Vole - Genetics and Sexual Behavior

Genetics and Sexual Behavior

The prairie vole is a notable animal model for its monogamous sexual fidelity, since the male is usually faithful to the female, and shares in the raising of pups. (The woodland vole is also usually monogamous.) Another species from the same genus, the meadow vole, has promiscuously mating males, and scientists have changed adult male meadow voles' behavior to resemble that of prairie voles in experiments in which a single gene was introduced into the brain via a virus.

The behavior is influenced by the number of repetitions of a particular string of microsatellite DNA, and the same DNA sequence is found in humans. Male prairie voles with the longest DNA strings spend more time with their mates and pups than male prairie voles with shorter strings. However, other scientists have disputed the gene's relationship to monogamy, and cast doubt on whether the human version plays an analogous role. Physiologically, pair-bonding behavior has been shown to be connected to vasopressin, dopamine, and oxytocin levels, with the genetic influence apparently arising via the number of receptors for these substances in the brain; the pair-bonding behavior has also been shown in experiments to be strongly modifiable by administering some of these substances directly.

Voles have a number of unusual chromosomal traits. Species have been found with 17 to 64 chromosomes, and in some species, males and females have different chromosome numbers. Female voles have been found with chromosomes from both sexes, and in one species, the sex chromosomes contain 20% of the genome. All of these variations result in very little physical aberration; most vole species are virtually indistinguishable.