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Do KT, Paolizzi SG, Hallquist MN. How adolescents learn to build social bonds: A developmental computational account of social explore-exploit decision-making. Dev Cogn Neurosci 2024; 69:101415. [PMID: 39089173 PMCID: PMC11342119 DOI: 10.1016/j.dcn.2024.101415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 07/01/2024] [Accepted: 07/12/2024] [Indexed: 08/03/2024] Open
Abstract
Building social bonds is a critical task of adolescence that affords opportunities for learning, identity formation, and social support. Failing to develop close relationships in adolescence hinders adult interpersonal functioning and contributes to problems such as loneliness and depression. During adolescence, increased reward sensitivity and greater social flexibility both contribute to healthy social development, yet we lack a clear theory of how these processes interact to support social functioning. Here, we propose synthesizing these two literatures using a computational reinforcement learning framework that recasts how adolescents pursue and learn from social rewards as a social explore-exploit problem. To become socially skilled, adolescents must balance both their efforts to form individual bonds within specific groups and manage memberships across multiple groups to maximize access to social resources. We draw on insights from sociological studies on social capital in collective networks and neurocognitive research on foraging and cooperation to describe the social explore-exploit dilemma faced by adolescents navigating a modern world with increasing access to diverse resources and group memberships. Our account provides important new directions for examining the dynamics of adolescent behavior in social groups and understanding how social value computations can support positive relationships into adulthood.
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Affiliation(s)
- Kathy T Do
- Department of Psychology and Neuroscience, University of North Carolina Chapel Hill, 235 E. Cameron Avenue, Chapel Hill, NC 27599-3270, United States.
| | - Sophie G Paolizzi
- Department of Psychology and Neuroscience, University of North Carolina Chapel Hill, 235 E. Cameron Avenue, Chapel Hill, NC 27599-3270, United States
| | - Michael N Hallquist
- Department of Psychology and Neuroscience, University of North Carolina Chapel Hill, 235 E. Cameron Avenue, Chapel Hill, NC 27599-3270, United States
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Young ME, Howatt BC. Resource limitations: A taxonomy. Behav Processes 2023; 206:104823. [PMID: 36682436 DOI: 10.1016/j.beproc.2023.104823] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/02/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023]
Abstract
Decision making within the context of resource limitations requires balancing the short-term benefits of obtaining a resource and the long-term consequences of depleting those resources. The present manuscript focuses on four types of tasks that share this tradeoff to develop a taxonomy that will encourage a deeper understanding of the psychological processes at play. The four types considered are foraging, common pool traps, deterioration traps, and a novel designation referred to as resource cliffs. All four will be shown to include two opposite processes - depletion of the resource and its replenishment over time. By considering the unique and shared features of these tasks, a taxonomy of features emerges that can be combined to not only create novel tasks but also to shift the research focus to task features rather than specific tasks. The paper closes with a consideration of current theoretical frameworks previously applied to one or more of these resource-limitation tasks as well as the promise of reinforcement learning as a unifying theory.
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Lin D, Zang N, Zhu K, Li G, Chen X. Energy acquisition strategy for reproduction in a semelparous squid. Front Zool 2022; 19:28. [DOI: 10.1186/s12983-022-00473-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 11/02/2022] [Indexed: 11/17/2022] Open
Abstract
Abstract
Background
Energy demand for reproduction leads to a wide diversity of foraging and life-history strategy among wild animals, linking to a common objective to maximize reproductive success. Semelparous squid species in particular can use up to 50% of the total energy intake for reproduction. However, the energy acquisition strategy for reproduction is still a controversial issue regarding whether the squid shift in diet ontogenetically. Here we used Argentinean shortfin squid (Illex argentinus) as a case study to investigate the strategy of energy acquisition for reproduction, by analyzing energy density of the squid’s reproductive tissues including ovary, nidamental glands and oviduct eggs, and stable isotopes and fatty acids of the squid’s ovary.
Results
The reproductive energy (the sum of the energy accumulated in ovary, nidamental glands and oviduct eggs) increased significantly with maturation. The ovary nitrogen stable isotopes (δ15N) showed a significant increase with maturation, but the increase by maturity stage was not equal to the typical enrichment of about 3‰ per trophic level. Isotopic niche width showed an increasing trend with maturation, and isotopic niche space exhibited greater overlap at advanced maturity stages. The relative amounts of 16:0, 20:5n3 and 20:4n6 in the ovary, tracing for carnivores and top predators, increased after the onset of maturation. The overall fatty acid profiles of the ovary showed significant differences among maturity stages, but obvious overlaps were found for mature squids. Mixed-effects model results revealed that reproductive energy was positively correlated with δ15N values. The reproductive energy was also positively related to the relative amounts of 18:0 and 20:4n6, respectively tracing for herbivores and top predators.
Conclusions
Our results validate that the squid shifts to feed on higher trophic prey for reproduction as energy demand increases once maturation commences. However, the squid does not shift feeding habits at a trophic level but instead broadens prey spectrum, coupled with increasing intake of higher trophic prey items, to meet the energy demand for reproduction. Such energy acquisition strategy may be selected by the squid to maximize reproductive success by balancing energy intake and expenditure from foraging, warranting future studies that aim to clarify such strategy for reproduction among semelparous species.
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Ma Y, Bao H, Bencini R, Raubenheimer D, Dou H, Liu H, Wang S, Jiang G. Macro-Nutritional Adaptive Strategies of Moose ( Alces alces) Related to Population Density. Animals (Basel) 2019; 10:ani10010073. [PMID: 31906149 PMCID: PMC7022907 DOI: 10.3390/ani10010073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/13/2019] [Accepted: 12/21/2019] [Indexed: 11/16/2022] Open
Abstract
The distribution area of moose in China has been shrinking back toward the north and northeast because of climate change and human disturbance, and the population number has been declining. Between 2011 and 2015, we studied moose at six sites in the northeast of China during the snowy seasons. We collected fecal samples and plant samples that were used to estimate population densities for moose, as well as their macro-nutrient selection. Out of a total of 257 fecal samples collected at six sites, we identified a total of 120 individual moose (57 females and 63 males). The population density (moose/km2 ± SE) was highest at Hanma with 0.305 ± 0.064 moose/km2 and lowest at Meitian with only 0.028 ± 0.013 moose/km2. Forage availability was different among sites, with the lowest availability at Mohe (58.17 number/20 m2) and highest was Zhanhe (250.44 number/20 m2). Moose at Zhanhe, Hanma, and Nanwenghe had a balanced diet with higher N:C (1:7), while at Meitian, Shuanghe and Mohe the N:C was 1:8. Our results indicate that the southern areas had low forage quality and quantity and this may be the reason for the distribution of the population of moose shrinking northward.
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Affiliation(s)
- Yingjie Ma
- Feline Research Center of Chinese State Forestry Administration, College of Wildlife and Protected Areas, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China; (Y.M.); (H.B.); (S.W.)
- Key Lab of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1-5 Beichenxi Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Heng Bao
- Feline Research Center of Chinese State Forestry Administration, College of Wildlife and Protected Areas, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China; (Y.M.); (H.B.); (S.W.)
| | - Roberta Bencini
- School of Agriculture and Environment, The University of Western Australia, 35 Stirling Highway, Perth 6009, Australia;
| | - David Raubenheimer
- Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia;
| | - Hongliang Dou
- College of Animal Science and Technology, Jinlin Agricultural University, Changchun 130118, China;
| | - Hui Liu
- Institute of Tropical Agriculture and Forestry, Hainan University, No. 58, Renmin Avenue, Haikou 570228, China;
| | - Sirui Wang
- Feline Research Center of Chinese State Forestry Administration, College of Wildlife and Protected Areas, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China; (Y.M.); (H.B.); (S.W.)
| | - Guangshun Jiang
- Feline Research Center of Chinese State Forestry Administration, College of Wildlife and Protected Areas, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China; (Y.M.); (H.B.); (S.W.)
- Correspondence:
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Bose T, Reina A, Marshall JAR. Inhibition and Excitation Shape Activity Selection: Effect of Oscillations in a Decision-Making Circuit. Neural Comput 2019; 31:870-896. [PMID: 30883280 DOI: 10.1162/neco_a_01185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Decision making is a complex task, and its underlying mechanisms that regulate behavior, such as the implementation of the coupling between physiological states and neural networks, are hard to decipher. To gain more insight into neural computations underlying ongoing binary decision-making tasks, we consider a neural circuit that guides the feeding behavior of a hypothetical animal making dietary choices. We adopt an inhibition motif from neural network theory and propose a dynamical system characterized by nonlinear feedback, which links mechanism (the implementation of the neural circuit and its coupling to the animal's nutritional state) and function (improving behavioral performance). A central inhibitory unit influences evidence-integrating excitatory units, which in our terms correspond to motivations competing for selection. We determine the parameter regime where the animal exhibits improved decision-making behavior and explain different behavioral outcomes by making the link between accessible states of the nonlinear neural circuit model and decision-making performance. We find that for given deficits in nutritional items, the variation of inhibition strength and ratio of excitation and inhibition strengths in the decision circuit allows the animal to enter an oscillatory phase that describes its internal motivational state. Our findings indicate that this oscillatory phase may improve the overall performance of the animal in an ongoing foraging task and underpin the importance of an integrated functional and mechanistic study of animal activity selection.
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Affiliation(s)
- Thomas Bose
- Department of Computer Science, University of Sheffield, Sheffield, U.K.
| | | | - James A R Marshall
- Department of Computer Science, University of Sheffield, Sheffield, U.K.
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Ito H. Risk sensitivity of a forager with limited energy reserves in stochastic environments. Ecol Res 2019. [DOI: 10.1111/1440-1703.1058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hiromu Ito
- Department of General Systems Studies The University of Tokyo Tokyo Japan
- Department of International Health Institute of Tropical Medicine, Nagasaki University Nagasaki Japan
- Department of Environmental Sciences, Zoology University of Basel Basel Switzerland
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Moore JF, Mulindahabi F, Gatorano G, Niyigaba P, Ndikubwimana I, Cipolletta C, Masozera MK. Shifting through the forest: home range, movement patterns, and diet of the eastern chimpanzee (Pan troglodytes schweinfurthii) in Nyungwe National Park, Rwanda. Am J Primatol 2018; 80:e22897. [PMID: 29992652 DOI: 10.1002/ajp.22897] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 06/28/2018] [Accepted: 07/01/2018] [Indexed: 11/08/2022]
Abstract
Populations of the endangered eastern chimpanzee (Pan troglodytes schweinfurthii) are declining throughout their range. Although Nyungwe National Park (NNP) harbors the largest remaining eastern chimpanzee population in Rwanda, we know little about their space use and dietary patterns. We studied home range, movement, and diet of two communities of chimpanzees in NNP using daily tracking data (6:00 am to 6:00 pm) collected from 2000 to 2015. One community, Mayebe, resided in the forest center, and the other community, Cyamudongo, inhabited a forest fragment located about 10 km from the main forest. Home range estimated with the 95% kernel density estimation (KDE) method was 21 km2 for the Mayebe community and 4 km2 for the Cyamudongo community. Chimpanzee home range sizes were smaller during the dry versus wet season and varied monthly throughout the year. The Mayebe community had an average hourly step length of 75 ± SE 5 m with a daily movement range of 987 ± SE 71 m, while the Cyamudongo community had a shorter hourly step length of 52 ± SE 3 m with a daily movement range of 651 ± SE 71 m. Both chimpanzee communities fed primarily on Ficus spp. Other important dietary items included fruits of Symphonia globulifera, Syzygium guineense, and Chrysophyllum gorungosanum for the Mayebe community and Trilepisium madagascariense for the Cyamudongo community. Food choice varied monthly and seasonally for each chimpanzee community. Our study provides the first estimates of home range size and movement parameters for chimpanzees in Rwanda and documents their food habits and seasonal variations therein. We also identified the 50% core home range for each chimpanzee community and suggest this area as the focus of management actions. These results could help park management reduce threats to chimpanzees and other sympatric species by improving the efficiency of ranger patrols.
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Affiliation(s)
- Jennifer F Moore
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida
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Raubenheimer D, Simpson SJ. Nutritional ecology and foraging theory. CURRENT OPINION IN INSECT SCIENCE 2018; 27:38-45. [PMID: 30025633 DOI: 10.1016/j.cois.2018.02.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 06/08/2023]
Abstract
Historically, two fields of research have developed theory around foraging and feeding that have influenced biology more broadly, optimal foraging theory and nutritional ecology. While these fields have developed largely in parallel, they are complementary with each offering particular strengths. Here we show how an approach developed in the study of insect nutrition, called nutritional geometry, has provided a framework for incorporating key aspects of optimal foraging theory into nutritional ecology. This synthesis provides a basis for integrating with foraging and feeding the many facets of biology that are linked to nutrition and is now influencing diverse areas of the biological and biomedical sciences.
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Affiliation(s)
- David Raubenheimer
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia; School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
| | - Stephen J Simpson
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia; School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
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10
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Lenhart PA. Using plant nutrient landscapes to assess Anthropocene effects on insect herbivores. CURRENT OPINION IN INSECT SCIENCE 2017; 23:51-58. [PMID: 29129282 DOI: 10.1016/j.cois.2017.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 06/30/2017] [Accepted: 07/19/2017] [Indexed: 06/07/2023]
Abstract
Global climate change will dramatically affect insect herbivores through changes in plant quality. Linking how multiple climate factors affect plant macronutrient content may be the most accurate way to understand the response of insect herbivores. Studies should embrace the complexity of interacting climate factors in natural systems and characterize shifts in multidimensional plant nutrient landscapes. This nutrient landscape simplifies interpretation of climate effects, although selection of appropriate currencies, scale, and interactions with allelochemicals present challenges. By assessing climate change through the filter of nutrient landscapes we could gain an understanding of how complex interacting climate change drivers affect the 'buffet' available to different insect herbivores.
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Affiliation(s)
- Paul A Lenhart
- S-225 Agricultural Science Center N, Department of Entomology, University of Kentucky, Lexington, KY, United States.
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Hansen MJ, Schaerf TM, Simpson SJ, Ward AJW. Group foraging decisions in nutritionally differentiated environments. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12646] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew J. Hansen
- Animal Behaviour Lab School of Biological Sciences The University of Sydney Sydney New South Wales 2006 Australia
| | - Timothy M. Schaerf
- Animal Behaviour Lab School of Biological Sciences The University of Sydney Sydney New South Wales 2006 Australia
- School of Science and Technology University of New England Armidale New South Wales 2351 Australia
| | - Stephen J. Simpson
- Charles Perkins Centre The University of Sydney Sydney New South Wales 2006 Australia
| | - Ashley J. W. Ward
- Animal Behaviour Lab School of Biological Sciences The University of Sydney Sydney New South Wales 2006 Australia
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Affiliation(s)
- David Raubenheimer
- Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia;
| | - Stephen J. Simpson
- Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia;
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Vergara PM, Soto GE, Moreira-Arce D, Rodewald AD, Meneses LO, Pérez-Hernández CG. Foraging Behaviour in Magellanic Woodpeckers Is Consistent with a Multi-Scale Assessment of Tree Quality. PLoS One 2016; 11:e0159096. [PMID: 27416115 PMCID: PMC4945014 DOI: 10.1371/journal.pone.0159096] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/27/2016] [Indexed: 11/19/2022] Open
Abstract
Theoretical models predict that animals should make foraging decisions after assessing the quality of available habitat, but most models fail to consider the spatio-temporal scales at which animals perceive habitat availability. We tested three foraging strategies that explain how Magellanic woodpeckers (Campephilus magellanicus) assess the relative quality of trees: 1) Woodpeckers with local knowledge select trees based on the available trees in the immediate vicinity. 2) Woodpeckers lacking local knowledge select trees based on their availability at previously visited locations. 3) Woodpeckers using information from long-term memory select trees based on knowledge about trees available within the entire landscape. We observed foraging woodpeckers and used a Brownian Bridge Movement Model to identify trees available to woodpeckers along foraging routes. Woodpeckers selected trees with a later decay stage than available trees. Selection models indicated that preferences of Magellanic woodpeckers were based on clusters of trees near the most recently visited trees, thus suggesting that woodpeckers use visual cues from neighboring trees. In a second analysis, Cox’s proportional hazards models showed that woodpeckers used information consolidated across broader spatial scales to adjust tree residence times. Specifically, woodpeckers spent more time at trees with larger diameters and in a more advanced stage of decay than trees available along their routes. These results suggest that Magellanic woodpeckers make foraging decisions based on the relative quality of trees that they perceive and memorize information at different spatio-temporal scales.
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Affiliation(s)
- Pablo M. Vergara
- Universidad de Santiago de Chile, Laboratorio de Ecología y Conservación, Departamento de Gestión Agraria, Libertador Bernardo O’Higgins 3363, Santiago, Chile
- * E-mail:
| | - Gerardo E. Soto
- Universidad de Santiago de Chile, Laboratorio de Ecología y Conservación, Departamento de Gestión Agraria, Libertador Bernardo O’Higgins 3363, Santiago, Chile
- Cornell University, Cornell Lab of Ornithology and Department of Natural Resources, Ithaca, NY, United States of America
| | - Darío Moreira-Arce
- Universidad de Chile, Laboratorio de Conservación, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Santiago, Chile
| | - Amanda D. Rodewald
- Cornell University, Cornell Lab of Ornithology and Department of Natural Resources, Ithaca, NY, United States of America
| | - Luis O. Meneses
- Universidad de Santiago de Chile, Laboratorio de Ecología y Conservación, Departamento de Gestión Agraria, Libertador Bernardo O’Higgins 3363, Santiago, Chile
| | - Christian G. Pérez-Hernández
- Universidad de Santiago de Chile, Laboratorio de Ecología y Conservación, Departamento de Gestión Agraria, Libertador Bernardo O’Higgins 3363, Santiago, Chile
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Catanese F, Distel RA, Fernández P, Villalba JJ. How the foraging decisions of a small ruminant are influenced by past feeding experiences with low-quality food. Behav Processes 2016; 126:12-20. [PMID: 26927320 DOI: 10.1016/j.beproc.2016.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 02/03/2016] [Accepted: 02/23/2016] [Indexed: 11/15/2022]
Abstract
Feeding experiences with low-quality foods can be improved when these foods are ingested in close temporal association with foods of higher nutritional quality. However, preference for low-quality foods in nature seems to be rather insensitive to past positive experiences and more related to their intrinsic nutritional value. An explanation for this observation is still lacking, mainly because little is known about how herbivores use information about low-quality foods during foraging. Our objective was to provide original information about this issue using a small ruminant (sheep; Ovis aries) as animal model. We manipulated the sheep's experience with a low-quality food (wheat straw) using a conditioning procedure ("oral-delay conditioning procedure"), and then we evaluated the use of this information in a simulated foraging scenario provided with wheat straw and a variable amount of a high-quality food in spatially separated feeding stations. Inclusion of wheat straw into the diet was strongly dependent on the availability of the high-quality food. We observed a threshold level in the availability of the high-quality food, which defined a zone of drastic change in the likelihood of inclusion of the wheat straw into the diet (i.e., acceptance or rejection of wheat straw). This threshold level did not change for sheep with (CS+) or without (CS-) a previous positive experience with wheat straw. However, once foraging conditions stimulated all sheep to start including the wheat straw into the diet (i.e., below the threshold level), the intake of this food was greater by CS+ sheep. This increased intake was not explained by a higher motivation to eat the wheat straw but to a greater amount of time spent foraging this food and less time spent searching for the preferred higher-quality alternative. We discuss these results based on optimal foraging models and learning models of diet selection.
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Affiliation(s)
- F Catanese
- CONICET, CERZOS, 8000 Bahía Blanca, Argentina.
| | - R A Distel
- CONICET, CERZOS, 8000 Bahía Blanca, Argentina; Departamento de Agronomía, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina
| | - P Fernández
- CONICET, CERZOS, 8000 Bahía Blanca, Argentina; Departamento de Agronomía, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina
| | - J J Villalba
- Department of Wildland Resources, Utah State University, Logan, UT 84322-5230, USA
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Francis JS, Muth F, Papaj DR, Leonard AS. Nutritional complexity and the structure of bee foraging bouts. Behav Ecol 2016. [DOI: 10.1093/beheco/arv229] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Sperfeld E, Raubenheimer D, Wacker A. Bridging factorial and gradient concepts of resource co-limitation: towards a general framework applied to consumers. Ecol Lett 2015; 19:201-215. [DOI: 10.1111/ele.12554] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/14/2015] [Accepted: 11/13/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Erik Sperfeld
- School of Biological Sciences and The Charles Perkins Centre; The University of Sydney; Sydney NSW 2006 Australia
| | - David Raubenheimer
- School of Biological Sciences and The Charles Perkins Centre; The University of Sydney; Sydney NSW 2006 Australia
- Faculty of Veterinary Science; The University of Sydney; Sydney NSW 2006 Australia
| | - Alexander Wacker
- Ecology and Ecosystem Modelling; Institute of Biochemistry and Biology; University of Potsdam; Am Neuen Palais 10 Potsdam 14469 Germany
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18
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Waters EM, Watson MA. Live substrate positively affects root growth and stolon direction in the woodland strawberry, Fragaria vesca. FRONTIERS IN PLANT SCIENCE 2015; 6:814. [PMID: 26483826 PMCID: PMC4588215 DOI: 10.3389/fpls.2015.00814] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 09/17/2015] [Indexed: 05/23/2023]
Abstract
Studies of clonal plant foraging generally focus on growth responses to patch quality once rooted. Here we explore the possibility of true plant foraging; the ability to detect and respond to patch resource status prior to rooting. Two greenhouse experiments were conducted to investigate the morphological changes that occur when individual daughter ramets of Fragaria vesca (woodland strawberry) were exposed to air above live (non-sterilized) or dead (sterilized) substrates. Contact between daughter ramets and substrate was prohibited. Daughter ramet root biomass was significantly larger over live versus dead substrate. Root:shoot ratio also increased over live substrate, a morphological response we interpret as indicative of active nutrient foraging. Daughter ramet root biomass was positively correlated with mother ramet size over live but not dead substrate. Given the choice between a live versus a dead substrate, primary stolons extended preferentially toward live substrates. We conclude that exposure to live substrate drives positive nutrient foraging responses in F. vesca. We propose that volatiles emitted from the substrates might be effecting the morphological changes that occur during true nutrient foraging.
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Affiliation(s)
- Erica M. Waters
- Department of Biology, Indiana University, Bloomington, INUSA
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Senior AM, Nakagawa S, Lihoreau M, Simpson SJ, Raubenheimer D. An Overlooked Consequence of Dietary Mixing: A Varied Diet Reduces Interindividual Variance in Fitness. Am Nat 2015; 186:649-59. [PMID: 26655777 DOI: 10.1086/683182] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The determinants of diet breadth are of interest to nutritionists, ecologists, and evolutionary biologists. A recent synthesis addressing this issue found conflicting evidence for the relationship between diet breadth and mean individual fitness. Specifically, it found that while, on average, a mixed diet does increase mean fitness, in some instances, a single food provides equal (or higher) fitness than a mixed diet. Critical to ecological and evolutionary considerations of diet, however, is not only mean fitness but also variance in fitness. We combine contemporary meta-analytic methods with models of nutritional geometry to evaluate how diet affects between-individual variance in fitness within generalist consumers from a range of trophic levels. As predicted by nutritional geometry, we found that between-individual variance in fitness-related traits is higher on single-food than mixed diets. The effect was strong for longevity traits (57% higher) and reproductive traits (37%) and present but weaker for size-related traits (10%). Further, the effect became stronger as the number of available foods increased. The availability of multiple foods likely allows individuals with differing nutritional optima to customize intake, each maximizing their own fitness. Importantly, these findings may suggest that selection on traits correlated with nutritional requirements is weak in heterogeneous nutritional environments.
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Affiliation(s)
- Alistair M Senior
- Charles Perkins Centre and School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia
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Potts JR, Bastille-Rousseau G, Murray DL, Schaefer JA, Lewis MA. Predicting local and non-local effects of resources on animal space use using a mechanistic step selection model. Methods Ecol Evol 2014; 5:253-262. [PMID: 25834721 PMCID: PMC4375923 DOI: 10.1111/2041-210x.12150] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 12/02/2013] [Indexed: 11/29/2022]
Abstract
Predicting space use patterns of animals from their interactions with the environment is fundamental for understanding the effect of habitat changes on ecosystem functioning. Recent attempts to address this problem have sought to unify resource selection analysis, where animal space use is derived from available habitat quality, and mechanistic movement models, where detailed movement processes of an animal are used to predict its emergent utilization distribution. Such models bias the animal's movement towards patches that are easily available and resource-rich, and the result is a predicted probability density at a given position being a function of the habitat quality at that position. However, in reality, the probability that an animal will use a patch of the terrain tends to be a function of the resource quality in both that patch and the surrounding habitat.We propose a mechanistic model where this non-local effect of resources naturally emerges from the local movement processes, by taking into account the relative utility of both the habitat where the animal currently resides and that of where it is moving. We give statistical techniques to parametrize the model from location data and demonstrate application of these techniques to GPS location data of caribou (Rangifer tarandus) in Newfoundland.Steady-state animal probability distributions arising from the model have complex patterns that cannot be expressed simply as a function of the local quality of the habitat. In particular, large areas of good habitat are used more intensively than smaller patches of equal quality habitat, whereas isolated patches are used less frequently. Both of these are real aspects of animal space use missing from previous mechanistic resource selection models.Whilst we focus on habitats in this study, our modelling framework can be readily used with any environmental covariates and therefore represents a unification of mechanistic modelling and step selection approaches to understanding animal space use.
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Affiliation(s)
- Jonathan R Potts
- Centre for Mathematical Biology, Department of Mathematical and Statistical Sciences, University of Alberta Edmonton, AB, T6G 1G1, Canada
| | | | - Dennis L Murray
- Environmental and Life Sciences Graduate Program, Trent University Peterborough, ON K9J 7B8, Canada
| | - James A Schaefer
- Environmental and Life Sciences Graduate Program, Trent University Peterborough, ON K9J 7B8, Canada
| | - Mark A Lewis
- Centre for Mathematical Biology, Department of Mathematical and Statistical Sciences, University of Alberta Edmonton, AB, T6G 1G1, Canada ; Department of Biological Sciences, University of Alberta Edmonton, AB T6G 2E9, Canada
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Wehi PM, Raubenheimer D, Morgan-Richards M. Tolerance for nutrient imbalance in an intermittently feeding herbivorous cricket, the Wellington tree weta. PLoS One 2013; 8:e84641. [PMID: 24358369 PMCID: PMC3866171 DOI: 10.1371/journal.pone.0084641] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 11/26/2013] [Indexed: 11/18/2022] Open
Abstract
Organisms that regulate nutrient intake have an advantage over those that do not, given that the nutrient composition of any one resource rarely matches optimal nutrient requirements. We used nutritional geometry to model protein and carbohydrate intake and identify an intake target for a sexually dimorphic species, the Wellington tree weta (Hemideina crassidens). Despite pronounced sexual dimorphism in this large generalist herbivorous insect, intake targets did not differ by sex. In a series of laboratory experiments, we then investigated whether tree weta demonstrate compensatory responses for enforced periods of imbalanced nutrient intake. Weta pre-fed high or low carbohydrate: protein diets showed large variation in compensatory nutrient intake over short (<48 h) time periods when provided with a choice. Individuals did not strongly defend nutrient targets, although there was some evidence for weak regulation. Many weta tended to select high and low protein foods in a ratio similar to their previously identified nutrient optimum. These results suggest that weta have a wide tolerance to nutritional imbalance, and that the time scale of weta nutrient balancing could lie outside of the short time span tested here. A wide tolerance to imbalance is consistent with the intermittent feeding displayed in the wild by weta and may be important in understanding weta foraging patterns in New Zealand forests.
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Affiliation(s)
- Priscilla M. Wehi
- Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - David Raubenheimer
- Institute of Natural Sciences, Massey University, North Shore, Auckland, New Zealand
- The Charles Perkins Centre and Faculty of Veterinary Science and School of Biological Sciences, The University of Sydney, New South Wales, Australia
| | - Mary Morgan-Richards
- Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
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Hirsch BT, Tujague MP, Di Blanco YE, Di Bitetti MS, Janson CH. Comparing capuchins and coatis: causes and consequences of differing movement ecology in two sympatric mammals. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.05.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Yoshimura J, Ito H, Miller III DG, Tainaka KI. Dynamic decision-making in uncertain environments I. The principle of dynamic utility. J ETHOL 2013. [DOI: 10.1007/s10164-013-0362-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Lee KP, Kwon ST, Roh C. Caterpillars use developmental plasticity and diet choice to overcome the early life experience of nutritional imbalance. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.06.033] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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