Insect compound eyes are composed of ommatidia, which contain photoreceptor cells that are sensitive to different wavelengths of light defined by the specific rhodopsin proteins that they express. ...The fruit fly Drosophila melanogaster has several different ommatidium types that can be localised to specific retinal regions, such as the dorsal rim area (DRA), or distributed stochastically in a mosaic across the retina, like the 'pale' and 'yellow' types. Variation in these ommatidia patterns very likely has important implications for the vision of insects and could underlie behavioural and environmental adaptations. However, despite the detailed understanding of ommatidia specification in D. melanogaster, the extent to which the frequency and distribution of the different ommatidium types vary between sexes, strains and species of Drosophila is not known.
We investigated the frequency and distribution of ommatidium types based on rhodopsin protein expression, and the expression levels of rhodopsin transcripts in the eyes of both sexes of different strains of D. melanogaster, D. simulans and D. mauritiana. We found that while the number of DRA ommatidia was invariant, Rh3 expressing ommatidia were more frequent in the larger eyes of females compared to the males of all species analysed. The frequency and distribution of ommatidium types also differed between strains and species. The D. simulans strain ZOM4 has the highest frequency of Rh3 expressing ommatidia, which is associated with a non-stochastic patch of pale and odd-coupled ommatidia in the dorsal-posterior of their eyes.
Our results show that there is striking variation in the frequency and distribution of ommatidium types between sexes, strains and species of Drosophila. This suggests that evolutionary changes in the underlying regulatory mechanisms can alter the distribution of ommatidium types to promote or restrict their expression in specific regions of the eye within and between species, and that this could cause differences in vision among these flies.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In total, 120 Thai-native pullets (Gallus domesticus) aged 18 wk were housed in floor pens, located in a conventional open-sided shed under natural daylight (12L:12D) and randomly divided into 3 ...groups; Groups 1 (DF) and 2 (DR) were reared under natural daylight and supplemented with fluorescent or red light, respectively, whereas group 3 (R) was maintained in light-controlled pens and exposed only to red light. The red light was produced by light-emitting diodes. All treatments were provided with 16 h of light per day (16L:8D) during a 26-wk egg-laying period, and there were 4 replicate pens of 10 hens for each treatment. Photostimulation of these light sources was initiated at 18 wk of age and subsequent effects on reproductive performance were observed during the experimental period. Morphological characteristics of the eyes and eggshell microstructure were examined at the end of the study. Feed and water were provided ad libitum. There were no significant differences in BW, feed intake, egg weight, egg quality, or mortality rate due to the treatment. Pullets in the R and DR treatment groups commenced egg production significantly earlier than those in the DF treatment group. In early-season egg production (0–8 wk), cumulative egg number was significantly (P < 0.05) higher for the R treatment (25.9 eggs/hen) than for the DR (20.9) and DF (19.5) treatment groups. No significant differences in total egg production per hen occurred among the treatment groups. At 2 wk following photostimulation, hens in the R treatment group had significantly (P < 0.05) higher serum estradiol concentrations compared with hens in the other treatment groups. Neither eggshell structure nor eye morphology was affected by the treatments. It was concluded that the spectrum of red light did not affect live performance, egg production, egg quality, eggshell microstructure, or eye morphology of Thai-native hens, except for in accelerating sexual development. The light-emitting diode lighting system would be beneficial for energy savings and the reduction of rearing costs.
Abstract There is a wide variation in the external eye morphology across species in primates, which is considered to reflect adaptation to ecological factors such as body size and habitat type. ...However, little attention has been paid to the contribution of social factors to the evolution of primate eye morphology. To explore this, we analyzed correlations among eye morphology, social factors (neocortex ratio and group size) and other factors (habitat type and body mass) in 30 living primate species including humans, using phylogenetically independent contrasts. The results indicated that parameters of primate eye morphology correlate with group size and neocortex ratio (Study 1). Further analysis of behavior indicated that the proportion of scanning with eyeball movement alone per total scanning correlated with group size and neocortex ratio (Study 2). The results support the view that the scanning with independent eyeball movement and its morphological basis is an adaptation to larger social groups. Communicative functions of the gaze signal other than the expression of aggression, observed in some primate species, may be based on features related to eye morphology. Furthermore, the evolution of a contact-free, social grooming function of gaze, especially predominant in humans, may reflect one extreme case of this kind of adaptation, which we call the “gaze-grooming” hypothesis.
Recent methodological and technical developments in comparative morphology have broadened understanding of evolutionary traits in molluscs. Scientists are capable of reconstructing organ systems and ...entire architectural physiologies with utmost precision. The pallial eyes of Pectinidae are amongst the most complex visual systems found in molluscs and have aroused scientific curiosity for decades. This investigation presents the most comprehensive description of pallial eye morphology in four major groups of Pectinidae: Aequipectini group, Pectininae, Chlamydinae and Palliolinae. The cornea, lens, retinae and branching of the optic nerve are depicted in topographic detail. Three‐dimensional reconstructions of microtome sections enable the comparison of whole eyes and structures in contrast to single‐section analysis. Here, we demonstrate two significant findings: (i) the morphology of corneae and lenses varies in scallop species and (ii) the retinae are innervated in different ways in different species. Moreover, we show how morphological characteristics such as the hyperbolic shape of the lens can be overlooked if only single sections are investigated.
Morphometric differences in the optical morphology of symbiotic palaemonid shrimps can be observed among species symbiotic with different host organisms. Discriminant functional analysis revealed ...three distinct groups within the species examined. Of these, bivalve symbionts appear to have an eye design that is solely unique to this host-symbiont grouping, a design that spans across multiple genera of phylogenetically unrelated animals. Although some taxonomic effects may be evident, this does not explain the difference and similarities in eye morphology that are seen within these shrimps. Therefore evolutionary pressures from their host environments are having an impact on the optical morphology of their eyes however, as indicated by host-hopping events there ecological adaptations occur post host invasion.
In the beginning of the new millennium, professional engineering cannot be imagined exclusive of the use of computers. Engineers who use computers or some other monitoring display terminals, both in ...design and various manufacturing phases, have been exposed to the effects of computer vision syndrome. Computer has become almost an indispensable piece of equipment both in the office and at home. This paper defines the computer vision syndrome, describes its genesis and explains related consequences. In the central part of this paper, results are presented of the research conducted in the Republic of Serbia regarding computer users, detected computer vision syndrome symptoms as well as the genuine actuality of computer vision syndrome among computer users. The final part of the paper offers possible solutions for reducing the effects and preventing occurrence of the observed syndrome.
Most caridean decapods have compound eyes of the reflecting superposition kind, and additionally some possess an accessory eye-like organ of unknown function, also referred to as the nebenauge. We ...examined 308 caridean genera to assess the general morphology of the eye, rostrum length, eye diameter and the presence or absence and, when present, the diameter of the nebenauge. We have attempted to relate these data to ecological and taxonomic considerations. We consider there to be 6 distinct eye types based on the margin between the eyestalk and cornea. The presence of nebenaugen appears to be generally linked to an active lifestyle, as evidenced by the fact that species that have nebenaugen tend to have larger eyes and are more likely to have a distinct rostrum. We suggest that the inconsistencies in its presence/absence under both systematic and ecological lenses may indicate that when present it has various roles relating to behavioural and physiological rhythms.
•Eye morphology and worker size correlated within one colony and between colonies.•Within a colony light sensitivity correlated with morphological parameters.•Between colonies more factors determine ...light sensitivity.•The initial foraging capacity of colonies correlated with their light sensitivity.•Not only morphology determined bumblebees eager to forage in weak light conditions.
Bumblebees of Bombus terrestris are essential pollinators in natural and managed ecosystems. Their foraging ability relies on the individual morphology, task allocation within the colony, and external factors, such as light intensity. The foraging activities of commercial bumblebees can sometimes be impaired, especially in the artificial and weak light intensities of greenhouses at high altitudes. Here we investigated whether the eagerness (or willingness) to forage of bumblebee colonies in different light conditions is correlated with the light sensitivity of bumblebees colonies and/or different external morphological parameters. The initial foraging capacity of bumblebee colonies correlated with their light sensitivity. However, light sensitive bumblebee colonies did not necessarily had a higher foraging activity at lower light intensities. Differences in initial foraging capacity and light sensitivity among colonies could not be explained by the external morphological parameters. In conclusion, our data illustrated that the recruitment to forage in artificial low light is less impaired in light sensitive colonies, and that not only the external morphology parameters determine the light sensitivity of bumblebees and their eagerness to forage in weak light conditions. The data obtained here create a better understanding of which criteria are able to select towards light sensitive bumblebees and their link with the foraging capacity of these bumblebees.
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