Meeting Abstract

89.7  Monday, Jan. 6 15:00  Effects of age on selectivity for dominant males in female golden Syrian hamsters PLACE, N.J.*; JOHNSTON, R.E.; Cornell University njp27@cornell.edu

Under most circumstances life history theory predicts that old females should be less selective in choosing a mate than young females. Relatively few studies have investigated this concept experimentally, and most experiments demonstrating reduced selectivity in old females involved insects. Research on guppies has provided strong evidence for an age-associated decline in choosiness in female vertebrates, but reports of this phenomenon in mammals are lacking. To address this deficiency, young and old female golden hamsters (Mesocricetus auratus) were evaluated for their preference for dominant vs. subordinate males. Females were placed in an arena in which they observed male dyads as the dominance relationship was established. Dominant and subordinate males were then placed within enclosures at the opposite ends of a Y-maze, and the first approach, scent marking, lordosis, and time spent near each male were evaluated in young and old females. During estrus, neither young nor old females demonstrated a preference for the dominant male; the only age effect being that lordosis was more commonly displayed by young than by old females. Conversely, during proestrus – a time when females solicit visits by prospective mates by leaving vaginal scent marks – all young females first approached the dominant male, whereas only 50% of old females did. Similarly, the number of vaginal scent marks left by young females favored the dominant male, but old females left slightly more vaginal scent marks near the subordinate male. Both young and old females spent more time near the dominant than the subordinate male, but the time differential was greater in young than in old females. Collectively, these preliminary results are consistent with a decline in selectivity for dominant males by old female hamsters.