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381.
382.
The emergence of collective foraging in the arboreal<Emphasis Type="Italic"> Gnamptogenys menadensis</Emphasis> (Hymenoptera: Formicidae) 总被引:1,自引:0,他引:1
Gnamptogenys menadensis is an arboreal nester that forages opportunistically almost exclusively on vegetation, sometimes recruiting others to participate in prey retrieval. The three-dimensional characteristics of vegetation suggest that functions describing recruitment decision thresholds or the pattern of recruitment in arboreal species may differ from those predicted by optimal foraging theory. To examine the effects of prey abundance and distance on the recruitment dynamics of G. menadensis, we baited nests with one termite, five termites or a number of termites between 20 and 40 either near to or far from the entrance and observed the ensuing behaviors. G. menadensis recruited others when encountering multiple termites regardless of the termite pile's distance from the nest, although a few individuals remained at the site and defended the resource. The pattern of arrivals at the site indicates that the majority and sometimes all arrivals were recruited from the branch trails. In combination, these results suggest that the architecture of the foraging habitat, which limits available return routes to the nest and thus increases encounter probabilities with potential recruits, shaped the process of information transfer and generated a collective pattern of foraging and prey retrieval. 相似文献
383.
Marina Préault Olivier Chastel Frank Cézilly Bruno Faivre 《Behavioral ecology and sociobiology》2005,58(5):497-505
In monogamous bird species, male parental investment may influence offspring fitness and females may gain advantages through mating with males providing extensive paternal care. However, paternal care is a benefit that can only be assessed indirectly because mate choice precedes paternal activities. Individual quality and age, both signalled by morphological characteristics, may reflect parental abilities. Because they may reflect individual foraging abilities, carotenoid-based colorations have been proposed to honestly signal parental quality. The blackbird (Turdus merula), a socially monogamous species, exhibits biparental care and males show bills that vary from pale yellow to orange due to carotenoid pigments. In this study, we investigated whether male bill colour and age are associated with parental ability. Our results suggest that males with more orange bills and older males are better fathers. Indeed, male visit rate increased with their bill colour index independently of age, and brood condition was higher for adult males, compared to yearlings, independently of bill colour. Overall, the number of fledglings produced was positively influenced by both the age of males and the colour intensity of their bills. Males with more orange bills and adults had a greater number of fledglings and these males also had higher levels of prolactin, a hormone known to promote parental care. This latter finding suggests that prolactin may be the link between carotenoid based colorations and the intensity of paternal effort. Thus, male bill colour seems to honestly reveal male physiological adjustment to paternal activities. 相似文献
384.
Summary This paper deals with the flight speeds of migrating birds observed by radar over a Swiss Alpine pass. The distributions of air speeds for different classes of birds and the influence of the wind on air speeds were investigated. Our findings differ greatly from observations of bird migration over the North Atlantic Ocean and the North American continent. Our data reveal: (1) that the air speeds of the bulk of migrating birds were in the range of 8–18 m/s and that the amount of slow flyers (air speed below 5 m/s) was less than 5%; (2) that there was an obvious influence of the wind on air speeds and, moreover, the data showed a distinctly variable compensatory behavior among different bird classes; (3) that the wind component in the direction of the bird's heading was a better predictor for air speed than the wind direction. Although we do not speculate about possibilities and mechanisms of wind detection, a simple argument shows how birds could estimate wind directions if they do use the moving surface as a reference system. 相似文献
385.
Ruurd de Jong Nevile Maher Bruno Patrian Erich St?dler Tammo Winkler 《Chemoecology》2000,10(4):205-209
Summary. Two recently identified compounds ("CIFs"), present on the leaf surface of Brassica oleracea (cabbage), are the strongest oviposition stimulants known for the cabbage root fly, Delia radicum. Cabbage leaves contain these compounds in extremely low concentrations, and the amount of CIFs obtained from purifying leaf
extracts was so small that it limited further research. We were able to purify far more of these two compounds from the roots
of Brassica napus var. napobrassica (rutabaga). Apart from being a richer source of CIFs, rutabaga roots are considerably easier to collect and process than
leaves. In addition, we isolated and identified a new CIF compound from the roots that is also very active in stimulating
oviposition in the cabbage root fly.
Received 26 May 2000; accepted 26 July 2000 相似文献
386.
We propose a new approach for modeling extreme values that are measured in time and space. First we assume that the observations
follow a Generalized Extreme Value (GEV) distribution for which the location, scale or shape parameters define the space–time
structure. The temporal component is defined through a Dynamic Linear Model (DLM) or state space representation that allows
to estimate the trend or seasonality of the data in time. The spatial element is imposed through the evolution matrix of the
DLM where we adopt a process convolution form. We show how to produce temporal and spatial estimates of our model via customized
Markov Chain Monte Carlo (MCMC) simulation. We illustrate our methodology with extreme values of ozone levels produced daily
in the metropolitan area of Mexico City and with rainfall extremes measured at the Caribbean coast of Venezuela. 相似文献
387.
Maria Paola Iampieri Rita Mingarelli Eric Le Guern Giuseppe Novelli Professor Bruno Dallapiccola 《黑龙江环境通报》1994,14(4):285-289
Five pregnancies at risk for X-linked retinitis pigmentosa (RP) have been monitored by first-trimester prenatal diagnosis using DNA markers flanking the RP2 and RP3 loci. Three affected and two unaffected fetuses, including a female carrying a wild-type genotype, were predicted on the basis of marker segregation and estimation of the recombination fraction. 相似文献
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390.