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A scatterplot of optic tectum (TeO) volume against brain minus TeO volume. The solid line indicate the least-squares linear regression line. The black circles are the owls (Strigiformes), the gray circles are the Oilbird (Steatornis caripensis), Feline Owlet-nightjar (Aegotheles insignis) and the Tawny Frogmouth (Podargus strigoides ) and the open circles are all other species sampled (see Table 1)
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In mammals, species with more frontally oriented orbits have broader binocular visual fields and relatively larger visual regions in the brain. Here, we test whether a similar pattern of correlated evolution is present in birds. Using both conventional statistics and modern comparative methods, we tested whether the relative size of the Wulst and o...
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Context 1
... volume was significantly correlated with brain volume (F = 95.78, df = 1, 58, P \ 0.01, Fig. 5), but the strength of this correlation was lower (r 2 = 0.62) than that of the Wulst and brain volume (see above). Unlike the Wulst, the TeO was relatively small in the owls. It was also relatively small in the parrots. At the opposite end of the spectrum, the Greater Rhea (Rhea americana, Order Rheiformes), egrets and herons (Order ...
Context 2
... as independent variables, there was no significant interaction effect (F = 1.27, df = 1, 56, P = 0.27) on TeO volume. The effect of orbit orientation was also not significant (F = 0.02, df = 1, 57, P = 0.88), but a significant effect of brain volume was detected (F = 89.41, df = 1, 57, P \ 0.01). Again, analysis of TeO residuals (derived from Fig. 5) and orbit orientation yielded no significant relationship (Fig. ...
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... Although dietary exogenous protease is still at infant stage in aquaculture sector but several works has been carried out on protease and other enzymes (phytase, carbohydrase, amylase) in livestock sectors with the objective of assessing the action of an enzyme or combinationsof enzymes on broilers performance [5,6,7]. Results from the studies showed improvement in digestion and utilization of nutrients in animal production apart from making diet formulation more flexible and cost effective. ...
Soyabean meal (SBM) could be a suitable replacement for the expensive fishmeal but for its low digestibility in fish. However, protease supplementation could improve digestibility of SBM based diets. Therefore, apparent and true digestibility in Clarias gariepinus fed SBM based diets supplemented with protease were investigated. Six diets containing varied inclusion levels of protease (ppm) in solvent extracted soybean-based diets (SESBD) were formulated; Control (without protease), SS100 (100), SS200 (200), SS300 (300), SS400 (400), SS500 (500). The Clarias gariepinus (n=720) weighing 12.00±0.10g were fed to satiation with the diets for 12 weeks. Each treatment was in triplicate. Protease supplementation significantly (P<0.05) influenced the weight gain of C. gariepinus with the higher value in fish fed SS400 (44.63±3.13) and least value in control diet (32.03±0.65). FCR had a significantly (P<0.05) least value in C. gariepinus fed SS400 (1.62±0.18) but similar (P>0.05) to C. gariepinus diet SS300 (1.88±0.11). Supplemental protease in soyabean-based diet improved (P<0.05) apparent protein digestibility of C. gariepinus on diet SS400 (87.38±1.10) but similar (P>0.05) to C. gariepinus on diet SS200 (87.29±0.97). Also, true lysine digestibility was enhanced with protease supplementation in soybean-based diet with the higher value in diet SS200 (95.90±0.07). Optimal FCR occurred SESBD of 350ppm dietary inclusion (R2= 0.8147) of protease. The findings suggest that, protease supplementation in solvent extracted soyabean based diet could improve growth performance and amino acid digestibility in C. gariepinus at 350ppm inclusion level.
... Although previous studies have established a positive correlation between the size of the eye and certain visual brain centers (e.g., Barton, 2007;Němec et al., 2007;Prins & Schellart, 1992), dark environments might shape the visual system in a more complex way. An expansion of the visual brain centers is expected with increased demands for visual acuity, reflecting the need of enhanced processing capacity (Caves et al., 2018;Iwaniuk et al., 2008). However, if an enlarged corneal diameter effectively enhances light sensitivity at the cost of reduced visual acuity (Land & Nilsson, 2012;Martin, 1982Martin, , 2017Pettigrew et al., 1988), this might alter the demand for processing capacity. ...
... We excluded studies that measured the mass of the optic tectum on the basis of its surgical excision from the brainstem (Kalisińska, 2005;Portmann, 1947) because the dissected region combines the mass of the optic tectum, torus semicircularis, and likely also part of the tegmental gray matter, but not of the optic tectum alone. Therefore, we extracted data on wulst and optic tectum volumes (in cubic millimeters), measured volumetrically from sections according to the method of Boire (1989), from six different articles (Boire 1989;Gutiérrez-Ibáñez et al., 2013, 2014Iwaniuk et al., , 2008Iwaniuk et al., , 2010a. The article that provided the majority of our wulst volume data (Iwaniuk et al., 2008) also provided tectum volume measured on the same specimen. ...
... Therefore, we extracted data on wulst and optic tectum volumes (in cubic millimeters), measured volumetrically from sections according to the method of Boire (1989), from six different articles (Boire 1989;Gutiérrez-Ibáñez et al., 2013, 2014Iwaniuk et al., , 2008Iwaniuk et al., , 2010a. The article that provided the majority of our wulst volume data (Iwaniuk et al., 2008) also provided tectum volume measured on the same specimen. We prioritized this source for species with several measures of tectum volume. ...
Despite vision is an essential sense for many animals, the intuitively appealing notion that the visual system has been shaped by environmental light conditions is backed by insufficient evidence. Based on a comprehensive phylogenetic comparative analysis of birds, we investigate if exposure to different light conditions might have triggered evolutionary divergence in the visual system through pressures on light sensitivity, visual acuity, and neural processing capacity. Our analyses suggest that birds that have adopted nocturnal habits evolved eyes with larger corneal diameters and, to a lesser extent, longer axial length than diurnal species. However, we found no evidence that sensing and processing organs were selected together, as observed in diurnal birds. Rather than enlarging the processing centers, we found a tendency among nocturnal species to either reduce or maintain the size of the two main brain centers involved in vision –the optic tectum and the wulst. These results suggest a mosaic pattern of evolution, wherein optimization of the eye optics for efficient light capture in nocturnal species may have compromised visual acuity and central processing capacity.
... The visual field has only been determined for a few species. However, that of other species may be relatively easy to estimate, given that Iwaniuk [106] has shown good correlation between the bony orbital orientation and the binocular overlap of the visual field as measured by other methods. This would help resolve another bone of contention between different authors. ...
Penguins require vision that is adequate for both subaerial and submarine environments under a wide range of illumination. Here we provide a structured overview of what is known about their visual system with an emphasis on how and how well they achieve these goals. Amphibious vision is facilitated by a relatively flat cornea, the power in air varying from 10.2 dioptres (D) to 41.3 D depending on the species, and there is good evidence for emmetropia both above and below water. All penguins are trichromats with loss of rhodopsin 2, a nocturnal feature, but only deeper diving penguins have been noted to have pale oil droplets and a preponderance of rods. Conversely, the diurnal, shallow-diving little penguin has a higher ganglion cell density (28,867 cells/mm2) and f-number (3.5) than those that operate in dimmer light. In most species studied, there is some binocular overlap, but this reduces upon submergence. However, gaps in our knowledge remain, particularly with regard to the mechanism of accommodation, spectral transmission, behavioural measurements of visual function in low light, and neural adaptations to low light. The rarer species also deserve more attention.
... In contrast, the optic lobes of S. neocaledoniae are relatively the smallest of all galliforms (Fig. 3a, Tables S1, S3). When the relative size of the optic lobe is compared with that of all birds or large birds 33,34,50,51 , it is positioned close to the medians and means in both cases (Fig. 3b, Tables S1, S3): S. neocaledoniae has an optic lobe as reduced as that of the cassowary (Casuarius casuarius, Casuariidae), an extinct penguin (Paraptenodytes antarcticus, Spheniscidae) and the magnificent bird of Scaglia (Llallawavis scagliai, Phorusrhacidae). In birds, the relative size of the optic lobe is correlated with optical capacity 22,33,50,51 . ...
... When the relative size of the optic lobe is compared with that of all birds or large birds 33,34,50,51 , it is positioned close to the medians and means in both cases (Fig. 3b, Tables S1, S3): S. neocaledoniae has an optic lobe as reduced as that of the cassowary (Casuarius casuarius, Casuariidae), an extinct penguin (Paraptenodytes antarcticus, Spheniscidae) and the magnificent bird of Scaglia (Llallawavis scagliai, Phorusrhacidae). In birds, the relative size of the optic lobe is correlated with optical capacity 22,33,50,51 . Sylviornis neocaledoniae therefore probably had a weak visual acuity, as is also suggested by its proportionately reduced optic nerve and its small orbits (see electronic supplementary material, Fig. S11). ...
... Relative to endocast, the wulst of S. neocaledoniae is one of the largest among galliforms, with T. urogallus and Meleagris gallopavo (Fig. 3a, Tables S1, S3). However, when the relative size of this wulst is compared to that of large birds 34,50,51 , it is one of the smallest wulsts of large birds (Fig. 3b, Table S3). ...
Sylviornis neocaledoniae (Galliformes, Sylviornithidae), a recently extinct bird of New-Caledonia (Galliformes, Sylviornithidae) is the largest galliform that ever lived and one of the most enigmatic birds in the world. Herein, for the first time, we analyze its neuroanatomy that sheds light on its lifestyle, its brain shape and patterns being correlated to neurological functions. Using morphometric methods, we quantified the endocranial morphology of S. neocaledoniae and compared it with extinct and extant birds in order to obtain ecological and behavioral information about fossil birds. Sylviornis neocaledoniae exhibited reduced optic lobes, a condition also observed in nocturnal taxa endemic to predator-depauperate islands, such as Elephant birds. Functional interpretations suggest that S. neocaledoniae possessed a well-developed somatosensorial system and a good sense of smell in addition to its specialized visual ability for low light conditions, presumably for locating its food. We interpret these results as evidence for a crepuscular lifestyle in S. neocaledoniae.
... Imidacloprid has also been found to be the most toxic to birds and fishes [17,18]. Both imidacloprid and thiamethoxam are highly toxic to honeybees [19]. ...
Pesticides are widely used in Ghana, especially in cocoa farming. However, the practice is suboptimal and unsupervised. Incorrect use of these chemicals can seriously harm human health, the environment, and economies that rely on these farmers' output. The study assessed cocoa farmers' pesticide knowledge, practices, and risk perception. Four hundred and four cocoa farmers were chosen randomly from 26 communities in four cocoa-growing regions of Ghana to answer questions about their risk knowledge, awareness, and practices, including personal protective equipment, storage and disposal of leftover pesticides, and used containers. The study revealed that 87% of the respondents belonged to cooperatives and certification groups. There was a significant positive relationship between group membership and benefits derived from inputs and training in pesticide use. About 70% of insecticides used were approved by the Ghana Cocoa Board, with neonicotinoids and pyrethroids being the most highly used insecticide classes in cocoa farms. Although farmers claimed adequate pesticide knowledge, this did not translate into practice, with the majority exhibiting improper pesticide storage, application, and disposal practices. Farmers appeared to know a lot but lacked the skills and attitude to put their knowledge to use. The improper practices appear to manifest in a variety of health symptoms experienced by farmers as a result of chemical exposure. The findings from this study suggest that cocoa farmers in Ghana require adequate practical training and support on pesticide use to reduce their associated health risks, protect the environment and ensure sustainable cocoa production in the world’s second-largest cocoa bean exporter.
... Although there is no consensus about the degree of functional modularity in the brain, most researchers agree that some functional areas can be determined, some of which are purely dedicated to sensory processing, motor control and/or cognition (e.g. eminentia sagittalis to stereopsis or three-dimensional vision, Iwaniuk and Wylie 2006;Iwaniuk et al. 2008). As a consequence, we generally assume that the increase in a given region is correlated with an increase in the complexity of its functions. ...
... Visual fields can be measured directly in vivo (Martin 2007) or indirectly from the volume of the eminentia sagittalis of the brain (Iwaniuk et al. 2008) or bony markers on the skull. Cerio and Witmer (2020) proposed a new methodology called virtual ophthalmoscopy methodology (VO) that allows comparison of schematic eyeballs and in-silico visual fields. ...
Brain morphology has become a key element to predict a wide array of cognitive and behavioral, sensory and motor abilities, and to determine evolutionary rates of phenotypic transformation. Our information on early bird brain morphology comes of natural endocasts or studies of the intracranial cavity. Although the first studies of fossil bird brains were published almost two centuries ago, there is still relatively little known about the avian brain and its evolution compared with other groups such as mammals. This is due primarily to the fact that few three-dimensionally preserved skulls of early birds are recognized. The avian brain occupies the entire intracranial cavity, so that it is possible to reconstruct high-quality 3D virtual endocast models that can be used as excellent proxies for both volume and morphology of the brain. This technique has driven advances in avian paleoneurology from 2000 onwards. In this chapter, we provide a holistic view of the main features of the avian brain and senses, its disparity and potential use in paleobiological inferences, and discuss the main changes across the transition from non-avian theropods to derived Neornithes.
... The reflex may be specified as optokinetic (OKR, eye movement based), optocollic (OCR, head movement based) or optomotor (OMR, based on movements of the whole body). Barn owls can rotate their eyes only by a few degrees (Steinbach and Money 1973;Du Lac and Knudsen 1990;Nieder and Wagner 2000;Iwaniuk et al. 2008;Netser et al. 2010), and show a pronounced optocollic response when stationary. Note that when we mention the OCR in this work, we always mean the horizontal rotational OCR (hOCR); if we mention "owl", we always mean "barn owl". ...
Adult barn owls and primates possess an almost symmetric monocular rotational horizontal optocollic reflex. In primates, the reflex is initially asymmetric and becomes symmetric with time after birth. The condition in barn owls has not been studied so far. Here, we present data on the development of this reflex in this bird. We tested juvenile barn owls from the time before they open their eyes after hatching to the time they reach adult feather length. Wide-field visual patterns served as stimuli. They were presented at different rotational speeds in binocular and monocular settings. The binocular horizontal optocollic responses of juvenile barn owls were symmetric and adult-like on the first day that the birds responded to the stimulus. The monocular responses showed different rates of development in respect to stimulus velocity and stimulus direction. For velocities up to 20 deg/s, the monocular reflex was also adult-like on the first day that the birds responded to the stimulus. An initially higher asymmetry for 30 deg/s compared to adults disappeared within about two weeks. The development at even higher velocities remained unclear.
... The evolution of nocturnality in birds is associated with a suite of anatomical changes [3,4,[11][12][13]. The size of the eye corresponds with the number of photoreceptors in the retina [5], making large eyes advantageous in nocturnal species that rely on vision [4,14]. ...
... The thalamofugal pathway, which projects from the retina to the dorsal thalamus and onto the hyperpallium ( [18]; figure 1), is enlarged and has more prominent layers in owls and three other nocturnal species: Feline owlet-nightjar (Aegotheles insignis), tawny frogmouth (Podargus strigoides) and oilbird (Steatornis caripensis). This is thought to reflect a larger amount of visual processing associated with stereopsis in these species, rather than acuity [12]. The tectofugal pathway, which projects to the optic tectum, nucleus rotundus and up to the entopallium [18,20], comprises the majority of retinal afferents in birds [21] and exhibits a different pattern to the thalamofugal pathway in nocturnal birds. ...
... The wulst is the dorsal extension of the hyperpallium of the thalamofugal pathway and is visible on the dorsal surface of the brain. As mentioned above, it is greatly enlarged in owls and other nocturnal birds, and it is associated with binocular vision and depth perception [12,13]. The optic tectum is housed in the optic lobes that protrude on the ventro-lateral aspect of the avian brain [20,25]. ...
Nocturnal birds display diverse adaptations of the visual system to low-light conditions. The skulls of birds reflect many of these and are used increasingly to infer nocturnality in extinct species. However, it is unclear how reliable such assessments are, particularly in cases of recent evolutionary transitions to nocturnality. Here, we investigate a case of recently evolved nocturnality in the world's only nocturnal hawk, the letter-winged kite Elanus scriptus . We employed phylogenetically informed analyses of orbit, optic foramen and endocast measurements from three-dimensional reconstructions of micro-computed tomography scanned skulls of the letter-winged kite, two congeners, and 13 other accipitrid and falconid raptors. Contrary to earlier suggestions, the letter-winged kite was not unique in any of our metrics. However, all species of Elanus have significantly higher ratios of orbit versus optic foramen diameter, suggesting high visual sensitivity at the expense of acuity. In addition, visual system morphology varies greatly across accipitrid species, likely reflecting hunting styles. Overall, our results suggest that the transition to nocturnality can occur rapidly and without changes to key hard-tissue indicators of vision, but also that hard-tissue anatomy of the visual system may provide a means of inferring a range of raptor behaviours, well beyond nocturnality.
... Both visual and auditory stimuli are processed in the chicken OT (Cotter, 1976), and young chicks show audiovisual integration (Verhaal and Luksch, 2016). In contrast to the barn owl, which possesses auditory specializations and frontally oriented eyes as adaptations for nocturnal hunting (Harmening and Wagner, 2011;Wagner et al., 2013), generalist birds mainly rely on vision and have laterally oriented eyes to monitor the surroundings (Iwaniuk et al., 2008). Thus, the lateral visual axis strongly overlaps with the interaural axis (Schnyder et al., 2014). ...
The optic tectum (OT) is an avian midbrain structure involved in the integration of visual and auditory stimuli. Studies in the barn owl, an auditory specialist, have shown that spatial auditory information is topographically represented in the OT. Little is known about how auditory space is represented in the midbrain of birds with generalist hearing, i.e., most of avian species lacking peripheral adaptations such as facial ruffs or asymmetric ears. Thus, we conducted in vivo extracellular recordings of single neurons in the OT and in the external portion of the formatio reticularis lateralis (FRLx) – a brain structure located between the inferior colliculus and the OT - in anaesthetized chickens of either sex.
We found that most of the auditory spatial receptive fields (aSRFs) were spatially confined both in azimuth and elevation, divided into two main classes: round aSRFs, mainly present in the OT, and annular aSRFs - with a ring-like shape around the interaural axis - mainly present in the FRLx. Our data further indicate that ITD and ILD play a role in the formation of both aSRF classes. These results suggest that, unlike mammals and owls which have a congruent representation of visual and auditory space in the OT, generalist birds separate the computation of auditory space in two different midbrain structures. We hypothesize that the FRLx-annular aSRFs define the distance of a sound source from the axis of the lateral visual fovea, whereas the OT-round aSRFs are involved in multimodal integration of the stimulus around the lateral fovea.
... In owls, for instance, visual Wulst neurons present precise retinotopic organisation, direction and orientation selectivity and binocular disparity (Pettigrew and Konishi 1976;Nieder and Wagner 2000). Indeed, in birds with frontally placed eyes, processing of binocular information for depth estimation seems to be one of the main functions of the visual Wulst (Nieder and Wagner 2000;Blake and Wilson 2011), whose size seems to correlate with the amount of binocular overlap of each species (Iwaniuk et al. 2008). ...
Since the ground-breaking discovery that in-egg light exposure triggers the emergence of visual lateralisation, domestic chicks became a crucial model for research on the interaction of environmental and genetic influences for brain development. In domestic chick embryos, light exposure induces neuroanatomical asymmetries in the strength of visual projections from the thalamus to the visual Wulst. Consequently, the right visual Wulst receives more bilateral information from the two eyes than the left one. How this impacts visual Wulst’s physiology is still unknown. This paper investigates the visual response properties of neurons in the left and right Wulst of dark- and light-incubated chicks, studying the effect of light incubation on bilaterally responsive cells that integrate information from both eyes. We recorded from a large number of visually responsive units, providing the first direct evidence of lateralisation in the neural response properties of units of the visual Wulst. While we confirm that some forms of lateralisation are induced by embryonic light exposure, we found also many cases of light-independent asymmetries. Moreover, we found a strong effect of in-egg light exposure on the general development of the functional properties of units in the two hemispheres. This indicates that the effect of embryonic stimulation goes beyond its contribution to the emergence of some forms of lateralisation, with influences on the maturation of visual units in both hemispheres.
