scholarly journals Plasticity of behavioural variability reflects conflicting selection in group-living and solitary desert locusts

2020 ◽  
Author(s):  
Ben Cooper ◽  
Jonathan M. Smith ◽  
Tom Matheson ◽  
Swidbert R. Ott

Animals living in groups tend to express less variable behaviour than animals living alone. It is widely assumed that this difference reflects, at least in part, an adaptive response to contrasting selection pressures: group-living should favour the evolution of more uniform behaviour whereas lone-living should favour behaviour that is less predictable. Empirical evidence linking these contrasting selection pressures to intrinsic differences in behavioural variability is, however, largely lacking. The desert locust, Schistocerca gregaria, manifests in two very distinct eco-phenotypes, a lone-living cryptic “solitarious phase” and a swarming “gregarious phase” that aggregates into very large and dense groups. This “phase polyphenism” has evolved in response to contrasting selection pressures that change rapidly and unpredictably. Phase differences in mean behaviour are well-characterised, but no previous study has considered differences in variability. Here we used locust phase polyphenism to test the hypothesis that group living leads to the evolution of reduced intrinsic variability in behaviour. We measured two behaviours in both phenotypes: locomotor activity in the presence of conspecifics, and locomotor hesitation in approaching food when alone. We assayed each individual repeatedly and estimated variability relative to the mean in log-normal mixed-effects models that explicitly account for the means-variance dependency in the behavioural measures. Our results demonstrate that relative behavioural variability differs between the two phases in line with predictions from ecological theory: both within-individual and between-individual variability were lower in the group-living gregarious phenotype. This contrasts with previous studies on social niche construction in spiders and crickets, and highlights the importance of social ecology: in animals that form non-social collectives, such as locusts, reduced individual behavioural variability is key for coherent collective behaviour. The differences in variability persisted when gregarious locusts were tested in isolation and solitarious locusts were tested in groups, indicating that they arise not simply as flexible reactions to different social contexts, but are intrinsic to the individual animals of each phase. This “variance polyphenism” in locusts provides empirical evidence that evolutionary adaptation for group living has driven a reduction in within- and between-individual behavioural variability.

1993 ◽  
Vol 125 (5) ◽  
pp. 919-930 ◽  
Author(s):  
Hervé Jactel

AbstractIndividual variability in the flight potential of Ips sexdentatus Boern. was investigated using flight mill experiments. Non-flyer status and flight durations were studied in relation to day of emergence, sex, pronotum width, dried body weight (after lipid ether extraction), and lipid content estimate. Lipid content estimation was determined in beetles reared on the same trees and under identical conditions as the flight test insects.The four flight-tested cohorts showed that approximately one-third were non-flyers. The distribution of individual flight durations was described by a log-normal curve. Consequently, the dispersal variability within the population could be fitted to a linear model on a log-probit scale. The concept of FD50 (flight duration 50), defined as the flight duration of 50% of a sample population, was used to describe population flight potential.There was no significant correlation between the individual flight duration and the day of emergence, sex, body size or weight, or lipid content estimate. A significant positive correlation was recorded between the different classes of flyer (i.e. non-, short, long, and very long flyers) and the average lipid content estimate. It was hypothesized that (1) a minimum threshold fuel supply was necessary to initiate the dispersal flight and (2) fuel supply could result in dispersal tendencies representing a specific response to habitat constraints.


2019 ◽  
Vol 16 (153) ◽  
pp. 20190115 ◽  
Author(s):  
Mark E. Hauber ◽  
Alexander L. Bond ◽  
Amy-Lee Kouwenberg ◽  
Gregory J. Robertson ◽  
Erpur S. Hansen ◽  
...  

In group-living species with parental care, the accurate recognition of one's own young is critical to fitness. Because discriminating offspring within a large colonial group may be challenging, progeny of colonial breeders often display familial or individual identity signals to elicit and receive parental provisions from their own parents. For instance, the common murre (or common guillemot: Uria aalge ) is a colonially breeding seabird that does not build a nest and lays and incubates an egg with an individually unique appearance. How the shell's physical and chemical properties generate this individual variability in coloration and maculation has not been studied in detail. Here, we quantified two characteristics of the avian-visible appearance of murre eggshells collected from the wild: background coloration spectra and maculation density. As predicted by the individual identity hypothesis, there was no statistical relationship between avian-perceivable shell background coloration and maculation density within the same eggs. In turn, variation in both sets of traits was statistically related to some of their physico-chemical properties, including shell thickness and concentrations of the eggshell pigments biliverdin and protoporphyrin IX. These results illustrate how individually unique eggshell appearances, suitable for identity signalling, can be generated by a small number of structural mechanisms.


Author(s):  
O.V. Mareev ◽  
◽  
G.O. Mareev ◽  
M.E. Gutynina ◽  
D.A. Maksimova ◽  
...  

2017 ◽  
Vol 1 (1) ◽  
pp. 15-31
Author(s):  
Francisco Xavier Morales

The problem of identity is an issue of contemporary society that is not only expressed in daily life concerns but also in discourses of politics and social movements. Nevertheless, the I and the needs of self-fulfillment usually are taken for granted. This paper offers thoughts regarding individual identity based on Niklas Luhmann’s systems theory. From this perspective, identity is not observed as a thing or as a subject, but rather as a “selfillusion” of a system of consciousness, which differentiates itself from the world, event after event, in a contingent way. As concerns the definition  of contents of self-identity, the structures of social systems define who is a person, how he or she should act, and how much esteem he or she should receive. These structures are adopted by consciousness as its own identity structures; however, some social contexts are more relevant for self-identity construction than others. Moral communication increases the probability that structure appropriation takes place, since the emotional element of identity is linked to the esteem/misesteem received by the individual from the interactions in which he or she participates.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Leanne Proops ◽  
Camille A. Troisi ◽  
Tanja K. Kleinhappel ◽  
Teresa Romero

AbstractEcological factors, such as predation, have traditionally been used to explain sociability. However, it is increasingly recognised that individuals within a group do not associate randomly, and that these non-random associations can generate fitness advantages. The majority of the empirical evidence on differentiated associations in group-living mammals, however, comes from a limited number of taxa and we still know very little about their occurrence and characteristics in some highly social species, such as rats (Rattus spp.). Here, using network analysis, we quantified association patterns in four groups of male fancy rats. We found that the associations between rats were not randomly distributed and that most individuals had significantly more preferred/avoided associates than expected by random. We also found that these preferences can be stable over time, and that they were not influenced by individuals’ rank position in the dominance hierarchy. Our findings are consistent with work in other mammals, but contrast with the limited evidence available for other rat strains. While further studies in groups with different demographic composition are warranted to confirm our findings, the occurrence of differentiated associations in all male groups of rats have important implications for the management and welfare of captive rat populations.


2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Nick A. R. Jones ◽  
Helen C. Spence-Jones ◽  
Mike Webster ◽  
Luke Rendell

Abstract Learning can enable rapid behavioural responses to changing conditions but can depend on the social context and behavioural phenotype of the individual. Learning rates have been linked to consistent individual differences in behavioural traits, especially in situations which require engaging with novelty, but the social environment can also play an important role. The presence of others can modulate the effects of individual behavioural traits and afford access to social information that can reduce the need for ‘risky’ asocial learning. Most studies of social effects on learning are focused on more social species; however, such factors can be important even for less-social animals, including non-grouping or facultatively social species which may still derive benefit from social conditions. Using archerfish, Toxotes chatareus, which exhibit high levels of intra-specific competition and do not show a strong preference for grouping, we explored the effect of social contexts on learning. Individually housed fish were assayed in an ‘open-field’ test and then trained to criterion in a task where fish learnt to shoot a novel cue for a food reward—with a conspecific neighbour visible either during training, outside of training or never (full, partial or no visible presence). Time to learn to shoot the novel cue differed across individuals but not across social context. This suggests that social context does not have a strong effect on learning in this non-obligatory social species; instead, it further highlights the importance that inter-individual variation in behavioural traits can have on learning. Significance statement Some individuals learn faster than others. Many factors can affect an animal’s learning rate—for example, its behavioural phenotype may make it more or less likely to engage with novel objects. The social environment can play a big role too—affecting learning directly and modifying the effects of an individual’s traits. Effects of social context on learning mostly come from highly social species, but recent research has focused on less-social animals. Archerfish display high intra-specific competition, and our study suggests that social context has no strong effect on their learning to shoot novel objects for rewards. Our results may have some relevance for social enrichment and welfare of this increasingly studied species, suggesting there are no negative effects of short- to medium-term isolation of this species—at least with regards to behavioural performance and learning tasks.


2021 ◽  
pp. 220-231
Author(s):  
Carmel Cefai

In contrast to the earlier understandings of resilience for the select, invulnerable few, an ecological perspective provides the opportunity for all children to develop resilience given resilience-enhancing, protective social contexts. In this chapter, the author explores a transactional-ecological perspective of resilience in the context of educational systems, underlining the limitations of an overreliance on the individual in resilience building. The chapter presents a transactional, whole-school, resilience framework for educational systems informed by the research evidence, focusing on both curricular competence-building and contextual processes across multiple systems. The chapter concludes with an illustration of a recent resilience program, RESCUR Surfing the Waves, informed by this approach.


Author(s):  
Mohammed A. Alhossini ◽  
Collins G. Ntim ◽  
Alaa Mansour Zalata

This paper comprehensively reviews the current body of international accounting literature regarding advisory/monitoring committees and corporate outcomes. Specifically, it synthesizes, appraises, and extends current knowledge on the (a) theoretical (i.e., economic, accounting/corporate governance, sociological and socio-psychological) perspectives and (b) empirical evidence of the observable and less visible attributes at both the individual and committee levels and their link with a wide range (financial/non-financial) of corporate outcomes. Using the systematic literature review method, 304 articles from 59 journals in the fields of accounting and finance that were published between January 1992 and December 2018 are reviewed. The main findings are as follows. First and theoretically, agency theory is the most dominant applied theory/studies with no application of theory at all (descriptive), while the application of integrated theoretical frameworks is lacking in the reviewed articles. Secondly, the existing empirical evidence focusses excessively on (a) monitoring instead of advisory committees and (b) observable rather than less visible committee attributes. Thirdly, scarcity of cross-country studies along with methodological limitations relating to measurement inconsistencies, insufficiency of variables, and dominance of quantitative studies, among others, are identified. Finally, promising future research avenues are outlined.


2019 ◽  
Author(s):  
John Mcbride ◽  
Tsvi Tlusty

Musical scales are used throughout the world, but the question of how they evolved remains open. Some suggest that scales based on the harmonic series are inherently pleasant, while others propose that scales are chosen that are easy to communicate.However, testing these theories has been hindered by the sparseness of empirical evidence. Here, we assimilate data from diverse ethnomusicological sources into a cross-cultural database of scales. We generate populations of scales based on multiple theories and assess their similarity to empirical distributions from the database. Most scales tend to include intervals which are close in size to perfect fifths (“imperfect fifths”), and packing arguments explain the salient features of the distributions. Scales are also preferred if their intervals are compressible, which may facilitate efficient communication and memory of melodies. While scales appear to evolve according to various selection pressures, the simplest, imperfect-fifths packing model best fits the empirical data.


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