scholarly journals Eusociality through conflict dissolution

2021 ◽  
Vol 288 (1949) ◽  
Author(s):  
Mauricio González-Forero ◽  
Jorge Peña
Keyword(s):  
Division Of Labour ◽  
Worker Reproduction ◽  
Maternal Influence ◽  
Dissolution Mechanism ◽  
Evolutionary Transition ◽  
Evolutionary Time ◽  
Trade Offs ◽  
Reproductive Division Of Labour ◽  
Reproductive Division ◽  
General Explanation

Eusociality, where largely unreproductive offspring help their mothers reproduce, is a major form of social organization. An increasingly documented feature of eusociality is that mothers induce their offspring to help by means of hormones, pheromones or behavioural displays, with evidence often indicating that offspring help voluntarily. The co-occurrence of maternal influence and offspring voluntary help may be explained by what we call the converted helping hypothesis, whereby maternally manipulated helping subsequently becomes voluntary. Such hypothesis requires that parent-offspring conflict is eventually dissolved—for instance, if the benefit of helping increases sufficiently over evolutionary time. We show that help provided by maternally manipulated offspring can enable the mother to sufficiently increase her fertility to transform parent-offspring conflict into parent-offspring agreement. This conflict-dissolution mechanism requires that helpers alleviate maternal life-history trade-offs, and results in reproductive division of labour, high queen fertility and honest queen signalling suppressing worker reproduction—thus exceptionally recovering diverse features of eusociality. As such trade-off alleviation seemingly holds widely across eusocial taxa, this mechanism offers a potentially general explanation for the origin of eusociality, the prevalence of maternal influence, and the offspring’s willingness to help. Overall, our results explain how a major evolutionary transition can happen from ancestral conflict.

scholarly journals Eusociality through conflict dissolution

2020 ◽  
Author(s):  
Mauricio González-Forero ◽  
Jorge Peña
Keyword(s):  
Worker Reproduction ◽  
Maternal Influence ◽  
Dissolution Mechanism ◽  
Evolutionary Transition ◽  
Evolutionary Time ◽  
Trade Off ◽  
Maternal Manipulation ◽  
Reproductive Division Of Labor ◽  
Reproductive Division ◽  
General Explanation

AbstractEusociality, where largely unreproductive offspring help their mothers reproduce, is a major form of social organization in social insects and other animals. An increasingly documented feature of eusociality is that mothers induce their offspring to help by means of hormones, pheromones, or behavioral displays, with evidence often indicating that offspring help voluntarily. The co-occurrence of widespread maternal influence and voluntary offspring help may be explained by what we call the converted helping hypothesis, whereby helping originally arising from maternal manipulation subsequently becomes voluntary. This hypothesis requires that parent-offspring conflict is eventually dissolved—for instance, if the benefit of helping increases sufficiently over evolutionary time. Here we show that maternal manipulation of offspring help enables the mother to increase her fertility to such extent that parent-offspring conflict is transformed into parent-offspring agreement. Such conflict dissolution mechanism requires that helpers alleviate the total percent life-history trade-off limiting maternal fertility, and results in reproductive division of labor, high queen fertility, and honest queen signaling suppressing worker reproduction, thus exceptionally recovering diverse features of eusociality. This mechanism is widely applicable, thus suggesting a general explanation for the origin of eusociality, the prevalence of maternal influence, and the offspring’s willingness to help. Overall, our results explain how a major evolutionary transition can happen from ancestral conflict.

scholarly journals Conserved queen pheromones in bumblebees: A reply to Amsalem et al.

2016 ◽  
Author(s):  
Luke Holman ◽  
Jelle S van Zweden ◽  
Ricardo Caliari Oliveira ◽  
Annette van Oystaeyen ◽  
Tom Wenseleers
Keyword(s):  
Statistical Tests ◽  
Cuticular Hydrocarbon ◽  
Division Of Labour ◽  
Queen Pheromone ◽  
Worker Reproduction ◽  
Egg Laying ◽  
False Negatives ◽  
Evolutionarily Conserved ◽  
Reproductive Division Of Labour ◽  
Reproductive Division

In a recent study, Amsalem et al. performed experiments with Bombus impatiens bumblebees to test the hypothesis that saturated cuticular hydrocarbons are evolutionarily conserved signals used to regulate reproductive division of labour in many Hymenopteran social insects. They concluded that the cuticular hydrocarbon pentacosane (C25), previously identified as a queen pheromone in a congeneric bumblebee, does not affect worker reproduction in B. impatiens. Here we identify some significant shortcomings of Amsalem et al.’s study that make its conclusions unreliable. In particular, inappropriate statistical tests were used, and a reanalysis of their dataset found that C25 substantially reduced and delayed worker egg laying in B. impatiens. Additionally, the study’s low sample sizes (mean n per treatment = 13.6, range: 4-23) give it low power, not 99% power as claimed, meaning that some its non-significant results may be false negatives. Additionally, several confounding effects may have affected the results of both experimental manipulations in the study

scholarly journals A conserved class of queen pheromones? Re-evaluating the evidence in bumblebees ( Bombus impatiens )

2015 ◽  
Vol 282 (1817) ◽  
pp. 20151800 ◽  
Author(s):  
Etya Amsalem ◽  
Margarita Orlova ◽  
Christina M. Grozinger
Keyword(s):  
Bombus Terrestris ◽  
Division Of Labour ◽  
Queen Pheromone ◽  
Worker Reproduction ◽  
Egg Laying ◽  
Bombus Impatiens ◽  
Queen Pheromones ◽  
Reproductive Division Of Labour ◽  
Reproductive Division ◽  
Adult Exposure

The regulation of reproductive division of labour is a key component in the evolution of social insects. Chemical signals are important mechanisms to regulate worker reproduction, either as queen-produced pheromones that coercively inhibit worker reproduction or as queen signals that honestly advertise her fecundity. A recent study suggested that a conserved class of hydrocarbons serve as queen pheromones across three independent origins of eusociality. In bumblebees ( Bombus terrestris ), pentacosane ( C 25) was suggested to serve as a queen pheromone. Here, we repeat these studies using a different species of bumblebee ( Bombus impatiens ) with a more controlled experimental design. Instead of dequeened colonies, we used same-aged, three-worker queenless groups comprising either experienced or naive workers (with/without adult exposure to queen pheromone). We quantified three hydrocarbons ( C 23, C 25 and C 27) on the cuticular surfaces of females and tested their effects on the two worker types. Our results indicate differences in responses of naive and experienced workers, genetic effects on worker reproduction, and general effects of hydrocarbons and duration of egg laying on ovary resorption rates. However, we found no evidence to support the theory that a conserved class of hydrocarbons serve as queen pheromones or queen signals in Bombus impatiens .

scholarly journals Methylation and worker reproduction in the bumble-bee ( Bombus terrestris )

2014 ◽  
Vol 281 (1780) ◽  
pp. 20132502 ◽  
Author(s):  
Harindra E. Amarasinghe ◽  
Crisenthiya I. Clayton ◽  
Eamonn B. Mallon
Keyword(s):  
Genomic Imprinting ◽  
Social Insects ◽  
Social Insect ◽  
Bombus Terrestris ◽  
Division Of Labour ◽  
Worker Reproduction ◽  
Bumble Bee ◽  
Reproductive Division Of Labour ◽  
Reproductive Division

Insects are at the dawn of an epigenetics era. Numerous social insect species have been found to possess a functioning methylation system, previously not thought to exist in insects. Methylation, an epigenetic tag, may be vital for the sociality and division of labour for which social insects are renowned. In the bumble-bee Bombus terrestris , we found methylation differences between the genomes of queenless reproductive workers and queenless non-reproductive workers. In a follow up experiment, queenless workers whose genomes had experimentally altered methylation were more aggressive and more likely to develop ovaries compared with control queenless workers. This shows methylation is important in this highly plastic reproductive division of labour. Methylation is an epigenetic tag for genomic imprinting (GI). It is intriguing that the main theory to explain the evolution of GI predicts that GI should be important in this worker reproduction behaviour.

scholarly journals Conserved queen pheromones in bumblebees: A reply to Amsalem et al.

2016 ◽  
Author(s):  
Luke Holman ◽  
Jelle S van Zweden ◽  
Ricardo Caliari Oliveira ◽  
Annette van Oystaeyen ◽  
Tom Wenseleers
Keyword(s):  
Statistical Tests ◽  
Cuticular Hydrocarbon ◽  
Division Of Labour ◽  
Queen Pheromone ◽  
Worker Reproduction ◽  
Egg Laying ◽  
False Negatives ◽  
Evolutionarily Conserved ◽  
Reproductive Division Of Labour ◽  
Reproductive Division

In a recent study, Amsalem et al. performed experiments with Bombus impatiens bumblebees to test the hypothesis that saturated cuticular hydrocarbons are evolutionarily conserved signals used to regulate reproductive division of labour in many Hymenopteran social insects. They concluded that the cuticular hydrocarbon pentacosane (C25), previously identified as a queen pheromone in a congeneric bumblebee, does not affect worker reproduction in B. impatiens. Here we identify some significant shortcomings of Amsalem et al.’s study that make its conclusions unreliable. In particular, inappropriate statistical tests were used, and a reanalysis of their dataset found that C25 substantially reduced and delayed worker egg laying in B. impatiens. Additionally, the study’s low sample sizes (mean n per treatment = 13.6, range: 4-23) give it low power, not 99% power as claimed, meaning that some its non-significant results may be false negatives. Additionally, several confounding effects may have affected the results of both experimental manipulations in the study

scholarly journals Adaptation and the genetics of social behaviour

2009 ◽  
Vol 364 (1533) ◽  
pp. 3209-3216 ◽  
Author(s):  
Laurent Keller
Keyword(s):  
Social Behaviour ◽  
Social Evolution ◽  
Division Of Labour ◽  
Chemical Signalling ◽  
Insect Societies ◽  
Genetic Mechanisms ◽  
Selective Forces ◽  
Group Members ◽  
Reproductive Division Of Labour ◽  
Reproductive Division

In recent years much progress has been made towards understanding the selective forces involved in the evolution of social behaviour including conflicts over reproduction among group members. Here, I argue that an important additional step necessary for advancing our understanding of the resolution of potential conflicts within insect societies is to consider the genetics of the behaviours involved. First, I discuss how epigenetic modifications of behaviour may affect conflict resolution within groups. Second, I review known natural polymorphisms of social organization to demonstrate that a lack of consideration of the genetic mechanisms involved may lead to erroneous explanations of the adaptive significance of behaviour. Third, I suggest that, on the basis of recent genetic studies of sexual conflict in Drosophila , it is necessary to reconsider the possibility of within-group manipulation by means of chemical substances (i.e. pheromones). Fourth, I address the issue of direct versus indirect genetic effects, which is of particular importance for the study of behaviour in social groups. Fifth, I discuss the issue of how a genetic influence on dominance hierarchies and reproductive division of labour can have secondary effects, for example in the evolution of promiscuity. Finally, because the same sets of genes (e.g. those implicated in chemical signalling and the responses that are triggered) may be used even in species as divergent as ants, cooperative breeding birds and primates, an integration of genetic mechanisms into the field of social evolution may also provide unifying ideas.

scholarly journals Does the evolution of division of labour require accelerating returns from individual specialisation?

2021 ◽  
Author(s):  
Guy Cooper ◽  
Hadleigh Frost ◽  
Ming Liu ◽  
Stuart West
Keyword(s):  
Group Structure ◽  
Natural World ◽  
Division Of Labour ◽  
Recent Theory ◽  
Topological Constraints ◽  
Initial Evolution ◽  
Individual Specialisation ◽  
Reproductive Division Of Labour ◽  
Reproductive Division ◽  
Structure Division

Recent theory has overturned the assumption that accelerating returns from individual specialisation are required to favour the evolution of division of labour. Yanni et al. (2020) showed that topologically constrained groups, where cells cooperate with only direct neighbours such as for filaments or branching growths, can evolve a reproductive division of labour even with diminishing returns from individual specialisation. We developed a conceptual framework and specific models to investigate the factors that can favour the initial evolution of reproductive division of labour. We found that selection for division of labour in topologically constrained groups: (1) is not a single mechanism to favour division of labour – depending upon details of the group structure, division of labour can be favoured for different reasons; (2) always involves an efficiency benefit at the level of group fitness; and (3) requires a mechanism of coordination to determine which individuals perform which tasks. Given that such coordination is unlikely to evolve before division of labour, this limits the extent to which topological constraints could have favoured the initial evolution of division of labour. We conclude by suggesting experimental designs that could determine why division of labour is favoured in the natural world.

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