Social dominance, copulatory behavior, and differential reproduction in deer mice (Peromyscus maniculatus).

Three experiments were conducted with blonde and wild-type deer mice in which dominance, copulatory behavior, and the production of offspring were measured. In both short-term tests in small cages and long-term tests in large enclosures, dominant males completed more copulations than subordinates. This increased copulatory behavior resulted in no significant increase in differential reproduction in small cages and in increases of marginal significance in large enclosures. Although copulatory behavior was minimally changed as a function of cage size, social interactions were more substantially changed. Caution is required when inferring differences in fitness from differences in rank and copulatory behavior. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of predatory behaviors of deer mice (Peromyscus maniculatus) and grasshopper mice (Onychomys leucogaster).

Deer mice (Peromyscus maniculatus) and grasshopper mice (Onychomys leucogaster) are morphologically similar and coexist in many habitats. I compared certain aspects of their insect-catching behavior for insights into the ecology and evolution of predatory behavior in rodents. The predatory attack of grasshopper mice appears more specialized than that of deer mice: The former attacked faster and more consistently, used their paws more to seize a fast-moving prey, and showed more resistance to the inhibitory effects of novel, aversive, or intimidating stimuli from a prey than did the latter. Nonetheless, deer mice are effective insect predators and exhibit a more developed predatory attack than hamsters, whose attack response is considered typical of many rodents. Grasshopper mice exhibit behavioral and morphological adaptations expected of a carnivorous mammal, and these adaptations also aid in its competition for insect prey with other rodents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of deer mice (Peromyscus maniculatus): III. Effects on pregnancy initiation.

10 experiments defining the nature and dynamics of the responsivity pattern of female deer mice to copulatory stimulation are reported. In cycling estrus, copulation beyond the 1st ejaculatory series was critical for maximal probabilities of pregnancy. The stimulus requirements appeared elevated in older, multiparous Ss. Young Ss tested in postpartum estrus were more responsive, with a single ejaculatory series sufficient for maximal probabilities of pregnancy. Artificial vaginal-cervical stimulation triggered pseudopregnancy in Ss when given in the appropriate amount and pattern. The responsivity followed an orderly dose–response relation in Ss without extensive test experience. The dose–response relation was not an artifact of changes in responsivity within the dark phase. Ss became more responsive to artificial stimulation as a function of experience and/or age. The female "vaginal code" is seen as a critical link in successful reproduction, but one that is both sensitive to prevailing conditions for the individual female and evolutionarily labile. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of deer mice (Peromyscus maniculatus): I. Normative data, subspecific differences, and effects of cross-fostering.

In Exp I, normative data were collected on copulatory behavior in 16 male–female pairs of Peromyscus maniculatus bairdi, each mated for 5 tests. P. m. bairdi display a pattern with no lock, no intravaginal thrusting, multiple intromissions prerequisite to ejaculation, and multiple ejaculations. They had a mean of 3.6 ejaculations, with the 1st ejaculation preceded by a mean of 6.4 intromissions spaced 72 sec apart. In Exp II, data from 17 male–female pairs of P. m. Blandus were compared with data from 2 samples of P. m. bairdi and a sample of P. m. gambeli from an earlier study. Although there were no qualitative differences among subspecies, significant quantitative differences were found for 11 of the 14 measures considered. In Exp III, data from 17 males cross-fostered to Mus musculus parents on the day of birth were compared with those of deer mice reared by their own parents. Cross-fostering produced no major qualitative alterations of copulatory behavior, with significant differences from normally reared males in 4 of 18 comparisons. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Odor preferences of female house mice (Mus domesticus) in seminatural enclosures.

Preferences for male odors by female house mice (Mus domesticus) were examined with respect to age, dominance status, and spatial relationships. Mice were free living in 6 field enclosures. Estrous or nonestrous females were placed in an aquarium with soiled bedding from live traps as the odor source. Females were tested for preferences between (1) adult and juvenile male odors, (2) dominant and subordinate male odors, and (3) "near" and "far" male odors. In dominance odor tests, estrous females preferred odors from dominant males; nonestrous females exhibited no significant preferences. In adult juvenile and spatial odor tests, there were no significant differences between odor preferences of estrous and nonestrous females. However, most females preferred odors from adult and "near" males. Male dominance status appears to be the strongest influence on female odor preference in these seminatural enclosures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of deer mice (Peromyscus maniculatus): II. A study of some factors regulating the fine structure of behavior.

In 7 experiments on factors regulating copulatory behavior in deer mice, changes in copulatory behavior across series within a test reflected changes in both male and female, with the male apparently predominant. Even when mating with females of a species with a very different copulatory pattern (cactus mice), male deer mice retained the species-typical pattern. Mating in a 2-male/1-female condition produced little alteration in copulatory behavior from that in the 1-male/1-female condition. Under some test conditions, levels of aggressive behavior in the 2-male/1-female condition was considerable. There was generally covariation among body weight, social dominance, and copulation, with heavier males being dominant and ejaculating more often than lighter males. When females were in hormone-induced estrus, mount and intromission latencies were longer and ejaculation frequencies were lower than with either cycling or postpartum estrus. Significant differences between cycling and postpartum estrus were detectable with a within-Ss design. Mate familiarity had little effect on parameters of copulatory behavior once initiated. Effects of both male and female were detected when mating partners were changed between tests and test–retest correlation coefficients were calculated. (67 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of the nonagouti coat-color allele on behavior of deer mice (Peromyscus maniculatus): A comparison with Norway Rats (Rattus norvegicus).

The agouti locus influences coat color by antagonizing melanocyte-stimulating hormone (MSH) at its receptor on pigment cells and may antagonize MSH in neural tissue. This study replicates work on rats to assess whether behavioral (neural) effects of the agouti locus are as similar across mammals as those on coat color. Handling, open-field, platform jump, and food-novelty tests were conducted on agouti and nonagouti deer mice (Peromyscus maniculatus) following protocols in C. A. Cottle and E. O. Price (1987). As with rats, nonagouti deer mice were less aggressive, less active, and easier to handle compared with their agouti counterparts. Nonagouti deer mice also groomed more than agouti subjects. Thus, behavioral effects of the agouti locus are conservative, and agouti may be an important modulator of melanocortins in neural as well as integumentary tissue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery from sexual satiety in deer mice (Peromyscus maniculatus bairdi).

Conducted 2 experiments with 20 deer mice to delineate the time course of recovery from sexual satiety. In Exp I, the total numbers of ejaculations and intromissions attained in satiety tests were significantly decreased on the day following satiation and recovered gradually as measured in tests run after 3 and 7 days of recovery. Whereas some measures characteristic of individual series were altered by incomplete recovery, others were unaffected. In Exp II, most males ejaculated every day when tested for 5 consecutive days; the number of ejaculations per test was lowered after Day 1, but then remained relatively constant. The pattern of measures changing with recovery has implications for the development of control models of sexual behavior. The limited capacity of males to produce ejaculates implies that males should be selected for prudence in allocating ejaculates. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Poison-based taste aversion learning in deer mice (Peromyscus maniculatus bairdi).

Used a series of experiments to test the ability of 219 adult Peromyscus mice to form learned taste aversions. It was found that (a) the mice acquired a strong aversion after a single flavor/toxicosis pairing, (b) naive mice drinking a LiCl solution apparently began to experience toxic effects within 90 sec after the beginning of consumption, (c) the mice acquired a total aversion after a single flavor/delayed illness pairing when high doses of toxin were employed, and (d) the aversion produced by a single flavor/delayed-illness pairing was specific to the flavor paired with illness and was dependent on the contingency between the flavor and illness. Although these responses are qualitatively similar to those reported for domestic rats, the mice formed considerably weaker aversions than those previously reported for laboratory rats tested with the same weight-specific doses of LiCl. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tests of preferences of adult deer mice (Peromyscus maniculatus bairdi) for siblings versus nonsiblings.

Seven experiments were conducted to test the performance of adult deer mice (Peromyscus maniculatus bairdi) in discriminating and preferring siblings versus nonsiblings. In two experiments, there was no indication of preferences based on odor alone. Further there was no indication of kin discrimination in a seminatural enclosure. There was some indication that in a test apparatus, estrous females associate preferentially with male siblings rather than nonsiblings. The effect appears dependent on the presence of siblings during development. Although the finding of a preference for siblings in estrous females is counter to expectations from an inbreeding avoidance approach, this is one of a variety of findings to suggest that not all animals avoid inbreeding all of the time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tests of preferences of young deer mice (Peromyscus maniculatus bairdi) for siblings versus nonsiblings.

Three experiments were conducted to test the performance of young deer mice (Peromyscus maniculatus bairdi) in associating preferentially with siblings versus nonsiblings. In Experiment 1, neither males nor females preferred caged siblings versus nonsiblings. In Experiment 2, with full contact permitted, nonsibling males were in contact as much as were sibling males. In Experiment 3, with pairs of littermate pairs permitted full contact, there was no significant differential association. Although discrimination and preferences related to kinship have been demonstrated in some species, they cannot be assumed to be universal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of photoperiod and social environment on sexual maturation in female deer mice (Peromyscus maniculatus bairdii).

Tested the reproductive response of young female deer mice to either a long or short photoperiod combined with the presence of adult males, adult females, or social isolation. 266 Ss were reared on either a long photoperiod (15 hrs light, 9 hrs dark) or on short days (8 hrs light, 16 hrs dark) from birth. Beginning at weaning, females were housed with an adult male, with an adult female, or in social isolation. In Exp I, vaginas opened more slowly in Ss on short days than in those on long days. Vaginal introitus was also retarded in Ss reared with an adult female in comparison with Ss reared in isolation. When examined at 37 days of age, Ss reared with an adult male had larger uteri than those reared alone; uteri were also larger in long-day than in short-day Ss. In Exp II, Ss were killed at 30 days of age; again, uterine growth was stimulated by exposure to either long days or an adult male. As was previously demonstrated for male deer mice, sexual maturation in females is regulated by photoperiod and social cues. Heterospecific social stimuli accelerate maturation in individuals that otherwise would be inhibited by having been reared on a short photoperiod. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bitter avoidance in guinea pigs (Cavia porcellus) and mice (Mus musculus and Peromyscus leucopus).

Rejection of bitter substances is common in many species and may function to protect an animal from ingestion of bitter-tasting toxins. Since many plants are bitter, it has been proposed that high tolerance for bitterness would be adaptive for herbivores. Earlier studies conducted on herbivorous guinea pigs (Cavia porcellus) have been used to support this proposal. We tested guinea pigs with bitter plant secondary metabolites (salicin, caffeine, quinine hydrochloride) and bitter protein hydrolysates (two types of hydrolyzed casein, hydrolyzed soy) in a series of two-choice preference tests. For comparison, we tested two nonherbivorous mouse species (Mus musculus and Peromyscus leucopus). Guinea pigs did show weaker avoidance of quinine hydrochloride than did the mice, confirming predictions generated from earlier work. However, guinea pigs had similar responses to caffeine as did Peromyscus. Both of these species showed weaker avoidance responses than Mus to 10 mM caffeine. For salicin, guinea pigs were the only species to avoid it at 10 mM and their preference scores at this concentration were significantly lower than for the two mice species. Guinea pigs avoided all of the protein hydrolysates more strongly than the other species. Responses to the protein hydrolysates did not reflect the patterns observed with the simple bitter compounds, suggesting that other properties of these complex stimuli may be responsible for guinea pig avoidance of them. Our results suggest caution in accepting, without further empirical support, the premise that guinea pigs (and herbivores in general) have a generalized reduced bitter sensitivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning in mature mice (Peromyscus leucopus) subjected to deep hypothermia as neonates.

In certain species of nonhibernating rodents, although young nestlings cease breathing and heart action when their body temperature is lowered to near freezing, the nestlings need only be rewarmed to recover. This remarkable capacity for immediate recovery has been known many years, but long-range consequences of deep neonatal hypothermia have never before been investigated. Mice (Peromyscus leucopus) that had been exposed to four 2.5-hr episodes of deep (2–4°C) hypothermia when 4–20 days old were later compared with littermate controls in their performance on two learning tasks. The two groups did not differ in their acquisition or extinction of a lithium-induced learned taste aversion to sucrose. Nor did they differ in learning to find a hidden platform in a swimming pool. Thus in a nonhibernating rodent species, deep hypothermia experienced neonatally—unlike similar hypothermia administered in adulthood—seems not to induce deficits in subsequent learning capabilities. The resistance of neonates to damage probably represents an adaptation, for their modest thermoregulatory abilities render them vulnerable to deep hypothermia in frigid environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tests of preferences of deer mice (Peromyscus maniculatus bairdi) for individuals and their odors as a function of sex and estrous condition.

18 experiments investigated deer mice's preferences for cues from conspecifics in relation to their presence, sex, and estrous condition. Both males and females consistently preferred bedding soiled by conspecifics to clean bedding. Males given recent testing in a seminatural enclosure preferred bedding soiled for 6–7 hrs by females to that soiled by males. Other sexually experienced males displayed no such preference; however, such males did prefer bedding soiled by females for 6–9 days to that soiled by males. There was no consistent evidence that males preferred the odor of estrous females to those in diestrus. Results suggest that there is great variability among rodent species regarding the effectiveness of cues related to sex and estrus; preferences for estrus are not universal. In nature the important signal for a male deer mouse may be the presence of a female that may soon become estrous. The current estrous state may be of less importance. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic influences on digging behaviors in mice (Mus musculus) in laboratory and seminatural settings.

Examined digging behaviors of several inbred strains of laboratory mice and some of their crosses in 3 contexts. In laboratory burrow boxes, C57BL/6Abg mice constructed more sophisticated burrow systems than did BALB/cAbg mice. Their F? hybrids built burrow systems more complex than either parental strain. The same pattern of genetic influence was observed in an outdoor pen. In an escape task that required digging, BALB/c mice escaped more quickly than did C57BL/6 mice; their F? hybrids showed dominance toward the BALB/c phenotype. Results indicate that behavioral polymorphisms in digging behavior, which may relate to habitat selection, have a genetic basis. The dominance and overdominance toward the better digging parental strain in each type of task suggest the possible evolutionary importance of these digging behaviors. (18 ref) ?55 (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Testosterone acts as a prohormone to stimulate male copulatory behavior in male deer mice (Peromyscus maniculatus bairdi).

Determined the importance of reduced and aromatized metabolites of testosterone for male sexual behavior in 111 male castrated deer mice treated with 5-alpha reductase and aromatase inhibitors. In Exp I, testosterone propionate (TP) activation of male copulatory behavior was blocked by the administration of the 5-alpha-reductase inhibitor 4-androsten-3-17-beta-carboxylic acid (17BC). These treatments also prevented TP stimulation of seminal vesicles and ventral prostate gland weight. The inhibitory effects of 17BC were specific to testosterone, since 17BC did not prevent dihydrotestosterone propionate (DHTP) induction of male sexual behavior or seminal vesicles and ventral prostate gland weight increases. In Exp II, TP activation of male copulatory behavior was prevented by the administration of the aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD). The ATD did not interfere with DHTP activation of male reproductive behavior. Also, TP and DHTP stimulation of accessory sex organ weight was not blocked by ATD. It is suggested that metabolism of testosterone to both 5-alpha-reduced androgens and estrogens is obligatory for testosterone to reliably stimulate male sexual behavior in castrated male deer mice. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gonadal hormone activation of male courtship ultrasonic vocalizations and male copulatory behavior in castrated male deer mice (Peromyscus maniculatus bairdi).

Examined the influence of testosterone (T), a 5-alpha-reduced metabolite of T (dihydrotestosterone), and an aromatized metabolite of T (estradiol) on 35-kHz ultrasonic calling and copulatory behavior by 72 male deer mice. Daily treatment with T propionate (TP), dihydrotestosterone propionate (DHTP), or estradiol benzoate (EB) restored ultrasonic calling in long-term castrated Ss. Both TP and DHTP restored copulatory behavior, but EB was ineffective. Synergism of EB and DHTP action was observed; when subthreshold doses of EB (1 μg/day) and DHTP (50 μg/day) were administered in combination, ultrasonic calling and copulatory behavior were activated. In relation to other comparative findings, results indicate that the degree to which male sexual behavior is facilitated by 5-alpha-reduced androgens and/or estrogens is influenced by the species and the particular pattern of masculine behavior under consideration. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of environmental complexity and space on social interactions of mice (Mus musculus and Peromyscus leucopus).

Examined the effects of environmental space and complexity on social behavior in albino laboratory and wild house mice (M. musculus) and wild white-footed mice (Peromyscus leucopus). Pairs of males or females of each type were introduced into circular arenas of 0.5-, 1-, or 2-m diameter containing 0, 8, or 16 internal barriers. Behavioral characteristics were assessed by multivariate cluster and principal components analyses. Differences between laboratory Ss and the 2 wild groups of Ss reflected the better sensory capabilities and greater reactivity of the wild Ss. M. musculus and P. leucopus were reactive at greater distances, they spent more time freezing and/or grooming, and their behavior was influenced by environmental complexity. The laboratory Ss exhibited reactions only at short distances. M. musculus were more aggressive than P. leucopus, and M. Musculus males were more aggressive than females. Although the amount of space available influenced all 3 types of Ss, effects differed. Laboratory Ss simply encountered each other less often in larger areas, whereas both groups of wild Ss actively used the space to avoid other individuals. Male M. musculus were more aggressive as space decreased; female M. musculus and P. leucopus showed no such change. Behaviors related to orienting toward other mice and moving away from them were more frequent in more open areas. Vision appeared to be the sensory modality used, although audition may have played a role. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kinship and familiarity as factors affecting social transfer of food preferences in adult Mongolian gerbils (Meriones unguiculatus).

Experiments were carried out with Mongolian gerbils (Meriones unguiculatus) to assess whether a socially mediated acquisition of diet selection exists in this species. Results showed that a gerbil was influenced in its diet choices by information extracted during a brief period of interaction with a familiar conspecific that had recently eaten a novel food. Data revealed that the acquisition of a food preference from a conspecific depends on the existence of a social bond between the interacting gerbils. Either genetic relatedness (being brother or sister raised in different litters) or familiarity (being bred in the same litter or being member of a reproductive pair) is necessary for the transfer of information. Unfamiliar and unrelated observer gerbils did not selectively choose their demonstrator's food. (PsycINFO Database Record (c) 2010 APA, all rights reserved)