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At least 415 records · Page 23Linked to original sources
PubMed1975

A comparative field study of the social behavior and related ecology of reef fishes of the family Chaetodontidae1)2).

20 Species of Chaetodontidae were observed in the field for a total of about 150 hrs at Eniwetok Atoll in the Marshall Islands, at Heron Island on the Great Barrier Reef, and at Johnson Island. During observations the diver either stayed in one place for 30 min, swam transects or followed individual fish. Social groupings of the different species, their intra- and interspecific agonistic interactions and their feeding are described. The frequent occurrence of Chaetodontidae in pairs and the relatively low observed level of agonistic encounters are discussed.

Aggression↗
PubMed2001

Energetic and fitness costs of mismatching resource supply and demand in seasonally breeding birds.

By advancing spring leaf flush and ensuing food availability, climatic warming results in a mismatch between the timing of peak food supply and nestling demand, shifting the optimal time for reproduction in birds. Two populations of blue tits (Parus caeruleus) that breed at different dates in similar, but spatially distinct, habitat types in Corsica and southern France provide a unique opportunity to quantify the energetic and fitness consequences when breeding is mismatched with local productivity. As food supply and demand become progressively mismatched, the increased cost of rearing young pushes the metabolic effort of adults beyond their apparent sustainable limit, drastically reducing the persistence of adults in the breeding population. We provide evidence that the economics of parental foraging and limits to sustainable metabolic effort are key selective forces underlying synchronized seasonal breeding and long-term shifts in breeding date in response to climatic change.

Adaptation, Physiological↗
PubMed2002

Multisensory contributions to the shelter-seeking behavior of a mormyrid fish, Gnathonemus petersii Günther (Mormyridae, Teleostei): the role of vision, and the passive and active electrosenses.

This study examined how weakly electric fish, Gnathonemus petersii, integrate multiple sensory modalities (passive and active electrosenses, and vision) to maintain proximity to tubular structures, serving as the fish's hiding place or shelter during the daytime. By moving the shelter along a linear 2-meter path, causing a mechanical disturbance, we challenged the fish's shelter-seeking behavior and used the length of travel that shelter proximity was maintained (contact distance) as an indicator of how well the animal maintained its shelter. In order to determine the contribution of vision and electrosense to this behavior, four groups of fish were tested in which: (1) all three modalities were intact; (2) vision alone was eliminated by optic nerve transection; (3) the active electrosense was silenced by spinal cord transection rendering the electric organ inoperative; and (4) both vision and active electrosense were deactivated. Further elimination or minimization of various sensory cues was achieved by testing the fish with optically transparent, acrylic shelters (Plexiglas) that stimulate active, but not passive, electrosense, and aluminum shelters that theoretically stimulate all three modalities. As expected, performance was optimal when all three modalities were operating, but better than expected from quantitative models based on additive processes alone. Although the absence of one sense (vision or active electrosense) caused initial deficits, these were fully compensated for over repeated daily exposure to the task, suggesting that learning might generate sensory substitution and/or the formation of sensory expectation. Finally, environmental conditions, such as shelter opacity, also affected shelter-seeking performance, sometimes in a negative direction. These results demonstrate that: (1) the integration of multiple sensory inputs in G. petersii can be synergistic, additive, redundant, or even inhibitory, and (2) multisensory processes also take into account the respective sensory cues; i.e. (a) the prevailing ambient light intensity and optical qualities of the object; (b) the geometry and strength of the DC potential emanating from the object ('battery effect'); and (c) the complex perceived impedance differential with the surrounding medium.

Animals↗
PubMed1982

Postpartum luteinizing hormone release and maternal behavior in the rat after late-gestational depletion of hypothalamic norepinephrine.

The effects of depletion of hypothalamic norepinephrine (NE) during late pregnancy on the postpartum ovulatory LH surge, the onset and maintenance of maternal behavior and lactation were examined in adult female rats. Bilateral transections of the ascending noradrenergic pathways (ANP) between days 14 and 17 of gestation resulted in a 70% depletion in hypothalamic NE content when assayed on day 6 postpartum. In spite of this depletion in hypothalamic NE content, a postpartum ovulatory surge of LH was observed in transected rats at 18:00 h on either the day of parturition or 1 day later. The magnitude of the LH surge in experimental animals at this time appeared equal to that of controls. A second group of transected and sham-transected rats was tested for maternal responsiveness postpartum and through day 6 postpartum. Primiparous transected females displayed normal maternal behavior during this period with only minor disruptions in nest-building behavior. The lactational performance of transected rats, however, was inferior to that of sham-transected animals. The hypothalamic content of NE in females that showed impairment of lactation was consistently below the NE content found in the controls. The importance of the noradrenergic system in the control of maternal behavior is discussed, and it is proposed that noradrenergic involvement in maternal behavior is modulatory rather than directly regulatory.

Animals↗
PubMed1979

Luteinizing hormone-releasing factor (LRF) and reproductive behavior in male doves exposed to long and short photoperiods.

In order to determine whether the variable degree of nest-building behavior displayed by male doves exposed to different photoregimes is related to differences in luteinizing hormone-releasing factor (LRF) levels, androgen-treated castrates held on long (16L:8D) or short (8L:16D) daylengths were treated with 20 microgram LRF or saline daily. Birds in both groups exhibited higher levels of initial courtship and nest-building when held on long days. LRF treatment had no effect on any of the behavior patterns examined. The results suggest that photoperiod does not affect reproductive behavior in male doves through changes in endogenous levels of LRF.

Animals↗
PubMed2006

Multiple occurrences of spiggin genes in sticklebacks.

The threespine stickleback (Gasterosteus aculeatus) is known to have a unique reproductive mode including male nest-building with a secreted glue-like protein named spiggin. Spiggin is a key character for studying the molecular mechanism in the evolution of this intriguing nest-building behavior, since the glue-like protein is essential for nest-building. However, it is unclear whether spiggin is encoded by a single gene or multiple genes; there are conflicting reports on this point. To resolve this discrepancy, we cloned this gene in a threespine stickleback collected in Japan. We found seven types of cDNAs including at least four genes, indicating that spiggin is encoded by a multi-gene family. On close inspection of the cDNAs, we found that one of these spiggin genes had four splicing variants. Although the cDNA sequences conserved functional domain structures, considerable diversity was observed in the sequence of each domain. Altogether, the current results imply that the structure and function of the spiggins are more complex than ever previously thought. Phylogenetic analysis of the cDNAs with related sequences including ninespine stickleback (Pungitius pungitius) spiggin genes and homologues of zebrafish (Danio rerio), torafugu (Takifugu rubripes), and spotted green pufferfish (Tetraodon nigroviridis) implied the existence of an ancestral "spiggin" gene and multiple duplication events of the gene in the stickleback lineage before and after the divergence of the threespine and ninespine sticklebacks.

Alternative Splicing↗
PubMed2000

Paternal hamsters mechanically assist the delivery, consume amniotic fluid and placenta, remove fetal membranes, and provide parental care during the birth process.

We report the first description of a male mammal behaviorally participating in the birth of his young. Djungarian hamsters, Phodopus campbelli, are naturally biparental and males contribute to pup survival and growth through direct paternal care and indirect effects on maternal physiology. Males of the closely related Siberian hamster, P. sungorus, have only seasonal opportunities to interact with pups and neither contribute to pup survival and growth nor provide extensive paternal care under laboratory conditions. Male P. campbelli undergo a series of hormonal changes prior to the birth of their first litter which are not shared with P. sungorus males and may "prime" males to express paternal behavior. We hypothesized that P. campbelli males would behave paternally on first contact with pups during the birth process, whereas P. sungorus males would not. In addition to showing paternal behavior toward neonates, male P. campbelli licked amniotic fluid before the birth, mechanically assisted the delivery, opened an airway by clearing the nostrils (so that pups flushed red with oxygenation), licked and sniffed pups in the moments and minutes after birth to clean the pups of membranes, and ate the placenta. None of these behaviors were observed in P. sungorus. We anticipate that P. campbelli will not be the only species with highly developed paternal behavioral repertoires during the birth.

Amnion↗
PubMed1986

Photoperiod time measurement for activity, torpor, molt and reproduction in mice.

Resonance light:dark cycles (LD 6:18, 6:30, 6:42, or 6:54) were used to establish that a circadian rhythm of light sensitivity is involved in the thermoregulatory and reproductive responses to a short day photoperiod in the mouse, Peromyscus leucopus. A fifth group was maintained on the long day photoperiod of LD 16:8. After 19 weeks animals presented with LD 6:18 or 6:42 exhibited short day photoperiod responses: gonadal regression, incidence of spontaneous daily torpor and molt to the winter pelage. In contrast animals responded to LD 6:30 and 6:54 as long day photoperiods: maintenance of gonadal system, no incidence of spontaneous daily torpor, and summer pelage. In a second study a T-experiment was conducted to determine that more than one circadian system may regulate these multiple photoperiodic effects. Mice were exposed to 1 of 8 LD cycles for 15 weeks (1:22.00, 1:22.25, 1:22.50, 1:23.00, 1:23.50, 1:23.75, 9:15, or 16:8), Entrained wheel-running activity occurred under all LD regimes. Mice on LD 1:22.50, 1:23.00, and 1:23.50, however, exhibited activity patterns similar to mice on LD 9:15, and they exhibited gonadal regression. Mice on LD 1:22.00, 1:22.25, and 1:23.75 exhibited activity patterns similar to LD 16:8 animals, and most of these animals remained reproductively competent. There was also a close association between occurrence of reproductive regression and daily torpor. In contrast, molt to the winter pelt occurred under all non-24-hr LD cycles. This dysynchrony in response suggests that at least 2 circadian systems are involved in photoperiodic time measurement in P. leucopus.

Animals↗
PubMed1978

Geotropism of hornet comb construction under persistent acceleration.

Social wasps (Vespinae) are insects which build in a precise geotactical orientation. The effect of persistent acceleration on comb construction by Oriental hornet (Vespa orientalis) workers was assessed experimentally within breeding boxes of various size and shape. Groups of hornets at the building phase were subjected to a centrifugal and gravitational force with a resultant ranging between 26 degrees and 45 degrees. The comb construction within such boxes was compared to that within control boxes under ordinary gravitational pull. It was found that: a) juvenile hornets (1-2 days of age) placed in quasi-rectangular boxes built in the direction of the resultant force; b) juvenile and adult hornets (3-7 days of age) placed in spherical shaped containers also built in the direction of the resultant force; c) adult hornets who had spent their first days of life in a stationary rectangular box, apparently learned the direction of the gravitational force and "tried" to build in this direction when exposed to a centrifugal force; d) adult hornets made to spin in quasi-rectangular boxes tilted in the direction of the calculated resultant force built in the direction of the resultant. These results suggest that hornets learn the direction of the gravitational force during the first days of life and that geometrical cues within the breeding box enable them to build in the direction of the force to which they have become habituated. From the standpoint of geometric cues, only the roof of the breeding box is of critical importance.

Aging↗
PubMed2006

Species and individual differences in juvenile female alloparental care are associated with oxytocin receptor density in the striatum and the lateral septum.

The neuropeptide oxytocin has been implicated in the regulation of affiliative behavior and maternal responsiveness in several mammalian species. Rodent species vary considerably in the expression of juvenile alloparental behavior. For example, alloparental behavior is spontaneous in juvenile female prairie voles (approximately 20 days of age), takes 1-3 days of pup exposure to develop in juvenile rats, and is nearly absent in juvenile mice and meadow voles. Here, we tested the hypothesis that species differences in pup responsiveness in juvenile rodents are associated with oxytocin receptor (OTR) density in specific brain regions. We found that OTR density in the nucleus accumbens (NA) is highest in juvenile prairie voles, intermediate in juvenile rats, and lowest in juvenile mice and meadow voles. In the caudate putamen (CP), OTR binding was highest in prairie voles, intermediate in rats and meadow voles, and lowest in mice. In contrast, the lateral septum (LS) shows an opposite pattern, with OTR binding being high in mice and meadow voles and low in prairie voles and rats. Thus, alloparental responsiveness in juvenile rodents is positively correlated with OTR density in the NA and CP and negatively correlated with OTR density in the LS. We then investigated whether a similar receptor-behavior relationship exists among juvenile female prairie voles by correlating individual variation in alloparental behavior with variation in OTR density. The time spent adopting crouching postures, the most distinctive component of alloparental behavior in juveniles, was positively correlated with OTR density in the NA (r = 0.47) and CP (r = 0.45) and negatively correlated with OTR density in the lateral septum (r = -0.53). Thus, variation in OTR density in the NA, CP, and LS may underlie both species and individual differences in alloparental care in rodents.

Age Factors↗