Age Affects Over‐Marking of Opposite‐Sex Scent Marks in Meadow Voles, Microtus pennsylvanicus

Abstract

Models of age-related effects on behavior predict that among short-lived species younger adults are more attractive and attracted to opposite-sex conspecifics than are older adults, whereas the converse is predicted for long-lived species. Although most studies of age-related effects on behavior support these predictions, they are not supported by many studies of scent marking, a behavior used in mate attraction. Over-marking, a form of scent marking, is a tactic used by many terrestrial mammals to convey information about themselves to opposite-sex conspecifics. The present study tested the hypothesis that the age of meadow voles, Microtus pennsylvanicus; a microtine rodent, affects their over- and scent marking behaviors when they encounter the marks of opposite-sex conspecifics. Sex differences existed in the over-marking behavior of adult voles among the three different age groups that were tested. Male voles that were 5-7 mo-old and 10-12 mo-old over-marked a higher proportion of the marks of females than did 2-3 mo-old male voles. Female voles that were 2-3 mo-old, 5-7 mo-old, and 10-12 mo-old over-marked a similar number of marks deposited by male voles. Overall, the data were not consistent with models predicting the behavior of short-lived animals such as rodents when they encounter the opposite sex. The differences in over-marking displayed by older and younger adult male voles may be associated with life history tradeoffs, the likelihood that they will encounter sexually receptive females, and being selected as mates.

The scent of senescence: sexual signalling and female preference in house mice

“…In many other mammals sexually dimorphic odours have important roles in sexual selection; these signals are often left in the environment in the form of scent marks (Blaustein, 1981). Changes in olfactory signalling and subsequent female response have been observed between young adult and middle‐aged male meadow voles (Ferkin, 1999, 2010) and laboratory mice (Osada et al. , 2003, 2008), but the effects of senescence on olfactory signalling have been little explored.…”

“…In many other mammals sexually dimorphic odours have important roles in sexual selection; these signals are often left in the environment in the form of scent marks (Blaustein, 1981). Changes in olfactory signalling and subsequent female response have been observed between young adult and middleaged male meadow voles (Ferkin, 1999(Ferkin, , 2010 and laboratory mice (Osada et al, 2003(Osada et al, , 2008, but the effects of senescence on olfactory signalling have been little explored. As investment in sexual scent signalling may have metabolic costs (Gosling et al, 2000;Radwan et al, 2006;Zala et al, 2008), senesced males may be unable to maintain signalling at the same high level as younger males.…”

Dietary protein content affects the response of meadow voles, Microtus pennsylvanicus, to over-marks

“…Methods for the test phase are similar to those used in other studies involving over-marks (Ferkin et al 1999(Ferkin et al , 2010Woodward et al 2000;Vlautin et al 2010). We presented the male and female voles (subjects) with a glass slide (2.5×7.6 cm) that contained the feces scent marks of the two opposite-sex conspecifics that provided the top-and bottom-scent marks of the over-mark during the subject's exposure phase.…”

“…Each feces scent mark was approximately 1.2 cm in length and 0.3 cm in width. Thus, we were able to control for the size of the scent marks (Ferkin et al 1999(Ferkin et al , 2010Woodward et al 2000;Vlautin et al 2010).…”

“…However, we do not know how meadow voles or other terrestrial mammals respond to such over-marks. If the scent donors are opposite-sex conspecifics of the investigating animal, its response may reflect its interest in the scent donors as potential mates (Ferkin 2007(Ferkin , 2010. Responses to such over-marks when the scent donors differ in their nutritional state may be important when we consider many animals, such as meadow voles, live in environments where quality forage is distributed in patches (Batzli 1985;Jodoin 1987, 1989).…”