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371.
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
372.
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
373.
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
374.
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
375.
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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379.
To date, the field of contaminant geochemistry—which deals with the study of chemical interactions in soil and aquifer environments—has
focused mainly on pollutant toxicity, retention, persistence, and transport and/or on remediation of contaminated sites. Alteration
of subsurface physicochemical properties by anthropogenic chemicals, which reach the land surface as a result of human activity,
has been essentially neglected. Contaminant-induced changes in subsurface properties are usually considered as deviations
from a normal geological environment, which will disappear under natural attenuation or following remediation procedures.
However, contaminants may in many cases cause irreversible changes in both structure and properties of the soil–subsurface
geosystem between the land surface and groundwater. The time scales associated with these changes are on a “human time scale”,
far shorter than geological scales relevant for geochemical processes. In this review, we draw attention to a new perspective
of contaminant geochemistry, namely, irreversible changes in the subsurface as a result of anthropogenic chemical pollution.
We begin by briefly reviewing processes governing contaminant–subsurface interactions. We then survey how chemical contamination
causes irreversible changes in subsurface structure and properties. The magnitude of the anthropogenic impact on the soil
and subsurface is linked directly to the amounts of chemical contaminants applied and/or disposed of on the land surface.
This particular aspect is of major importance when examining the effects of humans on global environmental changes. Consideration
of these phenomena opens new perspectives for the field of contaminant geochemistry and for research of human impacts on the
soil and subsurface regimes. 相似文献
380.
The ghost shrimp Neotrypaea californiensis is imported into southern California from Oregon and Washington for use as live bait in recreational marine fisheries. We
studied the population genetic structure of N. californiensis across much its range to assess the possibility that the transport of ghost shrimp across phylogeographic boundaries poses
a risk of homogenizing existing genetic variation in the species. Analyses of two mitochondrial DNA markers showed little
phylogeographic structure across the sampled range, suggesting that this risk is low. Unexpectedly, mitochondrial DNA analyses
revealed that a second putative species of ghost shrimp frequently coexisted with N. californiensis in southern California intertidal habitats; almost all previous studies of soft-sediment communities in the region report
the presence of N. californiensis only. We also assessed the possibility that the import of ghost shrimp might pose a risk of introduction of a parasitic castrator,
the bopyrid isopod Ione cornuta, into southern California waters, where it does not appear to be native. Prevalence of living I. cornuta in samples purchased from bait shops was high (5.8%), suggesting that this is a real risk that merits further study. 相似文献