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Anti-parasite treatment removes negative effects of environmental pollutants on reproduction in an Arctic seabird.

Recent studies have shown that the detrimental effects of anthropogenic pollutants may be worse if organisms are exposed to natural stress. In this study, we examined whether negative effects of organochlorines (OCs) could be influenced by parasites. In two breeding seasons, we administered an anti-helminthic drug to groups of breeding glaucous gulls (Larus hyperboreus), whereas control groups were placebo treated. In all birds, blood residues of the most important OCs in the study population (hexachlorobenzene, oxychlordane, p,p'-dichlorodiphenyldichloroethylene and polychlorinated biphenyl), were measured. The relationships between OCs and fitness components (i.e. nesting success and return rate between breeding seasons) were then compared between the birds receiving anti-parasite treatment and the controls. Among untreated males, higher blood residues of OCs were associated with lowered nesting success, while in males receiving anti-parasite treatment, there was no detrimental effect of OCs on fitness. Return rate was not affected by treatment or OCs. Our findings suggest that parasites may be an important factor in triggering reproductive effects of such pollutants, and that relatively low levels of OCs may have serious reproductive consequences in natural populations when stress from other sources is high.

Animals↗

Nests, tree holes, and the evolution of primate life histories.

In contrast to the majority of primates, many prosimians, some New World monkeys, and the great apes rest in tree holes or self-constructed nests during their inactive periods. The goal of this comparative study was to examine possible functions of this interspecific variation. Information on resting behavior, maternal behavior, and basic life-history traits was gleaned from the literature and mapped onto a phylogenetic tree of primates for various comparative tests. Parsimony-based reconstructions revealed that only the use of nests or tree holes as shelters for young infants can be unequivocally reconstructed for various higher taxa, suggesting that it is functionally different from the use of shelters by adults (who may be accompanied by infants). Further reconstructions revealed that the ancestral primate was most likely nocturnal and solitary and produced a single infant that was initially left in a shelter and later carried orally to a parking place in the vegetation--a combination of traits exhibited by many living galagos. Evolutionary losses of the use of nests were concentrated among diurnal and nonsolitary taxa and weakly associated with evolutionary increases in body size. Thus, protective functions of nests or tree holes used by prosimians are either secondary or there are alternative ways of obtaining protection. Because the evolution of larger litters was significantly associated with the presence of shelters, the presence of relatively altricial young among prosimians best explains the use of nests and tree holes, which are in most but not all cases also used by adults. These shelters therefore play an integral part in the life-history strategies of primitive primates and their ancestors and evolved secondarily among anthropoids for other purposes.

Animals↗

The effects of olfactory experience on nest odor preferences and pup retrieval in rats.

Previous studies have shown that maternal rats are attracted to their own bedding and that of other dams but not to that of virgins. The present studies were designed to test two hypotheses: First, that the addition of a novel botanical odor to the bedding of maternal animals would result in subsequent preferences for such an odor. Second, such a preference should enable dams to discriminate between pups odorized with familiar and unfamiliar odors as measured by differential retrieval of the pups. Both hypotheses were confirmed. In addition, we found that preferences established during a first pregnancy and lactation affected the retrieval of pups during a second lactational period, but could be overturned by new olfactory experience during that second lactational period.

Animals↗

Hormones and external factors: are they "on/off" signals for maternal nest-building in rabbits?

Estradiol, progesterone, and prolactin regulate digging, carrying straw, and plucking hair for maternal nest-building in rabbits. To explore whether external factors also modulate this process, we assessed whether shaved pregnant rabbits with straw nests would collect their own, male, or synthetic hair for nest-building. Pregnant (but not estrous) does collected and used all hair types, indicating that hair-plucking can be bypassed and a nest constructed with "alternative" hair. Unshaved pregnant does with straw nests also collected synthetic hair, indicating that this behavior is not triggered by the absence of maternal hair. Yet, if hair-plucking/nest-building had occurred, hair-collecting was prevented, suggesting that an internally triggered "drive" was turned off by perceiving a built nest. When given only straw or hair, shaved pregnant does collected and used the material provided, indicating that nest-building is internally driven and accomplished by using any available elements. When given both materials, increasingly more shaved does built straw nests across prepartum days 7 to 2. Straw-carrying declined thereafter, suggesting that perceiving a straw nest limits the collection of such material. Hair-collecting was postponed until prepartum day 1 to postpartum day 2, indicating that: (a) mothers distinguish between straw and hair and (b) hormonal factors regulate the sequential selection of straw and then hair and when the change from straw to hair occurs. Maternal behavior was normal at parturition and for the next 4 days in a similar proportion of does among all experimental groups. We conclude that hormones and external factors regulate nest-building by acting as "on/off/on" signals.

Animals↗

Phylogenetic relationships, evolution of broodcare behavior, and geographic speciation in the wrasse tribe Labrini.

The family Labridae is a large assemblage of marine fish composed of about 580 species in 82 genera distributed in tropical and temperate marine waters around the world. Several subgroups, currently classified as tribes, have been identified in this large family, yet only a few phylogenetic analyses have been performed on labrid clades. We confirm monophyly of the labrid tribe Labrini and propose a phylogeny of the 23 species of the genera Acantholabrus, Centrolabras, Ctenolabrus, Labrus, Lappanella, Symphodus, Tautoga, and Tautogolabrus occurring in the eastern and western Atlantic and the Mediterranean. We analyzed a 577-bp segment of the mitochondrial 16S rDNA and a 506-bp segment of the mitochondrial control region in 22 species, for a total of up to 1069 bp per species. We used both parsimony and likelihood approaches under a variety of assumptions and models to generate phylogenetic hypotheses. The main features of the molecular phylogeny for the Labrini turned out to be the same for the two algorithms applied. The tree structure is similar to a previous, unpublished morphological phylogeny for a subset of labrine species. Estimated divergence times of the Labrini based on fossils and a molecular clock range from about 15 mya for the deepest splits to less than 1 mya for younger clades. Biogeographic patterns of the Symphodus species group and the genus Labrus are dominated by speciation events driven by the closing and opening of the Mediterranean Sea and periodic glaciation events during the past 1 million years. The Labrini are the only clade in the entire Labridae that exhibit nest-building and broodcare behavior. We use the phylogeny to show that similar broodcare behavior has evolved twice in the labrine fish and discuss scenarios for the evolution of broodcare from the diandric protogynous hermaphroditism found in ancestral labrines and many other wrasses.

Animals↗

Effect of early auditory stimulation on the choice of acoustical environment by adult Swiss albino mice (Mus musculus).

Nine-week-old untreated albino mice, when placed in a novel environment composed of a central cage surrounded by four dark boxes in which different sounds were emitted, explored the boxes for 1 or 2 hr. In most cases the mice settled into one of the four boxes and built their nest. Most of the control animals (65%) chose the silent compartment, whatever the sound delivered in the other boxes. An acoustic choice test was then carried out. A criterion of preference was adopted: If the mouse remained within one of the four boxes for at least 20 min during the third hour, that box was assumed to be its preference. Four groups of mice were exposed to a particular sound for 10 days: Group 1: Gestation Day 10 to birth; Group 2: birth to Day 10; Group 3: Day 10 to Day 20; Group 4: Day 20 to Day 30. Mice were then tested for box preference on Day 63 in the four-box choice, one of which contained the sound of the earlier exposure. Animals stimulated before the 10th day after birth behaved in the same way as controls, whereas animals stimulated between the 10th and the 20th days after birth exhibited a strong preference for the box delivering the sound of the previous treatment. This choice was significant, whatever the harmonic or impulsive nature of the sound. Animals stimulated between the 20th and 30th days showed (53%) a preference for the silent box, but among the others, 75% chose the sound received during infancy. The behavior of animals stimulated when adult was the same as that of the controls.

Acoustic Stimulation↗

Sagittal knife cuts in the near and far lateral preoptic area-hypothalamus disrupt maternal behaviour in female hamsters.

Parasagittal knife cuts with a varied mediolateral position were placed along the medial preoptic-medial anterior hypothalamic continuum (MPOA-MAH) in female hamsters. Near lateral (NL) knife cuts severed mediolateral connections between the MPOA-MAH and the medial forebrain bundle (MFB) while far lateral cuts (FL) were placed more laterally, sparing MPOA-MAH connections with the MFB. Across the knife cut condition, hamsters were either allowed to construct and maintain a food hoard or allowed to feed ad lib but not permitted to hoard. Animals were then tested for maternal behaviours. Both NL and FL cuts disrupted pup-directed behaviours in virgin maternal tests. NL, but not FL cuts severely disrupted nest building. These same animals were then mated and tested for maternal behaviour with their own young. There were no differences among the experimental groups in various maternal behaviours during these tests. Throughout lactation, however, the majority of NL and FL hamsters not permitted to hoard progressively cannibalized their entire litters. NL and FL counterparts with the hoarding opportunity, on the other hand, cannibalized fewer pups and reared healthy, moderate-sized litters that were smaller than those of surgical controls. That FL cuts were just as effective as NL cuts in disrupting pup-directed behaviour suggests that the mediolateral connections of the MPOA-MAH, other than with the MFB, are important for these behaviours.

Animals↗

Behavioral variation and its consequences during incubation for American kestrels exposed to polychlorinated biphenyls.

We investigated whether polychlorinated biphenyl (PCB) exposure in American kestrels (Falco sparverius) influenced incubation behavior and whether altered behavior could lead to poor reproductive success. Captive kestrels were fed a mixture of PCBs (Aroclors 1248:1254:1260) at an approximate daily dose of 7 mg/kg body weight, 1 month prior to pairing and throughout incubation. Behaviors of 23 control and 23 PCB-exposed pairs were monitored throughout incubation using an electronic balance in the nest box. PCB exposure resulted in longer incubation periods and in altered incubation behaviors. Seven of 14 behavioral variables showed some association with treatment, with sex-specific effects largely biased toward disrupted male behavior. For most behaviors, the treatment effect was explained by the delayed clutch initiation induced by PCBs rather than by a direct physiological impact of the contaminants. PCB-exposed pairs with greater attendance to their eggs and better coordination of incubation duties had improved hatching success.

Animals↗

Investigation of a common physiological mechanism underlying progesterone-induced and maternal nesting in mice, Mus musculus.

These experiments addressed the possibility that genetic differences in plasma progesterone levels underlie genetic differences observed in maternal nesting (nest building by pregnant mice). Because this hypothesis requires that different circulating levels of progesterone result in a corresponding elevation of nesting, groups of outbred females were treated with varying doses of progesterone, and their nesting was measured. The relation between progesterone dose and nesting was not linear; rather, there appeared to be a threshold dose above which all groups responded similarly. Next, the progesterone levels of four inbred strains and lines selectively bred for differences in nonpregnant (thermoregulatory) nesting were measured directly by radioimmunoassay. The rank order of the inbred strains' and selected lines' progesterone levels did not correspond to the rank order of their nesting. Thus, genetically based differences in maternal nesting are not due to differences in circulating progesterone levels. Other results are presented which suggest a thermo-regulatory mechanism underlying progesterone-mediated maternal nesting which may involve genetic differences in thermal set point.

Animals↗

Bed and bed-site reuse by western lowland gorillas (Gorilla g. gorilla) in Moukalaba-Doudou National Park, Gabon.

In this paper we describe bed (nest) and bed-site reuse by western lowland gorillas (Gorilla g. gorilla) in Moukalaba-Doudou National Park, south-eastern Gabon. During an eight-month study 44 bed sites and 506 beds were found. Among these, 38.6% of bed sites and 4.1% of beds were reused. We analyzed the monthly frequency of bed-site reuse in relation to rainfall, fruit abundance, and fruit consumption by the gorillas. The different frequency of bed-site reuse in the rainy and dry seasons was not significant. More bed-site reuse was observed during the fruiting season than during the non-fruiting season. Results from fecal analysis suggested that gorillas ate more fruit in the fruiting season than in the non-fruiting season. The frugivorous diet of western gorillas may possibly cause gorillas to stay in some areas and, consequently, reuse their bed sites. Reuse of bed sites by gorillas suggests their frequent return to an area where preferred fruit is readily available. A higher percentage of arboreal beds may also affect bed-site reuse, because of the shortage of bed material.

Animals↗

Development of a Bird Integrity Index: measuring avian response to disturbance in the Blue Mountains of Oregon, USA.

The Bird Integrity Index (BII) presented here uses bird assemblage information to assess human impacts to 28 stream reaches in the Blue Mountains of eastern Oregon. Eighty-one candidate metrics were extracted from bird survey data for testing. The metrics represented aspects of bird taxonomic richness, tolerance or intolerance to human disturbance, dietary preferences, foraging techniques, and nesting strategies that were expected to be positively or negatively affected by human activities in the region. To evaluate the responsiveness of each metric, it was plotted against an index of reach and watershed disturbance that included attributes of land use/land cover, road density, riparian cover, mining impacts, and percent area in clearcut and partial-cut logging. Nine of the 81 candidate bird metrics remained after eliminating unresponsive and highly correlated metrics. Individual metric scores ranged from 0 to 10, and BII scores varied between 0 and 100. BII scores varied from 78.6 for a minimally disturbed, reference stream reach to 30.4 for the most highly disturbed stream reach. The BII responded clearly to varying riparian conditions and to the cumulative effects of disturbances, such as logging, grazing, and mining, which are common in the mountains of eastern Oregon. This BII for eastern Oregon was compared to an earlier BII developed for the agricultural and urban disturbance regime of the Willamette Valley in western Oregon. The BII presented here was sensitive enough to distinguish differences in condition among stream riparian zones with disturbances that were not as obvious or irreversible as those in the agricultural/urban conditions of western Oregon.

Animals↗

Communal peeing: a new mode of flood control in ants.

The behavioral response of the obligate bamboo-nesting ant Cataulacus muticus to nest flooding was studied in a perhumid tropical rainforest in Malaysia and in the laboratory. The hollow internodes of giant bamboo, in which C. muticus exclusively nests, are prone to flooding by heavy rains. The ants showed a two-graded response to flooding. During heavy rain workers block the nest entrances with their heads to reduce water influx. However, rainwater may still intrude into the nest chamber. The ants respond by drinking the water, leaving the nest and excreting water droplets on the outer stem surface. This cooperative 'peeing' behavior is a new survival mechanism adaptive to the ants' nesting ecology. Laboratory experiments conducted with two other Cataulacus species, C. catuvolcus colonizing small dead twigs and C. horridus inhabiting rotten wood, did not reveal any form of water-bailing behavior.

Animals↗

The importance of learning young: the use of nesting material in laboratory rats.

Unlike mice, adult laboratory rats do not spontaneously build nests when nesting material is offered. As a result, nesting material is often regarded as unsuitable environmental enrichment for laboratory rats. Wild rats and pet rats, however, have been observed to build complex nests from nesting material at hand. It was hypothesized that nest building in rats is an acquired behaviour, rather than genetically predisposed. To test this hypothesis, the progeny of three Wistar rats provided with nesting material (Kleenex tissues) during pregnancy and three standard-housed rats were divided in 34 same-sex couples with access to nesting material: (1) from the age of 8 weeks (n=7); (2) from weaning (n=8); (3) from birth (n=17). The latter were subdivided into two groups after weaning, one provided with Kleenex tissues (n=9), the other with Enviro-dri (n=8). At the age of 12 weeks, all couples were provided with both types of nesting material for one week. Amount, shape, and soiling of the nesting material were scored on weekdays, and behaviour of the rats was scored twice weekly. Results indicated that the older the rats were when first provided with nesting material, the greater the amount of nesting material eaten and soiled, and the nests built were less elaborate. Overall, Enviro-dri was eaten less than Kleenex tissues. It is concluded that rats need to learn the proper use of nesting material. When provided from birth, nesting material is a suitable type of environmental enrichment for laboratory rats.

Aging↗

Plasma steroid interactions during high-density green turtle nesting and associated disturbance.

Raine Island in the Northern Great Barrier Reef constitutes an extremely high-density green turtle (Chelonia mydas) rookery. On this island, competitive interactions for nesting space and subsequent disturbance of individual nesting are widespread. High-density nesting often delays successful oviposition by one or more nights. There is little information on how hormones in female reptiles interact during competitive reproductive events in such high-density nesting populations. In this three-part study we investigated the interactions between density (within and between rookery/ies), nesting success and failure, and plasma steroid profiles in green turtles. First, we compared levels of plasma corticosterone (B) and combined testosterone + 5alpha-dihydrotestosterone (T + DHT) in turtles during five stages of oviposition in both a high-nesting-density sector (1 turtle/m2) and a low-nesting-density sector (0.1 turtle/m2). Second, we investigated the relationship between increasing delays (0, 1, 2, 3, and 6 days) in successful oviposition and the plasma steroids B and T + DHT. Third, we assessed a comparative measure of steroid hormone levels of females at low-density sites on Raine Island (high-density rookery) and Number Seven Sandbank (low-density rookery). Despite a significant trend suggesting high-density nesting turtles elaborated more plasma B than turtles in low-density sectors, the magnitude of this increase was small. We suggest that this increase may be an artifact of increased metabolic demand and hence catabolism of energy substrates associated with high-density nesting. Plasma T + DHT remained stable in response to density-dependent effects associated with nesting. Furthermore, prolonging successful oviposition because of multiple nightly disturbance failed to elicit any change in either plasma B or T + DHT. These data suggest that green turtles may be exhibiting adrenal desensitization to prevent both physical and behavioral disturbances interfering with reproduction. We suspect that down-regulating the acute adrenocortical response may represent an adaptive trade-off mechanism for optimizing current reproductive success at the potential expense of survivorship.

Animals↗

The effect of prolactin on fanning behavior in the male three-spined stickleback, Gasterosteus aculeatus L.

The effect of administration of homologous prolactin on fanning behavior, an important aspect of parental care in sticklebacks and many other teleost fish, was studied. Prolactin was administered by implantation of an additional pituitary prolactin lobe in the dorsal body musculature of males with a nest without eggs. The low but rather constant level of fanning behavior is significantly increased from Day 6 to Day 12 after administration of the prolactin lobe. The implantation has no noticeable effects on cell and nuclear size or on the ultrastructure of the in situ prolactin cells of the recipient fish. Recovered prolactin lobe implants show two categories of prolactin cells. The major category consists of cells that are well developed and, similar to in situ prolactin cells, show structural signs of high secretory activity. The other prolactin cell category in the implants shows signs of cellular involution. Ten days after implantation, the first category predominates, and 16 days after implantation the second category. Prolactin lobe implantation increases the number of mucocytes in the epithelium of the skin, in particular at Day 10, and to a lesser extent at Day 16. This is considered evidence for a transient rise in blood prolactin levels in the recipient fish. We conclude that prolactin stimulates fanning behavior in male sticklebacks.

Animals↗

Features of visual function in the naked mole-rat Heterocephalus glaber.

The eyes and visual capacity of the naked mole-rat, Heterocephalus glaber, a subterranean rodent, were evaluated using anatomical, biochemical, and functional assays, and compared to other rodents of similar body size (mouse and gerbil). The eye is small compared to mouse, yet possesses cornea, lens, and retina with typical mammalian organization. The optic nerve cross-sectional area and fiber density are approximately 10% and approximately 50% that of gerbil, respectively. Levels per unit retinal area of 11-cis and all-trans retinal, derivatives of vitamin A associated with the visual cycle, are comparable to mouse. The corneal electroretinogram (ERG) exhibits early and late negative components that scale with flash strength; raising the body temperature of this poikilothermic animal from 30 degrees C (normal for H. glaber ) to 37 degrees C (normal for mouse) revealed an ERG response with typically mammalian features, but greatly attenuated and with slower kinetics. Leaving the nest chamber was a behavior correlated with light onset displayed preferentially by breeding females. Optical models of five mole-rat eyes suggest reasonable, but variable, image formation at the retina, possibly related to age. Results are consistent with amorphous light detection, possibly useful for circadian entrainment or escape behavior in the event of tunnel breeches.

Adaptation, Ocular↗

Postpartum aggression and plasma prolactin levels in mice exposed to lead.

Young-adult, female Binghamton Heterogeneous Stock (HET) mice either were exposed to lead via drinking water from birth, or not. Eight days after giving birth to their first litter of pups (at about 70-75 days of age), postpartum aggression tests were conducted. Unfamiliar Het male intruders were introduced to the primiparous dams' nesting cages, and dyadic behavioral interactions were observed for 10 min. We also obtained plasma prolactin levels of these females, or others who had similar histories, but were not tested for maternal aggression. Behaviorally, the intensity of fighting was greater in lead-exposed pairs than in water-control pairs that fought. However, the percentage of pairs displaying aggressive behavior and average latency to initial contact were similar, regardless of dietary history. Plasma prolactin levels implied that lead exposure alone decreased circulating prolactin in primiparous Het dams eight days postpartum, but confrontation with a male intruder also was sufficient to reduce prolactin levels in water-control dams. It would be reasonable to assume that such changes in prolactin are dopaminergically mediated. The data suggest that lead ingestion may, in a species and strain specific manner, modify: 1) neurotransmitter and hormonal systems and 2) social behavior. The major effect of "subclinical" lead toxicity may be to change the limits of an organism's ability to cope with its environment.

Aggression↗

Ethological study of African carpenter bees of the genus Xylocopa (Hymenoptera, Anthophoridae).

Over 200 bees of 4 African Xylocopa species were observed for 3 months on the island of Rubondo (L. Victoria, Tanzania). Some 40 burrows were investigated, 100 bees marked. Building techniques are minutely reported; burrow construction simplifies defence and allows re-use by succeeding generations. Food plants, collecting, provisioning and all aspects of ontogenesis are treated, insight given into pupal leg mobility and the much-debated emergence order after eclosion: the first-hatched bee, in the rearmost cell, prepares the way for siblings. Copulation and the copulatory hold are studied using tethered femalefemale, and illustrated. A few colonization experiments are described and s spectrogram of begging sounds given. Meeting of the generations, feeding of the young and nest-defence by young siblings throw light on the evolution of primitively eusocial communities. The known literature is reviewed in each chapter.

Africa↗