Diagnosis of paternity by DNA confirmed: the heart of a beauty is prone to treason
Most female animals choose a mate for mating on the same basis every year. The female peacock chooses the male with the most extravagant tail, the doe chooses the male with the largest horns, and the blue–footed booby chooses the bluest paws.
However, as scientists at the University of California (Santa Cruz), working under the guidance of Dr. Alexis Chaine, have found, everything is much more complicated in lark buntings. Females of this bird species change the sign that determines the choice of a partner every year.
According to evolutionary theory, by giving preference to one or another characteristic of a partner, females direct the evolution of some sexual characteristics of males. The most obvious example is peacocks, whose particularly large and bright tail plumage indicates the "best" male representatives. It turned out that this scheme is not universal.
As part of the five-year work, the researchers evaluated the appearance and analyzed the DNA composition of males and chicks of lark buntings living in Colorado. Using methods used in criminology to establish paternity, they determined which of the external signs the females preferred in each of the four mating seasons during which the study was conducted. To the surprise of scientists who expected to identify 1-2 predominant characteristics, it turned out that the selection criteria for males changed every year.
In 1999, the largest number of chicks were conceived by males with large beaks, in 2000 – by males with dark plumage, in 2002 – by males with a small body size, and in 2003, on the contrary, by large individuals.
According to the generally accepted theory, the preferences of female individuals are constant, but the results indicate the opposite. The authors believe that, in general, such a scheme of choosing partners makes a lot of sense, because a "good" male is not always good in case of changes in environmental conditions.
What specific factors cause differences in female preferences is still a mystery. The authors suggest that the dark color indicates the ability to forage (because the color is often caused by eating berries and fruits), and the large body indicates the ability to protect the nest. However, further research is needed to obtain evidence of such relationships.
Based on the data obtained, it can be argued that female buntings do not follow the "peacock rule", which has been unconditionally recognized by biologists for a long time. Apparently, they take into account changing environmental conditions and prefer characteristics that indicate the advantages of males in specific conditions.
Most likely, lark buntings are not unique, and the authors believe that they will be able to find many more confirmations of the theory formed on the basis of the data they received.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of Nature.
29.01.2008