Effects of pre- and postpubertal social experience on sexual and social behavior in male and female brown lemmings (Lemmus sibiricus)

The effects of prepubertal social contact and postpubertal mating experience on sexual behavior were examined in male and female brown lemmings (Lemmus sibiricus). Subjects of both sexes were either isolated at weaning (18 days) or then housed with siblings for another 10 days before being isolated. Before testing for sexual behavior at the age of 75 days, half of each group of males received a series of exposures to estrous females and half of each group of females was housed with a stud male. The results of mating tests indicated that whereas prior sexual experience facilitated subsequent copulatory behavior in both sexes, prepubertal interactions subsequently facilitated contact social and sexual behavior in males but did not increase the behavioral scores of females, which engaged in high levels of sexual behavior regardless of prepubertal experience. The effect of prior copulatory activity on male sexual performance could not be attributed to increasing age (i.e., maturational processes) because the behavior of males tested once but at different ages did not differ appreciably. Prepubertal social interaction appeared to predispose males to benefit from sexual experience later in life.     

Determinants of mating success in the golden hamster (Mesocricetus auratus): I. Male capacity

Rested adult golden hamsters produced a mean of 13 ejaculations and then showed a modified copulatory pattern consisting of long intromissions (10-30 s of intravaginal thrusting) during which no sperm transfer occurs. When a second (fresh) female was introduced, 58% of the males produced at least one more ejaculation, and 17% of the males produced one further ejaculation when placed with a third female. In similar three-female tests conducted 24 hr later, all males ejaculated (M = 4 ejaculations); this level of ejaculatory output was maintained over a subsequent 10-day period of daily testing. Four ejaculations ensured a nearly 100% pregnancy rate and maximum litter size in the first females. Second and third females, however, received fewer ejaculations and subsequently showed reduced fertility and produced smaller litters. Most males showed high levels of long intromissions on all days and with all females. The physiological significance of these long intromissions may be to trigger the progestational response. Examination of the rate of recovery from sexual exhaustion indicated that 2 or 8 hr of rest resulted in fewer than 50% of the males being capable of one further ejaculation. However, most of these single ejaculations were accompanied by long intromissions and resulted in successful pregnancies. Four to eight days were required for full recovery of ejaculatory capacity. This study showed that the male golden hamster has a higher ejaculatory output and more rapid recovery from sexual exhaustion than other small rodents that have been studied. Thus, the limits of male capacity appear to vary widely among species.     

Connecting Opportunity and Strain to Understand Deviant Behavior: A Test of General Strain Theory

This study examined the connection of general strain theory to opportunity, as defined by one’s desire and ability to engage in criminal or deviant behavior. Over 1,000 undergraduate students completed the electronic survey with a response rate of 12.85%. Regression analyses showed removal of positive stimuli predicted deviant behavior in all models, but anger and other affective states were significant only in some models. Peer deviance, social bonds, and opportunity were important significant predictors. This study supports Agnew’s assertions that strain theory works in conjunction with social learning, social control, and, per this study, opportunity theories.     

Olfactory discrimination of estrous condition by the male golden hamster (Mesocricetus auratus)

After repeated exposure to receptive and nonreceptive females, male golden hamsters were tested for olfactory preferences in a four-choice olfactometer. Males discriminated between the odor of anesthetized females in different stages of their estrous cycle when the airstreams carrying the stimulus odors were diluted. Previous failures to demonstrate such an ability were probably due to ceiling effects resulting from laboratory testing. Males preferred the odor of females on the day before receptivity (a day coincident with maximal scent marking by the female) and least preferred the odor of females on diestrus-1 (the day on which females attacked and chased males during pretesting encounters). Detection and quick response to an impending estrus would be especially important for males of a solitary and promiscuous species in which there is a first male mating advantage.     

Behavioral and physiological correlates of aggressive dominance in male brown lemmings (Lemmus sibiricus)

Naive male brown lemmings were paired with the same opponent for 10 min/day for 11 consecutive days. Males of a control group were placed in an empty arena for the same period. There was no decrement in the incidence of attack and chase by dominant males in pairs showing stable dominant-subordinate relations. Subsequently, seminal vesicles of dominant animals were heavier than those of subordinate, control and “no rank” (pairs in which no clear-cut dominance relations were established) animals. Dominant animals also had greater mean testis weights and higher plasma testosterone levels than subordinates. Adrenal weights did not differ significantly between the various groups. Among dominant males there were significant positive correlations between plasma testosterone levels, testis and seminal vesicle weights, and attack and chase scores. These results suggest that many of the physiological correlates of dominance status reported in previous studies in which subjects were group housed are also observed when contact between naive individuals is limited to brief encounters.