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Ruttenberg DM, Levin SA, Wingreen NS, Kocher SD. Variation in season length and development time is sufficient to drive the emergence and coexistence of social and solitary behavioral strategies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.18.599518. [PMID: 38948882 PMCID: PMC11212982 DOI: 10.1101/2024.06.18.599518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Season length and its associated variables can influence the expression of social behaviors, including the occurrence of eusociality in insects. Eusociality can vary widely across environmental gradients, both within and between different species. Numerous theoretical models have been developed to examine the life history traits that underlie the emergence and maintenance of eusociality, yet the impact of seasonality on this process is largely uncharacterized. Here, we present a theoretical model that incorporates season length and offspring development time into a single, individual-focused model to examine how these factors can shape the costs and benefits of social living. We find that longer season lengths and faster brood development times are sufficient to favor the emergence and maintenance of a social strategy, while shorter seasons favor a solitary one. We also identify a range of season lengths where social and solitary strategies can coexist. Moreover, our theoretical predictions are well-matched to the natural history and behavior of two flexibly-eusocial bee species, suggesting our model can make realistic predictions about the evolution of different social strategies. Broadly, this work reveals the crucial role that environmental conditions can have in shaping social behavior and its evolution and underscores the need for further models that explicitly incorporate such variation to study evolutionary trajectories of eusociality.
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Affiliation(s)
- Dee M Ruttenberg
- Lewis-Sigler Institute for Integrative Genomics, Princeton University
- Department of Ecology and Evolutionary Biology, Princeton University
| | - Simon A Levin
- Lewis-Sigler Institute for Integrative Genomics, Princeton University
- Department of Ecology and Evolutionary Biology, Princeton University
| | - Ned S Wingreen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University
- Department of Molecular Biology, Princeton University
| | - Sarah D Kocher
- Lewis-Sigler Institute for Integrative Genomics, Princeton University
- Department of Ecology and Evolutionary Biology, Princeton University
- Howard Hughes Medical Institute
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2
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Jeanne RL, Loope KJ, Bouwma AM, Nordheim EV, Smith ML. Five decades of misunderstanding in the social Hymenoptera: a review and meta-analysis of Michener's paradox. Biol Rev Camb Philos Soc 2022; 97:1559-1611. [PMID: 35338566 PMCID: PMC9546470 DOI: 10.1111/brv.12854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 12/22/2022]
Abstract
In a much-cited 1964 paper entitled "Reproductive efficiency in relation to colony size in hymenopterous societies," Charles Michener investigated the correlation between a colony's size and its reproductive efficiency - the ability of its adult females to produce reproductives, measured as per-capita output. Based on his analysis of published data from destructively sampled colonies in 18 species, he reported that in most of these species efficiency decreased with increasing colony size. His conclusion that efficiency is higher in smaller groups has since gained widespread acceptance. But it created a seeming paradox: how can natural selection maintain social behaviour when a female apparently enjoys her highest per-capita output by working alone? Here we treat Michener's pattern as a hypothesis and perform the first large-scale test of its prediction across the eusocial Hymenoptera. Because data on actual output of reproductives were not available for most species, Michener used various proxies, such as nest size, numbers of brood, or amounts of stored food. We show that for each of Michener's data sets the reported decline in per-capita productivity can be explained by factors other than decreasing efficiency, calling into question his conclusion that declining efficiency is the cause of the pattern. The most prominent cause of bias is the failure of the proxy to capture all forms of output in which the colony invests during the course of its ontogeny. Other biasing factors include seasonal effects and a variety of methodological flaws in the data sets he used. We then summarize the results of 215 data sets drawn from post-1964 studies of 80 species in 33 genera that better control for these factors. Of these, 163 data sets are included in two meta-analyses that statistically synthesize the available data on the relationship between colony size and efficiency, accounting for variable sample sizes and non-independence among the data sets. The overall effect, and those for most taxonomic subgroups, indicates no loss of efficiency with increasing colony size. Two exceptional taxa, the halictid bees and independent-founding paper wasps, show negative trends consistent with the Michener hypothesis in some species. We conclude that in most species, particularly those with large colony sizes, the hypothesis of decreasing efficiency with increasing colony size is not supported. Finally, we explore potential mechanisms through which the level of efficiency can decrease, be maintained, or even increase, as colonies increase in size.
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Affiliation(s)
- Robert L Jeanne
- Department of Entomology, University of Wisconsin, 1630 Linden Drive, Madison, WI, 53706, U.S.A
| | - Kevin J Loope
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University (Virginia Tech), Cheatham Hall, 310 W. Campus Drive, Blacksburg, VA, 24060, U.S.A
| | - Andrew M Bouwma
- Department of Integrative Biology, Oregon State University, Cordley Hall, 3029, 2701 SW Campus Way, Corvallis, OR, 97331, U.S.A
| | - Erik V Nordheim
- Department of Statistics, University of Wisconsin, 1300 University Avenue, Madison, WI, 53706, U.S.A
| | - Michael L Smith
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, U.S.A
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3
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Hagadorn MA, Eck K, Del Grosso M, Haemmerle X, Wcislo WT, Kapheim KM. Age-related mushroom body expansion in male sweat bees and bumble bees. Sci Rep 2021; 11:17039. [PMID: 34426595 PMCID: PMC8382693 DOI: 10.1038/s41598-021-96268-w] [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: 06/14/2021] [Accepted: 08/04/2021] [Indexed: 01/20/2023] Open
Abstract
A well-documented phenomenon among social insects is that brain changes occur prior to or at the onset of certain experiences, potentially serving to prime the brain for specific tasks. This insight comes almost exclusively from studies considering developmental maturation in females. As a result, it is unclear whether age-related brain plasticity is consistent across sexes, and to what extent developmental patterns differ. Using confocal microscopy and volumetric analyses, we investigated age-related brain changes coinciding with sexual maturation in the males of the facultatively eusocial sweat bee, Megalopta genalis, and the obligately eusocial bumble bee, Bombus impatiens. We compared volumetric measurements between newly eclosed and reproductively mature males kept isolated in the lab. We found expansion of the mushroom bodies-brain regions associated with learning and memory-with maturation, which were consistent across both species. This age-related plasticity may, therefore, play a functionally-relevant role in preparing male bees for mating, and suggests that developmentally-driven neural restructuring can occur in males, even in species where it is absent in females.
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Affiliation(s)
- Mallory A Hagadorn
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA.
| | - Karlee Eck
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA
| | - Matthew Del Grosso
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA
| | - Xavier Haemmerle
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA
| | - William T Wcislo
- Smithsonian Tropical Research Institute, 0843-03092, Panama City, Republic of Panama
| | - Karen M Kapheim
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA.
- Smithsonian Tropical Research Institute, 0843-03092, Panama City, Republic of Panama.
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4
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Kennedy P, Sumner S, Botha P, Welton NJ, Higginson AD, Radford AN. Diminishing returns drive altruists to help extended family. Nat Ecol Evol 2021; 5:468-479. [PMID: 33589803 PMCID: PMC7610556 DOI: 10.1038/s41559-020-01382-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 12/10/2020] [Indexed: 11/09/2022]
Abstract
Altruism between close relatives can be easily explained. However, paradoxes arise when organisms divert altruism towards more distantly related recipients. In some social insects, workers drift extensively between colonies and help raise less related foreign brood, seemingly reducing inclusive fitness. Since being highlighted by W. D. Hamilton, three hypotheses (bet hedging, indirect reciprocity and diminishing returns to cooperation) have been proposed for this surprising behaviour. Here, using inclusive fitness theory, we show that bet hedging and indirect reciprocity could only drive cooperative drifting under improbable conditions. However, diminishing returns to cooperation create a simple context in which sharing workers is adaptive. Using a longitudinal dataset comprising over a quarter of a million nest cell observations, we quantify cooperative payoffs in the Neotropical wasp Polistes canadensis, for which drifting occurs at high levels. As the worker-to-brood ratio rises in a worker's home colony, the predicted marginal benefit of a worker for expected colony productivity diminishes. Helping related colonies can allow effort to be focused on related brood that are more in need of care. Finally, we use simulations to show that cooperative drifting evolves under diminishing returns when dispersal is local, allowing altruists to focus their efforts on related recipients. Our results indicate the power of nonlinear fitness effects to shape social organization, and suggest that models of eusocial evolution should be extended to include neglected social interactions within colony networks.
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Affiliation(s)
- P. Kennedy
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK,Correspondence:
| | - S. Sumner
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - P. Botha
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - N. J. Welton
- Population Health Sciences, Bristol Medical School, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - A. D. Higginson
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, EX4 4QG, UK
| | - A. N. Radford
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
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5
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Hagadorn MA, Johnson MM, Smith AR, Seid MA, Kapheim KM. Experience, but not age, is associated with volumetric mushroom body expansion in solitary alkali bees. J Exp Biol 2021; 224:jeb.238899. [DOI: 10.1242/jeb.238899] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/09/2021] [Indexed: 01/03/2023]
Abstract
ABSTRACT
In social insects, changes in behavior are often accompanied by structural changes in the brain. This neuroplasticity may come with experience (experience-dependent) or age (experience-expectant). Yet, the evolutionary relationship between neuroplasticity and sociality is unclear, because we know little about neuroplasticity in the solitary relatives of social species. We used confocal microscopy to measure brain changes in response to age and experience in a solitary halictid bee (Nomia melanderi). First, we compared the volume of individual brain regions among newly emerged females, laboratory females deprived of reproductive and foraging experience, and free-flying, nesting females. Experience, but not age, led to significant expansion of the mushroom bodies – higher-order processing centers associated with learning and memory. Next, we investigated how social experience influences neuroplasticity by comparing the brains of females kept in the laboratory either alone or paired with another female. Paired females had significantly larger olfactory regions of the mushroom bodies. Together, these experimental results indicate that experience-dependent neuroplasticity is common to both solitary and social taxa, whereas experience-expectant neuroplasticity may be an adaptation to life in a social colony. Further, neuroplasticity in response to social chemical signals may have facilitated the evolution of sociality.
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Affiliation(s)
- Mallory A. Hagadorn
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
| | - Makenna M. Johnson
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
| | - Adam R. Smith
- Department of Biological Sciences, George Washington University, 800 22nd St NW, Washington, DC 20052, USA
| | - Marc A. Seid
- Biology Department, University of Scranton, 800 Linden St, Scranton, PA 18510, USA
| | - Karen M. Kapheim
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
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6
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Linksvayer TA, Johnson BR. Re-thinking the social ladder approach for elucidating the evolution and molecular basis of insect societies. CURRENT OPINION IN INSECT SCIENCE 2019; 34:123-129. [PMID: 31401545 DOI: 10.1016/j.cois.2019.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/21/2019] [Accepted: 07/03/2019] [Indexed: 06/10/2023]
Abstract
The evolution of large insect societies is a major evolutionary transition that occurred in the long-extinct ancestors of termites, ants, corbiculate bees, and vespid wasps. Researchers have long used 'social ladder thinking': assuming progressive stepwise phenotypic evolution and asserting that extant species with simple societies (e.g. some halictid bees) represent the ancestors of species with complex societies, and thus provide insight into general early steps of eusocial evolution. We discuss how this is inconsistent with data and modern evolutionary 'tree thinking'. Phylogenetic comparative methods with broad sampling provide the best means to make rigorous inferences about ancestral traits and evolutionary transitions that occurred within each lineage, and to determine whether consistent phenotypic and genomic changes occurred across independent lineages.
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Affiliation(s)
| | - Brian R Johnson
- Department of Entomology and Nematology, University of California Davis, United States
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7
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Brain evolution in social insects: advocating for the comparative approach. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:13-32. [DOI: 10.1007/s00359-019-01315-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 01/09/2019] [Accepted: 01/11/2019] [Indexed: 10/27/2022]
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8
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Dew RM, Shell WA, Rehan SM. Changes in maternal investment with climate moderate social behaviour in a facultatively social bee. Behav Ecol Sociobiol 2018. [DOI: 10.1007/s00265-018-2488-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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9
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Shell WA, Rehan SM. The price of insurance: costs and benefits of worker production in a facultatively social bee. Behav Ecol 2017. [DOI: 10.1093/beheco/arx146] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Wyatt A Shell
- Department of Biological Sciences, University of New Hampshire, Durham, NH, USA
| | - Sandra M Rehan
- Department of Biological Sciences, University of New Hampshire, Durham, NH, USA
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10
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Jones BM, Kingwell CJ, Wcislo WT, Robinson GE. Caste-biased gene expression in a facultatively eusocial bee suggests a role for genetic accommodation in the evolution of eusociality. Proc Biol Sci 2017; 284:20162228. [PMID: 28053060 PMCID: PMC5247497 DOI: 10.1098/rspb.2016.2228] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/05/2016] [Indexed: 12/18/2022] Open
Abstract
Developmental plasticity may accelerate the evolution of phenotypic novelty through genetic accommodation, but studies of genetic accommodation often lack knowledge of the ancestral state to place selected traits in an evolutionary context. A promising approach for assessing genetic accommodation involves using a comparative framework to ask whether ancestral plasticity is related to the evolution of a particular trait. Bees are an excellent group for such comparisons because caste-based societies (eusociality) have evolved multiple times independently and extant species exhibit different modes of eusociality. We measured brain and abdominal gene expression in a facultatively eusocial bee, Megalopta genalis, and assessed whether plasticity in this species is functionally linked to eusocial traits in other bee lineages. Caste-biased abdominal genes in M. genalis overlapped significantly with caste-biased genes in obligately eusocial bees. Moreover, caste-biased genes in M. genalis overlapped significantly with genes shown to be rapidly evolving in multiple studies of 10 bee species, particularly for genes in the glycolysis pathway and other genes involved in metabolism. These results provide support for the idea that eusociality can evolve via genetic accommodation, with plasticity in facultatively eusocial species like M. genalis providing a substrate for selection during the evolution of caste in obligately eusocial lineages.
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Affiliation(s)
- Beryl M Jones
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Smithsonian Tropical Research Institute, Panama City 20521-9100, Panama
| | - Callum J Kingwell
- Smithsonian Tropical Research Institute, Panama City 20521-9100, Panama
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - William T Wcislo
- Smithsonian Tropical Research Institute, Panama City 20521-9100, Panama
| | - Gene E Robinson
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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11
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Smith AR, Kitchen SM, Toney RM, Ziegler C. Is Nocturnal Foraging in a Tropical Bee an Escape From Interference Competition? JOURNAL OF INSECT SCIENCE (ONLINE) 2017; 17:3743770. [PMID: 28931157 PMCID: PMC5469389 DOI: 10.1093/jisesa/iex030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Indexed: 06/07/2023]
Abstract
Temporal niche partitioning may result from interference competition if animals shift their activity patterns to avoid aggressive competitors. If doing so also shifts food sources, it is difficult to distinguish the effects of interference and consumptive competition in selecting for temporal niche shift. Bees compete for pollen and nectar from flowers through both interference and consumptive competition, and some species of bees have evolved nocturnality. Here, we use tropical forest canopy towers to observe bees (the night-flying sweat bees Megalopta genalis and M. centralis [Halictidae], honey bees, and stingless bees [Apidae]) visiting flowers of the balsa tree (Ochroma pyramalidae, Malvaceae). Because Ochroma flowers are open in the late afternoon through the night we can test the relative influence of each competition type on temporal nice. Niche shift due to consumptive competition predicts that Megalopta forage when resources are available: from afternoon into the night. Niche shift due to interference competition predicts that Megalopta forage only in the absence of diurnal bees. We found no overlap between diurnal bees and Megalopta in the evening, and only one instance of overlap in the morning, despite the abundance of pollen and nectar in the late afternoon and evening. This supports the hypothesis that Megalopta are avoiding interference competition, but not the hypothesis that they are limited by consumptive competition. We propose that the release from interference competition enables Megalopta to provision cells quickly, and spend most of their time investing in nest defense. Thus, increases in foraging efficiency directly resulting from temporal shifts to escape interference competition may indirectly lead to reduced predation and parasitism.
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Affiliation(s)
- Adam R. Smith
- Department of Biological Sciences, George Washington University, Washington, DC (; ; )
| | - Shannon M. Kitchen
- Department of Biological Sciences, George Washington University, Washington, DC (; ; )
| | - Ryan M. Toney
- Department of Biological Sciences, George Washington University, Washington, DC (; ; )
| | - Christian Ziegler
- Smithsonian Tropical Research Institute, Luis Clement Ave., Bldg. 401 Tupper, Balboa Ancon, Panama, Republic of Panama ()
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12
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Abstract
Why do most animals live solitarily, while complex social life is restricted to a few cooperatively breeding vertebrates and social insects? Here, we synthesize concepts and theories in social evolution and discuss its underlying ecological causes. Social evolution can be partitioned into (a) formation of stable social groups, (b) evolution of helping, and (c) transition to a new evolutionary level. Stable social groups rarely evolve due to competition over food and/or reproduction. Food competition is overcome in social insects with central-place foraging or bonanza-type food resources, whereas competition over reproduction commonly occurs because staying individuals are rarely sterile. Hence, the evolution of helping is shaped by direct and indirect fitness options and helping is only altruism if it reduces the helper's direct fitness. The helper's capability to gain direct fitness also creates within-colony conflict. This prevents transition to a new evolutionary level.
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Affiliation(s)
- Judith Korb
- Department of Evolutionary Biology & Ecology, University of Freiburg, D-79104 Freiburg, Germany;
| | - Jürgen Heinze
- Institute of Zoology/Evolutionary Biology, University of Regensburg, D-93040 Regensburg, Germany;
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13
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Quiñones AE, Wcislo WT. Cryptic extended brood care in the facultatively eusocial sweat bee Megalopta genalis. INSECTES SOCIAUX 2015; 62:307-313. [PMID: 26097252 PMCID: PMC4469088 DOI: 10.1007/s00040-015-0409-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 03/10/2015] [Accepted: 03/19/2015] [Indexed: 06/04/2023]
Abstract
As a result of different brood cell provisioning strategies, nest-making insects may differ in the extent to which adults regularly provide extended parental care to their brood beyond nest defense. Mass-provisioning species cache the entire food supply needed for larval development prior to the oviposition and typically seal the brood cell. It is usually assumed that there is no regular contact between the adult(s) and brood. Here, we show that the bee, Megalopta genalis, expresses a form of cryptic brood care, which would not be observed during normal development. Following experimental injections of different provisioning materials into brood cells, foundresses reopened manipulated cells and the brood were aborted in some cases, implying that the foundresses assessed conditions within the cells. In aborted cells, foundresses sometimes laid a second egg after first removing dead larvae, previously stored pollen and contaminants. Our results show that hygienic brood care can be cryptic and hence may be more widespread than previously believed, lending support to the hypothesis that extended parental care is a preadaptation toward eusociality.
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Affiliation(s)
- A. E. Quiñones
- />Theoretical biology group, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - W. T. Wcislo
- />Smithsonian Tropical Research Institute, 0843-03092 Balboa, Apartado Republic of Panama
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14
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Fu F, Kocher SD, Nowak MA. The risk-return trade-off between solitary and eusocial reproduction. Ecol Lett 2014; 18:74-84. [PMID: 25417761 DOI: 10.1111/ele.12392] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/22/2014] [Accepted: 10/12/2014] [Indexed: 11/30/2022]
Abstract
Social insect colonies can be seen as a distinct form of biological organisation because they function as superorganisms. Understanding how natural selection acts on the emergence and maintenance of these colonies remains a major question in evolutionary biology and ecology. Here, we explore this by using multi-type branching processes to calculate the basic reproductive ratios and the extinction probabilities for solitary vs. eusocial reproductive strategies. We find that eusociality, albeit being hugely successful once established, is generally less stable than solitary reproduction unless large demographic advantages of eusociality arise for small colony sizes. We also demonstrate how such demographic constraints can be overcome by the presence of ecological niches that strongly favour eusociality. Our results characterise the risk-return trade-offs between solitary and eusocial reproduction, and help to explain why eusociality is taxonomically rare: eusociality is a high-risk, high-reward strategy, whereas solitary reproduction is more conservative.
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Affiliation(s)
- Feng Fu
- Theoretical Biology, Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland
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15
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Rehan SM, Richards MH, Adams M, Schwarz MP. The costs and benefits of sociality in a facultatively social bee. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2014.08.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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17
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Ozan M, Helanterä H, Sundström L. The value of oviposition timing, queen presence and kinship in a social insect. Proc Biol Sci 2013; 280:20131231. [PMID: 23843391 DOI: 10.1098/rspb.2013.1231] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reproductive cooperation confers benefits, but simultaneously creates conflicts among cooperators. Queens in multi-queen colonies of ants share a nest and its resources, but reproductive competition among queens often results in unequal reproduction. Two mutually non-exclusive factors may produce such inequality in reproduction: worker intervention or queen traits. Workers may intervene by favouring some queens over others, owing to either kinship or queen signals. Queens may differ in their intrinsic fecundity at the onset of oviposition or in their timing of the onset of oviposition, leading to their unequal representation in the brood. Here, we test the role of queen kin value (relatedness) to workers, timing of the onset of oviposition and signals of presence by queens in determining the maternity of offspring. We show that queens of the ant Formica fusca gained a significantly higher proportion of sexuals in the brood when ovipositing early, and that the presence of a caged queen resulted in a significant increase in both her share of sexual brood and her overall reproductive share. Moreover, the lower the kin value of the queen, the more the workers invested in their own reproduction by producing males. Our results show that both kinship and breeding phenology influence the outcome of reproductive conflicts, and the balance of direct and indirect fitness benefits in the multi-queen colonies of F. fusca.
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Affiliation(s)
- Martina Ozan
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, PO Box 65, Helsinki 00014, Finland.
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18
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Kapheim KM, Smith AR, Nonacs P, Wcislo WT, Wayne RK. Foundress polyphenism and the origins of eusociality in a facultatively eusocial sweat bee, Megalopta genalis (Halictidae). Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1453-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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19
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Kapheim KM, Smith AR, Ihle KE, Amdam GV, Nonacs P, Wcislo WT. Physiological variation as a mechanism for developmental caste-biasing in a facultatively eusocial sweat bee. Proc Biol Sci 2012; 279:1437-46. [PMID: 22048951 PMCID: PMC3282364 DOI: 10.1098/rspb.2011.1652] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 10/13/2011] [Indexed: 11/12/2022] Open
Abstract
Social castes of eusocial insects may have arisen through an evolutionary modification of an ancestral reproductive ground plan, such that some adults emerge from development physiologically primed to specialize on reproduction (queens) and others on maternal care expressed as allo-maternal behaviour (workers). This hypothesis predicts that variation in reproductive physiology should emerge from ontogeny and underlie division of labour. To test these predictions, we identified physiological links to division of labour in a facultatively eusocial sweat bee, Megalopta genalis. Queens are larger, have larger ovaries and have higher vitellogenin titres than workers. We then compared queens and workers with their solitary counterparts-solitary reproductive females and dispersing nest foundresses-to investigate physiological variation as a factor in caste evolution. Within dyads, body size and ovary development were the best predictors of behavioural class. Queens and dispersers are larger, with larger ovaries than their solitary counterparts. Finally, we raised bees in social isolation to investigate the influence of ontogeny on physiological variation. Body size and ovary development among isolated females were highly variable, and linked to differences in vitellogenin titres. As these are key physiological predictors of social caste, our results provide evidence for developmental caste-biasing in a facultatively eusocial bee.
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Affiliation(s)
- Karen M Kapheim
- Department of Ecology and Evolutionary Biology, University of California, 621 Charles E. Young Dr. South, Los Angeles, CA 90095, USA.
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Lucas ER, Field J. Assured fitness returns in a social wasp with no worker caste. Proc Biol Sci 2011; 278:2991-5. [PMID: 21345863 DOI: 10.1098/rspb.2011.0128] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The theory of assured fitness returns proposes that individuals nesting in groups gain fitness benefits from effort expended in brood-rearing, even if they die before the young that they have raised reach independence. These benefits, however, require that surviving nest-mates take up the task of rearing these young. It has been suggested that assured fitness returns could have favoured group nesting even at the origin of sociality (that is, in species without a dedicated worker caste). We show that experimentally orphaned brood of the apoid wasp Microstigmus nigrophthalmus continue to be provisioned by surviving adults for at least two weeks after the orphaning. This was the case for brood of both sexes. There was no evidence that naturally orphaned offspring received less food than those that still had mothers in the nest. Assured fitness returns can therefore represent a real benefit to nesting in groups, even in species without a dedicated worker caste.
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Affiliation(s)
- Eric R Lucas
- School of Life Sciences, University of Sussex, John Maynard Smith Building, Brighton BN1 9QG, UK.
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REHAN SANDRAM, SCHWARZ MICHAELP, RICHARDS MIRIAMH. Fitness consequences of ecological constraints and implications for the evolution of sociality in an incipiently social bee. Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2011.01642.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Support for maternal manipulation of developmental nutrition in a facultatively eusocial bee, Megalopta genalis (Halictidae). Behav Ecol Sociobiol 2011; 65:1179-1190. [PMID: 21743768 PMCID: PMC3096767 DOI: 10.1007/s00265-010-1131-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 12/06/2010] [Accepted: 12/08/2010] [Indexed: 11/24/2022]
Abstract
Developmental maternal effects are a potentially important source of phenotypic variation, but they can be difficult to distinguish from other environmental factors. This is an important distinction within the context of social evolution, because if variation in offspring helping behavior is due to maternal manipulation, social selection may act on maternal phenotypes, as well as those of offspring. Factors correlated with social castes have been linked to variation in developmental nutrition, which might provide opportunity for females to manipulate the social behavior of their offspring. Megalopta genalis is a mass-provisioning facultatively eusocial sweat bee for which production of males and females in social and solitary nests is concurrent and asynchronous. Female offspring may become either gynes (reproductive dispersers) or workers (non-reproductive helpers). We predicted that if maternal manipulation plays a role in M. genalis caste determination, investment in daughters should vary more than for sons. The mass and protein content of pollen stores provided to female offspring varied significantly more than those of males, but volume and sugar content did not. Sugar content varied more among female eggs in social nests than in solitary nests. Provisions were larger, with higher nutrient content, for female eggs and in social nests. Adult females and males show different patterns of allometry, and their investment ratio ranged from 1.23 to 1.69. Adult body weight varied more for females than males, possibly reflecting increased variation in maternal investment in female offspring. These differences are consistent with a role for maternal manipulation in the social plasticity observed in M. genalis.
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Purcell J. Geographic patterns in the distribution of social systems in terrestrial arthropods. Biol Rev Camb Philos Soc 2010; 86:475-91. [PMID: 20840372 DOI: 10.1111/j.1469-185x.2010.00156.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The role of ecology in the evolution and maintenance of arthropod sociality has received increasing research attention in recent years. In some organisms, such as halictine bees, polistine wasps, and social spiders, researchers are investigating the environmental factors that may contribute to high levels of variation in the degree of sociality exhibited both among and within species. Within lineages that include only eusocial members, such as ants and termites, studies focus more on identifying extrinsic factors that may contribute to the dramatic variation in colony size, number of queens, and division of labour that is evident across these species. In this review, I propose a comparative approach that seeks to identify environmental factors that may have a common influence across such divergent social arthropod groups. I suggest that seeking common biogeographic patterns in the distribution of social systems or key social traits may help us to identify ecological factors that play a common role in shaping the evolution of sociality across different organisms. I first review previous studies of social gradients that form along latitudinal and altitudinal axes. Within families and within species, many organisms show an increasing degree of sociality at lower latitudes and altitudes. In a smaller number of cases, organisms form larger groups or found nests cooperatively at higher latitudes and altitudes. I then describe several environmental factors that vary consistently along such gradients, including climate variables and abundance of predators, and outline their proposed role in the social systems of terrestrial arthropods. Finally, I map distributions of a social trait against several climatic factors in five case studies to demonstrate how future comparative studies could inform empirical research.
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Affiliation(s)
- Jessica Purcell
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada.
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Yagi N, Hasegawa E. Both cooperation and nest position improve larval survival in the sweat bee, Lasioglossum (Evylaeus) baleicum. J ETHOL 2010. [DOI: 10.1007/s10164-010-0223-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Smith AR, Seid MA, Jiménez LC, Wcislo WT. Socially induced brain development in a facultatively eusocial sweat bee Megalopta genalis (Halictidae). Proc Biol Sci 2010; 277:2157-63. [PMID: 20335213 DOI: 10.1098/rspb.2010.0269] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Changes in the relative size of brain regions are often dependent on experience and environmental stimulation, which includes an animal's social environment. Some studies suggest that social interactions are cognitively demanding, and have examined predictions that the evolution of sociality led to the evolution of larger brains. Previous studies have compared species with different social organizations or different groups within obligately social species. Here, we report the first intraspecific study to examine how social experience shapes brain volume using a species with facultatively eusocial or solitary behaviour, the sweat bee Megalopta genalis. Serial histological sections were used to reconstruct and measure the volume of brain areas of bees behaving as social reproductives, social workers, solitary reproductives or 1-day-old bees that are undifferentiated with respect to the social phenotype. Social reproductives showed increased development of the mushroom body (an area of the insect brain associated with sensory integration and learning) relative to social workers and solitary reproductives. The gross neuroanatomy of young bees is developmentally similar to the advanced eusocial species previously studied, despite vast differences in colony size and social organization. Our results suggest that the transition from solitary to social behaviour is associated with modified brain development, and that maintaining dominance, rather than sociality per se, leads to increased mushroom body development, even in the smallest social groups possible (i.e. groups with two bees). Such results suggest that capabilities to navigate the complexities of social life may be a factor shaping brain evolution in some social insects, as for some vertebrates.
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Affiliation(s)
- Adam R Smith
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Republic of Panama.
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Salomon M, Vibert S, Bennett RG. Habitat use by western black widow spiders (Latrodectus hesperus) in coastal British Columbia: evidence of facultative group living. CAN J ZOOL 2010. [DOI: 10.1139/z10-004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Animal social systems come in a wide range of forms characterized by different types of group-living relationships. Species that express facultative group-living behaviours, where individuals only associate under certain conditions or at certain times, are especially interesting for studying social evolution. We investigated the social structure of the western black widow spider ( Latrodectus hesperus Chamberlin and Ivie, 1935) over 5 years in a coastal British Columbia habitat, and present the first comprehensive evidence of facultative group living in the genus Latrodectus Walckenaer, 1805. Latrodectus hesperus have a flexible social structure that varies seasonally, wherein individuals (mostly females) either form groups or live solitarily. In the fall and early winter, females spontaneously form groups of 2–8 individuals, but live alone during the oviposition season in the spring and summer. When living in groups spiders share large webs and are tolerant of each other, although they appear to forage individually. We also report on the relationships between different ecological factors and the social structure of L. hesperus, including the interaction of these spiders with two co-occurring species of introduced spiders ( Tegenaria agrestis (Walckenaer, 1802) and Tegenaria duellica Simon, 1875). Our findings suggest that L. hesperus is a good model system with which to explore the mechanisms involved in the evolution of sociality.
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Affiliation(s)
- Maxence Salomon
- Behavioural Ecology Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
- British Columbia Ministry of Forests and Range, 7380 Puckle Road, Saanichton, BC V8M 1W4, Canada
| | - Samantha Vibert
- Behavioural Ecology Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
- British Columbia Ministry of Forests and Range, 7380 Puckle Road, Saanichton, BC V8M 1W4, Canada
| | - Robert G. Bennett
- Behavioural Ecology Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
- British Columbia Ministry of Forests and Range, 7380 Puckle Road, Saanichton, BC V8M 1W4, Canada
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DUNCAN SARAHI, RIECHERT SUSANE, FITZPATRICK BENJAMINM, FORDYCE JAMESA. Relatedness and genetic structure in a socially polymorphic population of the spiderAnelosimus studiosus. Mol Ecol 2010; 19:810-8. [DOI: 10.1111/j.1365-294x.2010.04523.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Social competition but not subfertility leads to a division of labour in the facultatively social sweat bee Megalopta genalis (Hymenoptera: Halictidae). Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.06.032] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Kapheim KM, Pollinger JP, Wcislo WT, Wayne RK. Characterization of 12 polymorphic microsatellite markers for a facultatively eusocial sweat bee (Megalopta genalis). Mol Ecol Resour 2009; 9:1527-9. [PMID: 21564949 DOI: 10.1111/j.1755-0998.2009.02693.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We developed a library of twelve polymorphic di- and tri-nucleotide microsatellite markers for Megalopta genalis, a facultatively eusocial sweat bee. We tested each locus in a panel of 23 unrelated females and found 7-20 alleles per locus. Observed and expected heterozygosities ranged from 0.65 to 0.96 and from 0.69 to 0.95 respectively. None of the loci deviated from Hardy-Weinberg equilibrium proportions or was found to be in gametic disequilibrium.
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Affiliation(s)
- Karen M Kapheim
- Department of Ecology and Evolutionary Biology, 621 Charles E. Young Dr. South, University of California, Los Angeles, CA 90095 USA Smithsonian Tropical Research Institute, Box 0843-03092, Balboa, Ancon, Republic of Panama
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ULRICH YUKO, PERRIN NICOLAS, CHAPUISAT MICHEL. Flexible social organization and high incidence of drifting in the sweat bee,Halictus scabiosae. Mol Ecol 2009; 18:1791-800. [DOI: 10.1111/j.1365-294x.2009.04154.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Jones TC, Riechert SE. Patterns of reproductive success associated with social structure and microclimate in a spider system. Anim Behav 2008. [DOI: 10.1016/j.anbehav.2008.07.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tierney SM, Gonzales‐Ojeda T, Wcislo WT. Biology of a nocturnal bee,Megalopta atra(Hymenoptera: Halictidae; Augochlorini), from the Panamanian highlands. J NAT HIST 2008. [DOI: 10.1080/00222930802109124] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Bono JM, Crespi BJ. Cofoundress relatedness and group productivity in colonies of social Dunatothrips (Insecta: Thysanoptera) on Australian Acacia. Behav Ecol Sociobiol 2008; 62:1489-1498. [PMID: 26279604 DOI: 10.1007/s00265-008-0578-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Facultative joint colony founding by social insects provides opportunities to analyze the roles of genetic and ecological factors in the evolution of cooperation. Although cooperative nesting is observed in range of social insect taxa, the most detailed studies of this behavior have been conducted with Hymenoptera (ants, bees, and wasps). Here, we show that foundress associations in the haplodiploid social thrips Dunatothrips aneurae (Insecta: Thysanoptera) are most often comprised of close relatives (sisters), though groups with unrelated foundresses are also found. Associations among relatives appear to be facilitated by limited female dispersal, which results in viscous population structure. In addition, we found that per capita productivity declined with increasing group size, sex ratios were female-biased, and some female offspring apparently remained in their natal domicile for some time following eclosion. D. aneurae thus exhibits a suite of similarities with eusocial Hymenoptera, providing evidence for the convergent evolution of associated social and life-history traits in Hymenoptera and Thysanoptera.
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Affiliation(s)
- Jeremy M Bono
- Behavioural Ecology Research Group, Department of Biosciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Bernard J Crespi
- Behavioural Ecology Research Group, Department of Biosciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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