scholarly journals Major Evolutionary Transitions in Social Insects, the Importance of Worker Sterility and Life History Trade-Offs

2021 ◽  
Vol 9 ◽  
Author(s):  
Abel Bernadou ◽  
Boris H. Kramer ◽  
Judith Korb
Keyword(s):  
Life History ◽  
Social Insects ◽  
Division Of Labour ◽  
Evolutionary Transitions ◽  
Individual Level ◽  
Individual Fitness ◽  
Trade Offs ◽  
Group Members ◽  
The Individual ◽  
Worker Sterility

The evolution of eusociality in social insects, such as termites, ants, and some bees and wasps, has been regarded as a major evolutionary transition (MET). Yet, there is some debate whether all species qualify. Here, we argue that worker sterility is a decisive criterion to determine whether species have passed a MET (= superorganisms), or not. When workers are sterile, reproductive interests align among group members as individual fitness is transferred to the colony level. Division of labour among cooperating units is a major driver that favours the evolution of METs across all biological scales. Many METs are characterised by a differentiation into reproductive versus maintenance functions. In social insects, the queen specialises on reproduction while workers take over maintenance functions such as food provisioning. Such division of labour allows specialisation and it reshapes life history trade-offs among cooperating units. For instance, individuals within colonies of social insects can overcome the omnipresent fecundity/longevity trade-off, which limits reproductive success in organisms, when increased fecundity shortens lifespan. Social insect queens (particularly in superorganismal species) can reach adult lifespans of several decades and are among the most fecund terrestrial animals. The resulting enormous reproductive output may contribute to explain why some genera of social insects became so successful. Indeed, superorganismal ant lineages have more species than those that have not passed a MET. We conclude that the release from life history constraints at the individual level is a important, yet understudied, factor across METs to explain their evolutionary success.

Moral Universalism: Measurement and Economic Relevance

2021 ◽  
Author(s):  
Benjamin Enke ◽  
Ricardo Rodríguez-Padilla ◽  
Florian Zimmermann
Keyword(s):  
Individual Level ◽  
Trade Offs ◽  
Educational Investments ◽  
Self Reports ◽  
Study Heterogeneity ◽  
Group Members ◽  
Moral Universalism ◽  
The Rich ◽  
The Individual ◽  
Large Representative

Many applied economic settings involve trade-offs between in-group members and strangers. To better understand decision making in these contexts, this paper measures and investigates the economic relevance of heterogeneity in moral universalism: the extent to which people exhibit the same level of altruism and trust toward strangers as toward in-group members. We first introduce a new experimentally validated, survey-based measure of moral universalism that is simple and easily scalable. We then deploy this tool in a large, representative sample of the U.S. population to study heterogeneity and economic relevance. We find that universalism is a relatively stable trait at the individual level. In exploratory analyses, heterogeneity in universalism is significantly related to observables: Older people, men, the rich, the rural, and the religious exhibit less universalist preferences and beliefs. Linking variation in universalism to self-reports of economic and social behaviors, we document the following correlations. Universalists donate less money locally, but more globally, and are less likely to exhibit home bias in equity and educational investments. In terms of social networks, universalists have fewer friends, spend less time with them, and feel more lonely. These results provide a blueprint for measuring moral universalism in applied settings and suggest that variation in universalism is relevant for understanding a myriad of economic behaviors. This paper was accepted by Yan Chen, behavioral economics and decision analysis.

scholarly journals THE EVOLUTION OF MULTIPLE MATING BEHAVIOR BY HONEY BEE QUEENS (APIS MELLIFERA L.)

Genetics ◽  
1980 ◽  
Vol 96 (1) ◽  
pp. 263-273
Author(s):  
Robert E Page
Keyword(s):  
Mating Behavior ◽  
Honey Bee ◽  
Multiple Mating ◽  
Genetic Load ◽  
Individual Level ◽  
Individual Fitness ◽  
Essential Components ◽  
Honey Bee Queens ◽  
The Individual ◽  
Sex Determination System

ABSTRACT A model is presented showing that natural selection operating at the individual level can adequately explain the evolution of multiple mating behavior by honey bee queens. Group selection need not be invoked. The fitness of a given female genotype is a function of the number of sex alleles in the population, the number of matings by an individual female and the specific parameters that determine the relationship of brood viability to individual fitness. Even though the exact relationship is not known, it is almost certainly not linear. A nonlinear relationship between worker brood viability and fitness and a significant genetic load associated with the sex-determination system in honey bees are the essential components of this model.

scholarly journals Avoidance of Contaminated Food Correlates With Low Protozoan Infection in Bonobos

2021 ◽  
Vol 9 ◽  
Author(s):  
Cécile Sarabian ◽  
Raphaël Belais ◽  
Andrew J. J. MacIntosh
Keyword(s):  
Infectious Agent ◽  
Oral Route ◽  
Behavioral Experiments ◽  
Food Items ◽  
Individual Fitness ◽  
Behavioral Adaptations ◽  
Trade Offs ◽  
Protozoan Infection ◽  
Contaminated Food ◽  
The Individual

Intense selection pressure from parasites on free-living animals has resulted in behavioral adaptations that help potential hosts avoid sources of infection. In primates, such “behavioral immunity” is expressed in different contexts and may vary according to the ecology of the host, the nature of the infectious agent, and the individual itself. In this study, we investigated whether avoidance of contaminated food was associated with reduced parasite infection in sanctuary-housed bonobos. To do this, we used bonobos’ responses to soil- and fecally-contaminated food in behavioral experiments, and then compared the results with an estimate of protozoan infection across individuals. We found that avoidance of contaminated food correlated negatively with Balantioides coli infection, a potentially pathogenic protozoan transmitted through the fecal-oral route. The association between avoidance responses and parasitism were most evident in experiments in which subjects were offered a choice of food items falling along a gradient of fecal contamination. In the case of experiments with more limited options and a high degree of contamination, most subjects were averse to the presented food item and this may have mitigated any relationship between feeding decisions and infection. In experiments with low perceived levels of contamination, most subjects consumed previously contaminated food items, which may also have obscured such a relationship. The behavioral immunity observed may be a consequence of the direct effects of parasites (infection), reflecting the first scale of a landscape of disgust: individual responses. Indirect effects of parasites, such as modulation of feeding decisions and reduced social interactions—and their potential trade-offs with physiological immunity—are also discussed in light of individual fitness and primate evolution. This study builds on previous work by showing that avoidance behaviors may be effective in limiting exposure to a wide diversity of oro-fecally transmitted parasites.

scholarly journals Seasonal Temperature Fluctuations Differently Affect the Immune and Biochemical Parameters of Diploid and Triploid Oncorhynchus mykiss Cage-Cultured in Temperate Latitudes

2020 ◽  
Vol 12 (21) ◽  
pp. 8785 ◽  
Author(s):  
Andreia C. M. Rodrigues ◽  
Carlos Gravato ◽  
Carlos J. M. Silva ◽  
Sílvia F. S. Pires ◽  
Ana P. L. Costa ◽  
...  
Keyword(s):  
Oncorhynchus Mykiss ◽  
Energy Production ◽  
Antioxidant Defenses ◽  
Seasonal Temperature ◽  
Glutathione S Transferase ◽  
Blood Leukocytes ◽  
Individual Level ◽  
Trade Offs ◽  
Resistant Strains ◽  
The Individual

In the coming decades, and despite advances in the selection of resistant strains and the production of triploid organisms, the temperature could seriously affect salmonid aquaculture. Lower environmental tolerance has been hinted at for triploids, but the physiological mechanisms leading to such differences, and whether they are translated to the individual level, are poorly understood. This study aimed to evaluate the effects of seasonal variations on the humoral and immune status in the blood (peripheral blood leukocytes) and plasma (antiprotease, lysozyme and peroxidase activities), the oxidative stress (catalase, glutathione-S-transferase, total glutathione and lipid peroxidation) balance in the liver, and the energy budget (sugars, lipids, proteins and energy production) in the liver and muscle of diploid and triploid Oncorhynchus mykiss. Leukocytes’ numbers changed with the water temperature and differed between fish ploidies. Peroxidase activity was increased in the summer, but lysozyme and antiprotease activities were increased in the winter. Concomitantly, antioxidant defenses were significantly altered seasonally, increasing oxidative damage at higher temperatures. Moreover, warmer waters induced a reduction in the energy production measured in the liver. Differences in feed efficiency, which have been previously reported, were confirmed by the low lipid and protein contents of the muscle of the triploids. In sum, the inherent trade-offs to deal with the seasonal changes culminated in the higher growth observed for diploid fish.

scholarly journals The transformative service paradox: the dilemma of wellbeing trade-offs

2020 ◽  
Vol 31 (4) ◽  
pp. 637-663
Author(s):  
Rebekah Russell–Bennett ◽  
Rory Mulcahy ◽  
Kate Letheren ◽  
Ryan McAndrew ◽  
Uwe Dulleck
Keyword(s):  
Laboratory Experiment ◽  
Qualitative Interviews ◽  
Implicit Assumption ◽  
Trade Off ◽  
Content Type ◽  
Individual Level ◽  
Trade Offs ◽  
Physical Wellbeing ◽  
The Individual ◽  
Future Implication

PurposeA transformative service aims to improve wellbeing; however, current approaches have an implicit assumption that all wellbeing dimensions are equal and more dimensions led to higher wellbeing. The purpose of this paper is to present evidence for a new framework that identifies the paradox of competing wellbeing dimensions for both the individual and others in society – the transformative service paradox (TSP).Design/methodology/approachData is drawn from a mixed-method approach using qualitative (interviews) and quantitative data (lab experiment) in an electricity service context. The first study involves 45 household interviews (n = 118) and deals with the nature of trade-offs at the individual level to establish the concept of the TSP. The second study uses a behavioral economics laboratory experiment (n = 110) to test the self vs. other nature of the trade-off in day-to-day use of electricity.FindingsThe interviews and experiment identified that temporal (now vs. future) and beneficiary-level factors explain why individuals make wellbeing trade-offs for the transformative service of electricity. The laboratory experiment showed that when the future implication of the trade-off is made salient, consumers are more willing to forego physical wellbeing for environmental wellbeing, whereas when the “now” implication is more salient consumers forego financial wellbeing for physical wellbeing.Originality/valueThis research introduces the term “Transformative Service Paradox” and identifies two factors that explain why consumers make wellbeing trade-offs at the individual level and at the societal level; temporal (now vs. future) and wellbeing beneficiary.

scholarly journals Conformity in the collective: differences in hunger affect individual and group behavior in a shoaling fish

2019 ◽  
Vol 30 (4) ◽  
pp. 968-974 ◽  
Author(s):  
Alexander D M Wilson ◽  
Alicia L J Burns ◽  
Emanuele Crosato ◽  
Joseph Lizier ◽  
Mikhail Prokopenko ◽  
...  
Keyword(s):  
Collective Behavior ◽  
Nearest Neighbor ◽  
Collective Motion ◽  
Internal State ◽  
Group Behavior ◽  
Fundamental Interest ◽  
Individual Level ◽  
Group Members ◽  
The Individual ◽  
Nearest Neighbor Distances

Abstract Animal groups are often composed of individuals that vary according to behavioral, morphological, and internal state parameters. Understanding the importance of such individual-level heterogeneity to the establishment and maintenance of coherent group responses is of fundamental interest in collective behavior. We examined the influence of hunger on the individual and collective behavior of groups of shoaling fish, x-ray tetras (Pristella maxillaris). Fish were assigned to one of two nutritional states, satiated or hungry, and then allocated to 5 treatments that represented different ratios of satiated to hungry individuals (8 hungry, 8 satiated, 4:4 hungry:satiated, 2:6 hungry:satiated, 6:2 hungry:satiated). Our data show that groups with a greater proportion of hungry fish swam faster and exhibited greater nearest neighbor distances. Within groups, however, there was no difference in the swimming speeds of hungry versus well-fed fish, suggesting that group members conform and adapt their swimming speed according to the overall composition of the group. We also found significant differences in mean group transfer entropy, suggesting stronger patterns of information flow in groups comprising all, or a majority of, hungry individuals. In contrast, we did not observe differences in polarization, a measure of group alignment, within groups across treatments. Taken together these results demonstrate that the nutritional state of animals within social groups impacts both individual and group behavior, and that members of heterogenous groups can adapt their behavior to facilitate coherent collective motion.

scholarly journals Multidimensionality of gender ideology and relationships with gendered practices: an exploratory analysis across Europe in 2002 and 2012

2020 ◽  
Author(s):  
Heejung Chung ◽  
Pia S. Schober
Keyword(s):  
Gender Ideology ◽  
Division Of Labour ◽  
Gender Ideologies ◽  
Social Survey ◽  
Individual Level ◽  
Gender Culture ◽  
Country Level ◽  
The Family ◽  
The Individual ◽  
International Social

Many researchers assume a one-dimensionality of gender ideology constructs and/or stability of dimensions across countries and time, yet these assumptions have rarely been tested. WE apply factor analyses on two waves of the International Social Survey Programme in 2002 and 2012, and comparable European countries to test this. Our results show that gender ideologies can be distinguished into distinctive domains that relate to mother’s employment, women’s work, men’s role in the family, and finally women’s breadwinning. These dimensions have be found to be relatively stable across countries and time. Results from regression models investigating different aspects of the gender division of labour suggest that distinguishing dimensions is less important when considering gender ideologies at the individual level but can make a big difference when examining gender culture at the country level.

Internal head morphology of minor workers and soldiers in the hyperdiverse ant genus Pheidole

2018 ◽  
Vol 96 (5) ◽  
pp. 383-392 ◽  
Author(s):  
Angelica Lillico-Ouachour ◽  
Brian Metscher ◽  
Tominari Kaji ◽  
Ehab Abouheif
Keyword(s):  
Nervous System ◽  
Three Dimensional ◽  
Division Of Labour ◽  
Digestive Organ ◽  
Internal Anatomy ◽  
Individual Level ◽  
Organ Volume ◽  
Trade Offs ◽  
Alternative Hypotheses ◽  
Microct Imaging

In the hyperdiverse ant genus Pheidole Westwood, 1839, the worker caste evolved into two morphologically distinct subcastes: minor workers and soldiers. The evolution of soldiers, which are larger in size than minor workers and have disproportionately larger heads, are thought to be key to Phediole’s success. Although many studies have focused on external anatomy, little is known about their internal anatomy. We therefore used microCT imaging and quantitative three-dimensional image analysis to reconstruct the major glands of the head, the musculature, nervous system, and digestive organ of minor workers and soldiers of four Pheidole species. We expected these tissues to scale isometrically and to be proportionally larger in soldiers relative to the minor workers. Surprisingly, we found that the nervous system, cephalic gland, and digestive organ volume are absolutely and relatively smaller in soldiers, whereas muscle volume is absolutely and relatively larger, than in minor workers. This may reflect individual-level trade-offs, where muscles grow at the expense of all other cephalic organs. Alternatively, this relationship may reflect the specialization of internal anatomy in each subcaste to enhance division of labour at the colony level. Future studies should test these alternative hypotheses across a larger number of Pheidole species.

scholarly journals Identifying Causes of Social Evolution: Contextual Analysis, the Price Approach, and Multilevel Selection

2021 ◽  
Vol 9 ◽  
Author(s):  
Christoph Thies ◽  
Richard A. Watson
Keyword(s):  
Kin Selection ◽  
Causal Structure ◽  
Multilevel Selection ◽  
Contextual Analysis ◽  
Price Equation ◽  
Evolutionary Transitions ◽  
Selection Theory ◽  
Individual Fitness ◽  
Multilevel Selection Theory ◽  
The Individual

Kin selection theory and multilevel selection theory are distinct approaches to explaining the evolution of social traits. The latter claims that it is useful to regard selection as a process that can occur on multiple levels of organisation such as the level of individuals and the level of groups. This is reflected in a decomposition of fitness into an individual component and a group component. This multilevel view is central to understanding and characterising evolutionary transitions in individuality, e.g., from unicellular life to multicellular organisms, but currently suffers from the lack of a consistent, quantifiable measure. Specifically, the two major statistical tools to determine the coefficients of such a decomposition, the multilevel Price equation and contextual analysis, are inconsistent and may disagree on whether group selection is present. Here we show that the reason for the discrepancies is that underlying the multilevel Price equation and contextual analysis are two non-equivalent causal models for the generation of individual fitness effects (thus leaving different “remainders” explained by group effects). While the multilevel Price equation assumes that the individual effect of a trait determines an individual's relative success within a group, contextual analysis posits that the individual effect is context-independent. Since these different assumptions reflect claims about the causal structure of the system, the correct approach cannot be determined on general theoretical or statistical grounds but must be identified by experimental intervention. We outline interventions that reveal the underlying causal structure and thus facilitate choosing the appropriate approach. We note that kin selection theory with its focus on the individual is immune to such inconsistency because it does not address causal structure with respect to levels of organisation. In contrast, our analysis of the two approaches to measuring group selection demonstrates that multilevel selection theory adds meaningful (falsifiable) causal structure to explain the sources of individual fitness and thereby constitutes a proper refinement of kin selection theory. Taking such refined causal structure into account seems indispensable for studying evolutionary transitions in individuality because these transitions are characterised by changes in the selection pressures that act on the respective levels.

scholarly journals A small number of workers with specific personality traits perform tool use in ants

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
István Maák ◽  
Garyk Roelandt ◽  
Patrizia d'Ettorre
Keyword(s):  
Personality Traits ◽  
Tool Use ◽  
Division Of Labour ◽  
Exploratory Activity ◽  
Liquid Food ◽  
Personality Tests ◽  
Individual Level ◽  
Aphaenogaster Senilis ◽  
Individual Personality ◽  
The Individual

Ants use debris as tools to collect and transport liquid food to the nest. Previous studies showed that this behaviour is flexible whereby ants learn to use artificial material that is novel to them and select tools with optimal soaking properties. However, the process of tool use has not been studied at the individual level. We investigated whether workers specialise in tool use and whether there is a link between individual personality traits and tool use in the ant Aphaenogaster senilis. Only a small number of workers performed tool use and they did it repeatedly, although they also collected solid food. Personality predicted the probability to perform tool use: ants that showed higher exploratory activity and were more attracted to a prey in the personality tests became the new tool users when previous tool users were removed from the group. This suggests that, instead of extreme task specialisation, variation in personality traits within the colony may improve division of labour.

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