the females is good for the man (he has more offspring), it is probably bad for the woman to invest more (she has to work harder, which affects her chances, more offspring successfully raise) the future).
Using a mathematical population genetic model, Price, Maria Servedio of the University of North Carolina and their colleagues show how these scenarios could benefit the species by balancing the cost of their investment with the number of animals they use over many generations.
For example, the females of one species usually lay three eggs and their partner helps raise the young, but a male with increased blue color has his partner lay four eggs. The blue males have more offspring than dull males, so blue males become more common over the generations.
However, the increase in additional cubs is associated with high costs for the females, so a female laying only three eggs has an advantage over one laying four eggs, and these females are becoming more common. At the end of this process all males are blue and all females lay three eggs. However, if the male does not produce a display, the females lay only two eggs, which is good for neither.
In other words, males must stand around and indicate female as well as males and males for maximum benefit. The evolutionary process can be repeated many times with a different color or style of display. In the end, the female may become so dependent on various aspects of the male display that she hardly ovulates without the display, as shown for ring doves.
"The models enable us to see the wide ranges of conditions that can lead to it More than 80 years ago, British biologist Julian Huxley wrote about bird watching: It states:" Competition between men and partners, accompanied by Any form of female choice is not the usual phenomenon postulated by Darwin, and for most monogamous birds, the ad does not start until after the season's mating. " How these representations contribute to a stronger pair bond.
"Huxley was busy at the time, but his ideas were mostly ignored because he did not know how this could develop," Pri ce said. "We believe that this new research puts the affection between members of a couple and the loyalty of partners on a strong evolutionary footing."
The study "Evolution of Sexual Collaboration from Sexual Conflicts" was supported by the National Science Foundation and the Norwegian Research Council. Other authors include John M. Powers, formerly of the University of North Carolina and now of the University of California at Irvine; and Russell Lande of the Norwegian University of Science and Technology.
Reference: "Evolution of Sexual Collaboration from Sexual Conflicts" by Maria R. Servedio, John M. Powers, Russell Lande, and Trevor D. Price, October 14, 2019, Proceedings of the National Academy of Sciences ,
DOI: 10.1073 / pnas.1904138116