First explorations: ontogeny of central place foraging directions in two tropical seabirds

Abstract A widespread hypothesis for the ontogeny of behavior and decision-making is the early-exploration-later-canalization hypothesis. It postulates that juveniles are more exploratory and adults more consistent in their behavior. In addition, it is often assumed that naïve juveniles could overcome the costs of individual experience building by copying more the decisions of others than adults (early-conformism-later-self-defining hypothesis). Here, we compare the central place foraging movements of adults and postfledging juveniles in their first flights around the colony before dispersal and migration in two sympatric species of tropical seabirds: red-footed boobies and great frigatebirds. Using GPS records of individual movements, we analyzed the foraging directions of seabirds from the colony across successive trips. Juveniles of both species showed significant within-individual consistency in foraging direction but at lower levels than adults. Juveniles leaving the colony within the same time window showed significant but low between-individual resemblance in foraging direction at levels similar to adults. In both species, homing efficiency was lower in juveniles than in adults. Juvenile foraging directions were initially influenced by wind conditions, particularly in low wing loading frigatebirds. Wind conditions progressively lost influence on juvenile foraging directions during their first weeks of flights. In contrast, within-individual consistency, between-individual resemblance, and homing efficiency did not show signs of progression in juveniles. Our results support the early-exploration-later-canalization hypothesis but not the early-conformism-later-self-defining hypothesis. Relaxed constraints on self-feeding efficiency could favor high variability in postfledging tropical seabirds. Our simple approach could be applied to further test these hypotheses by comparing strategies across a wide range of central place foragers.

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Optimal sinuosity in central place foraging movements

Animal Behaviour ◽

10.1016/s0003-3472(05)80605-0 ◽

1991 ◽

Vol 42 (1) ◽

pp. 57-62 ◽

Cited By ~ 46

Author(s):

Pierre Bovet ◽

Simon Benhamou

Keyword(s):

Central Place ◽

Central Place Foraging ◽

Foraging Movements

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Reorientation patterns in central-place foraging: internal clocks and klinokinesis

Journal of The Royal Society Interface ◽

10.1098/rsif.2013.0859 ◽

2014 ◽

Vol 11 (90) ◽

pp. 20130859 ◽

Cited By ~ 10

Author(s):

Daniel Campos ◽

Frederic Bartumeus ◽

Vicenç Méndez ◽

Xavier Espadaler

Keyword(s):

Population Level ◽

Central Place ◽

Time Variability ◽

Risk Averse ◽

Central Place Foraging ◽

Stretched Exponential ◽

Aphaenogaster Senilis ◽

Model Combining ◽

Wide Range ◽

Efficient Exploration

We study central-place foraging patterns of Aphaenogaster senilis ants at a population level by video framing individual ant trajectories in a circular arena with a nest connected to its centre. The ants naturally leave and enter the nest and forage generating non-trivial movement patterns around the nest. Our data analysis indicated that the trajectories observed can be classified into two strategies: the risk-averse strategy, which involves wandering around the nest without departing far from it and the risk-prone strategy, which involves long exploration paths with periodic returns to the central region, nearby the nest. We found that both risk-prone and risk-averse strategies exhibit qualitatively the same reorientation patterns, with the time between consecutive reorientations covering a wide range of scales, and fitting a stretched exponential function. Nevertheless, differences in the temporal scales and the time variability of such reorientation events differ, together with other aspects of motion, such as average speed and turns. Our results give experimental evidence that the internal mechanisms driving reorientations in ants tend to favour frequently long relocations, as theory predicts for efficient exploration in patchy landscapes, but ants engaged in central-place foraging can modulate such behaviour to control distances from the nest. Previous works on the species support the idea that risk-prone and risk-averse strategies may reflect actual differences between individuals age and experience; these factors (age and experience) should be then relevant in modulating the internal reorientation clocks. To support the validity of our findings, we develop a random-walk model combining stretched exponential reorientation clocks with klinokinesis that fits the time length and the travelled distance distributions of the observed trajectories.

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Generative Adversarial Networks (GAN) for the simulation of central-place foraging trajectories

10.1101/2021.09.27.461940 ◽

2021 ◽

Author(s):

Amédée Roy ◽

Sophie Lanco Bertrand ◽

Ronan Fablet

Keyword(s):

Large Scale ◽

Animal Movement ◽

Multiple Scales ◽

Electronic Device ◽

Central Place ◽

Generative Adversarial Networks ◽

Central Place Foraging ◽

Ecological Processes ◽

Adversarial Networks ◽

Wide Range

1. Miniature electronic device such as GPS have enabled ecologists to document relatively large amount of animal trajectories. Modeling such trajectories may attempt (1) to explain mechanisms underlying observed behaviors and (2) to elucidate ecological processes at the population scale by simulating multiple trajectories. Existing approaches to animal movement modeling mainly addressed the first objective and they are yet soon limited when used for simulation. Individual-based models based on ad-hoc formulation and empirical parametrization lack of generability, while state-space models and stochastic differential equations models, based on rigorous statistical inference, consist in 1st order Markovian models calibrated at the local scale which can lead to overly simplistic description of trajectories. 2. We introduce a 'state-of-the-art' tool from artificial intelligence - Generative Adversarial Networks (GAN) - for the simulation of animal trajectories. GAN consist in a pair of deep neural networks that aim at capturing the data distribution of some experimental dataset, and that enable the generation of new instances of data that share statistical similarity. In this study, we aim on one hand to identify relevant deep networks architecture for simulating central-place foraging trajectories and on the second hand to evaluate GAN benefits over classical methods such as state-switching Hidden Markov Models (HMM). 3. We demonstrate the outstanding ability of GAN to simulate 'realistic' seabirds foraging trajectories. In particular, we show that deep convolutional networks are more efficient than LSTM networks and that GAN-derived synthetic trajectories reproduce better the Fourier spectral density of observed trajectories than those simulated using HMM. Therefore, unlike HMM, GAN capture the variability of large-scale descriptive statistics such as foraging trips distance, duration and tortuosity. 4. GAN offer a relevant alternative to existing approaches to modeling animal movement since it is calibrated to reproduce multiple scales at the same time, thus freeing ecologists from the assumption of first-order markovianity. GAN also provide an ultra-flexible and robust framework that could further take environmental conditions, social interactions or even bio-energetics model into account and tackle a wide range of key challenges in movement ecology.

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Population and Community Consequences of Spatial Subsidies Derived from Central-Place Foraging

The American Naturalist ◽

10.2307/4541163 ◽

2007 ◽

Vol 170 (6) ◽

pp. 902

Author(s):

Fagan ◽

Frithjof Lutscher ◽

Katie Schneider

Keyword(s):

Central Place ◽

Central Place Foraging ◽

Spatial Subsidies

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Tree Swallow selection for wetlands in agricultural landscapes predicted by central-place foraging theory

The Condor ◽

10.1093/condor/duaa039 ◽

2020 ◽

Author(s):

Andrew S Elgin ◽

Robert G Clark ◽

Christy A Morrissey

Keyword(s):

Habitat Selection ◽

Central Place ◽

Foraging Theory ◽

Agricultural Landscapes ◽

Tree Swallow ◽

Field Margins ◽

Central Place Foraging ◽

Prairie Pothole ◽

Prairie Wetlands ◽

Selection For

Abstract Millions of wetland basins, embedded in croplands and grasslands, are biodiversity hotspots in North America’s Prairie Pothole Region, but prairie wetlands continue to be degraded and drained, primarily for agricultural activities. Aerial insectivorous swallows are known to forage over water, but it is unclear whether swallows exhibit greater selection for wetlands relative to other habitats in croplands and grasslands. Central-place foraging theory suggests that habitat selectivity should increase with traveling distance from a central place, such that foragers compensate for traveling costs by selecting more profitable foraging habitat. Using global positioning system (GPS) tags, we evaluated habitat selection by female Tree Swallows (Tachycineta bicolor) at 4 sites containing wetlands and where terrestrial land cover was dominated by grasslands (grass, herbaceous cover) and/or cultivated cropland. We also used sweep-net transects to assess the abundance and biomass of flying insects in different habitats available to swallows (wetland pond margins, grassy field margins, and representative uplands). As expected for a central-place forager, GPS-tagged swallows selected more for wetland ponds (disproportionate to availability), and appeared to increasingly select for wetlands with increasing distance from their nests. On cropland-dominated sites, insect abundance and biomass tended to be higher in pond margins or grassy field margins compared to cropped uplands, while abundance and biomass were more uniform among sampled habitats at sites dominated by grass and herbaceous cover. Swallow habitat selection was not clearly explained by the distribution of sampled insects among habitats; however, traditional terrestrial sampling methods may not adequately reflect prey distribution and availability to aerially foraging swallows. Overall, our results underscore the importance of protecting and enhancing prairie wetlands and other non-crop habitats in agricultural landscapes, given their disproportionate use and capacity to support breeding swallow and insect populations.

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The PI3K/Akt Pathway: Emerging Roles in Skin Homeostasis and a Group of Non-Malignant Skin Disorders

Cells ◽

10.3390/cells10051219 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1219

Author(s):

Yan Teng ◽

Yibin Fan ◽

Jingwen Ma ◽

Wei Lu ◽

Na Liu ◽

...

Keyword(s):

Cell Carcinoma ◽

Akt Pathway ◽

Skin Disorders ◽

Phosphatidylinositol 3 Kinase ◽

Skin Development ◽

Wide Range ◽

Malignant Skin ◽

Solid Foundation ◽

And Migration ◽

Poor Outcomes

The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway regulates cell proliferation, differentiation, and migration, along with angiogenesis and metabolism. Additionally, it could mediate skin development and homeostasis. There is much evidence to suggest that dysregulation of PI3K/Akt pathway is frequently associated with several human cutaneous malignancies like malignant melanoma (MM), basal cell carcinoma (BCC), and cutaneous squamous cell carcinoma (SCC), as well as their poor outcomes. Nevertheless, emerging roles of PI3K/Akt pathway cascade in a group of common non-malignant skin disorders including acne and psoriasis, among others, have been recognized. The enhanced understanding of dysfunction of PI3K/Akt pathway in patients with these non-malignant disorders has offered a solid foundation for the progress of updated therapeutic targets. This article reviews the latest advances in the roles of PI3K/Akt pathway and their targets in the skin homeostasis and progression of a wide range of non-malignant skin disorders and describes the current progress in preclinical and clinical researches on the involvement of PI3K/Akt pathway targeted therapies.

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More than just a pressure relief valve: physiological roles of volume-regulated LRRC8 anion channels

Biological Chemistry ◽

10.1515/hsz-2019-0189 ◽

2019 ◽

Vol 400 (11) ◽

pp. 1481-1496 ◽

Cited By ~ 10

Author(s):

Lingye Chen ◽

Benjamin König ◽

Tianbao Liu ◽

Sumaira Pervaiz ◽

Yasmin S. Razzaque ◽

...

Keyword(s):

Volume Regulation ◽

Regulatory Volume Decrease ◽

Anion Channel ◽

Therapy Resistance ◽

Cell Swelling ◽

Organic Osmolytes ◽

Anion Channels ◽

Relief Valve ◽

Wide Range ◽

And Migration

Abstract The volume-regulated anion channel (VRAC) is a key player in the volume regulation of vertebrate cells. This ubiquitously expressed channel opens upon osmotic cell swelling and potentially other cues and releases chloride and organic osmolytes, which contributes to regulatory volume decrease (RVD). A plethora of studies have proposed a wide range of physiological roles for VRAC beyond volume regulation including cell proliferation, differentiation and migration, apoptosis, intercellular communication by direct release of signaling molecules and by supporting the exocytosis of insulin. VRAC was additionally implicated in pathological states such as cancer therapy resistance and excitotoxicity under ischemic conditions. Following extensive investigations, 5 years ago leucine-rich repeat-containing family 8 (LRRC8) heteromers containing LRRC8A were identified as the pore-forming components of VRAC. Since then, molecular biological approaches have allowed further insight into the biophysical properties and structure of VRAC. Heterologous expression, siRNA-mediated downregulation and genome editing in cells, as well as the use of animal models have enabled the assessment of the proposed physiological roles, together with the identification of new functions including spermatogenesis and the uptake of antibiotics and platinum-based cancer drugs. This review discusses the recent molecular biological insights into the physiology of VRAC in relation to its previously proposed roles.

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