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Sumpter, David J. T.
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Publications (10 of 54) Show all publications
Szorkovszky, A., Kotrschal, A., Herbert-Read, J. E., Buechel, S. D., Romensky, M., Rosén, E., . . . Sumpter, D. J. T. (2018). Assortative interactions revealed by sorting of animal groups. Animal Behaviour, 142, 165-179
Open this publication in new window or tab >>Assortative interactions revealed by sorting of animal groups
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2018 (English)In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 142, p. 165-179Article in journal (Refereed) Published
Abstract [en]

Animals living in groups can show substantial variation in social traits and this affects their social organization. However, as the specific mechanisms driving this organization are difficult to identify in already organized groups typically found in the wild, the contribution of interindividual variation to group level behaviour remains enigmatic. Here, we present results of an experiment to create and compare groups that vary in social organization, and study how individual behaviour varies between these groups. We iteratively sorted individuals between groups of guppies, Poecilia reticulata, by ranking the groups according to their directional alignment and then mixing similar groups. Over the rounds of sorting the consistency of the group rankings increased, producing groups that varied significantly in key social behaviours such as collective activity and group cohesion. The repeatability of the underlying individual behaviour was then estimated by comparing the experimental data to simulations. At the level of basic locomotion, individuals in more coordinated groups displayed stronger interactions with the centre of the group, and weaker interactions with their nearest neighbours. We propose that this provides the basis for a passive phenotypic assortment mechanism that may explain the structures of social networks in the wild.

Place, publisher, year, edition, pages
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2018
Keywords
collective behaviour, repeatability, sociability
National Category
Behavioral Sciences Biology
Identifiers
urn:nbn:se:uu:diva-362701 (URN)10.1016/j.anbehav.2018.06.005 (DOI)000441515500019 ()
Funder
Knut and Alice Wallenberg Foundation, 102 2013.0072
Available from: 2018-10-10 Created: 2018-10-10 Last updated: 2018-10-10Bibliographically approved
Spaiser, V., Hedström, P., Ranganathan, S., Jansson, K., Nordvik, M. K. & Sumpter, D. J. T. (2018). Identifying Complex Dynamics in Social Systems: A New Methodological Approach Applied to Study School Segregation. Sociological Methods & Research, 47(2), 103-135
Open this publication in new window or tab >>Identifying Complex Dynamics in Social Systems: A New Methodological Approach Applied to Study School Segregation
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2018 (English)In: Sociological Methods & Research, ISSN 0049-1241, E-ISSN 1552-8294, Vol. 47, no 2, p. 103-135Article in journal (Refereed) Published
Abstract [en]

It is widely recognized that segregation processes are often the result of complex nonlinear dynamics. Empirical analyses of complex dynamics are however rare, because there is a lack of appropriate empirical modeling techniques that are capable of capturing complex patterns and nonlinearities. At the same time, we know that many social phenomena display nonlinearities. In this article, we introduce a new modeling tool in order to partly fill this void in the literature. Using data of all secondary schools in Stockholm county during the years 1990 to 2002, we demonstrate how the methodology can be applied to identify complex dynamic patterns like tipping points and multiple phase transitions with respect to segregation. We establish critical thresholds in schools' ethnic compositions, in general, and in relation to various factors such as school quality and parents' income, at which the schools are likely to tip and become increasingly segregated.

Place, publisher, year, edition, pages
SAGE PUBLICATIONS INC, 2018
Keywords
dynamical systems, tipping points, nonlinearities, social systems, segregation, school segregation
National Category
Human Geography Mathematical Analysis
Identifiers
urn:nbn:se:uu:diva-352981 (URN)10.1177/0049124116626174 (DOI)000429944800001 ()
Available from: 2018-07-18 Created: 2018-07-18 Last updated: 2018-07-18Bibliographically approved
Liu, Y. & Sumpter, D. J. T. (2018). Is the golden ratio a universal constant for self-replication?. PLoS ONE, 13(7), Article ID e0200601.
Open this publication in new window or tab >>Is the golden ratio a universal constant for self-replication?
2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 7, article id e0200601Article in journal (Other academic) Published
Abstract [en]

The golden ratio, ϕ = 1.61803..., has often been found in connection with biological phenomena, ranging from spirals in sunflowers to gene frequency. One example where the golden ratio often arises is in self-replication, having its mathematical origins in Fibonacci's sequence for "rabbit reproduction". Recently, it has been claimed that ϕ determines the ratio between the number of different nucleobases in human genome. Such empirical examples continue to give credence to the idea that the golden ratio is a universal constant, not only in mathematics but also for biology. In this paper, we employ a general framework for chemically realistic self-replicating reaction systems and investigate whether the ratio of chemical species population follows "universal constants". We find that many self-replicating systems can be characterised by an algebraic number, which, in some cases, is the golden ratio. However, many other algebraic numbers arise from these systems, and some of them—such as and 1.22074... which is also known as the 3rd lower golden ratio—arise more frequently in self-replicating systems than the golden ratio. The "universal constants" in these systems arise as roots of a limited number of distinct characteristic equations. In addition, these "universal constants" are transient behaviours of self-replicating systems, corresponding to the scenario that the resource inside the system is infinite, which is not always the case in practice. Therefore, we argue that the golden ratio should not be considered as a special universal constant in self-replicating systems, and that the ratios between different chemical species only go to certain numbers under some idealised scenarios.

Keywords
Golden ratio, Fibonacci sequence, Self-replication, Fibonacci rabbit, Universal constant
National Category
Other Mathematics
Identifiers
urn:nbn:se:uu:diva-339888 (URN)10.1371/journal.pone.0200601 (DOI)000438829800032 ()30011316 (PubMedID)
Available from: 2018-01-23 Created: 2018-01-23 Last updated: 2018-09-27Bibliographically approved
Sumpter, D. J. T., Szorkovszky, A., Kotrschal, A., Kolm, N. & Herbert-Read, J. E. (2018). Using activity and sociability to characterize collective motion. Philosophical Transactions of the Royal Society of London. Biological Sciences, 373(1746), Article ID 20170015.
Open this publication in new window or tab >>Using activity and sociability to characterize collective motion
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2018 (English)In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 373, no 1746, article id 20170015Article, review/survey (Refereed) Published
Abstract [en]

A wide range of measurements can be made on the collective motion of groups, and the movement of individuals within them. These include, but are not limited to: group size, polarization, speed, turning speed, speed or directional correlations, and distances to near neighbours. From an ecological and evolutionary perspective, we would like to know which of these measurements capture biologically meaningful aspects of an animal's behaviour and contribute to its survival chances. Previous simulation studies have emphasized two main factors shaping individuals' behaviour in groups; attraction and alignment. Alignment responses appear to be important in transferring information between group members and providing synergistic benefits to group members. Likewise, attraction to conspecifics is thought to provide benefits through, for example, selfish herding. Here, we use a factor analysis on a wide range of simple measurements to identify two main axes of collective motion in guppies (Poecilia reticulata): (i) sociability, which corresponds to attraction (and to a lesser degree alignment) to neighbours, and (ii) activity, which combines alignment with directed movement. We show that for guppies, predation in a natural environment produces higher degrees of sociability and (in females) lower degrees of activity, while female guppies sorted for higher degrees of collective alignment have higher degrees of both sociability and activity. We suggest that the activity and sociability axes provide a useful framework for measuring the behaviour of animals in groups, allowing the comparison of individual and collective behaviours within and between species.

Place, publisher, year, edition, pages
ROYAL SOC, 2018
Keywords
collective behaviour, factor analysis, fish, Poecilia reticulata, personality
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:uu:diva-356886 (URN)10.1098/rstb.2017.0015 (DOI)000428370800012 ()29581400 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, 102 2013.0072
Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-08-09Bibliographically approved
Blomqvist, B. R. H., Mann, R. P. & Sumpter, D. J. T. (2018). Using Bayesian dynamical systems, model averaging and neural networks to determine interactions between socio-economic indicators. PLoS ONE, 13(5), Article ID e0196355.
Open this publication in new window or tab >>Using Bayesian dynamical systems, model averaging and neural networks to determine interactions between socio-economic indicators
2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 5, article id e0196355Article in journal (Refereed) Published
Abstract [en]

Social and economic systems produce complex and nonlinear relationships in the indicator variables that describe them. We present a Bayesian methodology to analyze the dynamical relationships between indicator variables by identifying the nonlinear functions that best describe their interactions. We search for the 'best' explicit functions by fitting data using Bayesian linear regression on a vast number of models and then comparing their Bayes factors. The model with the highest Bayes factor, having the best trade-off between explanatory power and interpretability, is chosen as the 'best' model. To be able to compare a vast number of models, we use conjugate priors, resulting in fast computation times. We check the robustness of our approach by comparison with more prediction oriented approaches such as model averaging and neural networks. Our modelling approach is illustrated using the classical example of how democracy and economic growth relate to each other. We find that the best dynamical model for democracy suggests that long term democratic increase is only possible if the economic situation gets better. No robust model explaining economic development using these two variables was found.

Place, publisher, year, edition, pages
PUBLIC LIBRARY SCIENCE, 2018
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:uu:diva-359665 (URN)10.1371/journal.pone.0196355 (DOI)000431757400027 ()29742126 (PubMedID)
Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-05Bibliographically approved
Szorkovszky, A., Kotrschal, A., Herbert Read, J. E., Sumpter, D. J. T., Kolm, N. & Pelckmans, K. (2017). An efficient method for sorting and quantifying individual social traits based on group-level behaviour. Methods in Ecology and Evolution, 8(12), 1735-1744
Open this publication in new window or tab >>An efficient method for sorting and quantifying individual social traits based on group-level behaviour
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2017 (English)In: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 8, no 12, p. 1735-1744Article in journal (Refereed) Epub ahead of print
National Category
Behavioral Sciences Biology Control Engineering
Identifiers
urn:nbn:se:uu:diva-330520 (URN)10.1111/2041-210X.12813 (DOI)000417239200010 ()
Projects
Linking social behaviour to the brain
Funder
Knut and Alice Wallenberg Foundation, 102 2013.0072
Available from: 2017-06-15 Created: 2017-10-02 Last updated: 2018-03-08Bibliographically approved
Romenskyy, M., Herbert-Read, J. E., Ward, A. J. W. & Sumpter, D. J. T. (2017). Body size affects the strength of social interactions and spatial organization of a schooling fish (Pseudomugil signifer). Royal Society Open Science, 4(4), Article ID 161056.
Open this publication in new window or tab >>Body size affects the strength of social interactions and spatial organization of a schooling fish (Pseudomugil signifer)
2017 (English)In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 4, no 4, article id 161056Article in journal (Refereed) Published
Abstract [en]

While a rich variety of self-propelled particle models propose to explain the collective motion of fish and other animals, rigorous statistical comparison between models and data remains a challenge. Plausible models should be flexible enough to capture changes in the collective behaviour of animal groups at their different developmental stages and group sizes. Here, we analyse the statistical properties of schooling fish (Pseudomugil signifer) through a combination of experiments and simulations. We make novel use of a Boltzmann inversion method, usually applied in molecular dynamics, to identify the effective potential of the mean force of fish interactions. Specifically, we show that larger fish have a larger repulsion zone, but stronger attraction, resulting in greater alignment in their collective motion. We model the collective dynamics of schools using a self-propelled particle model, modified to include varying particle speed and a local repulsion rule. We demonstrate that the statistical properties of the fish schools are reproduced by our model, thereby capturing a number of features of the behaviour and development of schooling fish.

Place, publisher, year, edition, pages
ROYAL SOC, 2017
Keywords
collective motion, interactions, statistical mechanics, fish school
National Category
Zoology Mathematics
Identifiers
urn:nbn:se:uu:diva-323662 (URN)10.1098/rsos.161056 (DOI)000400527200022 ()28484622 (PubMedID)
Available from: 2017-06-20 Created: 2017-06-20 Last updated: 2017-06-20Bibliographically approved
Herbert-Read, J. E., Ward, A. J., Sumpter, D. J. T. & Mann, R. P. (2017). Escape path complexity and its context dependency in Pacific blue-eyes (Pseudomugil signifer). Journal of Experimental Biology, 220(11), 2076-2081
Open this publication in new window or tab >>Escape path complexity and its context dependency in Pacific blue-eyes (Pseudomugil signifer)
2017 (English)In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 220, no 11, p. 2076-2081Article in journal (Refereed) Published
Abstract [en]

The escape paths prey animals take following a predatory attack appear to be highly unpredictable - a property that has been described as 'protean behaviour'. Here, we present a method of quantifying the escape paths of individual animals using a path complexity approach. When individual fish (Pseudomugil signifer) were attacked, we found that a fish's movement path rapidly increased in complexity following the attack. This path complexity remained elevated (indicating a more unpredictable path) for a sustained period (at least 10 s) after the attack. The complexity of the path was context dependent: paths were more complex when attacks were made closer to the fish, suggesting that these responses are tailored to the perceived level of threat. We separated out the components of speed and turning rate changes to determine which of these components contributed to the overall increase in path complexity following an attack. We found that both speed and turning rate measures contributed similarly to an individual's path complexity in absolute terms. Overall, our work highlights the context-dependent escape responses that animals use to avoid predators, and also provides a method for quantifying the escape paths of animals.

Keywords
Protean behaviour, Entropy, Escape behaviour
National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-360726 (URN)10.1242/jeb.154534 (DOI)000402407900024 ()28348040 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, 102 2013.0072
Available from: 2018-09-18 Created: 2018-09-18 Last updated: 2018-09-18Bibliographically approved
Herbert-Read, J. E., Rosén, E., Szorkovszky, A., Ioannou, C. C., Rogell, B., Perna, A., . . . Sumpter, D. J. T. (2017). How predation shapes the social interaction rules of shoaling fish. Proceedings of the Royal Society of London. Biological Sciences, 284(1861), Article ID 20171126.
Open this publication in new window or tab >>How predation shapes the social interaction rules of shoaling fish
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2017 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 284, no 1861, article id 20171126Article in journal (Refereed) Published
Abstract [en]

Predation is thought to shape the macroscopic properties of animal groups, making moving groups more cohesive and coordinated. Precisely how predation has shaped individuals' fine-scale social interactions in natural populations, however, is unknown. Using high-resolution tracking data of shoaling fish (Poecilia reticulata) from populations differing in natural predation pressure, we show how predation adapts individuals' social interaction rules. Fish originating from high predation environments formed larger, more cohesive, but not more polarized groups than fish from low predation environments. Using a new approach to detect the discrete points in time when individuals decide to update their movements based on the available social cues, we determine how these collective properties emerge from individuals' microscopic social interactions. We first confirm predictions that predation shapes the attraction-repulsion dynamic of these fish, reducing the critical distance at which neighbours move apart, or come back together. While we find strong evidence that fish align with their near neighbours, we do not find that predation shapes the strength or likelihood of these alignment tendencies. We also find that predation sharpens individuals' acceleration and deceleration responses, implying key perceptual and energetic differences associated with how individuals move in different predation regimes. Our results reveal how predation can shape the social interactions of individuals in groups, ultimately driving differences in groups' collective behaviour.

Place, publisher, year, edition, pages
ROYAL SOC, 2017
Keywords
group living, collective motion, Poecilia reticulata, collective behaviour, interaction rules
National Category
Zoology Ecology
Identifiers
urn:nbn:se:uu:diva-334852 (URN)10.1098/rspb.2017.1126 (DOI)000408662400016 ()
Funder
Knut and Alice Wallenberg Foundation, 0962-8452NERC - the Natural Environment Research Council, NE/K009370/1
Available from: 2017-11-28 Created: 2017-11-28 Last updated: 2017-12-01Bibliographically approved
Liu, Y. & Sumpter, D. (2017). Insights into resource consumption, cross-feeding, system collapse, stability and biodiversity from an artificial ecosystem. Journal of the Royal Society Interface, 14(126), Article ID 20160816.
Open this publication in new window or tab >>Insights into resource consumption, cross-feeding, system collapse, stability and biodiversity from an artificial ecosystem
2017 (English)In: Journal of the Royal Society Interface, ISSN 1742-5689, E-ISSN 1742-5662, Vol. 14, no 126, article id 20160816Article in journal (Refereed) Published
Abstract [en]

Community ecosystems at very different levels of biological organization often have similar properties. Coexistence of multiple species, cross-feeding, biodiversity and fluctuating population dynamics are just a few of the properties that arise in a range of ecological settings. Here we develop a bottom-up model of consumer-resource interactions, in the form of an artificial ecosystem ``number soup'', that reflects basic properties of many bacterial and other community ecologies. We demonstrate four key properties of the number soup model: (1) Communities self-organise so that all available resources are fully consumed; (2) Reciprocal cross-feeding is a common evolutionary outcome, which evolves in a number of stages, and many transitional species are involved; (3) The evolved ecosystems are often ``robust yet fragile'', with keystone species required to prevent the whole system from collapsing; (4) Non-equilibrium dynamics and chaotic patterns are general properties, readily generating rich biodiversity. These properties have been observed in empirical ecosystems, ranging from bacteria to rainforests. Establishing similar properties in an evolutionary model as simple as the number soup suggests that these four properties are ubiquitous features of all community ecosystems, and raises questions about how we interpret ecosystem structure in the context of natural selection.

Keywords
ecosystem evolution, consumer-resource interactions, emergence, community ecology, system-level property
National Category
Ecology Other Mathematics Other Biological Topics
Identifiers
urn:nbn:se:uu:diva-314360 (URN)10.1098/rsif.2016.0816 (DOI)000393380400009 ()
Funder
EU, European Research Council
Available from: 2017-02-01 Created: 2017-02-01 Last updated: 2018-01-23Bibliographically approved
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