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Šigutová H, Šigut M, Dolný A, Harabiš F. Individual variability in habitat selection by aquatic insects is driven by taxonomy rather than specialisation. Sci Rep 2022; 12:20735. [PMID: 36456650 PMCID: PMC9715563 DOI: 10.1038/s41598-022-25363-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022] Open
Abstract
Habitat selection, the choice of a habitat based on its perceived quality, is a key mechanism structuring freshwater communities. To date, individual variability in habitat selection has been neglected, and specialisation has never been considered in this type of studies. We examined the individual differences in the habitat selection of backswimmers (Notonectidae) and diving beetles (Dytiscidae). From each family, we selected one habitat generalist able to coexist with fish (Notonecta glauca, Dytiscus marginalis), and one species specialised to fishless habitats (Notonecta obliqua, Acilius sulcatus). We performed a mesocosm experiment quantifying the consistency in individuals' decisions in response to fish and vegetation structure, in relation to sex and specialisation. Neither the overall pattern of preferences nor consistency in individuals' decisions differed between specialists and generalists or between the sexes, but both were consistent within families. At the population level, backswimmers preferred fishless pools with submersed and floating macrophytes, while diving beetles showed no clear preferences. Individual decisions of backswimmers were consistent and likely driven by conspecific/heterospecific attraction. In diving beetles, individual decisions were primarily density-dependent. Our results reinforce the significance of habitat selectivity for aquatic community assembly, while suggesting a range of mechanisms driving variability in individual behaviour.
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Affiliation(s)
- Hana Šigutová
- grid.412684.d0000 0001 2155 4545Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic ,grid.10979.360000 0001 1245 3953Department of Zoology, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Martin Šigut
- grid.412684.d0000 0001 2155 4545Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Aleš Dolný
- grid.412684.d0000 0001 2155 4545Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Filip Harabiš
- grid.15866.3c0000 0001 2238 631XDepartment of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Prague, Czech Republic
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Temporal and spatial variation in sex-specific abundance of the avian vampire fly (Philornis downsi). Parasitol Res 2021; 121:63-74. [PMID: 34799771 PMCID: PMC8748338 DOI: 10.1007/s00436-021-07350-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/12/2021] [Indexed: 10/26/2022]
Abstract
Understanding the range and behaviour of an invasive species is critical to identify key habitat areas to focus control efforts. Patterns of range use in parasites can differ temporally, across life stages and between sexes. The invasive avian vampire fly, Philornis downsi, spends the larval stage of its life within bird nests, feeding on developing nestlings and causing high levels of mortality and deformation. However, little is known of the ecology and behaviour of the non-parasitic adult fly life stage. Here, we document sex-specific temporal and spatial patterns of abundance of adult avian vampire flies during a single Darwin's finch breeding season. We analyse fly trapping data collected across 7 weeks in the highlands (N = 405 flies) and lowlands (N = 12 flies) of Floreana Island (Galápagos). Lowland catches occurred later in the season, which supports the hypothesis that flies may migrate from the food-rich highlands to the food-poor lowlands once host breeding has commenced. Fly abundance was not correlated with host nesting density (oviposition site) but was correlated with distance to the agricultural zone (feeding site). We consistently caught more males closer to the agricultural zone and more females further away from the agricultural zone. These sex differences suggest that males may be defending or lekking at feeding sites in the agricultural zone for mating. This temporal and sex-specific habitat use of the avian vampire fly is relevant for developing targeted control methods and provides insight into the behavioural ecology of this introduced parasite on the Galápagos Archipelago.
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Overcoming Drag at the Water-Air Interface Constrains Body Size in Whirligig Beetles. FLUIDS 2021. [DOI: 10.3390/fluids6070249] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Whirligig beetles (Coleoptera: Gyrinidae) are among the best swimmers of all aquatic insects. They live mostly at the water’s surface and their capacity to swim fast is key to their survival. We present a minimal model for the viscous and wave drags they face at the water’s surface and compare them to their thrust capacity. The swimming speed accessible is thus derived according to size. An optimal size range for swimming at the water’s surface is observed. These results are in line with the evolutionary trajectories of gyrinids which evolved into lineages whose members are a few milimeter’s long to those with larger-sized genera being tens of millimeters in length. The size of these beetles appears strongly constrained by the fluid mechanical laws ruling locomotion and adaptation to the water-air interface.
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Crampe JP, Gerard JF, Goulard M, Milleret C, Gonzalez G, Bon R. Year-round sexual segregation in the Pyrenean chamois, a nearly monomorphic polygynous herbivore. Behav Processes 2021; 184:104300. [PMID: 33422643 DOI: 10.1016/j.beproc.2020.104300] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/01/2020] [Accepted: 12/17/2020] [Indexed: 11/18/2022]
Abstract
Adult females and males live apart outside the mating period in many social vertebrates, but the causes of this phenomenon remain a matter of debate. Current prevailing hypotheses predict no sexual segregation outside the early period of maternal care in nearly monomorphic species such as the Pyrenean chamois (Rupicapra pyrenaica). We examined sexual segregation in a population of the species, using data collected over 143 consecutive months on groups' location and composition, and extending statistical procedures introduced by Conradt (1998b) and Bonenfant et al. (2007). In addition, we analysed the social interactions recorded between group members. As expected, habitat segregation was low throughout the year, with a maximum during the early lactation period. However, social and spatial segregation was consistently high, contradicting the predictions of the current prevailing hypotheses, while suggesting social causes were predominant. The scarcity of social interactions outside the mating season makes unlikely the hypothesis that males segregate to improve their reproductive success. We rather suspect that higher social affinities within than between the two sexes are at work. However, this hypothesis alone is probably insufficient to account for spatial segregation. Our results should revive the debate regarding the causes of sexual segregation.
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Affiliation(s)
- Jean-Paul Crampe
- Parc National des Pyrénées, 2 rue du 4 septembre, 65000, Tarbes, France
| | - Jean-François Gerard
- INRAE, Comportement et Ecologie de la Faune Sauvage, B.P. 52627, 31326, Castanet-Tolosan Cedex, France.
| | - Michel Goulard
- INRAE, UMR 1201 Dynamiques et Ecologie des Paysages Agriforestiers, B.P. 52627, 31326, Castanet-Tolosan Cedex, France
| | - Cyril Milleret
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Ås, NO-1432 Norway
| | - Georges Gonzalez
- INRAE, Comportement et Ecologie de la Faune Sauvage, B.P. 52627, 31326, Castanet-Tolosan Cedex, France
| | - Richard Bon
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France.
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Moran NP, Sánchez‐Tójar A, Schielzeth H, Reinhold K. Poor nutritional condition promotes high‐risk behaviours: a systematic review and meta‐analysis. Biol Rev Camb Philos Soc 2020; 96:269-288. [DOI: 10.1111/brv.12655] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Nicholas P. Moran
- Evolutionary Biology Bielefeld University Morgenbreede 45 Bielefeld 33615 Germany
- Centre for Ocean Life DTU‐Aqua Technical University of Denmark Building 201, Kemitorvet Kgs. Lyngby 2800 Denmark
| | | | - Holger Schielzeth
- Institute of Ecology and Evolution Friedrich Schiller University Jena Dornburger Straße 159 Jena 07743 Germany
| | - Klaus Reinhold
- Evolutionary Biology Bielefeld University Morgenbreede 45 Bielefeld 33615 Germany
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van der Marel A, Waterman JM, López-Darias M. Social organization in a North African ground squirrel. J Mammal 2020. [DOI: 10.1093/jmammal/gyaa031] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Abstract
Research on sociality in temperate ground-dwelling squirrels has focused on female philopatry and other life history trade-offs, which are influenced by constraints in the duration of the active growing season. Temperate ground-dwelling squirrels that experience high predation pressure, are large in body size, and have a short active season, show a more complex social organization. In contrast, African ground squirrels are active year-round, suggesting that instead of a short active season, distinct selective pressures influence their social organization. We examined the social organization of Barbary ground squirrels, Atlantoxerus getulus, and compared the social organization of temperate and African ground-dwelling sciurids. Anecdotal accounts on Barbary ground squirrels’ social organization suggested that they were either solitary or gregarious, or live in small family groups. We recorded the group size, composition, cohesion, and genetic relatedness, of the population on the arid island of Fuerteventura, Spain. Our data indicate that females live in small (1–8) all-female kin groups separate from adult males, and that unrelated adult males share sleeping burrows with immature individuals of either sex. We observed sex-biased dispersal with males primarily the dispersing sex and females primarily philopatric. Females sleep solitarily during gestation and lactation and nest either communally or singly after juvenile emergence. During the day, males and females can be active in the same area. Barbary ground squirrels are social because the squirrels share sleeping burrows and show spatiotemporal overlap. Barbary ground squirrels’ social organization resembles that of the closely related Cape ground squirrel rather than that of the temperate ground-dwelling sciurids, although the former are more temperate, seasonal breeders. In addition to describing the social organization of a previously unstudied species, this paper sheds light on the ecological drivers of sociality, and the evolution of distinct social organizations in ground-dwelling sciurids.
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Affiliation(s)
| | - Jane M Waterman
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, Canada
| | - Marta López-Darias
- Island Ecology and Evolution Research Group, Instituto de Productos Naturales y Agrobiología (IPNA-CSIC), Av. Astrofisico Francisco Sánchez, 3, 38206 San Cristóbal de La Laguna, Santa Cruz de Tenerife, Canary Islands, Spain
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Salamanca DA, Brown F. Sub-functionalization of dorsal and ventral eyes in a whirligig beetle (Coleoptera: Gyrinidae). NEOTROPICAL BIODIVERSITY 2018. [DOI: 10.1080/23766808.2018.1510567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Stanley CR, Liddiard Williams H, Preziosi RF. Female clustering in cockroach aggregations-A case of social niche construction? Ethology 2018. [DOI: 10.1111/eth.12799] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christina R. Stanley
- Department of Biological Sciences; University of Chester; Chester UK
- Faculty of Life Sciences; University of Manchester; Manchester UK
| | | | - Richard F. Preziosi
- Faculty of Life Sciences; University of Manchester; Manchester UK
- School of Science and the Environment; Manchester Metropolitan University; Manchester UK
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9
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Farine DR, Strandburg-Peshkin A, Couzin ID, Berger-Wolf TY, Crofoot MC. Individual variation in local interaction rules can explain emergent patterns of spatial organization in wild baboons. Proc Biol Sci 2017; 284:20162243. [PMID: 28424342 PMCID: PMC5413915 DOI: 10.1098/rspb.2016.2243] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 03/20/2017] [Indexed: 11/21/2022] Open
Abstract
Researchers have long noted that individuals occupy consistent spatial positions within animal groups. However, an individual's position depends not only on its own behaviour, but also on the behaviour of others. Theoretical models of collective motion suggest that global patterns of spatial assortment can arise from individual variation in local interaction rules. However, this prediction remains untested. Using high-resolution GPS tracking of members of a wild baboon troop, we identify consistent inter-individual differences in within-group spatial positioning. We then apply an algorithm that identifies what number of conspecific group members best predicts the future location of each individual (we call this the individual's neighbourhood size) while the troop is moving. We find clear variation in the most predictive neighbourhood size, and this variation relates to individuals' propensity to be found near the centre of their group. Using simulations, we show that having different neighbourhood sizes is a simple candidate mechanism capable of linking variation in local individual interaction rules-in this case how many conspecifics an individual interacts with-to global patterns of spatial organization, consistent with the patterns we observe in wild primates and a range of other organisms.
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Affiliation(s)
- D R Farine
- Department of Anthropology, University of California, 1 Shields Avenue, Davis, CA, USA
- Smithsonian Tropical Research Institute, Ancon, Panama
- Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, South Parks Road, Oxford, UK
| | - A Strandburg-Peshkin
- Department of Ecology and Evolutionary Biology, Princeton University, 106A Guyot Hall, Princeton, NJ, USA
| | - I D Couzin
- Department of Collective Behaviour, Max Planck Institute for Ornithology, 78464 Konstanz, Germany
- Chair of Biodiversity and Collective Behaviour, Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - T Y Berger-Wolf
- Department of Computer Science, University of Illinois at Chicago, 851 South Morgan Street, Chicago, IL, USA
| | - M C Crofoot
- Department of Anthropology, University of California, 1 Shields Avenue, Davis, CA, USA
- Animal Behavior Graduate Group, University of California, 1 Shields Avenue, Davis, CA, USA
- Smithsonian Tropical Research Institute, Ancon, Panama
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11
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Abstract
In the selfish herd hypothesis, prey animals move toward each other to avoid the likelihood of being selected by a predator. However, many grouped animals move away from each other the moment before a predator attacks. Very little is known about this phenomenon, called flash expansion, such as whether it is triggered by one individual or a threshold and how information is transferred between group members. We performed a controlled experiment with whirligig beetles in which the ratio of sighted to unsighted individuals was systematically varied and emergent flash expansion was measured. Specifically, we examined: the percentage of individuals in a group that startled, the resulting group area, and the longevity of the flash expansion. We found that one or two sighted beetles in a group of 24 was not enough to cause a flash expansion after a predator stimulus, but four sighted beetles usually initiated a flash expansion. Also, the more beetles that were sighted the larger the resulting group area and the longer duration of the flash expansion. We conclude that flash expansion is best described as a threshold event whose adaptive value is to prevent energetically costly false alarms while quickly mobilizing an emergent predator avoidance response. This is one of the first controlled experiments of flash expansion, an important emergent property that has applications to understanding collective motion in swarms, schools, flocks, and human crowds. Also, our study is a convincing demonstration of social contagion, how the actions of one individual can pass through a group.
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Affiliation(s)
- William L. Romey
- Department of Biology, State University of New York at Potsdam, Potsdam, New York, United States of America
- * E-mail:
| | - Alicia R. Lamb
- Department of Biology, State University of New York at Potsdam, Potsdam, New York, United States of America
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12
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Gustafson GT, Miller KB. The New World whirligig beetles of the genus Dineutus Macleay, 1825 (Coleoptera, Gyrinidae, Gyrininae, Dineutini). Zookeys 2015:1-135. [PMID: 25685002 PMCID: PMC4311692 DOI: 10.3897/zookeys.476.8630] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/12/2014] [Indexed: 12/03/2022] Open
Abstract
All New World members of the whirligig beetle genus Dineutus Macleay, 1825 are treated. The New World Dineutus are found to be composed of 18 species and 6 subspecies: one species, Dineutusmexicanus Ochs, 1925, stat. n. is elevated from subspecies to species rank, and the subspecies Dineutuscarolinusmutchleri Ochs, 1925, syn. n. is synonymized here with the typical form. Lectotypes are designated for Dineutusdiscolor Aubé, 1838, Dineutesmetallicus Aubé, 1838, Dineutussolitarius Aubé, 1838, Dineutesanalis Régimbart, 1883, and Gyrinuslongimanus Olivier, 1795. Each taxonomic unit is provided with a taxonomic history, type locality, diagnosis, distribution, habitat information, and a discussion section. The aedeagus and male mesotarsal claws are illustrated, and dorsal and ventral habitus images of both sexes, for each species and subspecies are provided. General distribution maps are provided for all taxonimc units. A key to the genera of New World Gyrinidae, as well as all the New World Dineutus species is provided. General Dineutus anatomy as well as a clarification of homology and anatomical terms is included.
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Affiliation(s)
- Grey T Gustafson
- Department of Biology and Museum of Southwestern Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Kelly B Miller
- Department of Biology and Museum of Southwestern Biology, University of New Mexico, Albuquerque, NM 87131, USA
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Romey WL, Miller MM, Vidal JM. Collision avoidance during group evasive manoeuvres: a comparison of real versus simulated swarms with manipulated vision and surface wave detectors. Proc Biol Sci 2015; 281:20140812. [PMID: 24943378 DOI: 10.1098/rspb.2014.0812] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Coordinated group motion has been studied extensively both in real systems (flocks, swarms and schools) and in simulations (self-propelled particle (SPP) models using attraction and repulsion rules). Rarely are attraction and repulsion rules manipulated, and the resulting emergent behaviours of real and simulation systems are compared. We compare swarms of sensory-deprived whirligig beetles with matching simulation models. Whirligigs live at the water's surface and coordinate their grouping using their eyes and antennae. We filmed groups of beetles in which antennae or eyes had been unilaterally obstructed and measured individual and group behaviours. We then developed and compared eight SPP simulation models. Eye-less beetles formed larger diameter resting groups than antenna-less or control groups. Antenna-less groups collided more often with each other during evasive group movements than did eye-less or control groups. Simulations of antenna-less individuals produced no difference from a control (or a slight decrease) in group diameter. Simulations of eye-less individuals produced an increase in group diameter. Our study is important in (i) differentiating between group attraction and repulsion rules, (ii) directly comparing emergent properties of real and simulated groups, and (iii) exploring a new sensory modality (surface wave detection) to coordinate group movement.
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Affiliation(s)
- William L Romey
- Department of Biology, SUNY at Potsdam, Potsdam, NY 13676, USA
| | | | - Jose M Vidal
- Department of Computer Science and Engineering, University of South Carolina, Columbia, SC 29208, USA
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Eftimie R. Simultaneous use of different communication mechanisms leads to spatial sorting and unexpected collective behaviours in animal groups. J Theor Biol 2013; 337:42-53. [PMID: 23938233 DOI: 10.1016/j.jtbi.2013.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 07/30/2013] [Accepted: 08/02/2013] [Indexed: 11/18/2022]
Abstract
Communication among individuals forms the basis of social interactions in every animal population. In general, communication is influenced by the physiological and psychological constraints of each individual, and in large aggregations this means differences in the reception and emission of communication signals. However, studies on the formation and movement of animal aggregations usually assume that all individuals communicate with neighbours in the same manner. Here, we take a new approach on animal aggregations and use a nonlocal mathematical model to investigate theoretically the simultaneous use of two communication mechanisms by different members of a population. We show that the use of multiple communication mechanisms can lead to behaviours that are not necessarily predicted by the behaviour of subpopulations that use only one communication mechanism. In particular, we show that while the use of one communication mechanism by the entire population leads to deterministic movement, the use of multiple communication mechanisms can lead in some cases to chaotic movement. Finally, we show that the use of multiple communication mechanisms leads to the sorting of individuals inside aggregations: individuals that are aware of the location and the movement direction of all their neighbours usually position themselves at the centre of the groups, while individuals that are aware of the location and the movement direction of only some neighbours position themselves at the edges of the groups.
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Affiliation(s)
- Raluca Eftimie
- Department of Mathematics, University of Dundee, Dundee DD1 4HN, United Kingdom.
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15
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Hirsch BT, Stanton MA, Maldonado JE. Kinship shapes affiliative social networks but not aggression in ring-tailed coatis. PLoS One 2012; 7:e37301. [PMID: 22624010 PMCID: PMC3356279 DOI: 10.1371/journal.pone.0037301] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 04/19/2012] [Indexed: 11/24/2022] Open
Abstract
Animal groups typically contain individuals with varying degrees of genetic relatedness, and this variation in kinship has a major influence on patterns of aggression and affiliative behaviors. This link between kinship and social behavior underlies socioecological models which have been developed to explain how and why different types of animal societies evolve. We tested if kinship and age-sex class homophily in two groups of ring-tailed coatis (Nasua nasua) predicted the network structure of three different social behaviors: 1) association, 2) grooming, and 3) aggression. Each group was studied during two consecutive years, resulting in four group-years available for analysis (total of 65 individuals). Association patterns were heavily influenced by agonistic interactions which typically occurred during feeding competition. Grooming networks were shaped by mother-offspring bonds, female-female social relationships, and a strong social attraction to adult males. Mother-offspring pairs were more likely to associate and groom each other, but relatedness had no effect on patterns of aggressive behavior. Additionally, kinship had little to no effect on coalitionary support during agonistic interactions. Adult females commonly came to the aid of juveniles during fights with other group members, but females often supported juveniles who were not their offspring (57% of coalitionary interactions). These patterns did not conform to predictions from socioecological models.
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Affiliation(s)
- Ben T Hirsch
- School of Environment and Natural Resources, Ohio State University, Columbus, Ohio, United States of America.
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Voise J, Schindler M, Casas J, Raphaël E. Capillary-based static self-assembly in higher organisms. J R Soc Interface 2011; 8:1357-66. [PMID: 21367777 DOI: 10.1098/rsif.2010.0681] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Organized structures produced by dynamic self-assembly are often observed in animal groups. Static self-assembly, however, has to date only been observed at the cellular and sub-cellular levels. The aim of this study was to analyse organized structures in immobile whirligig beetle groups on the water surface. We used theoretical and computational approaches to model the meniscus around whirligig beetles and to calculate the surface energy for configurations involving two beetles. Theoretical predictions were then tested using live insects and resin casts. Observations were also made for three and more casts. The meniscus of whirligig beetles had a bipolar shape with two concave parts. For two beetles, predicted configurations based on energy minima corresponded to beetles in contact by their extremities, forming lines and arrows, and agreed well with observations. Experimental results for three and more beetle casts revealed new geometrical arrangements similar to those obtained with colloids at interfaces. This study provides the first example of static self-assembly at the inter-organism level and shows the importance of capillary interactions in such formations. We identify the ecological context in which our findings are of relevance.
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Affiliation(s)
- Jonathan Voise
- Université de Tours, IRBI UMR CNRS 6035, Parc Grandmont, 37200 Tours, France.
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18
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De Vos A, O'Riain MJ. Sharks shape the geometry of a selfish seal herd: experimental evidence from seal decoys. Biol Lett 2009; 6:48-50. [PMID: 19793737 DOI: 10.1098/rsbl.2009.0628] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many animals respond to predation risk by forming groups. Evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. However, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator-prey systems. To solve this, we manipulated the domains of danger of Cape fur seal (Arctocephalus pusillus pusillus) decoys to provide evidence that a selfish reduction in a seals' domain of danger results in a proportional reduction in its predation risk from ambush shark attacks. This behaviour confers a survival advantage to individual seals within a group and explains the evolution of selfish herds in a prey species. These findings empirically elevate Hamilton's selfish herd hypothesis to more than a 'theoretical curiosity'.
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Affiliation(s)
- Alta De Vos
- Department of Zoology, University Avenue, University of Cape Town, Cape Town, South Africa.
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20
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Romey WL, Galbraith E. Optimal group positioning after a predator attack: the influence of speed, sex, and satiation within mobile whirligig swarms. Behav Ecol 2008. [DOI: 10.1093/beheco/arm138] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Romey W, Walston A, Watt P. Do 3-D predators attack the margins of 2-D selfish herds? Behav Ecol 2007. [DOI: 10.1093/beheco/arm105] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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