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741.
742.
Timothée Romuald Cook Frédéric Bailleul Amélie Lescroël Yann Tremblay Charles-André Bost 《Marine Biology》2008,154(2):383-391
Knowing the depth zone of neutral buoyancy of divers is important because buoyancy can determine how animals manage their
energy budget. In this study, we estimate the depth zone of neutral buoyancy of free-ranging cormorants for the first time,
using time-depth recorders. We discovered that vertical ascent rates of 12 Crozet and 15 Kerguelen diving blue-eyed shags
(respectively Phalacrocorax
melanogenis and P.
verrucosus) slowed down considerably at the 50–60 m depth zone. We suggest this was due to birds trying to reach the surface from that
point upwards using reduced locomotor activity because the force of buoyancy becomes greater than the force of gravity at
that depth. The results show a shift of this depth zone in relation to maximum targeted dive depth, suggesting cormorants
may control buoyancy through respiratory air volume adjustment. Interestingly, 60 m is close to the maximum depth zone reached
by these two species during dives lasting 4 min, their estimated behavioural aerobic dive limit. This suggests that the decision
to swim deeper has a direct consequence on the energy budget, with time spent recovering at the surface (time thus lost to
foraging) strongly increasing relative to the preceding time of submergence. Resources found in deeper waters must be of sufficient
quantity or quality to justify crossing the frontier of physical neutral buoyancy. 相似文献
743.
Hegyi Gergely Jenni-Eiermann Susanne Boross Nóra Garamszegi László Zsolt Laczi Miklós Kötél Dóra Krenhardt Katalin Jablonszky Mónika Markó Gábor Nagy Gergely Rosivall Balázs Szász Eszter Török János 《Behavioral ecology and sociobiology》2019,73(6):1-14
Behavioral Ecology and Sociobiology - Cooperation plays a crucial role in primate social life. However, the evolution of large-scale human cooperation from the cognitive fundamentals found in other... 相似文献
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746.
747.
Mathieu?BonneauEmail author Nathalie?Peyrard Sabrina?Gaba Régis?Sabbadin 《Environmental and Ecological Statistics》2016,23(2):233-255
Weeds are species of interest for ecologists because they are competitors of the crop for resources but they also play an important role in maintaining biodiversity in agroecosystems. To study their spatial distribution at the field scale, only sampled observations are available due to the cost of sampling. Weeds sampling strategies are static. However, in the domain of spatial sampling, adaptive strategies have also been developed with, for some of them, an important on-line or off-line computational cost. In this article we provide answers to the following question: Are the current adaptive sampling methods efficient enough to motivate a wider use in practice when sampling a weed species at a field scale? We provide a comparison of the behaviour of 8 static strategies and 3 adaptive ones on four criteria: density class estimation, map restoration, spatial aggregation estimation, and sampling duration. From two weeds data sets, we estimated six contrasted Markov Random Field (MRF) models of weed density class spatial distribution and a model for sampling duration. The MRF models were then used to compare the strategies on a large set of simulated maps. Our main finding was that there is no clear gain in using adaptive sampling strategies rather than static ones for the three first criteria, and adaptive strategies were associated to longer sampling duration. This conclusion points out that for weed mapping, it is more important to build a good model of spatial distribution, than to propose complex adaptive sampling strategies. 相似文献
748.
Ryota?L.?SakamotoEmail author Shin-Ichi?Morinaga Motomi?Ito Nobumitsu?Kawakubo 《Behavioral ecology and sociobiology》2012,66(5):669-674
Most estimations of the pollination efficiency of insects have been based on observation by the naked human eye. However,
insect behaviors are often too rapid to analyze sufficiently this way. Here we demonstrate the use of high-speed cameras to
analyze the fine-scale behaviors of Macroglossum pyrrhosticta, Xylocopa appendiculata, and Papilio dehaanii when visiting Clerodendrum trichotomum. The fine-scale nectar drinking time, number of contacts with anthers and/or stigmas, and frequencies of body part contact
with anthers and/or stigmas differed significantly among pollinator species. Pollination efficiency was not equal among pollinators.
In addition, M. pyrrhosticta made the least number of contacts with anthers and/or stigmas even though it showed the highest visitation frequency. These
results demonstrate that when examined from the viewpoint of rapid visitation behaviors, pollination dynamics differ among
pollinator species, and flower visits and pollination rates are not equal. 相似文献
749.
N. B. Vogt E. Moksness S. P. Sporstøl H. Knutsen S. Nordenson K. Kolset 《Marine Biology》1986,92(2):173-182
Single cod [Gadus Morhua (L.)] and haddock [Melanogrammus aeglefinus (L.)] eggs from the first day and the eighth day after fertilization were acid hydrolised. Fatty acids were liberated and derivatized to methyl esters in a one-step reaction. The non-polar hexane extract was analysed by High Resolution Gas Chromatography (HRGC). Selected peaks, occuring in both types of samples and in all chromatograms, were used to create a matrix for multivariate analysis. HRGC and Mass Spectrometry have been used to identify the fatty acids. The approach is shown to be useful in distinguishing between cod and haddock eggs at both stages and information regarding changes in the fatty acid distributions are obtained. Implications on future possibilities within chemosystematics are discussed. 相似文献
750.
We explored the effects of prevalence, latitudinal range and clumping (spatial autocorrelation) of species distribution patterns on the predictive accuracy of eight state-of-the-art modelling techniques: Generalized Linear Models (GLMs), Generalized Boosting Method (GBM), Generalized Additive Models (GAMs), Classification Tree Analysis (CTA), Artificial Neural Network (ANN), Multivariate Adaptive Regression Splines (MARS), Mixture Discriminant Analysis (MDA) and Random Forest (RF). One hundred species of Lepidoptera, selected from the Distribution Atlas of European Butterflies, and three climate variables were used to determine the bioclimatic envelope for each butterfly species. The data set consisting of 2620 grid squares 30′ × 60′ in size all over Europe was randomly split into the calibration and the evaluation data sets. The performance of different models was assessed using the area under the curve (AUC) of a receiver operating characteristic (ROC) plot. Observed differences in modelling accuracy among species were then related to the geographical attributes of the species using GAM. The modelling performance was negatively related to the latitudinal range and prevalence, whereas the effect of spatial autocorrelation on prediction accuracy depended on the modelling technique. These three geographical attributes accounted for 19–61% of the variation in the modelling accuracy. Predictive accuracy of GAM, GLM and MDA was highly influenced by the three geographical attributes, whereas RF, ANN and GBM were moderately, and MARS and CTA only slightly affected. The contrasting effects of geographical distribution of species on predictive performance of different modelling techniques represent one source of uncertainty in species spatial distribution models. This should be taken into account in biogeographical modelling studies and assessments of climate change impacts. 相似文献