scholarly journals Predation selects for smaller eye size in a vertebrate: effects of environmental conditions and sex

2019 ◽  
Vol 286 (1897) ◽  
pp. 20182625 ◽  
Author(s):  
Richard Svanbäck ◽  
Frank Johansson
Keyword(s):  
Visual Acuity ◽  
Phenotypic Plasticity ◽  
Experimental Evidence ◽  
Predation Risk ◽  
Environmental Conditions ◽  
Retinal Image ◽  
The Other ◽  
Eye Size ◽  
Fish Predators ◽  
Resource Levels

Increased eye size in animals results in a larger retinal image and thus improves visual acuity. Thus, larger eyes should aid both in finding food as well as detecting predators. On the other hand, eyes are usually very conspicuous and several studies have suggested that eye size is associated with predation risk. However, experimental evidence is scant. In this study, we address how predation affects variation in eye size by performing two experiments using Eurasian perch juveniles as prey and either larger perch or pike as predators. First, we used large outdoor tanks to compare selection due to predators on relative eye size in open and artificial vegetated habitats. Second, we studied the effects of both predation risk and resource levels on phenotypic plasticity in relative eye size in indoor aquaria experiments. In the first experiment, we found that habitat altered selection due to predators, since predators selected for smaller eye size in a non-vegetated habitat, but not in a vegetated habitat. In the plasticity experiment, we found that fish predators induced smaller eye size in males, but not in females, while resource levels had no effect on eye size plasticity. Our experiments provide evidence that predation risk could be one of the driving factors behind variation in eye size within species.

Progeny Testing of Dairy Bulls at Different Levels of Management

1954 ◽  
Vol 1954 ◽  
pp. 83-85 ◽  
Author(s):  
I. L. Mason
Keyword(s):  
Dairy Cattle ◽  
Experimental Evidence ◽  
Environmental Conditions ◽  
The Other ◽  
Progeny Testing ◽  
Laboratory Mice ◽  
Dairy Bulls ◽  
The Tropics ◽  
Different Levels ◽  
European Cattle

There are two schools of thought concerning the most appropriate environment in which to select breeding animals. One says ‘ Always select animals under environmental conditions similar to those where they are to be used ‘. The other says ‘ Select breeding animals in the optimum environment so that they have the best chance of revealing their genetic capabilities ‘. Experiments on growth of laboratory mice and experience with European cattle in the tropics have shown the advisability of the first course in these cases. In regard to hill sheep and dairy cattle in Britain, on the other hand, practice favours the second course, but there is little experimental evidence to support it.

scholarly journals Inbreeding depression in adaptive plasticity under predation risk in a freshwater snail

2009 ◽  
Vol 6 (2) ◽  
pp. 222-224 ◽  
Author(s):  
Josh R. Auld ◽  
Rick A. Relyea
Keyword(s):  
Phenotypic Plasticity ◽  
Predation Risk ◽  
Inbreeding Depression ◽  
Environmental Conditions ◽  
Chemical Cues ◽  
Natural Populations ◽  
Freshwater Snail ◽  
Adaptive Plasticity ◽  
Plastic Response ◽  
Physa Acuta

While much attention has been paid to the effects of inbreeding on fitness, this has mostly come from a genetic perspective. Consequently, the interaction between inbreeding and the environment is less well understood. To understand the effects of inbreeding in natural populations where environmental conditions are variable, we need to examine not only how the effects of inbreeding change among environments but also how inbreeding may affect the ability to respond to environmental conditions (i.e. phenotypic plasticity). We reared selfed and outcrossed hermaphroditic snails ( Physa acuta ) in the presence and absence of chemical cues from predatory crayfish and quantified expression of an inducible defence, an adaptively plastic response to predation risk. Overall, inbred snails exhibited reduced defences, but more importantly, inbreeding reduced the expression of predator-induced adaptive plasticity. Inbreeding depression in defensive morphology was 26 per cent and inbreeding depression in the plasticity of this trait was 48 per cent. Inbreeding depression in adaptive plasticity may be important to understanding the effects of inbreeding in nature.

scholarly journals The Impact of Different Environmental Conditions during Vegetative Propagation on Growth, Survival, and Biochemical Characteristics in Populus Hybrids in Clonal Field Trial

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 892
Author(s):  
Valda Gudynaitė-Franckevičienė ◽  
Alfas Pliūra
Keyword(s):  
Climate Change ◽  
Phenotypic Plasticity ◽  
Environmental Conditions ◽  
Vegetative Propagation ◽  
Genotypic Variation ◽  
Hybrid Poplar ◽  
Field Trials ◽  
Biochemical Traits ◽  
Suburban Areas ◽  
Growing Conditions

To have a cleaner environment, good well-being, and improve the health of citizens it is necessary to expand green urban and suburban areas using productive and adapted material of tree species. The quality of urban greenery, resistance to negative climate change factors and pollution, as well as efficiency of short-rotation forestry in suburban areas, depends primarily on the selection of hybrids and clones, suitable for the local environmental conditions. We postulate that ecogenetic response, phenotypic plasticity, and genotypic variation of hybrid poplars (Populus L.) grown in plantations are affected not only by the peculiarities of hybrids and clones, but also by environmental conditions of their vegetative propagation. The aim of the present study was to estimate growth and biochemical responses, the phenotypic plasticity, genotypic variation of adaptive traits, and genetically regulated adaptability of Populus hybrids in field trials which may be predisposed by the simulated contrasting temperature conditions at their vegetative propagation phase. The research was performed with the 20 cultivars and experimental clones of one intraspecific cross and four different interspecific hybrids of poplars propagated under six contrasting temperature regimes in phytotron. The results suggest that certain environmental conditions during vegetative propagation not only have a short-term effect on tree viability and growth, but also can help to adapt to climate change conditions and grow successfully in the long-term. It was found that tree growth and biochemical traits (the chlorophyll A and B, pigments content and the chlorophyll A/B ratio) of hybrid poplar clones grown in field trials, as well as their traits’ genetic parameters, were affected by the rooting-growing conditions during vegetative propagation phase. Hybrids P. balsamifera × P. trichocarpa, and P. trichocarpa × P. trichocarpa have shown the most substantial changes of biochemical traits across vegetative propagation treatments in field trial. Rooting-growing conditions during vegetative propagation had also an impact on coefficients of genotypic variation and heritability in hybrid poplar clones when grown in field trials.

scholarly journals Morphological variation in Leptorhynchos squamatus (Gnaphalieae: Asteraceae)

2002 ◽  
Vol 15 (2) ◽  
pp. 205 ◽  
Author(s):  
Christina Flann ◽  
Pauline Y. Ladiges ◽  
Neville G. Walsh
Keyword(s):  
High Altitude ◽  
Morphological Variation ◽  
Environmental Conditions ◽  
Leaf Size ◽  
Alpine Plants ◽  
The Other ◽  
Herbarium Specimens ◽  
South Eastern ◽  
Eastern Australia ◽  
Low Altitude

A study of morphological variation in Leptorhynchos squamatus (Labill.) Less. across its range in south-eastern Australia was undertaken to test the hypothesis that L. squamatus includes two taxa. Phenetic pattern analyses of both field-collected and herbarium specimens on the basis of morphology confirmed two major groups. Bract, cypsela, pappus bristle and leaf characters were particularly important in separating the two groups. The taxa are separated by altitude differences with one being a low-altitude plant found in many habitats and the other being a high-altitude taxon that is a major component of alpine meadows. Lowland plants have dark bract tips, fewer and wider pappus bristles than alpine plants, papillae on the cypselas and more linear leaves. A somewhat intermediate population from the Major Mitchell Plateau in the Grampians shows some alpine and some lowland characters but is included in the lowland taxon. Seeds from five populations (two alpine, two lowland and Major Mitchell) were germinated and plants grown for 18 weeks under four controlled sets of environmental conditions. The experiment showed that leaf size and some other characters are affected by environmental conditions, but that there are underlying genetic differences between the lowland and alpine forms. Leptorhynchos squamatus subsp. alpinus Flann is described here to accommodate the highland taxon.

THE KILLER OF NATURE – ENVIRONMENTAL DEGRADATION

2015 ◽  
Vol 3 (3) ◽  
pp. 293-295
Author(s):  
Ekta Sharma
Keyword(s):  
Environmental Degradation ◽  
Environmental Conditions ◽  
The Other ◽  
Natural Environments ◽  
Human Being ◽  
Human Beings ◽  
The Public ◽  
Summary Paper ◽  
Living Being

The Presented summary paper target is to draw the attention of the public to the benefits of Environment and how we are connected to the Environment. To show that if there’s any change in the Environmental conditions, then how the conditions change in human beings lives. Living Being, whether a Human Being or Animals or plants,  are all directly or indirectly Dependent on the Environment for their Survival. When asked truly it can be said that none of the living being can survive without the presence of Environment. It is difficult to find absolutely natural environments, and it is common that the naturalness varies in a continuum, from ideally 100% natural in one extreme to 0% natural in the other. More precisely, we can consider the different aspects or components of an environment, and see that their degree of naturalness is not uniform.

How “Native” Are Heritage Speakers?

2013 ◽  
Vol 10 (2) ◽  
pp. 153-177 ◽  
Author(s):  
Silvina Montrul
Keyword(s):  
Language Learning ◽  
Experimental Evidence ◽  
Native Speakers ◽  
Learning Experience ◽  
Age Of Acquisition ◽  
The Other ◽  
Gender Agreement ◽  
Heritage Speakers ◽  
High Incidence ◽  
Incomplete Acquisition

One of the chief characteristics of heritage speakers is that they range in proficiency from “overhearers” to “native” speakers. To date, the vast majority of linguistic and psycholinguistic studies have characterized the non-target-like linguistic abilities of heritage speakers as a product of incomplete acquisition and/or attrition due to reduced exposure and opportunities to use the language during childhood. This article focuses on the other side of the problem, emphasizing instead the high incidence of native-like abilities in adult heritage speakers. I illustrate this issue with recent experimental evidence from gender agreement in Spanish, a grammatical feature that is mastered at almost 100% accuracy in production by native speakers;yet it is one of the most difficult areas to master for non-native speakers, including near-natives.I discuss how age of acquisition and language-learning experience explain these effects.

scholarly journals Eye shape and the nocturnal bottleneck of mammals

2012 ◽  
Vol 279 (1749) ◽  
pp. 4962-4968 ◽  
Author(s):  
Margaret I. Hall ◽  
Jason M. Kamilar ◽  
E. Christopher Kirk
Keyword(s):  
Visual Acuity ◽  
Detailed Analysis ◽  
Statistical Methods ◽  
Activity Pattern ◽  
Activity Patterns ◽  
Time Of Day ◽  
Visual Sensitivity ◽  
Early Evolution ◽  
Eye Size ◽  
Diurnal Species

Most vertebrate groups exhibit eye shapes that vary predictably with activity pattern. Nocturnal vertebrates typically have large corneas relative to eye size as an adaptation for increased visual sensitivity. Conversely, diurnal vertebrates generally demonstrate smaller corneas relative to eye size as an adaptation for increased visual acuity. By contrast, several studies have concluded that many mammals exhibit typical nocturnal eye shapes, regardless of activity pattern. However, a recent study has argued that new statistical methods allow eye shape to accurately predict activity patterns of mammals, including cathemeral species (animals that are equally likely to be awake and active at any time of day or night). Here, we conduct a detailed analysis of eye shape and activity pattern in mammals, using a broad comparative sample of 266 species. We find that the eye shapes of cathemeral mammals completely overlap with nocturnal and diurnal species. Additionally, most diurnal and cathemeral mammals have eye shapes that are most similar to those of nocturnal birds and lizards. The only mammalian clade that diverges from this pattern is anthropoids, which have convergently evolved eye shapes similar to those of diurnal birds and lizards. Our results provide additional evidence for a nocturnal ‘bottleneck’ in the early evolution of crown mammals.

Are mesoionic compounds aromatic?

1998 ◽  
Vol 76 (6) ◽  
pp. 869-872 ◽  
Author(s):  
Alfredo Mayall Simas ◽  
Joseph Miller ◽  
Petrônio Filgueiras de Athayade Filho
Keyword(s):  
Experimental Evidence ◽  
Key Words ◽  
Dipole Moments ◽  
The Other ◽  
Side Chain ◽  
Theoretical Studies ◽  
X Ray Diffraction ◽  
Ring Plane ◽  
X Ray ◽  
Single Bonds

We have evaluated the experimental evidence relevant to the structure and character of mesoionic compounds, accumulated for more than 100 years and including X-ray diffraction studies. We have also evaluated relevant theoretical studies. All these, including our own extensive work, lead us to conclude that mesoionic compounds are not aromatic. According to our recent definition “mesoionic compounds are planar five-membered heterocyclic betaines with at least one side chain whose α-atom is also in the ring plane and with dipole moments of the order of 5 D. Electrons are delocalized over two regions separated by what are essentially single bonds. One region, which includes the a-atom of the side chain is associated with the HOMO and negative π-charge whereas the other is associated with the LUMO and positive π-charge.” Key words: mesoionic compounds, betaines, aromaticity.

The Effects of Adverse Environmental Conditions on Workload

1975 ◽  
Vol 19 (3) ◽  
pp. 301-304
Author(s):  
Ann E. Martin
Keyword(s):  
Environmental Conditions ◽  
Environmental Variables ◽  
Secondary Task ◽  
The Other ◽  
Random Numbers ◽  
Performance Decrement ◽  
Experimental Conditions ◽  
Continuous Noise ◽  
Adverse Environmental Conditions ◽  
Intermittent Noise

The present study was conducted to investigate the effects of environmental conditions on visual workload. The environmental variables used were temperature, studied at levels of 45°F., WBGT, and 95°F., WBGT; and noise, studied at 83 dBA intermittent noise and 93 dBA continuous noise. Workload was defined as the amount of attention demanded from an operator as measured by performance decrement on a secondary task while performing a primary and secondary task simultaneously. The secondary task was reading random numbers, and the primary task was reading word lists. Significant differences (p<.05) were found between the control condition and all experimental conditions. The low temperature and high temperature-continuous noise conditions were significantly different from the other conditions. Noise and temperature were found to significantly increase workload (p<05).

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