Conspecific preferences in prairie voles, Microtus ochrogaster, and meadow voles, M. pennsylvanicus

Abstract

Interactions between congeneric species in sympatry offer opportunities to study mating preferences for conspecifics, preferences that maintain premating reproductive isolation between species. Sixteen males and 16 females of two sympatric species, prairie voles (Microtus ochrogaster) and meadow voles (M pennsylvanicus), were tested for conspecific as opposed to heterospecific preferences in an automated preference apparatus. The results indicated that male prairie and meadow voles displayed preferences for conspecifics when the females were in estrus, but showed no preference when females were in diestrus. Female prairie voles in both estrous and diestrous conditions likewise displayed a preference for conspecifics, whereas meadow vole females showed no such preference. These species differences may be related to social organization, for prairie voles are monogamous, pair-bonding, and contact-prone, whereas meadow voles, which are polygamous, display high intraspecific aggression during initial contact. Conspecific preferences can be considered as one factor that maintains existing isolation between the species.Interactions between congeneric species in sympatry offer opportunities to study the factors that maintain premating reproductive isolation between those species. The discrimination of and mating preferences for conspecifics constitute one such factor. This study was designed to investigate conspecific preferences in two sympatric species of voles, prairie voles (Microtus ochrogaster) and meadow voles (M. pennsylvanicus).For sympatric species, the ability to discriminate conspecifics from heterospecifics is important for such reasons as the selection of a mating partner and the exclusion of potential resource competitors. As one might expect, the species tested have generally shown a preference for conspecifics over members of closely related species. In two-choice preference tests, male preferences for female conspecifics have been demonstrated in several species of mice of the genus Peromyscus (Bradshaw, 1965;Moore, 1965;Smith, 1965). Murphy (1977) reported that females of three hamster species displayed preferences for conspecific males. Turkish hamsters, the species with the greatest sympatric overlap, showed the strongest conspecific preference (Murphy, 1977(Murphy, , 1978. Preferences for conspecific odors or avoidance of heterospecific odors have been noted for several vole species, including male Microtus califomicus (Heske & Repp, 1986), M. pennsylvanicus (McGuire & Novak, 1987), M. agrestis, and Clethrionomys glareolus (de longe,

Activation of the immune–endocrine system with lipopolysaccharide reduces affiliative behaviors in voles.

“…Consequently, both LPS-and saline-injected males were not familiar partners in the present study; thus, to avoid the confound of familiarity among prairie voles, we used only sexually naive females in the present study. Previous data suggested that female prairie voles exhibit distinct preferences for conspecific males regardless of estrous stage (Pierce, Ferguson, & Dewsbury, 1989). In contrast, female meadow voles in diestrus do not appear to distinguish between males during partner preference tests, suggesting that the observed species difference in partner preference behavior in the present study may reflect species differences in female reproductive status and social organization.…”

Three experiments on mate choice in meadow voles (Microtus pennsylvanicus).

“…Meadow voles have been shown to display avoidance of sibling inbreeding (Bollinger, Harper, Kramer, & Barrett, 1991). Male meadow voles prefer to associate with conspecific females, rather than with female prairie voles, but only when the females are in estrus (Pierce, Ferguson, & Dewsbury, 1989). Conspecific preferences appear rather unaffected by cross-fostering (McGuire & Novak, 1987).…”

Estrus induction in four species of voles (Microtus).

“…Additionally, the longer period of estrus induction may afford both the male and female greater opportunity for mate evaluation, thought to be important in monogamous species. Monogamous vole species generally display mate choice more readily than polygamous species (Pierce, 1989; Pierce & Dewsbury, 1991; Pierce, Ferguson, & Dewsbury, 1989; Shapiro, Austin, Ward, & Dewsbury, 1986; Shapiro & Dewsbury, 1986).…”