scholarly journals Cryptic lineages hybridize for worker production in the harvester ant Messor barbarus

2016 ◽  
Vol 12 (11) ◽  
pp. 20160542 ◽  
Author(s):  
Victoria Norman ◽  
Hugo Darras ◽  
Christopher Tranter ◽  
Serge Aron ◽  
William O. H. Hughes
Keyword(s):  
Reproductive System ◽  
Division Of Labour ◽  
Insect Larvae ◽  
Messor Barbarus ◽  
Harvester Ant ◽  
Mitochondrial Data ◽  
Genetic Caste Determination ◽  
Worker Castes ◽  
Genetically Determined ◽  
Reproductive Division

The reproductive division of labour between queen and worker castes in social insects is a defining characteristic of eusociality and a classic example of phenotypic plasticity. Whether social insect larvae develop into queens or workers has long been thought to be determined by environmental cues, i.e. larvae are developmentally totipotent. Contrary to this paradigm, several recent studies have revealed that caste is determined by genotype in some ant species, but whether this is restricted to just a few exceptional species is still unclear. Here, we show that the Mediterranean harvester ant Messor barbarus possesses an unusual reproductive system, in which the female castes are genetically determined. Using both nuclear and mitochondrial data, we show that Iberian populations have two distinct, cryptic lineages. Workers are always inter-lineage hybrids whereas queens are always produced from pure-lineage matings. The results suggest that genetic caste determination may be more widespread in ants than previously thought, and that further investigation in other species is needed to understand the frequency and evolution of this remarkable reproductive system.

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 Identification of an ant queen pheromone regulating worker sterility

2010 ◽  
Vol 277 (1701) ◽  
pp. 3793-3800 ◽  
Author(s):  
Luke Holman ◽  
Charlotte G. Jørgensen ◽  
John Nielsen ◽  
Patrizia d'Ettorre
Keyword(s):  
Evolutionary Biology ◽  
Cuticular Hydrocarbon ◽  
Division Of Labour ◽  
Queen Pheromone ◽  
Lasius Niger ◽  
Strong Response ◽  
Selective Forces ◽  
The Right ◽  
Worker Sterility ◽  
Reproductive Division

The selective forces that shape and maintain eusocial societies are an enduring puzzle in evolutionary biology. Ordinarily sterile workers can usually reproduce given the right conditions, so the factors regulating reproductive division of labour may provide insight into why eusociality has persisted over evolutionary time. Queen-produced pheromones that affect worker reproduction have been implicated in diverse taxa, including ants, termites, wasps and possibly mole rats, but to date have only been definitively identified in the honeybee. Using the black garden ant Lasius niger , we isolate the first sterility-regulating ant queen pheromone. The pheromone is a cuticular hydrocarbon that comprises the majority of the chemical profile of queens and their eggs, and also affects worker behaviour, by reducing aggression towards objects bearing the pheromone. We further show that the pheromone elicits a strong response in worker antennae and that its production by queens is selectively reduced following an immune challenge. These results suggest that the pheromone has a central role in colony organization and support the hypothesis that worker sterility represents altruistic self-restraint in response to an honest quality signal.

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.

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