A large number of brothers making marmots, females more masculine

If surochem litter dominated the boys, the girls left the behavior will not yield to the brothers: they are actively playing, quarreling, and explore new territories and more aggressively treat potential gentlemen.
 
Female marmot, which managed to be born with a bunch of brothers, will look and behave in a more "manly" than other females who have had a lot of sisters. This conclusion zoologists from the University of California at Los Angeles, studying the behavior of 202 female yellow-bellied marmot, who represented 82 different litters. The observation was made with the first exit of the animals burrow to one year of age.

Each specimen was measured by the distance between the anus and the genitals. This option is considered rigidly connected to the floor of the animal: it is smaller in females, males - more. Recent studies, however, have shown that when the litter was dominated by males, then their sisters, this figure will be increased. Presumably, males, testosterone affects females More body during fetal development that leads to such anatomical abnormalities. Naturally, zoologists wanted to find out whether this applies masculinization and social behavior of animals.

As the authors write in the journal Biology Letters, female marmots, who were born in the "men's" litter in the future become real daredevils: they "boyish" active games, prone to conflicts and clashes. Groundhog difficult to engage them in a romantic relationship; In addition, such low fertility females differ, but are very active in the prospecting and development of new territories.

According to the researchers, skewed toward males or females in the litter marmots dictated by environmental conditions. Males call from the mother of large energy consumption, so an excess of boys occurs when marmots at all well, and there is food in general, so to say, life is adjusted. Otherwise, and if the female is not in very good shape in the litter will be dominated by girls. Testosterone brothers affects the behavior of the uterine sisters, that in the future could affect the life of the whole colony. Therefore, the presence in the environment of any contaminant, which masks the action of the male sex hormone, may be quite out of place, endangering the future of the animal community.