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Tsuchida K, Ishiguro N, Saito-Morooka F, Kojima JI, Spradbery P. Nepotistic colony fission in dense colony aggregations of an Australian paper wasp. Sci Rep 2022; 12:12868. [PMID: 35896807 PMCID: PMC9329314 DOI: 10.1038/s41598-022-17117-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 07/20/2022] [Indexed: 12/02/2022] Open
Abstract
Social insects are highly diverse in their social structures, aside from the consistent presence of reproductive castes. Among social insects, the Australian paper wasp Ropalidia plebeiana constructs extremely dense colony aggregations consisting of hundreds of colonies within a few square meters; however, little is known about the aggregation structures. We genetically analyzed the colony and population structure of R. plebeiana, and concomitant variations in colony sex ratios. In spring, the foundress (candidate queen) group started their colonies on a single old comb from the previous season, subsequently dividing these old combs via relatedness-based comb-cutting. Female philopatry, a prerequisite condition of Local Resource Competition (LRC), was confirmed. The colony sex ratio of reproductive individuals (male and female offspring for the next generation) became slightly male-biased in larger colonies, as predicted under LRC. However, the number of foundresses was positively associated with the number of reproductive individuals, suggesting that Local Resource Enhancement (LRE) also operates. Although the population structure appears to meet the prerequisites of LRC, the sex ratio appears to be modulated by factors other than LRC. Rather, through LRE, the availability of female helpers at the founding stage is likely to mitigate the sex ratios predicted under LRC.
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Affiliation(s)
- Koji Tsuchida
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan. .,Australian National Insect Collection, CSIRO, Canberra, ACT, 2601, Australia. .,School of Biological Sciences, Flinders University, Adelaide, SA, 5001, Australia.
| | - Norio Ishiguro
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan
| | - Fuki Saito-Morooka
- Natural History Laboratory, Faculty of Science, Ibaraki University, Mito, Japan
| | - Jun-Ichi Kojima
- Australian National Insect Collection, CSIRO, Canberra, ACT, 2601, Australia.,Natural History Laboratory, Faculty of Science, Ibaraki University, Mito, Japan
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Who to help? Helping decisions in a cooperatively breeding bird with redirected care. Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03190-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Abstract
Cooperative breeding sometimes occurs when adult breeders form groups following natal dispersal and mating. In such cases, individuals typically face a choice of social partner with whom to cooperate. Selecting appropriate social partners is crucial to maximising the fitness payoffs from cooperation, but our understanding of the criteria guiding partner choice is limited. Here, we analyse helping decisions by long-tailed tits (Aegithalos caudatus), which may redirect their care to assist breeders in raising offspring following the failure of their own nests. In this species, helpers prefer to help relatives at nearby nests, but it is unclear whether other criteria that may affect helper fitness also influence helping decisions. When choosing among broods of equivalent kinship, we found that helpers did not prefer those broods that offered the greatest indirect fitness returns. Further analyses revealed that helpers did not choose nests on the basis of brood size or age, but were more likely to help broods that were closer to their own failed nests and that were already being cared for by other helpers. Both effects likely reflect the limited choice available to helpers: although individuals breed close to relatives within kin neighbourhoods, a high rate of nest predation constrains helpers’ choice of broods. In other species where cooperatively breeding groups form after natal dispersal, a greater range of options may be available and here detailed analysis of group formation will be helpful for determining the decision rules that underpin partner choice and permit stable cooperation in the face of alternative options.
Significance statement
Cooperative breeding occurs most frequently when offspring delay dispersal from their natal site and help to care for their younger siblings. In some species, however, individuals first disperse and then come together as adults to cooperate in rearing young. In the latter case, multiple social partners may be available — what then determines which partner is helped? We studied partner choice in long-tailed tits, which may help to feed other broods if their own brood fails. When multiple related broods were available, individuals were more likely to help those close by but showed no preference for broods offering the greatest indirect fitness returns. One explanation for this result is that helping options for most individuals are limited by high levels of nest predation, favouring a simpler decision-making process based on identifying close relatives breeding in close proximity.
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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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Seppä P, Bonelli M, Dupont S, Hakala SM, Bagnères AG, Lorenzi MC. Strong Gene Flow Undermines Local Adaptations in a Host Parasite System. INSECTS 2020; 11:insects11090585. [PMID: 32882832 PMCID: PMC7564341 DOI: 10.3390/insects11090585] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/12/2020] [Accepted: 08/26/2020] [Indexed: 11/20/2022]
Abstract
Simple Summary The co-evolution of hosts and parasites depends on their ability to adapt to each other’s defense and counter-defense mechanisms. The strength of selection on those mechanisms may vary among populations, resulting in a geographical mosaic of co-evolution. The boreo-montane paper wasp Polistes biglumis and its parasite Polistes atrimandibularis exemplify this type of co-evolutionary system. Here, we used genetic markers to examine the genetic population structures of these wasps in the western Alps. We found that both host and parasite populations displayed similar levels of genetic variation. In the host species, populations located near to each other were genetically similar; in both the host and the parasite species populations farther apart were significantly different. Thus, apparent dispersal barriers (i.e., high mountains) did not seem to restrict gene flow across populations as expected. Furthermore, there were no major differences in gene flow between the two species, perhaps because P. atrimandibularis parasitizes both alpine and lowland host species and annually migrates between alpine and lowland populations. The presence of strong gene flow in a system where local populations experience variable levels of selection pressure challenges the classical hypothesis that restricted gene flow is required for local adaptations to evolve. Abstract The co-evolutionary pathways followed by hosts and parasites strongly depend on the adaptive potential of antagonists and its underlying genetic architecture. Geographically structured populations of interacting species often experience local differences in the strength of reciprocal selection pressures, which can result in a geographic mosaic of co-evolution. One example of such a system is the boreo-montane social wasp Polistes biglumis and its social parasite Polistes atrimandibularis, which have evolved local defense and counter-defense mechanisms to match their antagonist. In this work, we study spatial genetic structure of P. biglumis and P. atrimandibularis populations at local and regional scales in the Alps, by using nuclear markers (DNA microsatellites, AFLP) and mitochondrial sequences. Both the host and the parasite populations harbored similar amounts of genetic variation. Host populations were not genetically structured at the local scale, but geographic regions were significantly differentiated from each other in both the host and the parasite in all markers. The net dispersal inferred from genetic differentiation was similar in the host and the parasite, which may be due to the annual migration pattern of the parasites between alpine and lowland populations. Thus, the apparent dispersal barriers (i.e., high mountains) do not restrict gene flow as expected and there are no important gene flow differences between the species, which contradict the hypothesis that restricted gene flow is required for local adaptations to evolve.
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Affiliation(s)
- Perttu Seppä
- Centre of Excellence in Biological Interactions, Organismal and Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65, 00014 Helsinki, Finland;
- Correspondence:
| | - Mariaelena Bonelli
- Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Torino, Italy; (M.B.); (M.C.L.)
- Institut de Recherche sur la Biologie de l’Insecte, UMR 7261, CNRS—Université de Tours, Avenue Monge, Parc Grandmont, 37200 Tours, France; (S.D.); (A.-G.B.)
| | - Simon Dupont
- Institut de Recherche sur la Biologie de l’Insecte, UMR 7261, CNRS—Université de Tours, Avenue Monge, Parc Grandmont, 37200 Tours, France; (S.D.); (A.-G.B.)
| | - Sanja Maria Hakala
- Centre of Excellence in Biological Interactions, Organismal and Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65, 00014 Helsinki, Finland;
| | - Anne-Geneviève Bagnères
- Institut de Recherche sur la Biologie de l’Insecte, UMR 7261, CNRS—Université de Tours, Avenue Monge, Parc Grandmont, 37200 Tours, France; (S.D.); (A.-G.B.)
- Centre d’Ecologie Fonctionnelle et Evolutive, CNRS UMR5175, Université Montpellier, Université Paul Valery Montpellier 3, EPHE, IRD, 34293 Montpellier, France
| | - Maria Cristina Lorenzi
- Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Torino, Italy; (M.B.); (M.C.L.)
- Laboratory of Experimental and Comparative Ethology (LEEC), University of Sorbonne Paris Nord, 93430 Villetaneuse, France
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