A longditudinal study of mother-young teraction in the rat: the effects of infantile stimulation, diurnal rhythms, and pup maturation.
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Many phylogenetic comparative methods that are currently widely used in the scientific literature assume a Brownian motion model for trait evolution, but the suitability of that model is rarely tested, and a number of important factors might affect whether this model is appropriate or not. For instance, we might expect evolutionary change in adaptive radiations to be driven by the availability of ecological niches. Such evolution has been shown to produce patterns of change that are different from those modelled by the Brownian process. We applied two tests for the assumption of Brownian motion that generally have high power to reject data generated under non-Brownian niche-filling models for the evolution of traits in adaptive radiations. As a case study, we used these tests to explore the evolution of feeding adaptations in two radiations of warblers. In one case, the patterns revealed do not accord with Brownian motion but show characteristics expected under certain niche-filling models.
The objective of this study was to determine whether administration of an analgesic to sows immediately after farrowing would allow them to lie more restfully. Sows lying on their pigs, causing them to be "crushed," is a major cause of pig mortality. Most deaths due to crushing occur during the first 3 d postpartum. For modern, lean-type sows, farrowing crates are relatively hard and unforgiving, even though they may be equipped with plastic-coated, expanded metal flooring. Indeed, many sows develop pressure sores on their shoulders, and this may contribute to the sows' discomfort. These sores may cause a sow to change position frequently to alleviate pain, thus increasing its chances of crushing pigs. Sixteen production sows were assigned to either a control group (C, n = 8) with litter size 11.71+/-.78 or an experimental group (B, n = 8) with litter size 11.63+/-1.22. Pigs born to C and B sows weighed 1.60+/-.04 and 1.37+/-.04 kg, respectively. The C sows were given no treatment, whereas the B sows were administered an i.m. injection of butorphanol tartrate at a dose of .15 mg/kg BW every 6 h until 3 d after farrowing. Data were collected on all sows using time-lapse photography (1 frame/.4 s) for a 3-d duration upon the initiation of farrowing. To assess the degree of comfort of each sow, body position changes were recorded when sows switched between lying, sitting, and standing. Data were analyzed by 12-h periods using Wilcoxon-Mann-Whitney equations. During the 72-h period, B sows tended to perform fewer position changes than C sows (P = .10). Specifically, position changes were fewer for B sows from 48 to 72 h postpartum (P<.06). There were no differences in position changes between treatments from 0 to 48 h postpartum (P>.50). There was no difference in the rate of crushing between treatments (C = 5, B = 5). The butorphanol did not seem to affect pig activity or normal behaviors or to create adverse effects, such as diarrhea. Although the sows given butorphanol showed a reduced number of position changes, the dose was intermediate, and a higher dose may have a greater effect. If pig mortality can be decreased, an analgesic protocol that is simple to administer and readily available to producers can be developed. Alternatively, using of more pliable flooring or an increase in sow body fat may allow sows to lie more stationary.
The stimuli acting upon the choice of shelter and resting place by the house cricket, Acheta domesticus (L.) were analysed. The places of preference in different types of terraria as well as the choice of tubes of different diameter and of various light conditions were investigated. Acheta domesticus avoids open and illuminated space in its choice of resting place. It prefers dark places, enclosed by walls, like a clefts or boxes. The influence of the conditions of environment configuration at the larval period of the crickets' development upon their subsequent preference as to rest place, has not been stated. Neither was this influence observed on their behavioural reactions as connected with the former. Crickets attain their ethological praeferendum of resting site owing to their innate photo- and thigmo-kinesis which are supplemented by hygrophilia and thermophilia. The influence of the group effect on the cricket's individual rate of development was confirmed.
Possible functions of territorial behavior were evaluated on the basis of observations of agonistic and reproductive activities of Uganda kob at a "territorial ground" (TG) in southwestern Uganda. We have found that male residents of a TG tend to occupy exclusive areas, and that agonistic interactions are concentrated along the boundaries separating adjacent occupied areas. Thus, we conclude that male kob do engage in the active defense of spatially exclusive territories at a TG.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
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Increases in nesting during pregnancy may be mediated by progesterone in mice. If the behaviors, maternal nesting (MN) and nesting induced by exogenous progesterone (PN), are controlled by the same physiological mechanism, it would be expected that they share a common genetic basis. The present experiment was designed to quantify the extent of genetic association between PN and MN. At Wesleyan University, baseline nesting was measured on females of 4 inbred strains. Subsequently, half of the mice in each strain received progesterone implants. There were significant increases in nesting due to progesterone treatment. After 21 days, implants were removed and nesting levels returned to baseline. The mice were mated and nesting measured throughout pregnancy. The strain rank order was the same for levels of PN and MN. The genetic correlation between PN and MN estimated from analysis of covariance within and between strains was not significantly different from 1.0. These results were replicated at the University of Iowa. The high genetic correlation implies a common physiological mechanism underlying PN and MN.
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Evolutionary models suggest that the cost of a signal can ensure its honesty. Empirical studies of nestling begging imply that predator attraction can impose such a cost. However, parents might reduce or abolish this cost by warning young of the presence of danger. We tested, in a controlled field playback experiment, whether alarm calls cause 5-, 8- and 11-day-old nestlings of the white-browed scrubwren, Sericornis frontalis, to suppress vocalization. In this species, nestlings vocalize when parents visit the nest ('begging') and when they are absent ('non-begging'), so we measured effects on both types of vocalization. Playback of parental alarm calls suppressed non-begging vocalization almost completely but only slightly reduced begging calls during a playback of parental feeding calls that followed. The reaction of nestlings was largely independent of age. Our results suggest two reasons why experiments ignoring the role of parents probably overestimate the real cost of nestling vocalizations. Parents can warn young from a distance about the presence of danger and so suppress non-begging vocalizations that might otherwise be overheard, and a parent's presence at the nest presumably indicates when it is safe to beg.
We studied incubation and feeding rates in two of five broods in two oven nests of Furnarius figulus at Lagoa Rodrigo de Freitas. During incubation, the number of visits and time spent in the nest did not differ between the adults. The number of feeding visits was significantly different between members of the breeding pair of the first but not of the second nest. Nestlings received arthropods, fishes, and larvae in the first nest and, in the second, arthropods, larvae, and fruits. The nestlings stayed about 23 days in the nests.
In rabbits, estradiol and progesterone (P) stimulate digging a maternal burrow while P withdrawal promotes straw-carrying. To investigate where such hormones act to regulate those activities, ovariectomized rabbits were implanted with estradiol benzoate (EB; Experiment 1) in the nucleus accumbens (ACC), the principal nucleus of the medial preoptic area or the dorsal hippocampus. Implants were combined with s.c. P injections. In Experiment 2, P (in crystals or dissolved in oil) was implanted in the same regions as in Experiment 1, combined with s.c. injections of EB. Implants of EB into the ACC or MPOA-bed nucleus of the stria terminalis (BNST) stimulated significant digging across the period of P injections in 72% and 67% of females, respectively. Neither EB implants in the hippocampus nor cholesterol implants in the MPOA-BNST were effective in eliciting digging. P withdrawal provoked a rapid decline of digging in all animals; it also stimulated straw-carrying in 53% of females implanted with EB in the MPOA-BNST. P implants failed to stimulate digging in most females injected with EB. Removal of P crystals did not promote straw-carrying. Results support an action of estradiol on the ACC and MPOA-BNST to promote digging while only the MPOA-BNST is involved in stimulating straw-carrying. The failure of P implants to stimulate digging or straw-carrying in EB-treated females suggests that the stimulation of other or additional brain areas by P is necessary to fully activate maternal nest-building.