scholarly journals The evolution of eusociality in allodapine bees: workers began by waiting

2010 ◽  
Vol 7 (2) ◽  
pp. 277-280 ◽  
Author(s):  
Michael P. Schwarz ◽  
Simon M. Tierney ◽  
Sandra M. Rehan ◽  
Luke B. Chenoweth ◽  
Steven J. B. Cooper
Keyword(s):  
Social Evolution ◽  
Early Step ◽  
Social Hierarchies ◽  
Insurance Benefits ◽  
Brood Rearing ◽  
Evolution Of Eusociality ◽  
Dual Constraints ◽  
Worker Castes ◽  
Worker Caste ◽  
Evo Devo

Understanding how sterile worker castes in social insects first evolved is one of the supreme puzzles in social evolution. Here, we show that in the bee tribe Allodapini, the earliest societies did not entail a foraging worker caste, but instead comprised females sharing a nest with supersedure of dominance. Subordinates delayed foraging until they became reproductively active, whereupon they provided food for their own brood as well as for those of previously dominant females. The earliest allodapine societies are, therefore, not consistent with an ‘evo-devo’ paradigm, where decoupling of foraging and reproductive tasks is proposed as a key early step in social evolution. Important features of these ancestral societies were insurance benefits for dominants, headstart benefits for subordinates and direct reproduction for both. The two lineages where morphologically distinct foraging worker castes evolved both occur in ecosystems with severe constraints on independent nesting and where brood rearing periods are very seasonally restricted. These conditions would have strongly curtailed dispersal options and increased the likelihood that dominance supersedure occurred after brood rearing opportunities were largely degraded. The origins of foraging castes, therefore, represented a shift towards assured fitness gains by subordinates, mediated by the dual constraints of social hierarchies and environmental harshness.

scholarly journals The validity and value of inclusive fitness theory

2011 ◽  
Vol 278 (1723) ◽  
pp. 3313-3320 ◽  
Author(s):  
Andrew F. G. Bourke
Keyword(s):  
Kin Selection ◽  
Evolutionary Biology ◽  
Social Evolution ◽  
Inclusive Fitness ◽  
Evidence Base ◽  
Alternative Theory ◽  
Selection Theory ◽  
Inclusive Fitness Theory ◽  
Evolution Of Eusociality ◽  
Natural Selection Theory

Social evolution is a central topic in evolutionary biology, with the evolution of eusociality (societies with altruistic, non-reproductive helpers) representing a long-standing evolutionary conundrum. Recent critiques have questioned the validity of the leading theory for explaining social evolution and eusociality, namely inclusive fitness (kin selection) theory. I review recent and past literature to argue that these critiques do not succeed. Inclusive fitness theory has added fundamental insights to natural selection theory. These are the realization that selection on a gene for social behaviour depends on its effects on co-bearers, the explanation of social behaviours as unalike as altruism and selfishness using the same underlying parameters, and the explanation of within-group conflict in terms of non-coinciding inclusive fitness optima. A proposed alternative theory for eusocial evolution assumes mistakenly that workers' interests are subordinate to the queen's, contains no new elements and fails to make novel predictions. The haplodiploidy hypothesis has yet to be rigorously tested and positive relatedness within diploid eusocial societies supports inclusive fitness theory. The theory has made unique, falsifiable predictions that have been confirmed, and its evidence base is extensive and robust. Hence, inclusive fitness theory deserves to keep its position as the leading theory for social evolution.

Social Behaviour in an Australian Allodapine Bee Exoneura (Brevineura) xanthoclypeata (Hymenoptera : Apidae)

1997 ◽  
Vol 45 (4) ◽  
pp. 385 ◽  
Author(s):  
Simon M. Tierney ◽  
Michael P. Schwarz ◽  
M. Adams
Keyword(s):  
Social Behaviour ◽  
Social Evolution ◽  
Extended Period ◽  
Sensu Stricto ◽  
Extensive Study ◽  
Egg Laying ◽  
Brood Production ◽  
Brood Rearing ◽  
Reproductive Differentiation ◽  
Two Factors

The allodapine bees are well suited for comparative studies of social evolution because of the wide variation in social behaviour within and between genera. There are three main clades in the endemic Australian genus Exoneura. Two groups (Exoneura sensu stricto and Exoneurella) have received extensive study. In this paper we provide the first detailed study of social behaviour in the third group, Brevineura, based on a heathland population of Exoneura (B.) xanthoclypeata Rayment. This species has two seasonal pulses of egg-laying and brood rearing occurs throughout most of the year, including winter. This extended period of egg-laying and brood development differs from the two other Australian Exoneura subgenera and provides extensive opportunities for eusocial-like sib-rearing. Dissection data indicate that reproductive differentiation among adult nestmates is well developed and dependent on body size, with smaller females being mostly or entirely non-reproductive. Per capita brood production is dramatically higher in multi-female nests than in single-female nests and relatedness between adult nestmates is moderately high (r ≈ 0·5). These two factors suggest that local fitness enhancement may be occurring and our limited sex allocation data suggest female-biased ratios. Because of the opportunities for sib-rearing in this species, local fitness enhancement has the potential to lower selective thresholds for eusociality.

scholarly journals Recombination mapping of the Brazilian stingless bee Frieseomelitta varia confirms high recombination rates in social hymenoptera

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Prashant Waiker ◽  
Fabiano Carlos Pinto de Abreu ◽  
Danielle Luna-Lucena ◽  
Flávia Cristina Paula Freitas ◽  
Zilá Luz Paulino Simões ◽  
...  
Keyword(s):  
Linkage Map ◽  
Social Evolution ◽  
Stingless Bee ◽  
Recombination Rates ◽  
Social Hymenoptera ◽  
Social Species ◽  
A Genome ◽  
Study Results ◽  
Worker Caste ◽  
Genomic Recombination

Abstract Background Meiotic recombination is a fundamental genetic process that shuffles allele combinations and promotes accurate segregation of chromosomes. Analyses of the ubiquitous variation of recombination rates within and across species suggest that recombination is evolving adaptively. All studied insects with advanced eusociality have shown exceptionally high recombination rates, which may represent a prominent case of adaptive evolution of recombination. However, our understanding of the relationship between social evolution and recombination rates is incomplete, partly due to lacking empirical data. Here, we present a linkage map of the monandrous, advanced eusocial Brazilian stingless bee, Frieseomelitta varia, providing the first recombination analysis in the diverse Meliponini (Hymenoptera, Apidae). Results Our linkage map includes 1417 markers in 19 linkage groups. This map spans approximately 2580 centimorgans, and comparisons to the physical genome assembly indicate that it covers more than 75 % of the 275 Megabasepairs (Mbp) F. varia genome. Thus, our study results in a genome-wide recombination rate estimate of 9.3–12.5 centimorgan per Mbp. This value is higher than estimates from nonsocial insects and comparable to other highly social species, although it does not support our prediction that monandry and strong queen-worker caste divergence of F. varia lead to even higher recombination rates than other advanced eusocial species. Conclusions Our study expands the association between elevated recombination and sociality in the order Hymenoptera and strengthens the support for the hypothesis that advanced social evolution in hymenopteran insects invariably selects for high genomic recombination rates.

scholarly journals Epigenetics in Social Insects: A New Direction for Understanding the Evolution of Castes

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Susan A. Weiner ◽  
Amy L. Toth
Keyword(s):  
Dna Methylation ◽  
Social Insects ◽  
Differential Methylation ◽  
Caste Determination ◽  
The Social ◽  
Worker Castes ◽  
Regulatory Flexibility ◽  
Worker Caste ◽  
Caste Differences ◽  
Epigenetic Research

Epigenetic modifications to DNA, such as DNA methylation, can expand a genome’s regulatory flexibility, and thus may contribute to the evolution of phenotypic plasticity. Recent work has demonstrated the importance of DNA methylation in alternative queen and worker “castes” in social insects, particularly honeybees. Social insects are an excellent system for addressing questions about epigenetics and evolution because: (1) they have dramatic caste polyphenisms that appear to be tied to differential methylation, (2) DNA methylation is widespread in various groups of social insects, and (3) there are intriguing connections between the social environment and DNA methylation in many species, from insects to mammals. In this article, we review research on honeybees, and, when available, other social insects, on DNA methylation and queen and worker caste differences. We outline a conceptual framework for the effects of methylation on caste determination in honeybees that may help guide studies of epigenetic regulation in other polyphenic taxa. Finally, we suggest future paths of study for social insect epigenetic research, including the importance of comparative studies of DNA methylation on a broader range of species, and highlight some key unanswered mechanistic questions about how DNA methylation affects gene regulation.

Biology of a weakly social bee, Exoneura (Exoneurella) setosa (Hymenoptera : Apidae) and implications for social evolution in Australian allodapine bees

1998 ◽  
Vol 46 (3) ◽  
pp. 221 ◽  
Author(s):  
Tania Neville ◽  
Michael P. Schwarz ◽  
Simon M. Tierney
Keyword(s):  
Group Size ◽  
Social Evolution ◽  
Sensu Stricto ◽  
Brood Production ◽  
Brood Rearing ◽  
Large Group ◽  
Basal Position ◽  
Social Bee

Australian allodapine bees provide excellent material for comparative approaches to understanding social evolution. The subgenus Exoneurella occupies a cladistically basal position in the Australian Exoneura group and comprises only four species. We describe sociality in one Exoneurella species, E. setosa, and combine this with other data to infer some patterns of social evolution in allodapines. E. setosa rears a first brood solitarily, although staggered brood production and the production of a second brood in some nests leads to a situation where older, recently emerged brood have the ability to help rear their younger siblings and this overlaps with opportunities to lay eggs. This is similar to the situation for two other phylogenetically distal species of Exoneurella, as well as for members of the genus Braunsapis, which is used as an outgroup for Exoneura. When combined with other studies, our results suggest that the opportunity for sib-rearing is a plesiomorphic trait for Australian allodapines and this has been largely lost in a distal subgenus, Exoneura sensu stricto. Instead, multifemale brood-rearing colonies in this latter group mostly comprise individuals of the same generation, and species exhibit large group size, univoltinism and kin cofounding. This suggests that evolution can favour semisociality and quasisociality, even when eusociality has already arisen.

scholarly journals Morphological evolution in the ant reproductive caste

2020 ◽  
Author(s):  
Raquel Divieso ◽  
Thiago S. R. Silva ◽  
Marcio R. Pie
Keyword(s):  
Body Size ◽  
Morphological Variation ◽  
Morphological Evolution ◽  
Division Of Labour ◽  
Comprehensive Treatment ◽  
Size Distributions ◽  
Reproductive Division Of Labour ◽  
Evolution Of Eusociality ◽  
Worker Caste ◽  
Reproductive Division

AbstractThe evolution of eusociality led to severe changes in the general hymenopteran body plan. In particular, the evolution of reproductive division of labour caused the worker caste to be largely freed from the demands involved in reproduction. As a consequence, workers were able to evolve highly specialized morphologies for foraging and colony maintenance, whereas the reproductive caste became specialized for reproduction. Despite these important changes, little is known about general patterns of morphological evolution within the ant reproductive caste. Our goals were to characterize morphological variation in the ant reproductive caste and to test whether different sexes display variation in their evolutionary rates. We obtained measurements of 897 specimens from a total of 678 ant species. The shapes of the size distributions were similar between sexes, with queens being larger than males in all traits except for eye length. Contrary to the expectation based on Rensch’s rule, although queens were larger, the degree of dimorphism increased with body size. Finally, there is strong evidence for an accelerated tempo of morphological evolution in queens in relation to males. These results represent the first comprehensive treatment of morphological variation in the ant reproductive caste and provide important new insights into their evolution.

scholarly journals Morphological evolution in the ant reproductive caste

2020 ◽  
Vol 131 (3) ◽  
pp. 465-475
Author(s):  
Raquel Divieso ◽  
Thiago S R Silva ◽  
Marcio R Pie
Keyword(s):  
Body Size ◽  
Morphological Variation ◽  
Morphological Evolution ◽  
Division Of Labour ◽  
Comprehensive Treatment ◽  
Size Distributions ◽  
Reproductive Division Of Labour ◽  
Evolution Of Eusociality ◽  
Worker Caste ◽  
Reproductive Division

Abstract The evolution of eusociality has led to considerable changes in the general hymenopteran body plan. In particular, the evolution of reproductive division of labour caused the worker caste to be largely freed from the demands involved in reproduction. As a consequence, workers were able to evolve highly specialized morphologies for foraging and colony maintenance, whereas the reproductive caste became specialized for reproduction. Despite these important changes, little is known about the general patterns of morphological evolution within the ant reproductive caste. Our goals here were to characterize morphological variation in the ant reproductive caste and to test whether different sexes display variation in their evolutionary rates. We obtained measurements of 897 specimens from a total of 678 ant species. The shapes of the size distributions were similar between sexes, with queens being larger than males in all traits except for eye length. Contrary to the expectation based on Rensch’s rule, although queens were larger, the degree of dimorphism increased with body size. Finally, there was strong evidence for an accelerated tempo of morphological evolution in queens in relation to males. These results represent the first comprehensive treatment of morphological variation in the ant reproductive caste and provide important new insights into their evolution.

scholarly journals The network motif architecture of dominance hierarchies

2015 ◽  
Vol 12 (105) ◽  
pp. 20150080 ◽  
Author(s):  
Daizaburo Shizuka ◽  
David B. McDonald
Keyword(s):  
Network Analysis ◽  
Social Evolution ◽  
Network Motif ◽  
Motif Analysis ◽  
Social Hierarchies ◽  
Dominance Hierarchies ◽  
High Frequencies ◽  
Dominance Relations ◽  
The Past ◽  
Two Factors

The widespread existence of dominance hierarchies has been a central puzzle in social evolution, yet we lack a framework for synthesizing the vast empirical data on hierarchy structure in animal groups. We applied network motif analysis to compare the structures of dominance networks from data published over the past 80 years. Overall patterns of dominance relations, including some aspects of non-interactions, were strikingly similar across disparate group types. For example, nearly all groups exhibited high frequencies of transitive triads, whereas cycles were very rare. Moreover, pass-along triads were rare, and double-dominant triads were common in most groups. These patterns did not vary in any systematic way across taxa, study settings (captive or wild) or group size. Two factors significantly affected network motif structure: the proportion of dyads that were observed to interact and the interaction rates of the top-ranked individuals. Thus, study design (i.e. how many interactions were observed) and the behaviour of key individuals in the group could explain much of the variations we see in social hierarchies across animals. Our findings confirm the ubiquity of dominance hierarchies across all animal systems, and demonstrate that network analysis provides new avenues for comparative analyses of social hierarchies.

scholarly journals Genomic signature of kin selection in an ant with obligately sterile workers

2016 ◽  
Author(s):  
Michael R. Warner ◽  
Alexander S. Mikheyev ◽  
Timothy A. Linksvayer
Keyword(s):  
Kin Selection ◽  
Social Evolution ◽  
Genomic Signature ◽  
Evolution Of Cooperation ◽  
Comparative Genomic ◽  
Genome Wide ◽  
Theoretical Predictions ◽  
Approaches To Study ◽  
Worker Caste ◽  
Upregulated Genes

AbstractKin selection is thought to drive the evolution of cooperation and conflict, but the specific genes and genome-wide patterns shaped by kin selection are unknown. We identified thousands of genes associated with the sterile ant worker caste, the archetype of an altruistic phenotype shaped by kin selection, and then used population and comparative genomic approaches to study patterns of molecular evolution at these genes. Consistent with population genetic theoretical predictions, worker-upregulated genes showed relaxed adaptive evolution compared to genes upregulated in reproductive castes. Worker-upregulated genes included more taxonomically-restricted genes, indicating that the worker caste has recruited more novel genes, yet these genes also showed relaxed selection. Our study identifies a putative genomic signature of kin selection and helps to integrate emerging sociogenomic data with longstanding social evolution theory.

scholarly journals A Morphological Integration Perspective on the Evolution of Dimorphism among Sexes and Social Insect Castes

2019 ◽  
Vol 59 (2) ◽  
pp. 410-419 ◽  
Author(s):  
Nicholas R Friedman ◽  
Vladimír Remeš ◽  
Evan P Economo
Keyword(s):  
Reproductive Strategies ◽  
Social Insect ◽  
Morphological Integration ◽  
Negative Association ◽  
Head Shape ◽  
Minor Worker ◽  
Independent Variation ◽  
Males And Females ◽  
Worker Castes ◽  
Worker Caste

Abstract Many species have evolved alternate phenotypes, thus enabling individuals to conditionally produce phenotypes that are favorable for reproductive success. Examples of this phenomenon include sexual dimorphism, alternative reproductive strategies, and social insect castes. While the evolutionary functions and developmental mechanisms of dimorphic phenotypes have been studied extensively, little attention has focused on the evolutionary covariance between each phenotype. We extend the conceptual framework and methods of morphological integration to hypothesize that dimorphic traits tend to be less integrated between sexes or social castes. In the case of social insects, we describe results from our recent study of an ant genus in which workers have major and minor worker castes that perform different behavioral repertoires in and around the nest. In the case of birds, we describe a new analysis of a family of songbirds that exhibits plumage coloration that can differ greatly between males and females, with apparently independent changes in each sex. Ant head shape, which is highly specialized in each worker caste, was weakly integrated between worker castes, whereas thorax shape, which is more monomorphic, was tightly integrated. Similarly, in birds, we found a negative association between dimorphism and the degree of integration between sexes. We also found that integration decreased in fairy wrens (Malurus) for many feather patches that evolved greater dichromatism. Together, this suggests that the process of evolving increased dimorphism results in a decrease in integration between sexes and social castes. We speculate that once a mechanism for dimorphism evolves, that mechanism can create independent variation in one sex or caste upon which selection may act.

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