Eye Size, Fovea, and Foraging Ecology in Accipitriform Raptors

Birds with larger eyes are predicted to have higher spatial resolution because of their larger retinal image. Raptors are well known for their acute vision, mediated by their deep central fovea. Because foraging strategies may demand specific visual adaptations, eye size and fovea may differ between species with different foraging ecology. We tested whether predators (actively hunting mobile prey) and carrion eaters (eating dead prey) from the order Accipitriformes differ in eye size, foveal depth, and retinal thickness using spectral domain optical coherence tomography and comparative phylogenetic methods. We found that (1) all studied predators (except one) had a central and a temporal fovea, but all carrion eaters had only the central fovea; (2) eye size scaled with body mass both in predators and carrion eaters; (3) predators had larger eyes relative to body mass and a thicker retina at the edge of the fovea than carrion eaters, but there was no difference in the depth of the central fovea between the groups. Finally, we found that (4) larger eyes generally had a deeper central fovea. These results suggest that the visual system of raptors within the order Accipitriformes may be highly adapted to the foraging strategy, except for the foveal depth, which seems mostly dependent upon the eye size.

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Relationship of Gender, Body Mass Index, and Axial Length with Central Retinal Thickness Using Optical Coherence Tomography

Eye ◽

10.1038/sj.eye.6701466 ◽

2004 ◽

Vol 19 (3) ◽

pp. 292-297 ◽

Cited By ~ 82

Author(s):

A C M Wong ◽

C W N Chan ◽

S P Hui

Keyword(s):

Body Mass Index ◽

Optical Coherence Tomography ◽

Body Mass ◽

Axial Length ◽

Retinal Thickness ◽

Central Retinal Thickness ◽

Optical Coherence ◽

Relationship Of

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Assessment of Macular Parameter Changes in Patients with Keratoconus Using Optical Coherence Tomography

Journal of Ophthalmology ◽

10.1155/2015/245953 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Srujana Sahebjada ◽

Fakir M. Amirul Islam ◽

Sanj Wickremasinghe ◽

Mark Daniell ◽

Paul N. Baird

Keyword(s):

Optical Coherence Tomography ◽

Ocular Surface ◽

Retinal Thickness ◽

Anterior Segment ◽

Equation Model ◽

Optical Coherence ◽

Macular Volume ◽

Generalized Estimation Equation ◽

Thickness Measurements ◽

Central Fovea

Keratoconus is typically diagnosed through changes at the anterior ocular surface. However, we wished to assess if macular parameter changes might also occur in these patients. We assessed posterior changes through the use of optical coherence tomography and compared to a nonkeratoconus patient group. All subjects underwent clinical examination including macular thickness measurements. The generalized estimation equation model was used to estimate the means and compare the differences in various measurements between keratoconus and nonkeratoconus patients. A total of 129 keratoconus eyes of 67 cases and 174 nonkeratoconus eyes of 87 controls were analysed. Keratoconus individuals presented with a significantly greater mean retinal thickness in the central fovea, inner, and outer macula compared to the nonkeratoconus group (p<0.05). In addition, individuals presenting with the early signs of keratoconus had significantly greater inner and outer macular volume compared to the nonkeratoconus group (p<0.05). This study indicates the retina appears to thicken at the fovea and macula and had increased macular volume in keratoconus individuals compared to nonkeratoconus individuals. Thus we posit that structural retinal changes exist in keratoconus eyes that are additional to those typically seen in the anterior segment.

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Retinal Optical Coherence Tomography Metrics Are Unchanged in Verubecestat Alzheimer’s Disease Clinical Trial but Correlate with Baseline Regional Brain Atrophy

Journal of Alzheimer s Disease ◽

10.3233/jad-200735 ◽

2021 ◽

Vol 79 (1) ◽

pp. 275-287

Author(s):

Robert C. Sergott ◽

Annaswamy Raji ◽

James Kost ◽

Cyrille Sur ◽

Saheeda Jackson ◽

...

Keyword(s):

Clinical Trial ◽

Optical Coherence Tomography ◽

Nerve Fiber ◽

Retinal Nerve Fiber Layer ◽

Brain Atrophy ◽

Retinal Thickness ◽

Optical Coherence ◽

Fiber Layer ◽

Nerve Fiber Layer ◽

Retinal Nerve Fiber

Background: We performed exploratory analyses of retinal thickness data from a clinical trial of the AβPP cleaving enzyme (BACE) inhibitor verubecestat in patients with Alzheimer’s disease (AD). Objective: To evaluate: 1) possible retinal thickness changes following BACE inhibition; and 2) possible association between retinal thickness and brain atrophy. Methods: Retinal thickness was measured using spectral-domain optical coherence tomography in a 78-week randomized placebo-controlled trial of verubecestat in 1,785 patients with mild-to-moderate AD. Changes from baseline in retinal pigment epithelium, macular grid retinal nerve fiber layer, central subfield retinal thickness, and macular grid volume were evaluated for verubecestat versus placebo. Correlation analyses were performed to investigate the potential association between macular grid retinal nerve fiber layer and central subfield retinal thickness with brain volumetric magnetic resonance imaging (vMRI) data at baseline, as well as correlations for changes from baseline at Week 78 in patients receiving placebo. Results: Verubecestat did not significantly alter retinal thickness during the trial compared with placebo. At baseline, mean macular grid retinal nerve fiber layer and central subfield retinal thickness were weakly but significantly correlated (Pearson’s r values≤0.23, p-values < 0.01) with vMRI of several brain regions including whole brain, hippocampus, and thalamus. At Week 78, correlations between retinal thickness and brain vMRI changes from baseline in the placebo group were small and mostly not statistically significant. Conclusion: BACE inhibition by verubecestat was not associated with adverse effects on retinal thickness in patients with mild-to-moderate AD. Correlations between retinal thickness and brain volume were observed at baseline. Trial registration: Clinicaltrials.gov NCT01739348 (registered December 3, 2012; https://clinicaltrials.gov/ct2/show/NCT01739348).

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Be different to be better: the effect of personality on optimal foraging with incomplete knowledge

Theoretical Ecology ◽

10.1007/s12080-021-00517-7 ◽

2021 ◽

Author(s):

Poppy M. Jeffries ◽

Samantha C. Patrick ◽

Jonathan R. Potts

Keyword(s):

Optimal Foraging ◽

Optimal Foraging Theory ◽

Foraging Strategy ◽

Foraging Strategies ◽

Partial Knowledge ◽

Marginal Value ◽

Animal Populations ◽

Plausible Mechanism ◽

Insight Into ◽

Modelling Approach

AbstractMany animal populations include a diversity of personalities, and these personalities are often linked to foraging strategy. However, it is not always clear why populations should evolve to have this diversity. Indeed, optimal foraging theory typically seeks out a single optimal strategy for individuals in a population. So why do we, in fact, see a variety of strategies existing in a single population? Here, we aim to provide insight into this conundrum by modelling the particular case of foraging seabirds, that forage on patchy prey. These seabirds have only partial knowledge of their environment: they do not know exactly where the next patch will emerge, but they may have some understanding of which locations are more likely to lead to patch emergence than others. Many existing optimal foraging studies assume either complete knowledge (e.g. Marginal Value Theorem) or no knowledge (e.g. Lévy Flight Hypothesis), but here we construct a new modelling approach which incorporates partial knowledge. In our model, different foraging strategies are favoured by different birds along the bold-shy personality continuum, so we can assess the optimality of a personality type. We show that it is optimal to be shy (resp. bold) when living in a population of bold (resp. shy) birds. This observation gives a plausible mechanism behind the emergence of diverse personalities. We also show that environmental degradation is likely to favour shyer birds and cause a decrease in diversity of personality over time.

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Assessment of Global and Local Alterations in Retinal Layer Thickness in Ins2 (Akita) Diabetic Mice by Spectral Domain Optical Coherence Tomography

Journal of Ophthalmology ◽

10.1155/2018/7253498 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Andrew W. Francis ◽

Justin Wanek ◽

Mahnaz Shahidi

Keyword(s):

Optical Coherence Tomography ◽

Mouse Model ◽

Layer Thickness ◽

Retinal Thickness ◽

Normative Values ◽

Retinal Layer ◽

Wild Type ◽

Global And Local ◽

Akita Mice ◽

Sd Oct

Purpose/Aim. The Ins2 (Akita) mouse is a spontaneous diabetic mouse model with a heterozygous mutation in the insulin 2 gene that results in sustained hyperglycemia. The purpose of the study was to assess global and local retinal layer thickness alterations in Akita mice by analysis of spectral domain optical coherence tomography (SD-OCT) images.Materials and Methods. SD-OCT imaging was performed in Akita and wild-type mice at 12 and 24 weeks of age. Inner retinal thickness (IRT), outer retinal thickness (ORT), total retinal thickness (TRT), and photoreceptor outer segment length (OSL) were measured. Mean global thickness values were compared between Akita and wild-type mice. Local thickness variations in Akita mice were assessed based on normative values in wild-type mice.Results. Akita mice had higher blood glucose levels and lower body weights (p<0.001). On average, IRT, ORT, and TRT were approximately 2% lower in Akita mice than in wild-type mice (p≤0.02). In Akita mice, the percent difference between retinal areas with thickness below and above normative values for IRT, ORT, and TRT was 22%, 32%, and 38%, respectively.Conclusions. These findings support the use of the Akita mouse model to study the retinal neurodegenerative effects of hyperglycemia.

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Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

Conservation Physiology ◽

10.1093/conphys/coaa111 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Monique Ladds ◽

David Rosen ◽

Carling Gerlinsky ◽

David Slip ◽

Robert Harcourt

Keyword(s):

Foraging Strategy ◽

Central Place ◽

Dive Duration ◽

Foraging Strategies ◽

Body Morphology ◽

Sea Lions ◽

Fur Seals ◽

Adequate Food ◽

Physiological Capacity ◽

Total Body Oxygen

Abstract Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.

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Condition-dependent foraging strategies in a coastal seabird: evidence for the rich get richer hypothesis

Behavioral Ecology ◽

10.1093/beheco/ary173 ◽

2018 ◽

Vol 30 (2) ◽

pp. 356-363 ◽

Cited By ~ 3

Author(s):

Brock Geary ◽

Scott T Walter ◽

Paul L Leberg ◽

Jordan Karubian

Keyword(s):

Individual Variation ◽

Multiple Scales ◽

Foraging Ecology ◽

Population Level ◽

Foraging Strategies ◽

Significant Relationships ◽

Fitness Consequences ◽

Brown Pelicans ◽

The Rich ◽

Foraging Movements

Abstract The degree to which foraging individuals are able to appropriately modify their behaviors in response to dynamic environmental conditions and associated resource availability can have important fitness consequences. Despite an increasingly refined understanding of differences in foraging behavior between individuals, we still lack detailed characterizations of within-individual variation over space and time, and what factors may drive this variability. From 2014 to 2017, we used GPS transmitters and accelerometers to document foraging movements by breeding adult Brown Pelicans (Pelecanus occidentalis) in the northern Gulf of Mexico, where the prey landscape is patchy and dynamic at various scales. Assessments of traditional foraging metrics such as trip distance, linearity, or duration did not yield significant relationships between individuals. However, we did observe lower site fidelity and less variation in energy expenditure in birds of higher body condition, despite a population-level trend of increased fidelity as the breeding season progressed. These findings suggest that high-quality individuals are both more variable and more efficient in their foraging behaviors during a period of high energetic demand, consistent with a “rich get richer” scenario in which individuals in better condition are able to invest in more costly behaviors that provide higher returns. This work highlights the importance of considering behavioral variation at multiple scales, with particular reference to within-individual variation, to improve our understanding of foraging ecology in wild populations.

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24-Hour variation of optical coherence tomography–measured retinal thickness in diabetic macular edema

European Journal of Ophthalmology ◽

10.5301/ejo.5000119 ◽

2012 ◽

Vol 22 (5) ◽

pp. 785-791 ◽

Cited By ~ 7

Author(s):

Sokratis T. Kotsidis ◽

Simeon S. Lake ◽

Alexandros D. Alexandridis ◽

Nikolaos G. Ziakas ◽

Panagiotis K. Ekonomidis

Keyword(s):

Optical Coherence Tomography ◽

Macular Edema ◽

Diabetic Macular Edema ◽

Retinal Thickness ◽

Optical Coherence

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Subcolony Variation in Breeding Success in the Tufted Puffin (Fratercula Cirrhata): Association With Foraging Ecology and Implications

The Auk ◽

10.1093/auk/124.4.1149 ◽

2007 ◽

Vol 124 (4) ◽

pp. 1149-1157

Author(s):

J. Mark Hipfner ◽

Mathieu R. Charette ◽

Gwylim S. Blackburn

Keyword(s):

Stable Isotope ◽

Breeding Success ◽

Large Scale ◽

Foraging Ecology ◽

Isotope Analysis ◽

Egg Yolk ◽

Foraging Strategies ◽

Small Scale ◽

Carbon And Nitrogen ◽

Tufted Puffin

Abstract Large-scale oceanographic processes are the main drivers of seabird breeding success, but small-scale processes, though not as well understood, can also be important. We compared the success of Tufted Puffins (Fratercula cirrhata) breeding at two subcolonies only 1.5 km apart on Triangle Island, British Columbia, Canada, 2002–2005. In addition, we used stable-isotope analysis to test the hypothesis that parental foraging strategies differed between the two subcolonies, potentially underlying the variation in breeding success. Success was concordant across years at the two sites but, overall, Tufted Puffins bred more successfully at Strata Rock than at Puffin Rock. They raised chicks in all four years at Strata Rock, but in only three years at Puffin Rock; in two of those three years, Strata Rock chicks were, on average, 60 g and 100 g heavier than Puffin Rock chicks just before fledging. Discriminant analysis of carbon and nitrogen stable-isotope ratios in egg yolk and chick blood in 2004 and 2005 indicated that parental foraging differed between the two subcolonies, with both spatial (δ13C) and trophic-level (δ15N) differences involved. Thus, our study demonstrates the existence of foraging asymmetries in a pelagic seabird at a small spatial scale (between subcolonies), complementing patterns found at larger scales (between colonies). Moreover, the foraging asymmetries were associated with inequalities in fitness measures. We conclude that small-scale processes—in this case, systematic differences in the foraging ecology of local groups—can interact with large-scale oceanographic processes to determine seabird breeding success. Variation sous-coloniale du succès de reproduction de Fratercula cirrhata: Association avec l'écologie de la quête alimentaire et implications

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