scholarly journals Colour as a backup for scent in the presence of olfactory noise: testing the efficacy backup hypothesis using bumblebees ( Bombus terrestris )

2017 ◽  
Vol 4 (11) ◽  
pp. 170996 ◽  
Author(s):  
David A. Lawson ◽  
Heather M. Whitney ◽  
Sean A. Rands
Keyword(s):  
Environmental Variability ◽  
Bombus Terrestris ◽  
Metabolic Cost ◽  
Visual Signals ◽  
Visual Signal ◽  
High Wind ◽  
Chemical Interference ◽  
Wind Speeds ◽  
Floral Displays ◽  
Artificial Flowers

The majority of floral displays simultaneously broadcast signals from multiple sensory modalities, but these multimodal displays come at both a metabolic cost and an increased conspicuousness to floral antagonists. Why then do plants invest in these costly multimodal displays? The efficacy backup hypothesis suggests that individual signal components act as a backup for others in the presence of environmental variability. Here, we test the efficacy backup hypothesis by investigating the ability of bumblebees to differentiate between sets of artificial flowers in the presence of either chemical interference or high wind speeds, both of which have the potential to impede the transmission of olfactory signals. We found that both chemical interference and high wind speeds negatively affected forager learning times, but these effects were mitigated in the presence of a visual signal component. Our results suggest that visual signals can act as a backup for olfactory signals in the presence of chemical interference and high wind speeds, and support the efficacy backup hypothesis as an explanation for the evolution of multimodal floral displays.

Innate recognition of flowers by bumble bees: orientation of antennae to visual stamen signals

1992 ◽  
Vol 70 (11) ◽  
pp. 2139-2144 ◽  
Author(s):  
Klaus Lunau
Keyword(s):  
Bombus Terrestris ◽  
Bumble Bees ◽  
Visual Signals ◽  
Spectral Purity ◽  
Corolla Colour ◽  
Olfactory Stimuli ◽  
Innate Behaviour ◽  
Bombus Lucorum ◽  
Artificial Flowers ◽  
Antennal Contact

The innate behaviour of flower-naive bumble bees (Bombus terrestris, Bombus lucorum) was observed at artificial flowers that consisted of a corolla and a guide area. A set of key stimuli was found to release a sequence of reactions, including the bee's approach, antennal reaction, and landing. For each reaction a binary choice between visual and olfactory signals was presented at the artificial flowers. Approach from a distance was released by the spectral purity of the corolla colour. The antennal reaction, which is the first antennal contact at an artificial flower, and occurs while the bumble bee is in flight, was oriented toward those areas with colours of the highest spectral purity. The landing reaction was released by visual and olfactory signals from the areas contacted during the antennal reaction. The combined presentation of visual signals from the anthers and olfactory signals from the pollen most effectively promoted landing. The antennal reaction allows precise alignment for landing and the antennal tips contact the visually conspicuous guide areas. This leads to effective perception of visual and olfactory stimuli from the guide area. The pollen and anthers, as well as the floral guides, which act as landing signals, of entomophilous flowers (Linaria vulgaris, Melampyrumpratense) possess olfactory qualities. In contrast, the pollen of one anemophilous plant (Pinus cedrus) exhibits no such qualities.

scholarly journals Dependence of Power Characteristics on Savonius Rotor Segmentation

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2912
Author(s):  
Krzysztof Doerffer ◽  
Janusz Telega ◽  
Piotr Doerffer ◽  
Paulina Hercel ◽  
Andrzej Tomporowski
Keyword(s):  
High Wind ◽  
Horizontal Axis Wind Turbine ◽  
Savonius Rotor ◽  
Power Characteristics ◽  
Wind Speeds ◽  
Single Segment ◽  
High Elongation ◽  
Low Wind Speeds ◽  
Number Of Segments ◽  
Rotor Type

Savonius rotors are large and heavy because they use drag force for propulsion. This leads to a larger investment in comparison to horizontal axis wind turbine (HAWT) rotors using lift forces. A simple construction of the Savonius rotor is preferred to reduce the production effort. Therefore, it is proposed here to use single-segment rotors of high elongation. Nevertheless, this rotor type must be compared with a multi-segment rotor to prove that the simplification does not deteriorate the effectiveness. The number of segments affects the aerodynamic performance of the rotor, however, the results shown in the literature are inconsistent. The paper presents a new observation that the relation between the effectiveness of single- and multi-segment rotors depends on the wind velocity. A single-segment rotor becomes significantly more effective than a four-segment rotor at low wind speeds. At high wind speeds, the effectiveness of both rotors becomes similar.

scholarly journals Mauritian coloured nectar no longer a mystery: a visual signal for lizard pollinators

2006 ◽  
Vol 2 (2) ◽  
pp. 165-168 ◽  
Author(s):  
Dennis M Hansen ◽  
Karin Beer ◽  
Christine B Müller
Keyword(s):  
Experimental Evidence ◽  
Plant Species ◽  
Flowering Plants ◽  
Visual Signal ◽  
Honest Signal ◽  
Endemic Plant ◽  
Floral Trait ◽  
Flower Visitation ◽  
Artificial Flowers ◽  
Endemic Plant Species

Most floral nectars are clear as water, and the enigmatic coloured nectar in three endemic plant species in Mauritius has puzzled scientists studying it. One hypothesis about the possible ecological function of coloured nectar is that it serves as a visual signal for pollinators. Recent studies have shown that at least two of the three Mauritian plant species with coloured nectar are visited and pollinated by endemic Phelsuma geckos. We here provide experimental evidence for the visual signal hypothesis by showing that Phelsuma ornata geckos prefer coloured over clear nectar in artificial flowers. In flowering plants, coloured nectar could additionally function as an honest signal that allows pollinators to assert the presence and judge the size of a reward prior to flower visitation, and to adjust their behaviour accordingly, leading to increased pollinator efficiency. Our study provides a first step in understanding this rare and intriguing floral trait.

Midlatitude cyclones in convection permitting climate simulations: the added value offered for extreme wind speeds and sting-jets

2021 ◽  
Author(s):  
Colin Manning ◽  
Elizabeth Kendon ◽  
Hayley Fowler ◽  
Nigel Roberts ◽  
Segolene Berthou ◽  
...  
Keyword(s):  
Climate Model ◽  
Surface Wind ◽  
Added Value ◽  
Large Contribution ◽  
High Wind ◽  
Wind Speeds ◽  
Wind Gusts ◽  
Climate Simulations ◽  
Extreme Wind ◽  
Extreme Wind Speeds

<p>Extra-tropical windstorms are one of the costliest natural hazards affecting Europe, and windstorms that develop a phenomenon known as a sting-jet account for some of the most damaging storms. A sting-jet (SJ) is a mesoscale core of high wind speeds that occurs in particular types of cyclones, specifically Shapiro-Keyser (SK) cyclones, and can produce extremely damaging surface wind gusts. High-resolution climate models are required to adequately model SJs and so it is difficult to gauge their contribution to current and future wind risk. In this study, we develop a low-cost methodology to automate the detection of sting jets, using the characteristic warm seclusion of SK cyclones and the slantwise descent of high wind speeds, within pan-European 2.2km convection-permitting climate model (CPM) simulations. Following this, we quantify the contribution of such storms to wind risk in Northern Europe in current and future climate simulations, and secondly assess the added value offered by the CPM compared to a traditional coarse-resolution climate model. This presentation will give an overview of the developed methods and the results of our analysis.</p><p>Comparing with observations, we find that the representation of wind gusts is improved in the CPM compared to ERA-Interim reanalysis data. Storm severity metrics indicate that SK cyclones account for the majority of the most damaging windstorms. The future simulation produces a large increase (>100%) in the number of storms exceeding high thresholds of the storm metric, with a large contribution to this change (40%) coming from windstorms in which a sting-jet is detected. Finally, we see a systematic underestimation in the GCM compared to the CPM in the frequency of extreme wind speeds at 850hPa in the cold sector of cyclones, likely related to better representation of sting-jets and the cold conveyor belt in the CPM. This underestimation is between 20-40% and increases with increasing wind speed above 35m/s. We conclude that the CPM adds value in the representation of severe surface wind gusts, providing more reliable future projections and improved input for impact models.</p>

scholarly journals Relationship between Sea Surface Drag Coefficient and Wave State

2021 ◽  
Vol 9 (11) ◽  
pp. 1248
Author(s):  
Jian Shi ◽  
Zhihao Feng ◽  
Yuan Sun ◽  
Xueyan Zhang ◽  
Wenjing Zhang ◽  
...  
Keyword(s):  
Drag Coefficient ◽  
Momentum Flux ◽  
Sea Surface ◽  
Sea Spray ◽  
Wave Age ◽  
High Wind ◽  
Surface Drag ◽  
Wave State ◽  
Wind Speeds ◽  
Strong Winds

The sea surface drag coefficient plays an important role in momentum transmission between the atmosphere and the ocean, which is affected by ocean waves. The total air–sea momentum flux consists of effective momentum flux and sea spray momentum flux. Sea spray momentum flux involves sea surface drag, which is largely affected by the ocean wave state. Under strong winds, the sea surface drag coefficient (CD) does not increase linearly with the increasing wind speed, namely, the increase of CD is inhibited by strong winds. In this study, a sea surface drag coefficient is constructed that can be applied to the calculation of the air–sea momentum flux under high wind speed. The sea surface drag coefficient also considers the influence of wave state and sea spray droplets generated by wave breaking. Specially, the wave-dependent sea spray generation function is employed to calculate sea spray momentum flux. This facilitates the analysis not only on the sensitivity of the sea spray momentum flux to wave age, but also on the effect of wave state on the effective CD (CD, eff) under strong winds. Our results indicate that wave age plays an important role in determining CD. When the wave age is >0.4, CD decreases with the wave age. However, when the wave age is ≤0.4, CD increases with the wave age at low and moderate wind speeds but tends to decrease with the wave age at high wind speeds.

scholarly journals A Review of Parameterizations for Enthalpy and Momentum Fluxes from Sea Spray in Tropical Cyclones

2021 ◽  
Author(s):  
Sydney Sroka ◽  
Kerry Emanuel
Keyword(s):  
Tropical Cyclones ◽  
Critical Role ◽  
Sea Spray ◽  
High Wind ◽  
High Wind Speed ◽  
Wind Speeds ◽  
Crucial Component ◽  
Momentum Fluxes ◽  
Interaction Scheme ◽  
Speed Regime

AbstractThe intensity of tropical cyclones is sensitive to the air-sea fluxes of enthalpy and momentum. Sea spray plays a critical role in mediating enthalpy and momentum fluxes over the ocean’s surface at high wind speeds, and parameterizing the influence of sea spray is a crucial component of any air-sea interaction scheme used for the high wind regime where sea spray is ubiquitous. Many studies have proposed parameterizations of air-sea flux that incorporate the microphysics of sea spray evaporation and the mechanics of sea spray stress. Unfortunately, there is not yet a consensus on which parameterization best represents air-sea exchange in tropical cyclones, and the different proposed parameterizations can yield substantially different tropical cyclone intensities. This paper seeks to review the developments in parameterizations of the sea spray-mediated enthalpy and momentum fluxes for the high wind speed regime and to synthesize key findings that are common across many investigations.

scholarly journals Testing Water Yield, Efficiency of Different Meshes and Water Quality with a Novel Fog Collector for High Wind Speeds

2018 ◽  
Vol 18 (1) ◽  
pp. 240-253 ◽  
Author(s):  
Christian Schunk ◽  
Peter Trautwein ◽  
Herbert Hruschka ◽  
Ernst Frost ◽  
Leslie Dodson ◽  
...  
Keyword(s):  
Water Quality ◽  
Water Yield ◽  
High Wind ◽  
Yield Efficiency ◽  
Wind Speeds ◽  
Fog Collector

scholarly journals Mass transfer velocity across the breaking air–water interface at extremely high wind speeds

Tellus B ◽  
2013 ◽  
Vol 65 (1) ◽  
pp. 21341 ◽  
Author(s):  
Koji Iwano ◽  
Naohisa Takagaki ◽  
Ryoichi Kurose ◽  
Satoru Komori
Keyword(s):  
Mass Transfer ◽  
Water Interface ◽  
High Wind ◽  
Transfer Velocity ◽  
Wind Speeds ◽  
Air Water Interface

scholarly journals Visual signal evolution along complementary color axes in four bird lineages

2019 ◽  
Author(s):  
Anand Krishnan ◽  
Avehi Singh ◽  
Krishnapriya Tamma
Keyword(s):  
Color Space ◽  
Dietary Factors ◽  
The Body ◽  
Color Variation ◽  
Visual Signals ◽  
Visual Signal ◽  
Relative Role ◽  
Chromatic Contrast ◽  
Present Evidence ◽  
Complementary Color

AbstractAnimal color patterns function in varied behavioral contexts including recognition, camouflage and even thermoregulation. The diversity of visual signals may be constrained by various factors, for example, dietary factors, and the composition of ambient environmental light (sensory drive). How have high-contrast and diverse signals evolved within these constraints? In four bird lineages, we present evidence that plumage colors cluster along a line in tetrachromatic color space. Additionally, we present evidence that this line represents complementary colors, which are defined as opposite sides of a line passing through the achromatic point (putatively for higher chromatic contrast). Finally, we present evidence that interspecific color variation over at least some regions of the body is not constrained by phylogenetic relatedness. Thus, we hypothesize that species-specific plumage patterns within these bird lineages evolve by swapping the distributions of a complementary color pair (or dark and light patches in one group, putatively representing an achromatic complementary axis). The relative role of chromatic and achromatic contrasts in discrimination may depend on the environment that each species inhabits.

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