1
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McNamara JM, Dall SRX, Houston AI, Leimar O. The evolutionary consequences of learning under competition. Proc Biol Sci 2024; 291:20241141. [PMID: 39110908 PMCID: PMC11305653 DOI: 10.1098/rspb.2024.1141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 06/17/2024] [Accepted: 06/17/2024] [Indexed: 08/10/2024] Open
Abstract
Learning is a taxonomically widespread process by which animals change their behavioural responses to stimuli as a result of experience. In this way, it plays a crucial role in the development of individual behaviour and underpins substantial phenotypic variation within populations. Nevertheless, the impact of learning in social contexts on evolutionary change is not well understood. Here, we develop game theoretical models of competition for resources in small groups (e.g. producer-scrounger and hawk-dove games) in which actions are controlled by reinforcement learning and show that biases in the subjective valuation of different actions readily evolve. Moreover, in many cases, the convergence stable levels of bias exist at fitness minima and therefore lead to disruptive selection on learning rules and, potentially, to the evolution of genetic polymorphisms. Thus, we show how reinforcement learning in social contexts can be a driver of evolutionary diversification. In addition, we consider the evolution of ability in our games, showing that learning can also drive disruptive selection on the ability to perform a task.
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Affiliation(s)
- John M. McNamara
- School of Mathematics, University of Bristol, BristolBS8 1UG, UK
| | - Sasha R. X. Dall
- Centre for Ecology and Conservation, University of Exeter, ExeterTR10 9FE, UK
| | | | - Olof Leimar
- Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
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2
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Wang D, Zhang W, Yang S, Richter XYL. Sex differences in avian parental care patterns vary across the breeding cycle. Nat Commun 2023; 14:6980. [PMID: 37914691 PMCID: PMC10620184 DOI: 10.1038/s41467-023-42767-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Parental care in birds consists of elaborate forms across stages, including nest building, incubation, and offspring provision. Despite their evolutionary importance, knowledge gaps exist in the extent to which parents contribute disproportionately to these forms and factors that are associated with variations in care patterns between sexes. Here, we analyzed 1533 bird species and discovered remarkable variability in care patterns. We show that parental care should not be viewed as a unitary trait but rather as a set of integrated features that exhibit considerable temporal and sex-specific variation. Our analyses also reveal moderate consistency in care patterns between breeding stages, pointing towards shared intrinsic factors driving sex-specific care. Notably, we found that species experiencing strong sexual selection on males or species facing paternity uncertainty display a tendency towards female-biased care. This work advances our understanding of the temporal variations in sex-specific contributions to avian parental care and their potential evolutionary drivers.
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Affiliation(s)
- Daiping Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
| | - Wenyuan Zhang
- Edward Grey Institute, Department of Biology, University of Oxford, Oxford, OX1 3SZ, UK
- Department of Biology, Quebec Centre for Biodiversity Science, McGill University, Montreal, QC, H3A 1B1, Canada
| | - Shuai Yang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xiang-Yi Li Richter
- Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, CH-3012, Bern, Switzerland.
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3
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Awasthi K, M Henshaw J. Can low-quality parents exploit their high-quality partners to gain higher fitness? J Evol Biol 2023; 36:795-804. [PMID: 37036579 DOI: 10.1111/jeb.14174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 02/10/2023] [Accepted: 03/15/2023] [Indexed: 04/11/2023]
Abstract
An individual's optimal investment in parental care potentially depends on many variables, including its future fitness prospects, the expected costs of providing care and its partner's expected or observed parental behaviour. Previous models suggested that low-quality parents could evolve to exploit their high-quality partners by reducing care, leading to the paradoxical prediction that low-quality parents could have higher fitness than their high-quality partners. However, these studies lacked a complete and consistent life-history model. Here, we challenge this result, developing a consistent analytical model of parental care strategies given individual variation in quality, and checking our results using agent-based simulations. In contrast to previous models, we predict that high-quality individuals always outcompete low-quality individuals in fitness terms. However, care effort may differ between high- and low-quality parents in either direction: low-quality individuals care more than high-quality individuals if their baseline mortality is higher, but less if their mortality increases more steeply with increasing care. We also highlight the ambiguity of the term 'quality' and stress the need for 'genealogical consistency' in evolutionary models.
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Affiliation(s)
| | - Jonathan M Henshaw
- Institute of Biology I, University of Freiburg, Hauptstraße 1, D-79104, Freiburg, Germany
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4
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McNamara JM, Wolf M. Social interaction can select for reduced ability. Proc Biol Sci 2022; 289:20221788. [PMID: 36259207 PMCID: PMC9579777 DOI: 10.1098/rspb.2022.1788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Animals, including humans, differ in a wide range of physical and cognitive abilities ranging from measures of running speed and physical strength to learning ability and intelligence. We consider the evolution of ability when individuals interact pairwise over their contribution to a common good. In this interaction, the contribution of each is assumed to be the best given their own ability and the contribution of their partner. Since there is a tendency for individuals to partially compensate for a low contribution by their partner, low-ability individuals can do well. As a consequence, for benefit and cost structures for which individuals have a strong response to partner's contribution, there can be selection for reduced ability. Furthermore, there can be disruptive selection on ability, leading to a bimodal distribution of ability under some modes of inheritance.
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Affiliation(s)
- John M McNamara
- School of Mathematics, University of Bristol, Fry Building, Woodland Road, Bristol BS8 1UG, UK
| | - Max Wolf
- Department of Biology and Ecology of Fishes, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin 12587, Germany.,Science of Intelligence, Research Cluster of Excellence, Marchstr. 23, Berlin 10587, Germany
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5
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Geeta Arun M, Chechi TS, Meena R, Bhosle SD, Srishti, Prasad NG. Investigating the interaction between inter-locus and intra-locus sexual conflict using hemiclonal analysis in Drosophila melanogaster. BMC Ecol Evol 2022; 22:38. [PMID: 35346023 PMCID: PMC8962633 DOI: 10.1186/s12862-022-01992-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/15/2022] [Indexed: 12/02/2022] Open
Abstract
Background Divergence in the evolutionary interests of males and females leads to sexual conflict. Traditionally, sexual conflict has been classified into two types: inter-locus sexual conflict (IeSC) and intra-locus sexual conflict (IaSC). IeSC is modeled as a conflict over outcomes of intersexual reproductive interactions mediated by loci that are sex-limited in their effects. IaSC is thought to be a product of selection acting in opposite directions in males and females on traits with a common underlying genetic basis. While in their canonical formalisms IaSC and IeSC are mutually exclusive, there is growing support for the idea that the two may interact. Empirical evidence for such interactions, however, is limited. Results Here, we investigated the interaction between IeSC and IaSC in Drosophila melanogaster. Using hemiclonal analysis, we sampled 39 hemigenomes from a laboratory-adapted population of D. melanogaster. We measured the contribution of each hemigenome to adult male and female fitness at three different intensities of IeSC, obtained by varying the operational sex ratio. Subsequently, we estimated the intensity of IaSC at each sex ratio by calculating the intersexual genetic correlation (rw,g,mf) for fitness and the proportion of sexually antagonistic fitness-variation. We found that the intersexual genetic correlation for fitness was positive at all three sex ratios. Additionally, at male biased and equal sex ratios the rw,g,mf was higher, and the proportion of sexually antagonistic fitness variation lower, relative to the female biased sex ratio, although this trend was not statistically significant. Conclusion Our results indicate a statistically non-significant trend suggesting that increasing the strength of IeSC ameliorates IaSC in the population. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-022-01992-0.
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Affiliation(s)
- Manas Geeta Arun
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Mohali, Punjab, 140306, India
| | - Tejinder Singh Chechi
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Mohali, Punjab, 140306, India
| | - Rakesh Meena
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Mohali, Punjab, 140306, India
| | - Shradha Dattaraya Bhosle
- Department of Biochemistry, Dr. Babasaheb Ambedkar Marathwada University, University Campus, Jaisigpura, Aurangabad, Maharashtra, 431004, India
| | - Srishti
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Mohali, Punjab, 140306, India
| | - Nagaraj Guru Prasad
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Mohali, Punjab, 140306, India.
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6
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Morvai B, Fazekas EA, Miklósi Á, Pogány Á. Genetic and Social Transmission of Parental Sex Roles in Zebra Finch Families. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.799996] [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
Parental care plays a central, reinforcing role in the evolution of sex roles and its development is often reported to be driven by genetic, rather than environmental effects. Based on these studies, however, genetic inheritance does not account fully for the often-significant phenotypic variability observed within species, a variation that we hypothesized may be explained by social effects from parents. Following a full cross-fostering design, here we aimed at disentangling genetic and social parental effects in the ontogeny of parental behaviours. Clutches of eggs were swapped, and we monitored parental behaviours in two consecutive generations of a captive population of the socially monogamous, biparental zebra finch (Taeniopygia guttata). Using nest box cameras, parental behaviour was recorded for 3 h in two reproductive stages: on day 8 of incubation and day 10 post-hatching. These fostered birds, after becoming fully matured, received a pair randomly and we observed parental care of this second generation too, following the same protocol. We then compared various parental behaviours (such as time spent incubating, or number of nest attendances during offspring provisioning) in the second generation to those of their genetic and social parents. Based on the results of our experiment, both genetic and social effects can contribute to intergenerational transmission of specific parental behaviours, with various weights. However, the strongest and most consistent effect that we found is that of the current mate; a social effect that can manifest both in negative and positive directions, depending on the behavioural trait. Our study suggests context-specific and sexually different genetic, social and non-social environmental effects in the ontogeny of parental sex roles and outline the importance of parental negotiation in explaining individual variation of parental behaviour in biparental species.
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7
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McNamara JM. Game Theory in Biology: Moving beyond Functional Accounts. Am Nat 2021; 199:179-193. [DOI: 10.1086/717429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- John M. McNamara
- School of Mathematics, University of Bristol, Bristol BS8 1UG, United Kingdom
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8
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Brustkern J, Heinrichs M, Walker M, Schiller B. Facial threat affects trust more strongly than facial attractiveness in women than it does in men. Sci Rep 2021; 11:22475. [PMID: 34795328 PMCID: PMC8602253 DOI: 10.1038/s41598-021-01775-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 11/02/2021] [Indexed: 11/23/2022] Open
Abstract
Trust is essential in initiating social relationships. Due to the differential evolution of sex hormones as well as the fitness burdens of producing offspring, evaluations of a potential mating partner's trustworthiness likely differ across sexes. Here, we explore unknown sex-specific effects of facial attractiveness and threat on trusting other-sex individuals. Ninety-three participants (singles; 46 women) attracted by the other sex performed an incentivized trust game. They had to decide whether to trust individuals of the other sex represented by a priori-created face stimuli gradually varying in the intensities of both attractiveness and threat. Male and female participants trusted attractive and unthreatening-looking individuals more often. However, whereas male participants' trust behavior was affected equally by attractiveness and threat, female participants' trust behavior was more strongly affected by threat than by attractiveness. This indicates that a partner's high facial attractiveness might compensate for high facial threat in male but not female participants. Our findings suggest that men and women prioritize attractiveness and threat differentially, with women paying relatively more attention to threat cues inversely signaling parental investment than to attractiveness cues signaling reproductive fitness. This difference might be attributable to an evolutionary, biologically sex-specific decision regarding parental investment and reproduction behavior.
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Affiliation(s)
- Johanna Brustkern
- Laboratory for Biological and Personality Psychology, Department of Psychology, University of Freiburg, Stefan-Meier-Str. 8, 79104, Freiburg, Germany
| | - Markus Heinrichs
- Laboratory for Biological and Personality Psychology, Department of Psychology, University of Freiburg, Stefan-Meier-Str. 8, 79104, Freiburg, Germany
| | - Mirella Walker
- Faculty of Psychology, University of Basel, Missionsstrasse 60/62, 4055, Basel, Switzerland
| | - Bastian Schiller
- Laboratory for Biological and Personality Psychology, Department of Psychology, University of Freiburg, Stefan-Meier-Str. 8, 79104, Freiburg, Germany.
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9
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Fritzsche K, Henshaw JM, Johnson BD, Jones AG. The 150th anniversary of The Descent of Man: Darwin and the impact of sex-role reversal on sexual selection research. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
The year 2021 marks the 150th anniversary of the publication of Charles Darwin’s extraordinary book The Descent of Man and Selection in Relation to Sex. Here, we review the history and impact of a single profound insight from The Descent of Man: that, in some few species, females rather than males compete for access to mates. In other words, these species are ‘sex-role reversed’ with respect to mating competition and sexual selection compared to the majority of species in which sexual selection acts most strongly on males. Over the subsequent 150 years, sex-role-reversed species have motivated multiple key conceptual breakthroughs in sexual selection. The surprising mating dynamics of such species challenged scientists’ preconceptions, forcing them to examine implicit assumptions and stereotypes. This wider worldview has led to a richer and more nuanced understanding of animal mating systems and, in particular, to a proper appreciation for the fundamental role that females play in shaping these systems. Sex-role-reversed species have considerable untapped potential and will continue to contribute to sexual selection research in the decades to come.
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Affiliation(s)
- Karoline Fritzsche
- Institute of Biology I, University of Freiburg, Hauptstraße 1, D-79104 Freiburg, Germany
| | - Jonathan M Henshaw
- Institute of Biology I, University of Freiburg, Hauptstraße 1, D-79104 Freiburg, Germany
| | | | - Adam G Jones
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA
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10
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Delia J, Bravo‐Valencia L, Warkentin KM. The evolution of extended parental care in glassfrogs: Do egg‐clutch phenotypes mediate coevolution between the sexes? ECOL MONOGR 2020. [DOI: 10.1002/ecm.1411] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jesse Delia
- Department of Biology Boston University Boston 02214 Massachusetts USA
| | - Laura Bravo‐Valencia
- Profesional equipo de fauna silvestre Corantioquia Santa Fe de Antioquia Colombia
| | - Karen M. Warkentin
- Department of Biology Boston University Boston 02214 Massachusetts USA
- Smithsonian Tropical Research Institute Panamá 0843-03092 República de Panamá
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11
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Whittington CM, Friesen CR. The evolution and physiology of male pregnancy in syngnathid fishes. Biol Rev Camb Philos Soc 2020; 95:1252-1272. [PMID: 32372478 DOI: 10.1111/brv.12607] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 04/09/2020] [Accepted: 04/09/2020] [Indexed: 12/24/2022]
Abstract
The seahorses, pipefishes and seadragons (Syngnathidae) are among the few vertebrates in which pregnant males incubate developing embryos. Syngnathids are popular in studies of sexual selection, sex-role reversal, and reproductive trade-offs, and are now emerging as valuable comparative models for the study of the biology and evolution of reproductive complexity. These fish offer the opportunity to examine the physiology, behavioural implications, and evolutionary origins of embryo incubation, independent of the female reproductive tract and female hormonal milieu. Such studies allow us to examine flexibility in regulatory systems, by determining whether the pathways underpinning female pregnancy are also co-opted in incubating males, or whether novel pathways have evolved in response to the common challenges imposed by incubating developing embryos and releasing live young. The Syngnathidae are also ideal for studies of the evolution of reproductive complexity, because they exhibit multiple parallel origins of complex reproductive phenotypes. Here we assay the taxonomic distribution of syngnathid parity mode, examine the selective pressures that may have led to the emergence of male pregnancy, describe the biology of syngnathid reproduction, and highlight pressing areas for future research. Experimental tests of a range of hypotheses, including many generated with genomic tools, are required to inform overarching theories about the fitness implications of pregnancy and the evolution of male pregnancy. Such information will be widely applicable to our understanding of fundamental reproductive and evolutionary processes in animals.
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Affiliation(s)
- Camilla M Whittington
- The University of Sydney, School of Life and Environmental Sciences, Sydney, New South Wales, 2006, Australia.,The University of Sydney, Sydney School of Veterinary Science, Sydney, New South Wales, 2006, Australia
| | - Christopher R Friesen
- The University of Wollongong, School of Earth, Atmospheric and Life Sciences, Faculty of Science, Medicine and Health, Wollongong, New South Wales, 2522, Australia.,Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales, 2522, Australia
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12
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Henshaw JM, Fromhage L, Jones AG. Sex roles and the evolution of parental care specialization. Proc Biol Sci 2019; 286:20191312. [PMID: 31455191 DOI: 10.1098/rspb.2019.1312] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Males and females are defined by the relative size of their gametes (anisogamy), but secondary sexual dimorphism in fertilization, parental investment and mating competition is widespread and often remarkably stable over evolutionary timescales. Recent theory has clarified the causal connections between anisogamy and the most prevalent differences between the sexes, but deviations from these patterns remain poorly understood. Here, we study how sex differences in parental investment and mating competition coevolve with parental care specialization. Parental investment often consists of two or more distinct activities (e.g. provisioning and defence) and parents may care more efficiently by specializing in a subset of these activities. Our model predicts that efficient care specialization broadens the conditions under which biparental investment can evolve in lineages that historically had uniparental care. Major transitions in sex roles (e.g. from female-biased care with strong male mating competition to male-biased care with strong female competition) can arise following ecologically induced changes in the costs or benefits of different care types, or in the sex ratio at maturation. Our model provides a clear evolutionary mechanism for sex-role transitions, but also predicts that such transitions should be rare. It consequently contributes towards explaining widespread phylogenetic inertia in parenting and mating systems.
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Affiliation(s)
- Jonathan M Henshaw
- Department of Biological Sciences, University of Idaho, 875 Perimeter MS 3051, Moscow, ID, USA.,Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Finland
| | - Lutz Fromhage
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Finland
| | - Adam G Jones
- Department of Biological Sciences, University of Idaho, 875 Perimeter MS 3051, Moscow, ID, USA
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13
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Polyandrous bee provides extended offspring care biparentally as an alternative to monandry based eusociality. Proc Natl Acad Sci U S A 2019; 116:6238-6243. [PMID: 30858313 DOI: 10.1073/pnas.1810092116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Parental care behavior evolves to increase the survival of offspring. When offspring care becomes complicated for ecological reasons, cooperation of multiple individuals can be beneficial. There are two types of cooperative care: biparental care and worker (helper)-based care (e.g., eusociality). Although biparental care is common in several groups of vertebrates, it is generally rare in arthropods. Conversely, eusociality is widespread in insects, especially the aculeate Hymenoptera. Here, we present a case of biparental care in bees, in Ceratina nigrolabiata (Apidae, Xylocopinae). Similar to eusocial behavior, biparental care leads to greater brood protection in this species. Male guarding increases provisioning of nests because females are liberated from the tradeoff between provisioning and nest protection. The main benefit of parental care for males should be increased paternity. Interestingly though, we found that paternity of offspring by guard males is extraordinarily low (10% of offspring). Generally, we found that nests were not guarded by the same male for the whole provisioning season, meaning that males arrive to nests as stepfathers. However, we show that long-term guarding performed by a single male does increase paternity. We suggest that the multiple-mating strategy of these bees increased the amount of time for interactions between the sexes, and this longer period of potential interaction supported the origin of biparental care. Eusociality based on monandry was thought to be the main type of extended brood protection in bees. We show that biparental care based on polyandry provides an interesting evolutionary alternative.
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14
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Schacht R, Davis HE, Kramer KL. Patterning of Paternal Investment in Response to Socioecological Change. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00142] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Mokkonen M, Koskela E, Procyshyn T, Crespi B. Socio-reproductive Conflicts and the Father's Curse Dilemma. Am Nat 2018; 192:250-262. [PMID: 30016171 DOI: 10.1086/698216] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Evolutionary conflicts between males and females can manifest over sexually antagonistic interactions at loci or over sexually antagonistic interests within a locus. The latter form of conflict, intralocus sexual conflict, arises from sexually antagonistic selection and constrains the fitness of individuals through a phenotypic compromise. These conflicts, and socio-reproductive interactions in general, are commonly mediated by hormones, and thus predictive insights can be gained from studying their mediating effects. Here, we integrate several lines of evidence to describe a novel, hormonally mediated reproductive dilemma that we call the father's curse, which results from an intralocus conflict between mating and parental efforts. Essentially, a genetic locus exerts pleiotropic and antagonistic effects on the mating effort of one individual and the parental effort of a related individual who is the primary provider of parental care. We outline the criteria for operation of the father's curse dilemma, provide evidence of the phenomenon, and discuss the predictions and outcomes arising from its dynamics. By integrating the effects of hormones into socio-reproductive conflicts and socio-reproductive effort, clearer links between genotypes, phenotypes, and fitness can be established.
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16
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Jennions MD, Fromhage L. Not all sex ratios are equal: the Fisher condition, parental care and sexual selection. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0312. [PMID: 28760755 DOI: 10.1098/rstb.2016.0312] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2017] [Indexed: 11/12/2022] Open
Abstract
The term 'sex roles' encapsulates male-female differences in mate searching, competitive traits that increase mating/fertilization opportunities, choosiness about mates and parental care. Theoretical models suggest that biased sex ratios drive the evolution of sex roles. To model sex role evolution, it is essential to note that in most sexually reproducing species (haplodiploid insects are an exception), each offspring has one father and one mother. Consequently, the total number of offspring produced by each sex is identical, so the mean number of offspring produced by individuals of each sex depends on the sex ratio (Fisher condition). Similarly, the total number of heterosexual matings is identical for each sex. On average, neither sex can mate nor breed more often when the sex ratio is even. But equally common in which sex ratio? The Fisher condition only applies to some reproductive measures (e.g. lifetime offspring production or matings) for certain sex ratios (e.g. operational or adult sex ratio; OSR, ASR). Here, we review recent models that clarify whether a biased OSR, ASR or sex ratio at maturation (MSR) have a causal or correlational relationship with the evolution of sex differences in parental care and competitive traits-two key components of sex roles. We suggest that it is more fruitful to understand the combined effect of the MSR and mortality rates while caring and competing than that of the ASR itself. In short, we argue that the ASR does not have a causal role in the evolution of parental care. We point out, however, that the ASR can be a cue for adaptive phenotypic plasticity in how each sex invests in parental care.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'.
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Affiliation(s)
- Michael D Jennions
- Ecology, Evolution and Genetics, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2600, Australia .,Wissenschaftkolleg zu Berlin, Wallotstraße 19, 14193 Berlin, Germany
| | - Lutz Fromhage
- Department of Biological and Environmental Science, University of Jyvaskyla, PO Box 35, 40014, Finland
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17
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Royle NJ, Alonzo SH, Moore AJ. Co-evolution, conflict and complexity: what have we learned about the evolution of parental care behaviours? Curr Opin Behav Sci 2016. [DOI: 10.1016/j.cobeha.2016.08.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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Barta Z. Individual variation behind the evolution of cooperation. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150087. [PMID: 26729927 DOI: 10.1098/rstb.2015.0087] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Life on Earth has two remarkable properties. The first is variation: even apart from the vast number of extant species, there are considerable differences between individuals within a single species. The second property is cooperation. It is surprising that until recently the interactions between these two properties have rarely been addressed from an evolutionary point of view. Here, I concentrate on how inter-individual differences influence the evolution of cooperation. First, I deal with cases where individuality is maintained by random processes like mutation or phenotypic noise. Second, I examine when differences in state cause differences in behaviour. Finally, I investigate the effects of individual role specialization. Variation can be important in several ways. Increased random variation can change the expectation about cooperativeness of future partners, altering behaviour in a current relationship. Differences in state may serve as a book-keeping mechanism that is necessary for the evolution of reciprocity. If the cost of cooperation can depend on state then strategic regulation of state makes it possible to coerce partners to cooperate. If conditions force individuals to specialize, cooperation becomes more valuable. My review of theoretical models suggests that variation plays an important role in the evolution of cooperation.
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Affiliation(s)
- Zoltán Barta
- MTA-DE 'Lendület' Behavioural Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Egyetem tér 1., Debrecen 4032, Hungary
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Fromhage L, Jennions MD. Coevolution of parental investment and sexually selected traits drives sex-role divergence. Nat Commun 2016; 7:12517. [PMID: 27535478 PMCID: PMC4992156 DOI: 10.1038/ncomms12517] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 07/11/2016] [Indexed: 12/03/2022] Open
Abstract
Sex-role evolution theory attempts to explain the origin and direction of male-female differences. A fundamental question is why anisogamy, the difference in gamete size that defines the sexes, has repeatedly led to large differences in subsequent parental care. Here we construct models to confirm predictions that individuals benefit less from caring when they face stronger sexual selection and/or lower certainty of parentage. However, we overturn the widely cited claim that a negative feedback between the operational sex ratio and the opportunity cost of care selects for egalitarian sex roles. We further argue that our model does not predict any effect of the adult sex ratio (ASR) that is independent of the source of ASR variation. Finally, to increase realism and unify earlier models, we allow for coevolution between parental investment and investment in sexually selected traits. Our model confirms that small initial differences in parental investment tend to increase due to positive evolutionary feedback, formally supporting long-standing, but unsubstantiated, verbal arguments.
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Affiliation(s)
- Lutz Fromhage
- Department of Biological and Environmental Science University of Jyvaskyla, PO Box 35, FI-40014 Jyvaskyla, Finland
| | - Michael D. Jennions
- Ecology, Evolution & Genetics, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
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Paquet M, Smiseth PT. Maternal effects as a mechanism for manipulating male care and resolving sexual conflict over care. Behav Ecol 2015. [DOI: 10.1093/beheco/arv230] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Roland AB, O’Connell LA. Poison frogs as a model system for studying the neurobiology of parental care. Curr Opin Behav Sci 2015. [DOI: 10.1016/j.cobeha.2015.10.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Abstract
Parental care is one of the most variable social behaviors and it is an excellent model system to understand cooperation between unrelated individuals. Three major hypotheses have been proposed to explain the extent of parental cooperation: sexual selection, social environment, and environmental harshness. Using the most comprehensive dataset on parental care that includes 659 bird species from 113 families covering both uniparental and biparental taxa, we show that the degree of parental cooperation is associated with both sexual selection and social environment. Consistent with recent theoretical models parental cooperation decreases with the intensity of sexual selection and with skewed adult sex ratios. These effects are additive and robust to the influence of life-history variables. However, parental cooperation is unrelated to environmental factors (measured at the scale of whole species ranges) as indicated by a lack of consistent relationship with ambient temperature, rainfall or their fluctuations within and between years. These results highlight the significance of social effects for parental cooperation and suggest that several parental strategies may coexist in a given set of ambient environment.
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