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351.
Christopher D. Pull William O. H. Hughes Mark J. F. Brown 《Die Naturwissenschaften》2013,100(12):1125-1136
Pathogens exert a strong selection pressure on organisms to evolve effective immune defences. In addition to individual immunity, social organisms can act cooperatively to produce collective defences. In many ant species, queens have the option to found a colony alone or in groups with other, often unrelated, conspecifics. These associations are transient, usually lasting only as long as each queen benefits from the presence of others. In fact, once the first workers emerge, queens fight to the death for dominance. One potential advantage of co-founding may be that queens benefit from collective disease defences, such as mutual grooming, that act against common soil pathogens. We test this hypothesis by exposing single and co-founding queens to a fungal parasite, in order to assess whether queens in co-founding associations have improved survival. Surprisingly, co-foundresses exposed to the entomopathogenic fungus Metarhizium did not engage in cooperative disease defences, and consequently, we find no direct benefit of multiple queens on survival. However, an indirect benefit was observed, with parasite-exposed queens producing more brood when they co-founded, than when they were alone. We suggest this is due to a trade-off between reproduction and immunity. Additionally, we report an extraordinary ability of the queens to tolerate an infection for long periods after parasite exposure. Our study suggests that there are no social immunity benefits for co-founding ant queens, but that in parasite-rich environments, the presence of additional queens may nevertheless improve the chances of colony founding success. 相似文献
352.
M. M. P. B. Fuentes M. R. Fish J. A. Maynard 《Mitigation and Adaptation Strategies for Global Change》2012,17(1):51-63
Climate change poses a serious threat to sea turtles (Cheloniidae) as their terrestrial reproductive phase is only successful
within a limited range of environmental and physical conditions. These conditions are likely to become less optimal as climate
change progresses. To date, management and conservation of sea turtles has focused almost entirely on non-climatic stressors,
due at least in part to practitioners not knowing what strategies to take and the feasibility and risks of potential strategies.
To aid the management of sea turtles in a changing environment, we identified management strategies via a focus workshop and
surveys to mitigate the impacts of climate change to the terrestrial reproductive phase of sea turtles. The effectiveness,
ecological risks and potential social and logistical constraints associated with implementing each of the identified management
strategies is discussed. Twenty management strategies were identified; strategies varied from habitat protection to more active
and direct manipulation of nests and the nesting environment. Based on our results, we suggest a three-pronged approach to
sea turtle conservation in light of climate change, where managers and researchers should: 1) enhance sea turtle resilience
to climate change by mitigating other threats; 2) prioritise implementing the ‘no regret’ and ‘reversible’ management strategies
identified here; and 3) fill the knowledge gaps identified to aid the trial and implementation of the potential strategies identified here. By combining these three approaches our collective toolkit of sea turtle management strategies
will expand, giving us an array of viable approaches to implement as climate change impacts become more extreme. 相似文献
353.
Does safety climate moderate the influence of staffing adequacy and work conditions on nurse injuries? 总被引:1,自引:0,他引:1
Mark BA Hughes LC Belyea M Chang Y Hofmann D Jones CB Bacon CT 《Journal of Safety Research》2007,38(4):431-446
PROBLEM: Hospital nurses have one of the highest work-related injury rates in the United States. Yet, approaches to improving employee safety have generally focused on attempts to modify individual behavior through enforced compliance with safety rules and mandatory participation in safety training. We examined a theoretical model that investigated the impact on nurse injuries (back injuries and needlesticks) of critical structural variables (staffing adequacy, work engagement, and work conditions) and further tested whether safety climate moderated these effects. METHOD: A longitudinal, non-experimental, organizational study, conducted in 281 medical-surgical units in 143 general acute care hospitals in the United States. RESULTS: Work engagement and work conditions were positively related to safety climate, but not directly to nurse back injuries or needlesticks. Safety climate moderated the relationship between work engagement and needlesticks, while safety climate moderated the effect of work conditions on both needlesticks and back injuries, although in unexpected ways. DISCUSSION AND IMPACT ON INDUSTRY: Our findings suggest that positive work engagement and work conditions contribute to enhanced safety climate and can reduce nurse injuries. 相似文献
354.
Unlike any other foraging phyllostomid bat studied to date, Poey’s flower bats (Phyllonycteris poeyi-Phyllostomidae) emit relatively long (up to 7.2 ms), intense, single-harmonic echolocation calls. These calls are readily
detectable at distances of at least 15 m. Furthermore, the echolocation calls contain only the first harmonic, which is usually
filtered out in the vocal tract of phyllostomids. The foraging echolocation calls of P. poeyi are more like search-phase echolocation calls of sympatric aerial-feeding bats (Molossidae, Vespertilionidae, Mormoopidae).
Intense, long, narrowband, single-harmonic echolocation calls focus acoustic energy maximizing range and favoring detection,
which may be particularly important for cruising bats, like P. poeyi, when flying in the open. Flying in enclosed spaces, P. poeyi emit short, low-intensity, frequency-modulated, multiharmonic echolocation calls typical of other phyllostomids. This is
the first report of a phyllostomid species emitting long, intense, single-harmonic echolocation calls with most energy in
the first harmonic. 相似文献
355.
Soil and preen waxes influence the expression of carotenoid-based plumage coloration 总被引:1,自引:1,他引:0
The signaling function of carotenoid-based plumage is mainly determined by the concentration of pigments in feathers. For
this reason, most studies of the proximate control of coloration focus on processes during and preceding moult. In great tits
Parus major, past research demonstrates that carotenoid-based plumage coloration honestly indicates male quality and, thus, may be a
sexually selected signal. In this study, we investigate how dirt and preen oil influence the coloration of carotenoid-based
feathers in the great tit. We collected six feathers from each individual bird; three feathers served as controls while the
remaining three feathers were washed with a chloroform/methanol mixture to remove soil and preen waxes. We assessed plumage
coloration using digital photography. This cleaning procedure slightly enhanced ornamentation; the experimentally cleaned
feathers expressed hues shifted towards shorter wavelengths and expressed brighter overall coloration than control feathers.
This is the first experimental study conducted on wild birds demonstrating that, in addition to pigment concentration, the
presence of preen waxes and soils on feathers may contribute to variation in coloration. 相似文献
356.
The continuing conundrum of the LEA proteins 总被引:9,自引:0,他引:9
Research into late embryogenesis abundant (LEA) proteins has been ongoing for more than 20 years but, although there is a strong association of LEA proteins with abiotic stress tolerance particularly dehydration and cold stress, for most of that time, their function has been entirely obscure. After their initial discovery in plant seeds, three major groups (numbered 1, 2 and 3) of LEA proteins have been described in a range of different plants and plant tissues. Homologues of groups 1 and 3 proteins have also been found in bacteria and in certain invertebrates. In this review, we present some new data, survey the biochemistry, biophysics and bioinformatics of the LEA proteins and highlight several possible functions. These include roles as antioxidants and as membrane and protein stabilisers during water stress, either by direct interaction or by acting as molecular shields. Along with other hydrophilic proteins and compatible solutes, LEA proteins might also serve as “space fillers” to prevent cellular collapse at low water activities. This multifunctional capacity of the LEA proteins is probably attributable in part to their structural plasticity, as they are largely lacking in secondary structure in the fully hydrated state, but can become more folded during water stress and/or through association with membrane surfaces. The challenge now facing researchers investigating these enigmatic proteins is to make sense of the various in vitro defined functions in the living cell: Are the LEA proteins truly multi-talented, or are they still just misunderstood? 相似文献
357.
Ghostin J Habib-Jiwan JL Rozenberg R Daloze D Pasteels JM Braekman JC 《Die Naturwissenschaften》2007,94(7):601-605
The adults of the leaf beetle Platyphora kollari (Chrysomelidae) are able to metabolise the oleanane triterpene β-amyrin (1) into the glycoside 3-O-β-d-glucopyranosyl-(1→4)-β-d-glucuronopyranosyl-hederagenin (2) that is stored in their defensive glands. The aim of this study was to test the hypothesis that oleanolic acid (3) is an intermediate in the conversion of 1 into 2 and to check whether the sequestration of pentacyclic triterpenes is selective in favour of β-amyrin (1). To this end, adults of P. kollari were fed with Ipomoea batatas leaf disks painted with a solution of [2,2,3-2H3]oleanolic acid or [2,2,3-2H3]α-amyrin and the secretion of their defensive glands analysed by HPLC–ESIMS. The data presented in this work indicated that
the first step of the transformation of β-amyrin (1) into the sequestered glycoside 2 is its oxidation into oleanolic acid (3) and that this conversion is selective but not specific in favour of β-amyrin (1). 相似文献
358.
Numerous studies have focussed on the relationship between female choice and the multiple exaggerated sexual traits of males.
However, little is known about the ability of males to actively enhance specific components of their display in response to
the loss of one component. We investigated the capacity of male satin bowerbirds (Ptilonorhynchus violaceus) to respond to the loss of one of their sexual signals by performing an experiment in which we removed decorations at their
bowers. We found that males compensated for decoration loss by increasing bower construction behaviour and decreasing their
latency to bower painting. These results are novel because they suggest that males can assess the quality of their own display
and make decisions about how to augment their displays. We discuss these results in the context of previous studies of mate
choice in satin bowerbirds, as both of the supplementary behaviours we observed are known correlates of male mating success. 相似文献
359.
Parasitoid-induced mortality of Araneus omnicolor (Araneae, Araneidae) by Hymenoepimecis sp. (Hymenoptera, Ichneumonidae) in southeastern Brazil 总被引:1,自引:0,他引:1
All species included in the Polysphincta genus-group develop as ectophagous parasitoids of active spiders, killing their hosts prior to pupation. However, little
information regarding natural history and ovipositing behavior of most species are available. In this study we inspected 85
webs of Araneus omnicolor to evaluate the frequency of parasitism and host size preferences of the wasp Hymenoepimecis sp. We also described the web characteristics of normal and parasitized spiders and the wasp ovipositing behavior. About
41% of the adult females of A. omnicolor inspected were parasitized. The highest incidence of parasitism was observed among relatively small females while no egg
or larva was found in large individuals. Araneus omnicolor builds a strong web composed of an orb and barrier threads, where the spider rests within a curled leaf. The parasitoid larva
builds its cocoon within this refuge, and modified cocoon webs were not observed. The ovipositing behavior of Hymenoepimecis sp. was very similar to that of Hymenoepimecis argyraphaga parasitizing Leucauge argyra, including the position of the sting, the killing of a previously attached larva, and the expelling of the egg from the base
of the ovipositor. 相似文献
360.
Recruitment precision, i.e. the proportion of recruits that reach an advertised food source, is a crucial adaptation of social
bees to their environment. Studies with honeybees showed that recruitment precision is not a fixed feature, but it may be
enhanced by factors like experience and distance. However, little is known regarding the recruitment precision of stingless
bees. Hence, in this study, we examined the effects of experience and spatial distance on the precision of the food communication
system of the stingless bee Scaptotrigona mexicana. We conducted the experiments by training bees to a three-dimensional artificial patch at several distances from the colony.
We recorded the choices of individual recruited foragers, either being newcomers (foragers without experience with the advertised
food source) or experienced (foragers that had previously visited the feeder). We found that the average precision of newcomers
(95.6 ± 2.61%) was significantly higher than that of experienced bees (80.2 ± 1.12%). While this might seem counter-intuitive
on first sight, this “loss” of precision can be explained by the tendency of experienced recruits to explore nearby areas
to find new rewarding food sources after they had initially learned the exact location of the food source. Increasing the
distance from the colony had no significant effect on the precision of the foraging bees. Thus, our data show that experience,
but not the distance of the food source, affected the patch precision of S. mexicana foragers. 相似文献