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Bell-Roberts L, Turner JFR, Werner GDA, Downing PA, Ross L, West SA. Larger colony sizes favoured the evolution of more worker castes in ants. Nat Ecol Evol 2024:10.1038/s41559-024-02512-7. [PMID: 39187609 DOI: 10.1038/s41559-024-02512-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 07/18/2024] [Indexed: 08/28/2024]
Abstract
The size-complexity hypothesis is a leading explanation for the evolution of complex life on earth. It predicts that in lineages that have undergone a major transition in organismality, larger numbers of lower-level subunits select for increased division of labour. Current data from multicellular organisms and social insects support a positive correlation between the number of cells and number of cell types and between colony size and the number of castes. However, the implication of these results is unclear, because colony size and number of cells are correlated with other variables which may also influence selection for division of labour, and causality could be in either direction. Here, to resolve this problem, we tested multiple causal hypotheses using data from 794 ant species. We found that larger colony sizes favoured the evolution of increased division of labour, resulting in more worker castes and greater variation in worker size. By contrast, our results did not provide consistent support for alternative hypotheses regarding either queen mating frequency or number of queens per colony explaining variation in division of labour. Overall, our results provide strong support for the size-complexity hypothesis.
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Affiliation(s)
| | | | - Gijsbert D A Werner
- Department of Biology, University of Oxford, Oxford, UK
- Netherlands Scientific Council for Government Policy, The Hague, The Netherlands
| | - Philip A Downing
- Ecology & Genetics Research Unit, University of Oulu, Oulu, Finland
| | - Laura Ross
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, UK
| | - Stuart A West
- Department of Biology, University of Oxford, Oxford, UK
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2
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Bird SA, Pope NS, McGrady CM, Fleischer SJ, López-Uribe MM. Mating frequency estimation and its importance for colony abundance analyses in eusocial pollinators: a case study of Bombus impatiens (Hymenoptera: Apidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2024:toae178. [PMID: 39137237 DOI: 10.1093/jee/toae178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 06/10/2024] [Accepted: 07/24/2024] [Indexed: 08/15/2024]
Abstract
The genus Bombus (bumble bees) includes approximately 265 species, many of which are in decline in North America and Europe. To estimate colony abundance of bumble bees in natural and agricultural habitats, sibship relationships are often reconstructed from genetic data with the assumption that colonies have 1 monandrous queen. However, some species such as the North American common eastern bumble bee (Bombus impatiens Cresson) can display low levels of polyandry, which may bias estimates of colony abundance based on monandrous sibship reconstructions. To accurately quantify rates of polyandry in wild and commercially mated queens of this species, we empirically estimated mating frequencies using a novel statistical model and genotypes from 730 bees. To genotype individuals, we used a highly polymorphic set of microsatellites on colonies established from 20 wild-caught gynes and 10 commercial colonies. We found multiple fathers in 3 of the wild colonies and 3 of the commercial colonies. This resulted in average effective mating frequencies of 1.075 ± 0.18 and 1.154 ± 0.25 for wild and commercial colonies, respectively. These findings agree with previous reports of low rates of polyandry for B. impatiens. Using a large empirical dataset, we demonstrate that assuming monandry for colony abundance estimation in species that violate this assumption results in an overestimation of the number of colonies. Our results emphasize the importance of studying mating frequencies in social species of conservation concern and economic importance for the accuracy of colony abundance estimation and for understanding their ecology and sociobiology.
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Affiliation(s)
- Sydney A Bird
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802, USA
- Temperate Tree Fruit and Vegetable Research Unit, United States Department of Agriculture, 5230 Konnowac Pass Rd, Wapato, WA 98951, USA
| | - Nathaniel S Pope
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Biology, Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Carley M McGrady
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Shelby J Fleischer
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Margarita M López-Uribe
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
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3
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Inokuchi F, Inoue MN, Kanbe Y, Ito M, Takahashi JI, Nomura T, Goka K, Tsuchida K. Polyandry may mitigate the negative impact of reproductive interference among bumblebees in Japan. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2024; 111:31. [PMID: 38780649 PMCID: PMC11116251 DOI: 10.1007/s00114-024-01917-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/26/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024]
Abstract
In social hymenopterans, monandry of the queen is an ancestral trait, and polyandry is a derived trait. Polyandry of the queen is the norm in a limited number of lineages, such as honeybees, leaf-cutting ants, Pogonomyrmex ants, and Vespula wasps, which presumably provide fitness advantages for the whole colony. The queen of the introduced bumblebee, Bombus terrestris, is polyandrous in Japan, whereas it is monandrous in native regions. We hypothesize that polyandry can evolve in a process that avoids the negative impacts of reproductive interference caused by interspecific mating and conducted genetic studies of the invasive species B. terrestris and two native subspecies, Bombus hypocrita sapporoensis and Bombus hypocrita hypocrita, in Japan. Our results revealed that although the native queens of B. hypocrita hypocrita allopatric with B. terrestris were strictly monandrous, the native queens of B. hypocrita sapporoensis sympatric with B. terrestris were polyandrous. These results suggested that the queens of native B. hypocrita sapporoensis do not experience negative impacts on interspecific mating from the invasive B. terrestris. We discuss the possibility that reproductive interference is a driving force in selection for multiple mating through an arms race between sympatric species.
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Affiliation(s)
- Fumina Inokuchi
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan
| | - Maki N Inoue
- Department of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai, Fuchu, Tokyo, 183-8509, Japan
| | - Yuya Kanbe
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan
- Arysta Lifescience Corporation BioSystems, Asia and Life Science Business Group, 418-404 Nishihara, Tsukuba, Ibaraki, 305-0832, Japan
| | - Masaaki Ito
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan
- Forestry and Forest Products Research Institute, Aomori Prefectural Industrial Technology Research Center, Hiranai-Machi 46-56, Higashi Tsugaru-Gun, Aomori, 039-3321, Japan
| | | | - Tetsuro Nomura
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Koichi Goka
- National Institute of Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki, 305-0053, Japan
| | - Koji Tsuchida
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan.
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4
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Mattila HR, Nguyen LT, Perrard A, Bain M, Otis GW. Biology of the southern giant hornet, Vespa soror: nest architecture, morphological differences among castes, and the genetic structure of colonies. FRONTIERS IN INSECT SCIENCE 2023; 3:1136297. [PMID: 38469522 PMCID: PMC10926378 DOI: 10.3389/finsc.2023.1136297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 05/31/2023] [Indexed: 03/13/2024]
Abstract
Giant hornets in the genus Vespa are apex predators that are known throughout Asia for their exceptional size and devastating group attacks on social insect colonies. The giant hornets include Vespa mandarinia, a well-studied and widespread temperate species, and Vespa soror, a poorly known sister species that is limited to subtropical and tropical regions of Southeast Asia. Both species have been recently documented on the west coast of North America, raising urgent questions about their potential impact in novel ecosystems. To better understand the biology of V. soror, we describe the nest architecture, caste morphology, and genetic structure of colonies collected in Vietnam. Comparisons of colony metrics between the two giant hornet species suggest important differences that are likely a consequence of the relatively warmer climate in which V. soror occurs. Like V. mandarinia, V. soror constructs large, underground nests of partially enveloped horizontal combs. However, compared to temperate V. mandarinia colonies, the longer nesting period of subtropical V. soror colonies likely resulted in relatively larger colony sizes and nests by the end of their annual cycle. Vespa soror workers and gynes were larger than males, distinguishable based on wing shape and body size (total length and measures of six body parts), and equivalent in size to female castes of V. mandarinia. We genotyped colony members from three mature nests, which revealed that males and females were offspring of singly mated queens. Two colonies were monogynous, but one colony was comprised of two unrelated matrilines. Polygyny has not been observed for V. mandarinia, but is more common in tropical hornet species. Our study sheds light on essential details about the biology of an understudied species of giant hornet, whose populous colonies and long nesting period suggest the potential for substantial ecological impact wherever they occur.
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Affiliation(s)
- Heather R. Mattila
- Department of Biological Sciences, Wellesley College, Wellesley, MA, United States
| | - Lien T.P. Nguyen
- Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Adrien Perrard
- Institute of Ecology and Environmental Sciences-Paris (iEES-Paris), Sorbonne Université, CNRS, IRD, INRAE, Universite Paris-Est Creteil (UPEC), Paris, France
- Sciences du vivant, Université Paris Cité, Paris, France
| | - Maggie Bain
- College of Biological Science, University of Guelph, Guelph, ON, Canada
| | - Gard W. Otis
- School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
- Institute of Bee Health, University of Bern and Agroscope, Bern, Switzerland
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Abstract
Metazoans function as individual organisms but also as “colonies” of cells whose single-celled ancestors lived and reproduced independently. Insights from evolutionary biology about multicellular group formation help us understand the behavior of cells: why they cooperate, and why cooperation sometimes breaks down. Current explanations for multicellularity focus on two aspects of development which promote cooperation and limit conflict among cells: a single-cell bottleneck, which creates organisms composed of clones, and a separation of somatic and germ cell lineages, which reduces the selective advantage of cheating. However, many obligately multicellular organisms thrive with neither, creating the potential for within-organism conflict. Here, we argue that the prevalence of such organisms throughout the Metazoa requires us to refine our preconceptions of conflict-free multicellularity. Evolutionary theory must incorporate developmental mechanisms across a broad range of organisms—such as unusual reproductive strategies, totipotency, and cell competition—while developmental biology must incorporate evolutionary principles. To facilitate this cross-disciplinary approach, we provide a conceptual overview from evolutionary biology for developmental biologists, using analogous examples in the well-studied social insects.
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Baer-Imhoof B, den Boer SPA, Boomsma JJ, Baer B. Sperm Storage Costs Determine Survival and Immunocompetence in Newly Mated Queens of the Leaf-Cutting Ant Atta colombica. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.759183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In the leaf-cutting ant Atta colombica, queens receive ejaculates from multiple males during one single mating event early in their lives. A queen’s fertility and fitness therefore depend on maximizing the number of sperm cells she can store and maintain inside her spermatheca. Previous studies implied significant physiological mating costs, either originating from energetic investments maximizing sperm survival, or from resolving sexual conflicts to terminate male-driven incapacitation of rival sperm via serine proteases found in seminal fluid. Here we conducted an artificial insemination experiment, which allowed us to distinguish between the effects of sperm and seminal fluid within the queen’s sexual tract on her survival and immunocompetence. We found significantly higher mortality in queens that we had inseminated with sperm, independently of whether seminal fluid was present or not. Additionally, after receiving sperm, heavier queens had a higher probability of survival compared to lightweight queens, and immunocompetence decreased disproportionally for queens that had lost weight during the experiment. These findings indicate that queens pay significant physiological costs for maintaining and storing sperm shortly after mating. On the other hand, the presence of seminal fluid within the queens’ sexual tract neither affected their survival nor their immunocompetence. This suggests that the energetic costs that queens incur shortly after mating are primarily due to investments in sperm maintenance and not costs of terminating conflicts between competing ejaculates. This outcome is consistent with the idea that sexually selected traits in social insects with permanent castes can evolve only when they do not affect survival or life-time fitness of queens in any significant way.
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7
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OUP accepted manuscript. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Dahan RA, Grove NK, Bollazzi M, Gerstner BP, Rabeling C. Decoupled evolution of mating biology and social structure in Acromyrmex leaf-cutting ants. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03113-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Abstract
Insect societies vary greatly in their social structure, mating biology, and life history. Polygyny, the presence of multiple reproductive queens in a single colony, and polyandry, multiple mating by females, both increase the genetic variability in colonies of eusocial organisms, resulting in potential reproductive conflicts. The co-occurrence of polygyny and polyandry in a single species is rarely observed across eusocial insects, and these traits have been found to be negatively correlated in ants. Acromyrmex leaf-cutting ants are well-suited for investigating the evolution of complex mating strategies because both polygyny and polyandry co-occur in this genus. We used microsatellite markers and parentage inference in five South American Acromyrmex species to study how different selective pressures influence the evolution of polygyny and polyandry. We show that Acromyrmex species exhibit independent variation in mating biology and social structure, and polygyny and polyandry are not necessarily negatively correlated within genera. One species, Acromyrmex lobicornis, displays a significantly lower mating frequency compared to others, while another species, A. lundii, appears to have reverted to obligate monogyny. These variations appear to have a small impact on average intra-colonial relatedness, although the biological significance of such a small effect size is unclear. All species show significant reproductive skew between patrilines, but there was no significant difference in reproductive skew between any of the sampled species. We find that the evolution of social structure and mating biology appear to follow independent evolutionary trajectories in different species. Finally, we discuss the evolutionary implications that mating biology and social structure have on life history evolution in Acromyrmex leaf-cutting ants.
Significance statement
Many species of eusocial insects have colonies with multiple queens (polygyny), or queens mating with multiple males (polyandry). Both behaviors generate potentially beneficial genetic diversity in ant colonies as well as reproductive conflict. The co-occurrence of both polygyny and polyandry in a single species is only known from few ant species. Leaf-cutting ants have both multi-queen colonies and multiply mated queens, providing a well-suited system for studying the co-evolutionary dynamics between mating behavior and genetic diversity in colonies of eusocial insects. We used microsatellite markers to infer the socio-reproductive behavior in five South American leaf-cutter ant species. We found that variation in genetic diversity in colonies was directly associated with the mating frequencies of queens, but not with the number of queens in a colony. We suggest that multi-queen nesting and mating frequency evolve independently of one another, indicating that behavioral and ecological factors other than genetic diversity contribute to the evolution of complex mating behaviors in leaf-cutting ants.
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Dyson CJ, Piscano OL, Durham RM, Thompson VJ, Johnson CH, Goodisman MAD. Temporal Analysis of Effective Population Size and Mating System in a Social Wasp. J Hered 2021; 112:626-634. [PMID: 34558622 DOI: 10.1093/jhered/esab057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 09/20/2021] [Indexed: 02/07/2023] Open
Abstract
Highly social species are successful because they cooperate in obligately integrated societies. We examined temporal genetic variation in the eusocial wasp Vespula maculifrons to gain a greater understanding of evolution in highly social taxa. First, we wished to test if effective population sizes of eusocial species were relatively low due to the reproductive division of labor that characterizes eusocial taxa. We thus estimated the effective population size of V. maculifrons by examining temporal changes in population allele frequencies. We sampled the genetic composition of a V. maculifrons population at 3 separate timepoints spanning a 13-year period. We found that effective population size ranged in the hundreds of individuals, which is similar to estimates in other, non-eusocial taxa. Second, we estimated levels of polyandry in V. maculifrons in different years to determine if queen mating system varied over time. We found no significant change in the number or skew of males mated to queens. In addition, mating skew was not significant within V. maculifrons colonies. Therefore, our data suggest that queen mate number may be subject to stabilizing selection in this taxon. Overall, our study provides novel insight into the selective processes operating in eusocial species by analyzing temporal genetic changes within populations.
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Affiliation(s)
- Carl J Dyson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Olivia L Piscano
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Rebecca M Durham
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Veronica J Thompson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Catherine H Johnson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
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Psalti MN, Gohlke D, Libbrecht R. Experimental increase of worker diversity benefits brood production in ants. BMC Ecol Evol 2021; 21:163. [PMID: 34461829 PMCID: PMC8404329 DOI: 10.1186/s12862-021-01890-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/18/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The reproductive division of labor of eusocial insects, whereby one or several queens monopolize reproduction, evolved in a context of high genetic relatedness. However, many extant eusocial species have developed strategies that decrease genetic relatedness in their colonies, suggesting some benefits of the increased diversity. Multiple studies support this hypothesis by showing positive correlations between genetic diversity and colony fitness, as well as finding effects of experimental manipulations of diversity on colony performance. However, alternative explanations could account for most of these reports, and the benefits of diversity on performance in eusocial insects still await validation. In this study, we experimentally increased worker diversity in small colonies of the ant Lasius niger while controlling for typical confounding factors. RESULTS We found that experimental colonies composed of workers coming from three different source colonies produced more larvae and showed more variation in size compared to groups of workers coming from a single colony. CONCLUSIONS We propose that the benefits of increased diversity stemmed from an improved division of labor. Our study confirms that worker diversity enhances colony performance, thus providing a possible explanation for the evolution of multiply mated queens and multiple-queen colonies in many species of eusocial insects.
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Affiliation(s)
- Marina N. Psalti
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Dustin Gohlke
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
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Delaplane KS, Given JK, Menz J, Delaney DA. Colony fitness increases in the honey bee at queen mating frequencies higher than genetic diversity asymptote. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03065-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Abstract
Across the eusocial Hymenoptera, a queen’s mating frequency is positively associated with her workers’ genetic diversity and colony’s fitness. Over 90% of a colony’s diversity potential is achieved by its mother’s tenth effective mating (me); however, many females mate at levels of me > 10, a zone we here call hyperpolyandry. We compared honey bee colony fitness at mating levels near and above this genetic diversity asymptote. We were interested in how hyperpolyandry affects colony phenotypes arising from both common tasks (brood care) and rare specialized tasks (parasite resistance). We used an unselected wild line of bees and a Varroa Sensitive Hygiene (VSH) line selected to resist the parasite Varroa destructor. Virgin queens were instrumentally inseminated to replicate the following queen/colony conditions: (1) VSH semen/low polyandry (observed mating number = mo = 9), (2) VSH semen/high polyandry (mo = 54), (3) wild type semen/low polyandry, or (4) wild semen/high polyandry. There was a positive effect of polyandry on brood survival, an outcome of common tasks, with highest values at mo = 54. There was an interaction between polyandry and genetics such that differences between genetic lines expressed only at mo = 54, with fewer mites in VSH colonies. These results are consistent with two hypotheses for the evolution of mating levels in excess of the genetic diversity asymptote: hyperpolyandry improves colony fitness by (1) optimizing genotype compositions for common tasks and (2) by capturing rare specialist allele combinations, resisting cliff-edge ecological catastrophes.
Significance statement
Polyandry is a female’s practice of mating with several males, storing their sperm, and using it to produce one or more clutches of genetically diverse offspring. In the social Hymenoptera, polyandry increases the genetic diversity and task efficiency of workers, leading to improved colony fitness. Over 90% of the increase in a colony’s diversity potential is achieved by its mother’s tenth mating; however, many females practice hyperpolyandry, a term we reserve here for mating levels above this genetic diversity asymptote. We show that a token of colony fitness arising from common tasks, brood survival, improves universally as one moves from sub- to hyperpolyandrous mating levels. However, a colony phenotype arising from a rare parasite resistance task is only expressed in the presence of the controlling alleles and under conditions of hyperpolyandry. These results suggest adaptive mechanisms by which hyperpolyandry could evolve.
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Lecocq de Pletincx N, Dellicour S, Aron S. The evolution of ant worker polymorphism correlates with multiple social traits. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03049-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Bensch HM, O'Connor EA, Cornwallis CK. Living with relatives offsets the harm caused by pathogens in natural populations. eLife 2021; 10:e66649. [PMID: 34309511 PMCID: PMC8313236 DOI: 10.7554/elife.66649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/19/2021] [Indexed: 01/23/2023] Open
Abstract
Living with relatives can be highly beneficial, enhancing reproduction and survival. High relatedness can, however, increase susceptibility to pathogens. Here, we examine whether the benefits of living with relatives offset the harm caused by pathogens, and if this depends on whether species typically live with kin. Using comparative meta-analysis of plants, animals, and a bacterium (nspecies = 56), we show that high within-group relatedness increases mortality when pathogens are present. In contrast, mortality decreased with relatedness when pathogens were rare, particularly in species that live with kin. Furthermore, across groups variation in mortality was lower when relatedness was high, but abundances of pathogens were more variable. The effects of within-group relatedness were only evident when pathogens were experimentally manipulated, suggesting that the harm caused by pathogens is masked by the benefits of living with relatives in nature. These results highlight the importance of kin selection for understanding disease spread in natural populations.
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14
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Majoe M, Libbrecht R, Foitzik S, Nehring V. Queen loss increases worker survival in leaf-cutting ants under paraquat-induced oxidative stress. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190735. [PMID: 33678018 PMCID: PMC7938173 DOI: 10.1098/rstb.2019.0735] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2020] [Indexed: 01/18/2023] Open
Abstract
Longevity is traded off with fecundity in most solitary species, but the two traits are positively linked in social insects. In ants, the most fecund individuals (queens and kings) live longer than the non-reproductive individuals, the workers. In many species, workers may become fertile following queen loss, and recent evidence suggests that worker fecundity extends worker lifespan. We postulated that this effect is in part owing to improved resilience to oxidative stress, and tested this hypothesis in three Myrmicine ants: Temnothorax rugatulus, and the leaf-cutting ants Atta colombica and Acromyrmex echinatior. We removed the queen from colonies to induce worker reproduction and subjected workers to oxidative stress. Oxidative stress drastically reduced survival, but this effect was less pronounced in leaf-cutting ant workers from queenless nests. We also found that, irrespective of oxidative stress, outside workers died earlier than inside workers did, likely because they were older. Since At. colombica workers cannot produce fertile offspring, our results indicate that direct reproduction is not necessary to extend the lives of queenless workers. Our findings suggest that workers are less resilient to oxidative stress in the presence of the queen, and raise questions on the proximate and ultimate mechanisms underlying socially mediated variation in worker lifespan. This article is part of the theme issue 'Ageing and sociality: why, when and how does sociality change ageing patterns?'
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Affiliation(s)
- Megha Majoe
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
- Institute for Biology I (Zoology), University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
| | - Susanne Foitzik
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
| | - Volker Nehring
- Institute for Biology I (Zoology), University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany
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15
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Eyer PA, Vargo EL, Peeters C. One tree, many colonies: colony structure, breeding system and colonization events of host trees in tunnelling Melissotarsus ants. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Ants exhibit a striking variety of lifestyles, including highly specialist or mutualist species. The minute blind workers of the African genus Melissotarsus chew tunnels in live trees to accommodate their obligate partner scale insects. Their modified legs are adapted for tunnelling, but are unsuited for walking outside, confining these ants to their initial host tree. Here, we investigated whether this unique lifestyle results in complex patterns of genetic diversity at different scales, from the same tree to different populations. Using 19 microsatellite markers, we assessed their mating strategy and colony structure among and across populations in South Africa. We showed that only one queen reproduces within a colony, mated with up to three males. However, several inseminated dealate queens are present in colonies; one probably replaces the older queen as the colony ages. The reproduction of a single queen per colony at a given time results in genetic differences between colonies, even those located on the same tree. We discuss how the slow process of colony digging under the bark and the lack of workers patrolling above the bark might result in reduced competition between colonies and allow several secluded colonies to cohabit the cramped space on a single tree.
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Affiliation(s)
- Pierre-André Eyer
- Department of Entomology, Texas A&M University, College Station, TXUSA
| | - Edward L Vargo
- Department of Entomology, Texas A&M University, College Station, TXUSA
| | - Christian Peeters
- Institut d’Écologie et des Sciences de l’Environnement, CNRS, Sorbonne Université, Paris, France
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16
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Abstract
Abstract
In eusocial Hymenoptera, queens and their helper offspring should favour different sex investment ratios. Queens should prefer a 1:1 investment ratio, as they are equally related to offspring of both sexes (r = 0.5). In contrast, helpers should favour an investment ratio of 3:1 towards the production of female brood. This conflict arises because helpers are more closely related to full sisters (r = 0.75) than brothers (r = 0.25). However, helpers should invest relatively more in male brood if relatedness asymmetry within their colony is reduced. This can occur due to queen replacement after colony orphaning, multiple paternity and the presence of unrelated alien helpers. We analysed an unprecedentedly large number of colonies (n = 109) from a UK population of Lasioglossum malachurum, an obligate eusocial sweat bee, to tease apart the effects of these factors on colony-level investment ratios. We found that multiple paternity, unrelated alien helpers and colony orphaning were all common. Queen-right colonies invested relatively more in females than did orphaned colonies, producing a split sex ratio. However, investment ratios did not change due to multiple paternity or the presence of alien helpers, reducing inclusive fitness pay-offs for helpers. Queen control may also have been important: helpers rarely laid male eggs, and investment in female brood was lower when queens were large relative to their helpers. Genetic relatedness between helpers and the brood that they rear was 0.43 in one year and 0.37 in another year, suggesting that ecological benefits, as well as relatedness benefits, are necessary for the maintenance of helping behaviour.
Significance statement
How helping behaviour is maintained in eusocial species is a key topic in evolutionary biology. Colony-level sex investment ratio changes in response to relatedness asymmetries can dramatically influence inclusive fitness benefits for helpers in eusocial Hymenoptera. The extent to which helpers in primitively eusocial colonies can respond adaptively to different sources of variation in relatedness asymmetry is unclear. Using data from 109 colonies of the sweat bee Lasioglossum malachurum, we found that queen loss, but not multiple paternity or the presence of alien helpers, was correlated with colony sex investment ratios. Moreover, we quantified average helper-brood genetic relatedness to test whether it is higher than that predicted under solitary reproduction (r = 0.5). Values equal to and below r = 0.5 suggest that relatedness benefits alone cannot explain the maintenance of helping behaviour. Ecological benefits of group living and/or coercion must also contribute.
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17
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Lecocq de Pletincx N, Aron S. Sociogenetic Organization of the Red Honey Ant ( Melophorus bagoti). INSECTS 2020; 11:E755. [PMID: 33158025 PMCID: PMC7693516 DOI: 10.3390/insects11110755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/28/2020] [Accepted: 11/02/2020] [Indexed: 11/21/2022]
Abstract
Kin selection and inclusive fitness are thought to be key factors explaining the reproductive altruism displayed by workers in eusocial insect species. However, when a colony's queen has mated with <2 males, workers may increase their fitness by producing their own male offspring. Conversely, when the queen has mated with ≥2 males, workers are expected to increase their inclusive fitness by eschewing the production of their sons and preventing other workers from reproducing as well. Here, we investigated sociogenetic structure and worker reproduction in the red honey ant, Melophorus bagoti. Morphometric analyses revealed that workers belong to one of two distinct subcastes: they are either majors or minors. Using DNA microsatellite markers, we showed that all the colonies had a single, multiple-mated queen and that there was no relationship between worker patriline and worker subcaste. Furthermore, we found that workers were producing males in the presence of the queen, which contrasts with the predictions of inclusive fitness theory. Although our results are based on a small sample, they can serve as the foundation for future research examining worker reproduction in M. bagoti.
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18
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Pull CD, McMahon DP. Superorganism Immunity: A Major Transition in Immune System Evolution. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00186] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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19
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de Souza AR, Santos EF, Nascimento FSD, Stanyon R, Lino-Neto J, Beani L. Sexually dimorphic traits and male fertility in a paper wasp. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Females of many social Hymenoptera commit their reproductive potential to a single male; they mate once and never re-mate. Sexual selection theory predicts that under this regimen female precopulatory mate choice is crucial. The targets of female choice, male secondary sexual traits, should convey information about the functional fertility of the male. Here, we evaluated semen quality and its correlates in the paper wasp Polistes dominula, a monandric species with a lek-based mating system. The main goal of the study was to test whether sperm viability and the total number of sperm covaried with sexually dimorphic abdominal spots, body size and parasitic infection by Xenos vesparum. Surprisingly, superior male fertility was not predicted by attractive sexual traits, such as little round spots and large body size. We also found no effect of the parasite on male fertility, sexual ornamentation or body size. We found only that sperm viability was positively associated with the number of sperm. Moreover, there was evidence of a counterintuitive relationship between (sexually unattractive) large irregular spots and large body size of dominant successful males. Overall, our results suggest a condition-dependent trade-off between body size and costly sexual signals.
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Affiliation(s)
- André Rodrigues de Souza
- Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - Eduardo Fernando Santos
- Departamento de Zoologia e Botânica, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista ‘Júlio de Mesquita Filho’, São José do Rio Preto, Brazil
| | - Fábio Santos Do Nascimento
- Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - Roscoe Stanyon
- Department of Biology, University of Florence, Florence, Italy
| | - José Lino-Neto
- Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Laura Beani
- Department of Biology, University of Florence, Florence, Italy
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20
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Masoni A, Frizzi F, Natali C, Ciofi C, Santini G. Mating frequency and colony genetic structure analyses reveal unexpected polygyny in the Mediterranean acrobat ant Crematogaster scutellaris. ETHOL ECOL EVOL 2020. [DOI: 10.1080/03949370.2019.1680449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Alberto Masoni
- Department of Biology, University of Florence, Sesto Fiorentino (Firenze), Italy
| | - Filippo Frizzi
- Department of Biology, University of Florence, Sesto Fiorentino (Firenze), Italy
| | - Chiara Natali
- Department of Biology, University of Florence, Sesto Fiorentino (Firenze), Italy
| | - Claudio Ciofi
- Department of Biology, University of Florence, Sesto Fiorentino (Firenze), Italy
| | - Giacomo Santini
- Department of Biology, University of Florence, Sesto Fiorentino (Firenze), Italy
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21
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Andras JP, Hollis KL, Carter KA, Couldwell G, Nowbahari E. Analysis of ants' rescue behavior reveals heritable specialization for first responders. J Exp Biol 2020; 223:jeb212530. [PMID: 32029458 DOI: 10.1242/jeb.212530] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 01/28/2020] [Indexed: 11/20/2022]
Abstract
In colonies of Cataglyphis cursor ants, a single queen mates with multiple males, creating the foundation for heritable behavioral specializations. A novel and unique candidate for such specializations is rescue behavior, a precisely delivered form of altruism in which workers attempt to release trapped nestmates and which relies on short-term memory of previous actions to increase its efficiency. Consistent with task specialization, not all individuals participate; instead, some individuals move away from the victim, which gives rescuers unrestricted access. Using a bioassay to identify rescuers and non-rescuers, coupled with paternity assignment via polymorphic microsatellite markers, we not only show that rescue behavior is heritable, with 34% of the variation explained by paternity, but also establish that rescue, heretofore overlooked in analyses of division of labor, is a true specialization, an ant version of first responders. Moreover, this specialization emerges as early as 5 days of age, and the frequency of rescuers remains constant across ants' age ranges. The extremely broad range of these ants' heritable polyethism provides further support for the critical role of polyandry in increasing the efficiency of colony structure and, in turn, reproductive success.
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Affiliation(s)
- Jason P Andras
- Department of Biological Sciences, Mount Holyoke College, 50 College Street, South Hadley, MA 01075-1462, USA
| | - Karen L Hollis
- Interdisciplinary Program in Neuroscience & Behavior, Mount Holyoke College, 50 College Street, South Hadley, MA 01075-1462, USA
| | - Kristyn A Carter
- Interdisciplinary Program in Neuroscience & Behavior, Mount Holyoke College, 50 College Street, South Hadley, MA 01075-1462, USA
| | - Genevieve Couldwell
- Interdisciplinary Program in Neuroscience & Behavior, Mount Holyoke College, 50 College Street, South Hadley, MA 01075-1462, USA
| | - Elise Nowbahari
- Laboratoire d'Ethologie Expérimentale et Comparée EA 4443, Université Sorbonne Paris Nord, 93430 Villetaneuse, France
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22
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Eyer P, Espinoza EM, Blumenfeld AJ, Vargo EL. The underdog invader: Breeding system and colony genetic structure of the dark rover ant ( Brachymyrmex patagonicus Mayr). Ecol Evol 2020; 10:493-505. [PMID: 31993123 PMCID: PMC6972842 DOI: 10.1002/ece3.5917] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 11/18/2019] [Indexed: 01/19/2023] Open
Abstract
Ants are among the most successful species at invading new environments. Their success undeniably comes from their various modes of reproduction and colony breeding structures, which influence their dispersal ability, reproductive potential, and foraging strategies. Almost all invasive ant species studied so far form supercolonies, a dense network of interconnected nests comprising numerous queens, without aggression toward non-nestmates. This strategy results in invasive colonies that are able to grow extremely fast and large while avoiding intraspecific competition, allowing them to monopolize environmental resources and outcompete native species. Here, we developed and used 10 microsatellite markers to investigate the population structure and breeding system of the dark rover ant Brachymyrmex patagonicus Mayr in its introduced range. We determined whether this species exhibits a supercolonial structure by assessing whether different nests belonged to the same genetic colony. We inferred its dispersal ability by investigating isolation by distance and estimated the numbers of queens per colonies and mating per queen through parent-offspring inferences. We found that most of the colonies of B. patagonicus were comprised of a single nest, headed by a single queen. Each nest was distinct from one another, without isolation by distance, which suggests strong dispersal ability through nuptial flights. These features are commonly observed in noninvasive and native ant species, but they are surprising for a successful invasive ant, as they strongly differ from other invasive ants. Overall, we discuss how this seemingly unfavorable strategy for an invasive ant might favor the invasive success of the dark rover ant in the United States.
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Affiliation(s)
| | - Elida M. Espinoza
- Department of EntomologyTexas A&M UniversityCollege StationTXUSA
- EnviroFlight, LLCYellow SpringsOHUSA
| | | | - Edward L. Vargo
- Department of EntomologyTexas A&M UniversityCollege StationTXUSA
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23
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Kuhn A, Darras H, Paknia O, Aron S. Repeated evolution of queen parthenogenesis and social hybridogenesis in
Cataglyphis
desert ants. Mol Ecol 2019; 29:549-564. [DOI: 10.1111/mec.15283] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 10/07/2019] [Accepted: 10/21/2019] [Indexed: 01/18/2023]
Affiliation(s)
- Alexandre Kuhn
- Evolutionary Biology and Ecology Université Libre de Bruxelles Brussels Belgium
| | - Hugo Darras
- Evolutionary Biology and Ecology Université Libre de Bruxelles Brussels Belgium
- Department of Ecology and Evolution Biophore UNIL Sorge University of Lausanne Lausanne Switzerland
| | - Omid Paknia
- ITZ, Ecology and Evolution TiHo Hannover Hannover Germany
| | - Serge Aron
- Evolutionary Biology and Ecology Université Libre de Bruxelles Brussels Belgium
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24
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Vollet-Neto A, Imperatriz-Fonseca VL, Ratnieks FLW. Queen Execution, Diploid Males, and Selection For and Against Polyandry in the Brazilian Stingless Bee Scaptotrigona depilis. Am Nat 2019; 194:725-735. [PMID: 31613668 DOI: 10.1086/705393] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Female mating frequency varies. Determining the causes of this variation is an active research area. We tested the hypothesis that in stingless bees, Meliponini, single mating is due to the execution of queens that make a matched mating at the complementary sex determination locus and have diploid male offspring. We studied the Brazilian species Scaptotrigona depilis. We made up 70 test colonies so that 50% (single matched mating), 25% (double mating), 12.5% (quadruple mating), or 0% (single nonmatched mating) of the emerging brood were diploid males. Queen execution following diploid male emergence was equal and high in colonies producing 50% (77% executed) and 25% (75%) diploid males versus equal and low in colonies producing 12.5% (7%) and 0% (0%) diploid males. These results show that queens that mate with two males with similar paternity suffer an increased chance of being executed, which selects against double mating. However, double mating with unequal paternity (e.g., 25∶75), which occasionally occurs in S. depilis, is selectively neutral. Single mating and double mating with unequal paternity form one adaptive peak. The results show a second adaptive peak at quadruple mating. However, this is inaccessible via gradual evolutionary change in a selective landscape with reduced fitness at double mating.
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25
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Quezada‐Euán JJG, Sanabria‐Urbán S, Smith C, Cueva del Castillo R. Patterns of sexual size dimorphism in stingless bees: Testing Rensch's rule and potential causes in highly eusocial bees (Hymenoptera: Apidae, Meliponini). Ecol Evol 2019; 9:2688-2698. [PMID: 30891209 PMCID: PMC6405504 DOI: 10.1002/ece3.4935] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 12/10/2018] [Accepted: 12/28/2018] [Indexed: 11/30/2022] Open
Abstract
Eusocial insects offer a unique opportunity to analyze the evolution of body size differences between sexes in relation to social environment. The workers, being sterile females, are not subject to selection for reproductive function providing a natural control for parsing the effects of selection on reproductive function (i.e., sexual and fecundity selection) from other kinds of natural selection. Patterns of sexual size dimorphism (SSD) and testing of Rensch's rule controlling for phylogenetic effects were analyzed in the Meliponini or stingless bees. Theory predicts that queens may exhibit higher selection for fecundity in eusocial taxa, but contrary to this, we found mixed patterns of SSD in Meliponini. Non-Melipona species generally have a female-biased SSD, while all analyzed species of Melipona showed a male-biased SSD, indicating that the direction and magnitude of the selective pressures do not operate in the same way for all members of this taxon. The phylogenetic regressions revealed that the rate of divergence has not differed between the two castes of females and the males, that is, stingless bees do not seem to follow Rensch's rule (a slope >1), adding this highly eusocial taxon to the various solitary insect taxa not conforming with it. Noteworthy, when Melipona was removed from the analysis, the phylogenetic regressions for the thorax width of males on queens had a slope significantly smaller than 1, suggesting that the evolutionary divergence has been larger in queens than males, and could be explained by stronger selection on female fecundity only in non-Melipona species. Our results in the stingless bees question the classical explanation of female-biased SSD via fecundity and provide a first evidence of a more complex determination of SSD in highly eusocial species. We suggest that in highly eusocial taxa, additional selection mechanisms, possibly related to individual and colonial interests, could influence the evolution of environmentally determined traits such as body size.
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Affiliation(s)
- José Javier G. Quezada‐Euán
- Departamento de Apicultura Tropical, Campus de Ciencias Biológicas y AgropecuariasUniversidad Autónoma de YucatánMéridaMéxico
| | - Salomón Sanabria‐Urbán
- UBIPRO, Lab. de Ecología, FES IztacalaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Corey Smith
- Invertebrate DivisionAmerican Museum of Natural HistoryNew York CityNew York
| | - Raúl Cueva del Castillo
- UBIPRO, Lab. de Ecología, FES IztacalaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
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26
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Chapman NC, Dos Santos Cocenza R, Blanchard B, Nguyen LM, Lim J, Buchmann G, Oldroyd BP. Genetic Diversity in the Progeny of Commercial Australian Queen Honey Bees (Hymenoptera: Apidae) Produced in Autumn and Early Spring. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:33-39. [PMID: 30285107 DOI: 10.1093/jee/toy308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Indexed: 06/08/2023]
Abstract
Honey bee [Apis mellifera L. (Hymenoptera: Apidae)] queens are polyandrous, mating with an average 12 males (drones). Polyandry has been shown to confer benefits to queens and the colonies they head, including avoidance of inviable brood that can arise via sex locus homozygosity, increased resilience to pests and pathogens, and increased survival and productivity, leading to improved colony-level fitness. Queens with an effective mating frequency (ke) greater than 7 are considered adequately mated, whereas queens that fall below this threshold head colonies that have increased likelihood of failure and may be less productive for beekeepers. We determined ke in queens produced in early Spring and Autumn by five Australian commercial queen producers to determine whether the queens they produced were suitably mated. Drone populations are low at these times of year, and therefore, there is an increased risk that queens would fall below the ke > 7 threshold. We found that 33.8% of Autumn-produced queens did not meet the threshold, whereas 93.8% of Spring queens were adequately mated. The number of colonies contributing drones to the mating pool was similarly high in both seasons, suggesting that although many colonies have drones, their numbers may be decreased in Autumn and management strategies may be required to boost drone numbers at this time. Finally, queens had similar levels of homozygosity to workers, and inbreeding coefficients were very low, suggesting that inbreeding is not a problem.
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Affiliation(s)
- Nadine C Chapman
- Ecology, Evolution and Environment, Behaviour and Genetics of Social Insects Laboratory, University of Sydney, School of Life and Environmental Science, Macleay Building, Sydney, NSW
| | - Rani Dos Santos Cocenza
- Ecology, Evolution and Environment, Behaviour and Genetics of Social Insects Laboratory, University of Sydney, School of Life and Environmental Science, Macleay Building, Sydney, NSW
| | - Benjamin Blanchard
- Ecology, Evolution and Environment, Behaviour and Genetics of Social Insects Laboratory, University of Sydney, School of Life and Environmental Science, Macleay Building, Sydney, NSW
| | - Lucy M Nguyen
- Ecology, Evolution and Environment, Behaviour and Genetics of Social Insects Laboratory, University of Sydney, School of Life and Environmental Science, Macleay Building, Sydney, NSW
| | - Julianne Lim
- Ecology, Evolution and Environment, Behaviour and Genetics of Social Insects Laboratory, University of Sydney, School of Life and Environmental Science, Macleay Building, Sydney, NSW
| | - Gabriele Buchmann
- Ecology, Evolution and Environment, Behaviour and Genetics of Social Insects Laboratory, University of Sydney, School of Life and Environmental Science, Macleay Building, Sydney, NSW
| | - Benjamin P Oldroyd
- Ecology, Evolution and Environment, Behaviour and Genetics of Social Insects Laboratory, University of Sydney, School of Life and Environmental Science, Macleay Building, Sydney, NSW
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27
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Eyer PA, McDowell B, Johnson LNL, Calcaterra LA, Fernandez MB, Shoemaker D, Puckett RT, Vargo EL. Supercolonial structure of invasive populations of the tawny crazy ant Nylanderia fulva in the US. BMC Evol Biol 2018; 18:209. [PMID: 30594137 PMCID: PMC6310932 DOI: 10.1186/s12862-018-1336-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 12/17/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Social insects are among the most serious invasive pests in the world, particularly successful at monopolizing environmental resources to outcompete native species and achieve ecological dominance. The invasive success of some social insects is enhanced by their unicolonial structure, under which the presence of numerous queens and the lack of aggression against non-nestmates allow high worker densities, colony growth, and survival while eliminating intra-specific competition. In this study, we investigated the population genetics, colony structure and levels of aggression in the tawny crazy ant, Nylanderia fulva, which was recently introduced into the United States from South America. RESULTS We found that this species experienced a genetic bottleneck during its invasion lowering its genetic diversity by 60%. Our results show that the introduction of N. fulva is associated with a shift in colony structure. This species exhibits a multicolonial organization in its native range, with colonies clearly separated from one another, whereas it displays a unicolonial system with no clear boundaries among nests in its invasive range. We uncovered an absence of genetic differentiation among populations across the entire invasive range, and a lack of aggressive behaviors towards conspecifics from different nests, even ones separated by several hundreds of kilometers. CONCLUSIONS Overall, these results suggest that across its entire invasive range in the U.S.A., this species forms a single supercolony spreading more than 2000 km. In each invasive nest, we found several, up to hundreds, of reproductive queens, each being mated with a single male. The many reproductive queens per nests, together with the free movement of individuals between nests, leads to a relatedness coefficient among nestmate workers close to zero in introduced populations, calling into question the stability of this unicolonial system in which indirect fitness benefits to workers is apparently absent.
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Affiliation(s)
- Pierre-André Eyer
- Department of Entomology, 2143 TAMU, Texas A&M University, College Station, TX, 77843-2143, USA.
| | - Bryant McDowell
- Department of Entomology, 2143 TAMU, Texas A&M University, College Station, TX, 77843-2143, USA
| | - Laura N L Johnson
- Department of Entomology, 2143 TAMU, Texas A&M University, College Station, TX, 77843-2143, USA
| | - Luis A Calcaterra
- Fundación para el Estudio de Especies Invasivas (FuEDEI) and CONICET, Bolívar 1559, B1686EFA, Hurlingham, Buenos Aires, Argentina
| | - Maria Belen Fernandez
- Fundación para el Estudio de Especies Invasivas (FuEDEI) and CONICET, Bolívar 1559, B1686EFA, Hurlingham, Buenos Aires, Argentina
| | - DeWayne Shoemaker
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, 37996-4560, USA
| | - Robert T Puckett
- Department of Entomology, 2143 TAMU, Texas A&M University, College Station, TX, 77843-2143, USA
| | - Edward L Vargo
- Department of Entomology, 2143 TAMU, Texas A&M University, College Station, TX, 77843-2143, USA
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28
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Eyer PA, Hefetz A. Cytonuclear incongruences hamper species delimitation in the socially polymorphic desert ants of the Cataglyphis albicans group in Israel. J Evol Biol 2018; 31:1828-1842. [PMID: 30240036 DOI: 10.1111/jeb.13378] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 08/01/2018] [Accepted: 09/13/2018] [Indexed: 11/27/2022]
Abstract
Assessing whether behavioural, ecological or geographical factors trigger population divergence provides key insights into the biological processes driving speciation. Recent speciation in restricted geographic area without obvious ecological barriers prompts the question of the behavioural mechanisms underlying species divergence. In this context, we investigated phylogenetic relationships in the Cataglyphis albicans desert ant complex in Israel. We first determined accurate species delimitation using two mitochondrial and six nuclear genes, as well as 11 microsatellite markers to investigate cryptic species in this group, assessing reduction in gene flow between populations. We then investigated whether different species in this group exhibit distinct reproductive strategies, inferring social structure and queen-mating frequency in each species uncovered. Our findings highlight the presence of at least six distinct Cataglyphis albicans species in the restricted range of Israel; four of them co-occur in a 50 × 50 km area in North Negev, while two are endemic from there. However, our results reveal incongruences between nuclear and mitochondrial clustering, which complicate species identification and preclude the exclusive use of mtDNA to confidently delimit species in this group. Finally, we show that the different species of the C. albicans group in Israel exhibit quite similar reproductive strategies with most of them having colonies headed by a single queen mated with several males; colonies of one species were, however, headed by several queens. Overall, this weak variation across species thereby unlikely represents the main evolutionary force behind speciation of these sympatric species. We then discuss the potential evolutionary processes that underlie speciation in this group in the absence of clear geographical or ecological barriers.
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Affiliation(s)
- Pierre-André Eyer
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Abraham Hefetz
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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29
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Saar M, Eyer PA, Kilon-Kallner T, Hefetz A, Scharf I. Within-colony genetic diversity differentially affects foraging, nest maintenance, and aggression in two species of harvester ants. Sci Rep 2018; 8:13868. [PMID: 30217995 PMCID: PMC6138738 DOI: 10.1038/s41598-018-32064-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 09/03/2018] [Indexed: 11/09/2022] Open
Abstract
There is accumulating evidence that genetic diversity improves the behavioral performance and consequently the fitness in groups of social animals. We examined the behavioral performance of colonies of two co-occurring, congeneric harvester ant species (Messor arenarius and a non-described Messor sp.) in fitness-related behaviors, pertaining to foraging performance, nest maintenance, and aggression. We linked these behaviors to the colonial genetic diversity, by genotyping workers, using six and five microsatellite markers for M. arenarius and M. sp., respectively. Correlations of genetic diversity with colony performance and aggression level contrasted between the two species. In M. arenarius, genetic diversity was correlated with foraging performance and nest maintenance but not with the overall aggression level, while in M. sp., genetic diversity was correlated with the overall aggression level, but not with foraging performance or nest maintenance. The two species exhibited similar specific aggression levels, with higher aggression shown towards heterospecifics and lower towards non-nestmate conspecifics and nestmates. However, M. sp. workers displayed a tendency to interact for longer with heterospecifics than did M. arenarius. We speculate that the different foraging strategies, group vs. individual foraging, and possibly also the different mating systems, contribute to the differences found in behavior between the two species.
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Affiliation(s)
- Maya Saar
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Pierre-André Eyer
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Tal Kilon-Kallner
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Abraham Hefetz
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Inon Scharf
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
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30
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Poidatz J, Bressac C, Bonnard O, Thiéry D. Comparison of reproductive traits of foundresses in a native and an invasive hornet in Europe. JOURNAL OF INSECT PHYSIOLOGY 2018; 109:93-99. [PMID: 30006107 DOI: 10.1016/j.jinsphys.2018.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 06/22/2018] [Accepted: 07/09/2018] [Indexed: 06/08/2023]
Abstract
The population dynamics of annual social hymenoptera such as vespids depend largely on the fertility of the foundresses, which, in turn, is a key factor in the context of biological invasions. The native European hornet Vespa crabro (Vc) and the invasive Asian hornet Vespa velutina (Vv) have generally similar ecological traits, e.g. nesting and feeding habits, although they differ in colony size, which is higher in Vv. Furthermore, in contrast to Vc, Vv is more specialized in its predatory habits, intensively hunting honey bees at the hive. Comparing the morphological and reproductive traits of two closely related species occupying the same ecological niche, one of which is a native species and the other an alien, can help us to gain an understanding of the invasion process. To this end, we here compare reproductive (ovarian size and maturation, fat level, spermatheca size and sperm stock, fecundity) and morphological traits (head size, weight) of the foundresses of these two hornet species. We observed that ovarian maturation began approximately one month earlier in Vv than in Vc, and that the fat level in the former was lower. We found twice the number of sperm in the mated foundresses of Vv than in those of Vc (more than 100 × 103 and less than 50 × 103 sperm, respectively), in a 16% smaller spermatheca in Vc. Furthermore, the sperm of Vv was found to be 65% shorter than that of Vc. The precocity and higher potential fecundity of Vv queens may have favoured this species over Vc in terms of predatory behaviour, and thereby contributed to its invasiveness.
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Affiliation(s)
- Juliette Poidatz
- INRA, UMR1065 Santé et Agroécologie du Vignoble, F-33883 Villenave d'Ornon, France; ISVV, UMR1065 Santé et Agroécologie du Vignoble, Bordeaux Sciences Agro, Université de Bordeaux, F-33883 Villenave d'Ornon, France
| | | | - Olivier Bonnard
- INRA, UMR1065 Santé et Agroécologie du Vignoble, F-33883 Villenave d'Ornon, France; ISVV, UMR1065 Santé et Agroécologie du Vignoble, Bordeaux Sciences Agro, Université de Bordeaux, F-33883 Villenave d'Ornon, France
| | - Denis Thiéry
- INRA, UMR1065 Santé et Agroécologie du Vignoble, F-33883 Villenave d'Ornon, France; ISVV, UMR1065 Santé et Agroécologie du Vignoble, Bordeaux Sciences Agro, Université de Bordeaux, F-33883 Villenave d'Ornon, France.
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31
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Avril A, Purcell J, Brelsford A, Chapuisat M. Asymmetric assortative mating and queen polyandry are linked to a supergene controlling ant social organization. Mol Ecol 2018; 28:1428-1438. [PMID: 30003603 DOI: 10.1111/mec.14793] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/02/2018] [Accepted: 07/06/2018] [Indexed: 01/04/2023]
Abstract
Nonrecombining genomic variants underlie spectacular social polymorphisms, from bird mating systems to ant social organization. Because these "social supergenes" affect multiple phenotypic traits linked to survival and reproduction, explaining their persistence remains a substantial challenge. Here, we investigate how large nonrecombining genomic variants relate to colony social organization, mating system and dispersal in the Alpine silver ant, Formica selysi. The species has colonies headed by a single queen (monogynous) and colonies headed by multiple queens (polygynous). We confirmed that a supergene with alternate haplotypes-Sm and Sp-underlies this polymorphism in social structure: Females from mature monogynous colonies had the Sm/Sm genotype, while those from polygynous colonies were Sm/Sp and Sp/Sp. Queens heading monogynous colonies were exclusively mated with Sm males. In contrast, queens heading polygynous colonies were mated with Sp males and Sm males. Sm males, which are only produced by monogynous colonies, accounted for 22.9% of the matings with queens from mature polygynous colonies. This asymmetry between social forms in the degree of assortative mating generates unidirectional male-mediated gene flow from the monogynous to the polygynous social form. Biased gene flow was confirmed by a significantly higher number of private alleles in the polygynous social form. Moreover, heterozygous queens were three times as likely as homozygous queens to be multiply mated. This study reveals that the supergene variants jointly affect social organization and multiple components of the mating system that alter the transmission of the variants and thus influence the dynamics of the system.
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Affiliation(s)
- Amaury Avril
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Jessica Purcell
- Department of Entomology, University of California Riverside, Riverside, California
| | - Alan Brelsford
- Department of Evolution, Ecology, and Organismal Biology, University of California Riverside, Riverside, California
| | - Michel Chapuisat
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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Dávila F, Botteaux A, Bauman D, Chérasse S, Aron S. Antibacterial activity of male and female sperm-storage organs in ants. ACTA ACUST UNITED AC 2018; 221:jeb.175158. [PMID: 29444845 DOI: 10.1242/jeb.175158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 02/05/2018] [Indexed: 01/08/2023]
Abstract
Bacteria can damage sperm and thus reduce the reproductive success of both males and females; selection should therefore favour the evolution of antimicrobial protection. Eusocial hymenopterans might be particularly affected by such bacterial infections because of their mating ecology. In both sexes, mating is restricted to a short window early in the adult stage; there are no further chances to mate later in life. Males die shortly after mating, but queens use the acquired sperm to fertilise their eggs for years, sometimes decades. The reproductive success of both sexes is, thus, ultimately sperm-limited, which maintains strong selection for high sperm viability before and after storage. We tested the antibacterial activity of the contents of the male and female sperm-storage organs - the accessory testes and the spermatheca, respectively. As our study species, we used the bacterium Escherichia coli and the garden ant Lasius niger, whose queens can live for several decades. Our results provide the first empirical evidence that male and female sperm-storage organs display different antibacterial activity. While the contents of the accessory testes actually enhanced bacterial growth, the contents of the spermatheca strongly inhibited it. Furthermore, mating appears to activate the general immune system in queens. However, antimicrobial activity in both the spermatheca and the control tissue (head-thorax homogenate) declined rapidly post-mating, consistent with a trade-off between immunity and reproduction. Overall, this study suggests that ejaculates undergo an immune 'flush' at the time of mating, allowing storage of sperm cells free of bacteria.
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Affiliation(s)
- Francisco Dávila
- Evolutionary Biology and Ecology, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Anne Botteaux
- Laboratory of Molecular Bacteriology, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - David Bauman
- Laboratory of Plant Ecology and Biogeochemistry, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Sarah Chérasse
- Evolutionary Biology and Ecology, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Serge Aron
- Evolutionary Biology and Ecology, Université Libre de Bruxelles, 1050 Brussels, Belgium
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33
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Villar G, Wolfson MD, Hefetz A, Grozinger CM. Evaluating the Role of Drone-Produced Chemical Signals in Mediating Social Interactions in Honey Bees (Apis mellifera). J Chem Ecol 2017; 44:1-8. [PMID: 29209933 DOI: 10.1007/s10886-017-0912-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 11/09/2017] [Accepted: 11/20/2017] [Indexed: 10/18/2022]
Abstract
Pheromones play a critical role in shaping societies of social insects, including honey bees, Apis mellifera. While diverse functions have been ascribed to queen- and worker-produced compounds, few studies have explored the identity and function of male-produced (drone) compounds. However, several lines of evidence suggest that drones engage in a variety of social interactions inside and outside of the colony. Here we elucidate the chemical composition of extracts of the drone mandibular gland, and test the hypothesis that compounds produced in these glands, or a synthetic blend consisting of the six main compounds, mediate drone social interactions in and out of the colony. Drone mandibular glands primarily produce a blend of saturated, unsaturated and methyl branched fatty acids ranging in chain length from nonanoic to docosanoic acids, and both gland extracts and synthetic blends of these chemicals serve to attract drones outside of the hive, but do not attract workers inside the hive. These studies shed light on the role drones and drone-produced chemicals have on mediating social interactions with other drones and highlight their potential importance in communicating with other castes.
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Affiliation(s)
- Gabriel Villar
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
| | - Megan D Wolfson
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Abraham Hefetz
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Ramat Aviv, Israel
| | - Christina M Grozinger
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
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34
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Yagound B, Duncan M, Chapman NC, Oldroyd BP. Subfamily-dependent alternative reproductive strategies in worker honeybees. Mol Ecol 2017; 26:6938-6947. [PMID: 29113015 DOI: 10.1111/mec.14417] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/06/2017] [Accepted: 10/16/2017] [Indexed: 02/01/2023]
Abstract
Functional worker sterility is the defining feature of insect societies. Yet, workers are sometimes found reproducing in their own or foreign colonies. The proximate mechanisms underlying these alternative reproductive phenotypes are keys to understanding how reproductive altruism and selfishness are balanced in eusocial insects. In this study, we show that in honeybee (Apis mellifera) colonies, the social environment of a worker, that is, the presence and relatedness of the queens in a worker's natal colony and in surrounding colonies, significantly influences her fertility and drifting behaviour. Furthermore, subfamilies vary in the frequency of worker ovarian activation, propensity to drift and the kind of host colony that is targeted for reproductive parasitism. Our results show that there is an interplay between a worker's subfamily, reproductive state and social environment that substantially affects her reproductive phenotype. Our study further indicates that honeybee populations show substantial genetic variance for worker reproductive strategies, suggesting that no one strategy is optimal under all the circumstances that a typical worker may encounter.
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Affiliation(s)
- Boris Yagound
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Michael Duncan
- School of Science and Health, Western Sydney University, Richmond, NSW, Australia
| | - Nadine C Chapman
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Benjamin P Oldroyd
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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35
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Forfert N, Troxler A, Retschnig G, Gauthier L, Straub L, Moritz RFA, Neumann P, Williams GR. Neonicotinoid pesticides can reduce honeybee colony genetic diversity. PLoS One 2017; 12:e0186109. [PMID: 29059234 PMCID: PMC5653293 DOI: 10.1371/journal.pone.0186109] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 09/25/2017] [Indexed: 12/02/2022] Open
Abstract
Neonicotinoid insecticides can cause a variety of adverse sub-lethal effects in bees. In social species such as the honeybee, Apis mellifera, queens are essential for reproduction and colony functioning. Therefore, any negative effect of these agricultural chemicals on the mating success of queens may have serious consequences for the fitness of the entire colony. Queens were exposed to the common neonicotinoid pesticides thiamethoxam and clothianidin during their developmental stage. After mating, their spermathecae were dissected to count the number of stored spermatozoa. Furthermore, their worker offspring were genotyped with DNA microsatellites to determine the number of matings and the genotypic composition of the colony. Colonies providing the male mating partners were also inferred. Both neonicotinoid and control queens mated with drones originating from the same drone source colonies, and stored similar number of spermatozoa. However, queens reared in colonies exposed to both neonicotinoids experienced fewer matings. This resulted in a reduction of the genetic diversity in their colonies (i.e. higher intracolonial relatedness). As decreased genetic diversity among worker bees is known to negatively affect colony vitality, neonicotinoids may have a cryptic effect on colony health by reducing the mating frequency of queens.
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Affiliation(s)
- Nadège Forfert
- Institute of Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Aline Troxler
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Gina Retschnig
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | | | - Lars Straub
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Robin F. A. Moritz
- Institute of Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
- Social Insect Research Group, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Peter Neumann
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Agroscope, Swiss Bee Research Centre, Bern, Switzerland
| | - Geoffrey R. Williams
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Agroscope, Swiss Bee Research Centre, Bern, Switzerland
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
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36
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Ding G, Xu H, Oldroyd BP, Gloag RS. Extreme polyandry aids the establishment of invasive populations of a social insect. Heredity (Edinb) 2017; 119:381-387. [PMID: 28832579 DOI: 10.1038/hdy.2017.49] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/27/2017] [Accepted: 07/12/2017] [Indexed: 11/09/2022] Open
Abstract
Although monandry is believed to have facilitated the evolution of eusociality, many highly eusocial insects have since evolved extreme polyandry. The transition to extreme polyandry was likely driven by the benefits of within-colony genetic variance to task specialization and/or disease resistance, but the extent to which it confers secondary benefits, once evolved, is unclear. Here we investigate the consequences of extreme polyandry on the invasive potential of the Asian honey bee, Apis cerana. In honey bees and other Hymenoptera, small newly founded invasive populations must overcome the genetic constraint of their sex determination system that requires heterozygosity at a sex-determining locus to produce viable females. We find A. cerana queens in an invasive population mate with an average of 27 males (range 16-42) that would result in the founding queen/s carrying 75% of their source population's sex alleles in stored sperm. This mating frequency is similar to native-range Chinese A. cerana (mean 29 males, range 19-46). Simulations reveal that extreme polyandry reduces the risk, relative to monandry or moderate polyandry, that colonies produce a high incidence of inviable brood in populations that have experienced a founder event, that is, when sex allele diversity is low and/or allele frequencies are unequal. Thus, extreme polyandry aids the invasiveness of A. cerana in two ways: (1) by increasing the sex locus allelic richness carried to new populations with each founder, thereby increasing sex locus heterozygosity; and (2) by reducing the population variance in colony fitness following a founder event.
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Affiliation(s)
- G Ding
- College of Plant Protection, China Agricultural University, Beijing, China.,Key Laboratory of Pollinating Insect Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China
| | - H Xu
- College of Plant Protection, China Agricultural University, Beijing, China
| | - B P Oldroyd
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - R S Gloag
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
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37
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Krapf P, Russo L, Arthofer W, Möst M, Steiner FM, Schlick-Steiner BC. An Alpine ant's behavioural polymorphism: monogyny with and without internest aggression in Tetramorium alpestre. ETHOL ECOL EVOL 2017; 30:220-234. [PMID: 29682632 PMCID: PMC5890305 DOI: 10.1080/03949370.2017.1343868] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 05/31/2017] [Indexed: 11/21/2022]
Abstract
Social structure influences animal societies on various levels (e.g., relatedness, behaviour). In ants, both the number of matings per queen and the number of queens per colony can vary strongly. While workers from both monogynous and polygynous colonies often fight fiercely, in supercolonies (an extreme form of polygyny comprising thousands of queens in spatially separated but interconnected nests), non-nestmates interact peacefully. Studies on social and behavioural polymorphism within ant species can help elucidate their influence on genetic diversity and behaviour and the factors triggering variation in social structure and behaviour. Here, we reveal a behavioural and social polymorphism comprising monogyny with and without internest aggression in Tetramorium alpestre sampled in Tyrol, Austria. The social polymorphism is based on genetic and behavioural evidence and contrasts with the supercolonial organisation known from another location in Austria (Carinthia), 150 km away. Microsatellite genotyping using eight polymorphic loci revealed monogyny-monandry and high intranest pairwise relatedness. Interestingly, various experimental one-on-one worker encounters revealed only occasional aggressive behaviour between monogynous colonies, and thus a behavioural polymorphism. Mantel tests revealed a significant negative correlation between spatial distance and relatedness, while worker behaviour was not correlated with relatedness or spatial distance. These results indicate that behaviour might be influenced by other factors - for example, the experience of workers, ecological, chemical, and/or genetic factors not characterised in this study. However, workers distinguished nestmates from non-nestmates also when aggression was lacking. We hypothesise an adaptive value of reduced aggression. We speculate that the non-aggressive and partly aggressive encounters observed represent different options in the social structure of T. alpestre, the non-aggressiveness possibly also promoting supercolony development. The social and behavioural polymorphisms observed offer opportunities to identify the factors triggering these changes and thus further explore the behavioural and social polymorphism of this ant species.
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Affiliation(s)
- Patrick Krapf
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Lucia Russo
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Wolfgang Arthofer
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Markus Möst
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Florian M. Steiner
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Birgit C. Schlick-Steiner
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
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38
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Quiñones AE, Pen I. A unified model of Hymenopteran preadaptations that trigger the evolutionary transition to eusociality. Nat Commun 2017; 8:15920. [PMID: 28643786 PMCID: PMC5490048 DOI: 10.1038/ncomms15920] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 05/12/2017] [Indexed: 11/09/2022] Open
Abstract
Explaining the origin of eusociality, with strict division of labour between workers and reproductives, remains one of evolutionary biology's greatest challenges. Specific combinations of genetic, behavioural and demographic traits in Hymenoptera are thought to explain their relatively high frequency of eusociality, but quantitative models integrating such preadaptations are lacking. Here we use mathematical models to show that the joint evolution of helping behaviour and maternal sex ratio adjustment can synergistically trigger both a behavioural change from solitary to eusocial breeding, and a demographic change from a life cycle with two reproductive broods to a life cycle in which an unmated cohort of female workers precedes a final generation of dispersing reproductives. Specific suits of preadaptations are particularly favourable to the evolution of eusociality: lifetime monogamy, bivoltinism with male generation overlap, hibernation of mated females and haplodiploidy with maternal sex ratio adjustment. The joint effects of these preadaptations may explain the abundance of eusociality in the Hymenoptera and its virtual absence in other haplodiploid lineages.
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Affiliation(s)
- Andrés E. Quiñones
- Theoretical Research in Evolutionary Life Sciences, Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
| | - Ido Pen
- Theoretical Research in Evolutionary Life Sciences, Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
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39
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Ernst UR, Cardoen D, Cornette V, Ratnieks FL, de Graaf DC, Schoofs L, Verleyen P, Wenseleers T. Individual and genetic task specialization in policing behaviour in the European honeybee. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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40
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Tregenza T, Wedell N. BENEFITS OF MULTIPLE MATES IN THE CRICKET GRYLLUS BIMACULATUS. Evolution 2017; 52:1726-1730. [PMID: 28565303 DOI: 10.1111/j.1558-5646.1998.tb02252.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/1997] [Accepted: 04/30/1998] [Indexed: 11/27/2022]
Abstract
Despite the importance of polyandry for sexual selection, the reasons why females frequently mate with several males remain poorly understood. A number of genetic benefits have been proposed, based on the idea that by taking multiple mates, females increase the likelihood that their offspring will be sired by genetically more compatible or superior males. If certain males have intrinsically "good genes," any female mating with them will produce superior offspring. Alternatively, if some males have genetic elements that are incompatible with a particular female, then she may benefit from polyandry if the sperm of such males are less likely to fertilize her eggs. We examined these hypotheses in the field cricket Gryllus bimaculatus (Orthoptera: Gryllidae). By allocating females identical numbers of matings but different numbers of mates we investigated the influence of number of mates on female fecundity, and both short- and long-term offspring fitness. This revealed no effect of number of mates on number of eggs laid. However, hatching success of eggs increased with number of mates. This effect could not be attributed to nongenetic effects such as the possibility that polyandry reduces variance in the quantity or fertilizing ability of sperm females receive, because a control group receiving half the number of copulations showed no drop in hatching success. Offspring did not differ in survival, adult mass, size, or development time with treatment. When males were mated to several different females there were no repeatable differences between individual males in the hatching success of their mate's eggs. This suggests that improved hatching success of polyandrous females is not due to certain males having genes that improve egg viability regardless of their mate. Instead, our results support the hypothesis that certain males are genetically more compatible with certain females, and that this drives polyandry through differential fertilization success of sperm from more compatible males.
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Affiliation(s)
- Tom Tregenza
- Ecology and Evolution Group, Department of Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Nina Wedell
- Department of Zoology, University of Stockholm, S-106 91, Stockholm, Sweden
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41
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Amiri E, Strand MK, Rueppell O, Tarpy DR. Queen Quality and the Impact of Honey Bee Diseases on Queen Health: Potential for Interactions between Two Major Threats to Colony Health. INSECTS 2017; 8:E48. [PMID: 28481294 PMCID: PMC5492062 DOI: 10.3390/insects8020048] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 04/15/2017] [Accepted: 05/04/2017] [Indexed: 12/21/2022]
Abstract
Western honey bees, Apis mellifera, live in highly eusocial colonies that are each typically headed by a single queen. The queen is the sole reproductive female in a healthy colony, and because long-term colony survival depends on her ability to produce a large number of offspring, queen health is essential for colony success. Honey bees have recently been experiencing considerable declines in colony health. Among a number of biotic and abiotic factors known to impact colony health, disease and queen failure are repeatedly reported as important factors underlying colony losses. Surprisingly, there are relatively few studies on the relationship and interaction between honey bee diseases and queen quality. It is critical to understand the negative impacts of pests and pathogens on queen health, how queen problems might enable disease, and how both factors influence colony health. Here, we review the current literature on queen reproductive potential and the impacts of honey bee parasites and pathogens on queens. We conclude by highlighting gaps in our knowledge on the combination of disease and queen failure to provide a perspective and prioritize further research to mitigate disease, improve queen quality, and ensure colony health.
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Affiliation(s)
- Esmaeil Amiri
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, USA.
- Department of Entomology & Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA.
| | - Micheline K Strand
- Life Science Division, U.S. Army Research Office, Research Triangle Park, Durham, NC 27709, USA.
| | - Olav Rueppell
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, USA.
| | - David R Tarpy
- Department of Entomology & Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA.
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42
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McCullough EL, Buzatto BA, Simmons LW. Benefits of polyandry: Molecular evidence from field-caught dung beetles. Mol Ecol 2017; 26:3546-3555. [PMID: 28370584 DOI: 10.1111/mec.14127] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 03/07/2017] [Accepted: 03/21/2017] [Indexed: 11/29/2022]
Abstract
When females mate with multiple males, they set the stage for postcopulatory sexual selection via sperm competition and/or cryptic female choice. Surprisingly little is known about the rates of multiple mating by females in the wild, despite the importance of this information in understanding the potential for postcopulatory sexual selection to drive the evolution of reproductive behaviour, morphology and physiology. Dung beetles in the genus Onthophagus have become a laboratory model for studying pre- and postcopulatory sexual selection, yet we still lack information about the reproductive behaviour of female dung beetles in natural populations. Here, we develop microsatellite markers for Onthophagus taurus and use them to genotype the offspring of wild-caught females and to estimate natural rates of multiple mating and patterns of sperm utilization. We found that O. taurus females are highly polyandrous: 88% of females produced clutches sired by at least two males, and 5% produced clutches with as many as five sires. Several females (23%) produced clutches with significant paternity skew, indicating the potential for strong postcopulatory sexual selection in natural populations. There were also strong positive correlations between the number of offspring produced and both number of fathers and paternity skew, which suggests that females benefit from mating polyandrously by inciting postcopulatory mechanisms that bias paternity towards males that can sire more viable offspring. This study evaluates the fitness consequences of polyandry for an insect in the wild and provides strong evidence that female dung beetles benefit from multiple mating under natural conditions.
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Affiliation(s)
- Erin L McCullough
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, Western Australia, Australia
| | - Bruno A Buzatto
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, Western Australia, Australia
| | - Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, Western Australia, Australia
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Loope KJ, Lopez-Osorio F, Dvořák L. Convergent Reversion to Single Mating in a Wasp Social Parasite. Am Nat 2017; 189:E138-E151. [PMID: 28514634 DOI: 10.1086/691405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
While eusociality arose in species with single-mating females, multiple mating by queens has evolved repeatedly across the social ants, bees, and wasps. Understanding the benefits and costs of multiple mating of queens is important because polyandry results in reduced relatedness between siblings, reducing kin-selected benefits of helping while also selecting for secondary social traits that reduce intracolony conflict. The leading hypothesis for the benefits of polyandry in social insects emphasizes advantages of a genetically diverse workforce. Workerless social parasite species (inquilines) provide a unique opportunity to test this hypothesis, since they are derived from social ancestors but do not produce workers of their own. Such parasites are thus predicted to evolve single mating because they would experience the costs of multiple mating but not the benefits if such benefits accrue through the production of a genetically diverse group of workers. Here we show that the workerless social parasite Dolichovespula arctica, a derived parasite of wasps, has reverted to obligate single mating from a facultatively polyandrous ancestor, mirroring a similar reversion from obligate polyandry to approximate monandry in a social parasite of fungus-farming ants. This finding and a comparison with two other cases where inquilinism did not induce reversal to monandry support the hypothesis that facultative polyandry can be costly and may be maintained by benefits of a genetically diverse workforce.
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Boulay R, Aron S, Cerdá X, Doums C, Graham P, Hefetz A, Monnin T. Social Life in Arid Environments: The Case Study of Cataglyphis Ants. ANNUAL REVIEW OF ENTOMOLOGY 2017; 62:305-321. [PMID: 27860520 DOI: 10.1146/annurev-ento-031616-034941] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Unlike most desert-dwelling animals, Cataglyphis ants do not attempt to escape the heat; rather, they apply their impressive heat tolerance to avoid competitors and predators. This thermally defined niche has promoted a range of adaptations both at the individual and colony levels. We have also recently discovered that within the genus Cataglyphis there are incredibly diverse social systems, modes of reproduction, and dispersal, prompting the tantalizing question of whether social diversity may also be a consequence of the harsh environment within which we find these charismatic ants. Here we review recent advances regarding the physiological, behavioral, life-history, colony, and ecological characteristics of Cataglyphis and consider perspectives on future research that will build our understanding of organic adaptive responses to desertification.
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Affiliation(s)
- Raphaël Boulay
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Institute of Insect Biology, Tours University, 37200 Tours, France
| | - Serge Aron
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Evolutionary Biology and Ecology, Université Libre de Bruxelles, 1050, Belgium
| | - Xim Cerdá
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Doñana Biological Station, CSIC, 41092 Seville, Spain
| | - Claudie Doums
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Institute of Systematics, Evolution, and Biodiversity, CNRS, UPMC, EPHE, MNHN, 75005 Paris, France
| | - Paul Graham
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, United Kingdom
| | - Abraham Hefetz
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Thibaud Monnin
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- UMR 7618, Institute of Ecology and Environmental Sciences of Paris, Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris, France
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45
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Viral prevalence increases with regional colony abundance in honey bee drones (Apis mellifera L). INFECTION GENETICS AND EVOLUTION 2016; 44:549-554. [DOI: 10.1016/j.meegid.2016.07.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 07/07/2016] [Accepted: 07/16/2016] [Indexed: 01/06/2023]
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46
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Cronin AL, Monnin T, Sillam-Dussès D, Aubrun F, Fédérici P, Doums C. Qualitative bias in offspring investment in a superorganism is linked to dispersal and nest inheritance. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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47
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Loope KJ. Matricide and queen sex allocation in a yellowjacket wasp. Naturwissenschaften 2016; 103:57. [PMID: 27350328 DOI: 10.1007/s00114-016-1384-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/11/2016] [Accepted: 06/09/2016] [Indexed: 11/25/2022]
Abstract
In many colonies of social insects, the workers compete with each other and with the queen over the production of the colony's males. In some species of social bees and wasps with annual societies, this intra-colony conflict even results in matricide-the killing of the colony's irreplaceable queen by a daughter worker. In colonies with low effective paternity and high worker-worker relatedness, workers value worker-laid males more than queen-laid males, and thus may benefit from queen killing. Workers gain by eliminating the queen because she is a competing source of male eggs and actively inhibits worker reproduction through policing. However, matricide may be costly to workers if it reduces the production of valuable new queens and workers. Here, I test a theoretical prediction regarding the timing of matricide in a wasp, Dolichovespula arenaria, recently shown to have facultative matricide based on intra-colony relatedness. Using analyses of collected, mature colonies and a surgical manipulation preventing queens from laying female eggs, I show that workers do not preferentially kill queens who are only producing male eggs. Instead, workers sometimes kill queens laying valuable females, suggesting a high cost of matricide. Although matricide is common and typically occurs only in low-paternity colonies, it seems that workers sometimes pay substantial costs in this expression of conflict over male parentage.
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Affiliation(s)
- Kevin J Loope
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA.
- Department of Entomology, University of California-Riverside, Riverside, CA, USA.
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48
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Evolution of reproductive traits in Cataglyphis desert ants: mating frequency, queen number, and thelytoky. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2144-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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49
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Boomsma JJ. When every sperm is sacred: the emergence and decline of superorganismal chimeras. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12617] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jacobus J. Boomsma
- Department of Biology Centre for Social Evolution University of Copenhagen Universitetsparken 15 2100 Copenhagen Denmark
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50
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Previtali C, Bongioni G, Costa C, Lodesani M, Galli A. Observation by microsatellite DNA analysis of sperm usage in naturally mated honeybee queens (Apis mellifera ligustica) over a period of two years. ITALIAN JOURNAL OF ANIMAL SCIENCE 2016. [DOI: 10.4081/ijas.2008.465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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