scholarly journals Ambient light and mimicry as drivers of wing transparency in Lepidoptera

2020 ◽  
Author(s):  
Mónica Arias ◽  
Jérôme Barbut ◽  
Rodolphe Rougerie ◽  
Manon Dutry ◽  
Mireia Kohler ◽  
...  
Keyword(s):  
Species Interactions ◽  
Light Availability ◽  
Transmitted Light ◽  
Light Transmittance ◽  
Dead Leaf ◽  
Ecological Traits ◽  
Avian Predators ◽  
Daytime Activity ◽  
Variable Light ◽  
Closed Habitat

AbstractTransparency reduces prey detectability by predators. While the proportion of transmitted light in aquatic species is higher as light availability increases, less is known about such variation in terrestrial species. Transparency has evolved several times in the typically opaque winged Lepidoptera order (moths and butterflies), displaying a large diversity of degrees. Using two complementary approaches, we explore how the evolution of the differences in light transmittance relates to habitat openness, daytime activity and mimicry syndrome (bee/wasp versus dead-leaf mimic). First, by exposing artificial moth-like prey to wild avian predators in open and closed habitats, we show that survival increases at higher proportions of transmitted light in open habitats. Second, by analysing the evolution of wing features and ecological traits in 107 clearwing species, we confirm that diurnal open-habitat species show higher light transmittances than diurnal closed-habitat species. Additionally, bee/wasp mimics are more often diurnal and have higher and less variable light transmittances than dead-leaf mimics, which are more often nocturnal. Bright conditions, such as open habitats during the day, and mimicry of insects with transparent wings seem to promote high light transmittance. Habitat openness, daytime activity and species interactions play a crucial role in determining transparency design.

The effect of fluctuating light on canopy photosynthesis: a focus on a chlorophyll-deficient Soybean mutant

2021 ◽  
Author(s):  
Nicole Salvatori
Keyword(s):  
Steady State ◽  
Dynamic Environment ◽  
Regulatory System ◽  
Total Carbon ◽  
Light Transmittance ◽  
Photochemical Quenching ◽  
Natural Environments ◽  
Deficient Mutant ◽  
Light Conditions ◽  
Variable Light

<p>In natural environments plants are subjected to variable light conditions and therefore need an efficient regulatory system to regulate photosynthesis and the downstream metabolism. Most of the measurements available are taken at steady state and at leaf level but those may overestimate total carbon uptake in a more dynamic environment. Furthermore, some plants may be more adapted than others to deal with light fluctuations and therefore is difficult to draw general conclusions. We then grew a commercial soybean variety and a chlorophyll deficient mutant in a recently developed growth chamber system (DYNAMISM) which allowed to obtain instantaneous gas exchange data at canopy level for several weeks. By doing so we could investigate both short term responses and long term adaptations to light dynamic conditions of the two varieties. At steady state, chlorophyll deficient crops are thought to have a similar or even a higher photosynthetic rate compared to the green wildtypes, enhanced by a higher light transmittance throughout the canopy. But little is known about how they respond to fluctuations in light. The two varieties were grown either in fluctuating (F) or non-fluctuating (NF) light conditions to evaluate how variable light would affect biomass accumulation. Two different light treatments were applied, low light (LL) and high light (HL) with different light intensities and amplitude of fluctuations. The LL treatment did not entail any difference among F and NF in both varieties. The chlorophyll-deficient mutant was instead found to be susceptible to the fluctuations of light in the HL treatment, by accumulating less biomass. It is hypothesised that this might be due to its longer non‐photochemical quenching relaxation time  in light transitions, but other acclimatation mechanisms need to be investigated.</p>

Light-dependent seedling survival and growth of four tree species in Costa Rican second-growth rain forests

2005 ◽  
Vol 21 (4) ◽  
pp. 383-395 ◽  
Author(s):  
Silvia Iriarte Vivar Balderrama ◽  
Robin L. Chazdon
Keyword(s):  
Tree Species ◽  
Seedling Survival ◽  
Light Availability ◽  
Light Transmittance ◽  
Growth Responses ◽  
Low Light ◽  
Growth Increments ◽  
Light Gradient ◽  
Second Growth ◽  
Survival And Growth

The dependence of tree seedling survival and growth on light availability was evaluated over 15 mo in three second-growth, wet forest stands (15–18 y old) in north-eastern Costa Rica. Seedlings of four canopy tree species (Dipteryx panamensis, Hyeronima alchorneoides, Virola koschnyi and Vochysia guatemalensis) were planted into four canopy treatments in three replicated stands and in a pasture site, spanning a nearly complete gradient of light availability. Survival and growth of all species increased in response to increasing light availability, but species differed in survival in shaded microsites (6–20% light transmittance) and in growth increments per light increase. Hyeronima showed the highest mortality at low light levels and the highest relative height growth increase per light increase. In contrast, Virola showed high survival at low and moderate light, but showed the lowest leaf area and above-ground biomass per light increase among all species. Dipteryx and Vochysia maintained relatively high rates of survival and growth across the entire light gradient. Hyeronima and Virola showed trade-offs between growth and survival responses to light, unlike Dipteryx and Vochysia. Differences among species in seedling survival at low light may be determined by a variety of physiological and morphological traits that may or may not be mechanistically linked to growth responses.

Optical Methods for Studying the Drying Dynamics of Fe2O3 Nanocolloid Droplets Depending on Variation of Substrate Temperature

2015 ◽  
Vol 789-790 ◽  
pp. 33-37
Author(s):  
Alexander Dmitriev ◽  
Petr Makarov
Keyword(s):  
Light Intensity ◽  
Lower Layer ◽  
Transmitted Light ◽  
Optical Methods ◽  
Light Transmittance ◽  
Quality Level ◽  
Transparent Substrate ◽  
Single Temperature ◽  
Water Drops ◽  
Shaped Pattern

This work is devoted to investigation of the way light transmittance of drying drop of Fe2O3 nanocolloid deposited on flat surface changes as liquid evaporates. According to results of transmitted light intensity measuring it is assumed that drying process can be divided into separate stages each being characterized by particular quality level of ability to transmit light because of different behavior and, thus, density of suspended nanoparticles inside the droplet. The last stage ends by forming of a ring-shaped pattern (known as “coffee ring”). Temperature of the surface was being changed by applying a varying potential difference to lower layer of transparent substrate made of ITO. Time dependences of integral transmitted light intensity for every single temperature are represented in graphs. They are compared with dependences for water drops of the same volume.

scholarly journals Human-mediated disturbance in multitrophic interactions results in outbreak levels of North America's most venomous caterpillar

2019 ◽  
Vol 15 (9) ◽  
pp. 20190470 ◽  
Author(s):  
Glen R. Hood ◽  
Mattheau Comerford ◽  
Amanda K. Weaver ◽  
Patricia M. Morton ◽  
Scott P. Egan
Keyword(s):  
Species Interactions ◽  
Large Scale ◽  
Population Level ◽  
Multitrophic Interactions ◽  
Enemy Release ◽  
Ecological Disturbance ◽  
Quercus Virginiana ◽  
Avian Predators ◽  
Live Oak ◽  
Oak Trees

Anthropogenic environmental change is predicted to disrupt multitrophic interactions, which may have drastic consequences for population-level processes. Here, we investigate how a large-scale human-mediated disturbance affects the abundance of North America's most venomous caterpillar species, Megalopyge opercularis . Specifically, we used a natural experiment where netting was deployed to cover the entire canopies of a subset of mature southern live oak trees ( Quercus virginiana ) to exclude urban pest birds (grackles and pigeons), throughout an 8.1 km 2 area encompassing a medical centre in Houston, Texas. We used this experimental exclusion to test the following hypothesis: release from avian predators increases caterpillar abundance to outbreak levels, which increases the risk to human health. Results from a multi-year survey show that caterpillar abundance increased, on average, more than 7300% on netted versus non-netted trees. Thus, increases in caterpillar abundance due to anthropogenic enemy release increase human exposure to this venomous pest, and should be considered a health threat in the area. This study emphasizes the unforeseen consequences of ecological disturbance for species interactions and highlights the importance of considering ecology in urban planning.

Ecological relationships among sympatric lizards in a transitional forest in the northern Amazon of Brazil

1998 ◽  
Vol 14 (1) ◽  
pp. 63-86 ◽  
Author(s):  
LAURIE J. VITT ◽  
PETER A. ZANI
Keyword(s):  
Species Interactions ◽  
Local Level ◽  
Light Availability ◽  
Prey Type ◽  
Lizard Species ◽  
Ecological Relationships ◽  
Amazon Rain Forest ◽  
Random Assortment ◽  
Transitional Forest ◽  
The Impact

Sympatric lizards in a transitional forest of Roraima, Brazil, dividing Amazon rain forest from savanna, contained a lizard assemblage of 16 species representing six families. Lizards varied in size, activity (diurnal versus nocturnal), microhabitats used, exposure to various conditions of light availability, prey types, and prey sizes. Overlaps in microhabitat occurrence varied from 0 (no overlap) to 1.0 (total overlap) whereas overlaps in prey types varied from 0.005 to 0.607. Microhabitat overlaps were higher overall than dietary overlaps. Pseudocommunity analyses on microhabitat data indicate that the community is not randomly assembled and that two distinct guilds exist, a leaf-litter guild and an arboreal guild, each with four species. Similar analyses on diet data revealed no apparent guild structure ast the first rank (nearest neighbour). Lizard diets did not differ from a random assortment based on prey type. At lower levels, the assemblage was structured with respect to food. Variation in prey use among lizard species was tied more closely to the effect of lizard body size on prey size (lizards ate different-sized prey items). Although exploitative competition among species may maintain structure within this assemblage it does not necessarily cause the observed differences. Several species are nearly identical ecologically to sister taxa in other environments and within different lizard assemblages suggesting that composition of the local assemblage limits the species that can enter the assemblage. Finally, lack of structure at the lowest (most similar) neighbour ranks may reflect the impact of a transitional habitat on stability of species interactions at the local level.

Initial Colonization of Artificial Substrate: Community Development and Structure Studied by Scanning Electron Microscopy

1981 ◽  
Vol 38 (11) ◽  
pp. 1371-1384 ◽  
Author(s):  
Christiane Hudon ◽  
Edwin Bourget
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Community Structure ◽  
Community Development ◽  
Species Interactions ◽  
Light Availability ◽  
Artificial Substrate ◽  
Lawrence Estuary ◽  
Cell Densities ◽  
Scanning Electron

The initial phases of subtidal and intertidal community development were observed using scanning electron microscopy on samples from plastic panels immersed monthly in the St. Lawrence Estuary.Bacteria and diatom populations were quantitatively evaluated on samples collected from May to November, 1978. The pattern of immersion and/or periodical emersion according to the level greatly influenced the community structure. Subtidal panels (−5.0 m) were rapidly colonized by bacteria while diatoms settled 2–7 wk later, depending on the season. Cocconeis spp. and Amphora spp. were the major diatom colonizers until mid-August. In September, Synedra tabulata settled on the panels. Until mid-September, all dominant species formed well-defined, generally monospecific clumps. In contrast with Cocconeis spp. and Amphora spp., which lie horizontally on the surface, S. tabulata, which is needlelike in shape, formed erect fan-shaped colonies. Other late invaders possessed a mucus stalk, raising themselves from the surface and thus better utilizing the vertical dimension. Clump overlap and increased species interactions occurred with higher cell densities. In the intertidal zone bacteria settled after 8–12 wk while Achnanthes brevipes var. parvula appeared after 20 wk, the only diatom species able to resist semidiurnal emersion. The ability of the panels to retain water through detritus and irregularities is probably the main factor allowing the development of this community. Panels emersed only at spring tides (monthly) were rapidly colonized by bacteria, and heavy diatom settlement occurred within 4 wk. Successive monthly emersions eliminated or strongly reduced diatom populations, which were replaced by filamentous (Ectocarpaceae) algae. The three types of communities are compared and the strategic advantage of upright forms is discussed in relation to population density, light availability, and detrital cover.Key words: St. Lawrence Estuary, artificial substrate, community structure, community development, Cocconeis spp., Synedra tabulata. Amphora spp., diatoms

Effects of canopy species dominance on understorey light availability in low-elevation secondary forest stands in Costa Rica

1996 ◽  
Vol 12 (6) ◽  
pp. 779-788 ◽  
Author(s):  
Randy P. Kabakoff ◽  
Robin L. Chazdon
Keyword(s):  
Costa Rica ◽  
Forest Canopy ◽  
Light Availability ◽  
Basal Area ◽  
Light Transmittance ◽  
Stem Density ◽  
Secondary Forests ◽  
Canopy Architecture ◽  
Species Dominance ◽  
Canopy Species

ABSTRACTThe effect of canopy species dominance on understorey light availability in secondary forests was examined for Pentaclethra macroloba and Goethalsia meiantha, two common tree species with contrasting canopy architecture at La Selva Biological Station in the Atlantic lowlands of Costa Rica. In each of six 12- to 16-year-old successional stands dominated by one of these species, relative abundance and basal area of the focal species were determined within a 20 m × 50 m plot. Light availability at 1 m height was measured within each plot using a Licor-2000 Plant Canopy Analyzer at 27 locations and by analysing hemispherical photographs taken at 10 locations. Across stands, mean LAI values were significantly negatively correlated with canopy openness. Understorey microsites beneath Pentaclethra had significantly higher light availability than microsites beneath Goethalsia. Across stands, however, light availability was not correlated with either total basal area or stem density of trees ≥10 cm DBH. These results indicate that basal area and stem density of trees in the upper levels of the forest canopy are poor predictors of light penetration to the understorey. One hypothesis suggested here is that dense subcanopy and understorey vegetation in tropical secondary forests can strongly influence understorey light levels. Alternatively, light transmittance characteristics of the upper forest canopy may be influenced by species-specific differences in canopy architecture or foliage density that vary independently from tree diameter and density.

scholarly journals Effects of low and high irradiation levels on growth and PSII efficiency in Lemna minor L.

2020 ◽  
Vol 79 (2) ◽  
pp. 185-192
Author(s):  
Hrvoje Lepeduš ◽  
Željka Vidaković-Cifrek ◽  
Iris Šebalj ◽  
Jasenka Antunović Dunić ◽  
Vera Cesar
Keyword(s):  
Lemna Minor ◽  
Light Availability ◽  
Pulse Method ◽  
Low Light ◽  
Saturation Pulse ◽  
Chl A ◽  
Acclimation Response ◽  
Variable Light ◽  
Biomass Reduction

Plant growth and reproduction depend on light energy that drives photosynthesis. In the present study we compared growth characteristics, photosynthetic pigments content and photosystem II (PSII) performance in Lemna minor L. grown in two different irradiation regimes: low light (LL) – 50 μmolPHOTONS m-2 s-1 and high light (HL) – 500 μmolPHOTONS m-2 s-1. The main goal was to investigate the photosynthetic regulatory mechanisms that ensure adjustment to different light conditions and integrate these observations with the data on plant multiplication and biomass production. For this purpose, we measured chlorophyll (Chls) and carotenoid (Cars) contents and analyzed the energy fluxes through the PSII by saturation pulse method as well as by Chl a transient induction and JIP test. In a comparison of the effect of LL and HL on plant multiplication and fresh biomass, it was shown that the effect on growth was primarily attributed to the biomass reduction in LL while the effect on number of plants was much smaller. Total Chl and Cars contents were decreased in plants exposed to HL which indicated long-term acclimation response to the increased irradiance. Furthermore, the HL plants revealed better capability for the utilization of absorbed light in photosynthesis accompanied by photoprotective adjustment of certain number of PSII reaction centers from active to dissipative mode of functioning. In conclusion, our study showed that duckweed plants had great adjustment potential to different irradiation conditions, which might be of great importance not only under variable light availability but also when simultaneously challenged by some other environmental disturbance (e.g. different pollutants).

scholarly journals Spectral Morphometric Characterization of B-CLL Cells Versus Normal Small Lymphocytes

1998 ◽  
Vol 46 (10) ◽  
pp. 1113-1118 ◽  
Author(s):  
Zvi Malik ◽  
Chana Rothmann ◽  
Tova Cycowitz ◽  
Zwi J. Cycowitz ◽  
Amos M. Cohen
Keyword(s):  
Optical Density ◽  
Morphometric Analysis ◽  
Human Lymphocytes ◽  
Transmitted Light ◽  
Light Transmittance ◽  
Spectral Library ◽  
Light Spectra ◽  
Nuclear Domains ◽  
Morphometric Characterization

Spectral morphometric characterization of typical chronic lymphocytic leukemia (B-CLL) cells vs normal small lymphocytes stained by May-Grunwald-Giemsa was carried out by multipixel spectral imaging. The light intensity (450–850 nm of 104 pixels) from nuclear domains of each stained cell was recorded and represented as light transmittance spectra and optical density. Transmitted light spectra of two nuclear domains were determined, one with low-intensity light transmittance (LIT) and the other with high-intensity light transmittance (HIT). A spectral library was constructed using the four transmitted light spectra representing the HIT and LIT domains of the normal human lymphocytes and the LIT and HIT domains of the CLL cells. The spectral library served to scan CLL lymphocytes from 10 cases of CLL and the lymphocytes of 10 healthy individuals. Each spectrally similar domain in the nuclei of the lymphocytes was assigned an arbitrary color. The morphometric analysis of the spectrally classified nuclei showed specific spectral patterns for B-CLL in 92% of the cells. The specific spectral characteristics of each of the two cell populations were also observed by their optical density light absorbance spectra. We propose that spectral morphometric analysis may serve as an additional diagnostic tool for detection of CLL lymphocytes in a hematological specimen.

scholarly journals Mimicry and masquerade from the avian visual perspective

2012 ◽  
Vol 58 (4) ◽  
pp. 630-648 ◽  
Author(s):  
Mary Caswell Stoddard
Keyword(s):  
Case Studies ◽  
Visual Signal ◽  
Dead Leaf ◽  
Visual Perspective ◽  
Brood Parasites ◽  
Müllerian Mimicry ◽  
Avian Predators ◽  
Swallowtail Butterflies ◽  
Mullerian Mimicry ◽  
Defensive Mimicry

Abstract Several of the most celebrated examples of visual mimicry, like mimetic eggs laid by avian brood parasites and palatable insects mimicking distasteful ones, involve signals directed at the eyes of birds. Despite this, studies of mimicry from the avian visual perspective have been rare, particularly with regard to defensive mimicry and masquerade. Defensive visual mimicry, which includes Batesian and Müllerian mimicry, occurs when organisms share a visual signal that functions to deter predators. Masquerade occurs when an organism mimics an inedible or uninteresting object, such as a leaf, stick, or pebble. In this paper, I present five case studies covering diverse examples of defensive mimicry and masquerade as seen by birds. The best-known cases of defensive visual mimicry typically come from insect prey, but birds themselves can exhibit defensive visual mimicry in an attempt to escape mobbing or dissuade avian predators. Using examples of defensive visual mimicry by both insects and birds, I show how quantitative models of avian color, luminance, and pattern vision can be used to enhance our understanding of mimicry in many systems and produce new hypotheses about the evolution and diversity of signals. Overall, I investigate examples of Batesian mimicry (1 and 2), Müllerian mimicry (3 and 4), and masquerade (5) as follows: 1) Polymorphic mimicry in African mocker swallowtail butterflies; 2) Cuckoos mimicking sparrowhawks; 3) Mimicry rings in Neotropical butterflies; 4) Plumage mimicry in toxic pitohuis; and 5) Dead leaf-mimicking butterflies and mantids.

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