166 results on '"GAVRILETS, S."'
Search Results
2. Pattern, process and geographic modes of speciation
- Author
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FITZPATRICK, B. M., FORDYCE, J. A., and GAVRILETS, S.
- Published
- 2009
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3. What, if anything, is sympatric speciation?
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FITZPATRICK, B. M., FORDYCE, J. A., and GAVRILETS, S.
- Published
- 2008
4. The dynamics of sexual conflict over mating rate with endosymbiont infection that affects reproductive phenotypes
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HAYASHI, T. I., MARSHALL, J. L., and GAVRILETS, S.
- Published
- 2007
5. Issues of terminology, gradient dynamics and the ease of sympatric speciation in Adaptive Dynamics
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WAXMAN, D. and GAVRILETS, S.
- Published
- 2005
6. 20 Questions on Adaptive Dynamics
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WAXMAN, D. and GAVRILETS, S.
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- 2005
7. Evolutionary biology: Sexual conflict and speciation
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Gavrilets, S.
- Published
- 2000
8. The evolution of extreme cooperation via shared dysphoric experiences
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Whitehouse, H, Jong, J, Buhrmester, M, Gómez, Á, Bastian, B, Kavanagh, C, Newson, M, Matthews, M, Lanman, J, McKay, R, and Gavrilets, S
- Subjects
Adult ,Male ,Motivation ,SDG 16 - Peace, Justice and Strong Institutions ,BF ,Euphoria ,Models, Psychological ,Violence ,Article ,Masochism ,SDG 3 - Good Health and Well-being ,Humans ,Terrorism ,Cooperative Behavior ,Mass Behavior - Abstract
Willingness to lay down one’s life for a group of non-kin, well documented in thehistorical and ethnographic records, represents an evolutionary puzzle. Here wepresent a novel explanation for the willingness to fight and die for a group, combining evolutionary theorizing with empirical evidence from real-world human groups. Building on research in social psychology, we develop a mathematical model showing how conditioning cooperation on previous shared experience can allow extreme (i.e., life-threatening) pro-social behavior to evolve. The model generates a series of predictions that we then test empirically in a range of special sample populations (including military veterans, college fraternity/sorority members, football fans, martial arts practitioners, and twins). Our results show that sharing painful experiences produces “identity fusion” – a visceral sense of oneness – more so even than bonds of kinship, in turn motivating extreme pro-group behavior, including willingness to fight and die for the group. These findings have theoretical and practical relevance. Theoretically, our results speak to the origins of human cooperation, as we offer an explanation of extremely costly actions left unexplained by existing models.Practically, our account of how shared dysphoric experiences produce identity fusion, which produces a willingness to fight and die for a non-kin group, helps us better understand such pressing social issues as suicide terrorism, holy wars, sectarian violence, gang-related violence, and other forms of intergroup conflict.
- Published
- 2017
9. Coalitions in theory and reality: a review of pertinent variables and processes
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Barrett, L, Flinn, M, de Waal, FBM, Perry, S, Mitani, JC, Gavrilets, S, and Bissonnette, A
- Published
- 2015
10. Case studies and mathematical models of ecological speciation. 1. Cichlids in a crater lake
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Gavrilets, S., Vose, A., Barluenga, M., Salzburger, W., and Meyer, A.
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Time Factors ,model ,Adaptation, Biological ,Fresh Water ,Cichlids ,parapatric ,Models, Biological ,Species Specificity ,speciation ,ddc:570 ,Animals ,Cichlids/classification ,Cichlids/physiology ,Ecosystem ,ecological ,mathematical - Abstract
A recent study of a pair of sympatric species of cichlids in Lake Apoyo in Nicaragua is viewed as providing probably one of the most convincing examples of sympatric speciation to date. Here, we describe and study a stochastic, individual-based, explicit genetic model tailored for this cichlid system. Our results show that relatively rapid (
- Published
- 2007
11. reply: Sexual conflict and speciation
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Gavrilets, S.
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Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Author(s): S. Gavrilets [1] Gavrilets replies -- Tregenza et al. maintain that my model's predictions [1] run counter to the model of Parker and Partridge [2], but it is not [...]
- Published
- 2000
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12. Case studies and mathematical models of ecological speciation. 3: Ecotype formation in a Swedish snail.
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SADEDIN, S., HOLLANDER, J., PANOVA, M., JOHANNESSON, K., and GAVRILETS, S.
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CASE studies ,MATHEMATICAL models ,SNAILS ,ENVIRONMENTAL sociology ,ANIMAL courtship ,MATE selection ,ANIMAL species - Abstract
Formation of partially reproductively isolated ecotypes in the rough periwinkle, Littorina saxatilis, may be a case of incipient nonallopatric ecological speciation. To better understand the dynamics of ecotype formation, its timescale, driving forces and evolutionary consequences, we developed a spatially explicit, individual-based model incorporating relevant ecological, spatial and mate selection data for Swedish L. saxatilis. We explore the impact of bounded hybrid superiority, ecological scenarios and mate selection systems on ecotype formation, gene flow and the evolution of prezygotic isolation. Our model shows that ecotypes are expected to form rapidly in parapatry under conditions applicable to Swedish L. saxatilis and may proceed to speciation. However, evolution of nonrandom mating had complex behaviour. Ecotype evolution was inhibited by pre-existing mating preferences, but facilitated by the evolution of novel preferences. While in many scenarios positive assortative mating reduced gene flow between ecotypes, in others negative assortative mating arose, preferences were lost after ecotype formation, preferences were confined to one ecotype or the ancestral ecotype became extinct through sexual selection. Bounded hybrid superiority (as observed in nature) enhanced ecotype formation but increased gene flow. Our results highlight that ecotype formation and speciation are distinct processes: factors that contribute to ecotype formation can be detrimental to speciation and vice versa. The complex interactions observed between local adaptation and nonrandom mating imply that generalization from data is unreliable without quantitative theory for speciation. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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13. STATISTICAL ANALYSIS OF DIVERSIFICATION WITH SPECIES TRAITS.
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Paradis, Emmanuel and Gavrilets, S.
- Subjects
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SPECIES , *MACROEVOLUTION , *BIOLOGICAL extinction , *PRIMATES , *SPECIES diversity - Abstract
Testing whether some species traits have a significant effect on diversification rates is central in the assessment of macroevolutionary theories. However, we still lack a powerful method to tackle this objective. I present a new method for the statistical analysis of diversification with species traits. The required data are observations of the traits on recent species, the phylogenetic tree of these species, and reconstructions of ancestral values of the traits. Several traits, either continuous or discrete, and in some cases their interactions, can be analyzed simultaneously. The parameters are estimated by the method of maximum likelihood. The statistical significance of the effects in a model can be tested with likelihood ratio tests. A simulation study showed that past random extinction events do not affect the Type I error rate of the tests, whereas statistical power is decreased, though some power is still kept if the effect of the simulated trait on speciation is strong. The use of the method is illustrated by the analysis of published data on primates. The analysis of these data showed that the apparent overall positive relationship between body mass and species diversity is actually an artifact due to a clade-specific effect. Within each clade the effect of body mass on speciation rate was in fact negative. The present method allows to take both effects (clade and body mass) into account simultaneously. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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14. EVOLUTION OF MIGRATION UNDER KIN SELECTION AND LOCAL ADAPTATION.
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Billiard, Sylvain, Lenormand, Thomas, and Gavrilets, S.
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BIOLOGICAL evolution ,KIN selection (Evolution) ,ANIMAL migration ,BIOLOGICAL adaptation ,ANIMAL populations - Abstract
We present here a stochastic two-locus, two-habitat model for the evolution of migration with local adaptation and kin selection. One locus determines the migration rate while the other causes local adaptation. We show that the opposing forces of kin competition and local adaptation can lead to the existence of one or two convergence stable migration rates, notably depending on the recombination rate between the two loci. We show that linkage between migration and local adaptation loci has two antagonist effects: when linkage is tight, cost of local adaptation increases, leading to smaller equilibrium migration rates. However, when linkage is tighter, the population structure at the migration locus tends to be very high because of the indirect selection, and thus equilibrium migration rates increases. This result, qualitatively different from results obtained with other models of migration evolution, indicates that ignoring drift or the detail of the genetic architecture may lead to incorrect conclusions. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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15. TO WHAT EXTENT DO DIFFERENT TYPES OF SEX RATIO DISTORTERS INTERFERE?
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Engelstädter, Jan, Montenegro, Horácio, Hurst, Gregory D. D., and Gavrilets, S.
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DIPTERA ,GENETICS ,SEX ratio ,BACTERIA ,X chromosome - Abstract
Within the Diptera, two different selfish genetic elements are known to cause the production of female-biased sex ratios: maternally inherited bacteria that kill male zygotes (male-killers), and X chromosomes causing the degeneration of Y-bearing sperm in males (meiotic drive). We here develop a mathematical model for the dynamics of these two sex-ratio distorters where they co-occur. We show that X chromosome meiotic drive elements can be expected to substantially lower the equilibrium frequency of male-killers and can even lead to their extinction. Conversely, male-killers can also decrease the equilibrium frequency of X drivers and cause their extinction. Thus, we predict that there will be some complementarity in the incidence of X chromosome meiotic drive and male-killing in natural populations, with a lower than expected number of species bearing both elements. [ABSTRACT FROM AUTHOR]
- Published
- 2004
16. SEXUAL CONFLICT AND PROTEIN POLYMORPHISM.
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Haygood, Ralph and Gavrilets, S.
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POLYMORPHISM (Zoology) , *BIOMOLECULES , *SPERMATOZOA , *GENETIC polymorphisms , *GENETIC research , *BIOCHEMISTRY - Abstract
Sexual conflict, where male and female reproductive interests differ, is probably widespread and often mediated by male or sperm proteins and female or egg proteins that bind to each other during mating or fertilization. One potential consequence is maintenance of polymorphism in these proteins, which might result in reproductive isolation between sympatric subpopulations. I investigate the conditions for polymorphism maintenance in a series of mathematical models of sexual conflict over mating or fertilization frequency. The models represent a male or sperm ligand and a female or egg receptor, and they differ in whether expression of either protein is haploid or diploid. For diploid expression, the conditions imply that patterns of dominance, which involve neither overdominance nor underdominance, can determine whether polymorphism is maintained. For example, suppose ligand expression is diploid, and consider ligand alleles L1 and L2 in interactions with a given receptor genotype; if L1/L1 males are fitter than L2/L2 males in these interactions, then polymorphism is more likely to be maintained when L1/L2 males more closely resemble L1/L1 males in these interactions. Such fitter-allele dominance might be typical of a ligand or its receptor due to their biochemistry, in which case polymorphism might be typical of the pair. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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17. ADAPTIVE EVOLUTION OF ASEXUAL POPULATIONS UNDER MULLER'S RATCHET.
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Bachtrog, Doris, Gordo, Isabel, and Gavrilets, S.
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POPULATION genetics ,GENETICS ,HEREDITY ,GENETIC polymorphisms ,GENETIC research ,CHROMOSOMES - Abstract
We study the population genetics of adaptation in nonequilibrium haploid asexual populations. We find that the accumulation of deleterious mutations, due to the operation of Muller's ratchet, can considerably reduce the rate of fixation of advantageous alleles. Such reduction can be approximated reasonably well by a reduction in the effective population size. In the absence of Muller's ratchet, a beneficial mutation can only become fixed if it creates the best possible genotype; if Muller's ratchet operates, however, mutations initially arising in a nonoptimal genotype can also become fixed in the population, since the loss of the least-loaded class implies that an initially nonoptimal background can become optimal. We show that, while the rate at which adaptive mutations become fixed is reduced, the rate of fixation of deleterious mutations due to the ratchet is not changed by the presence of beneficial mutations as long as the rate of their occurrence is low and the deleterious effects of mutations (s
d ) are higher than the beneficial effects (sa ). When sa > sd , the advantage of a beneficial mutation can outweigh the deleterious effects of associated mutations. Under these conditions, a beneficial allele can drag to fixation deleterious mutations initially associated with it at a higher rate than in the absence of advantageous alleles. We propose analytical approximations for the rates of accumulation of deleterious and beneficial mutations. Furthermore, when allowing for the possible occurrence of interference between beneficial alleles, we find that the presence of deleterious mutations of either very weak or very strong effect can marginally increase the rate of accumulation of beneficial mutations over that observed in the absence of such deleterious mutations. [ABSTRACT FROM AUTHOR]- Published
- 2004
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18. THE EVOLUTION OF PREMATING ISOLATION: LOCAL ADAPTATION AND NATURAL AND SEXUAL SELECTION AGAINST HYBRIDS.
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Servedio, Maria R. and Gavrilets, S.
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SEXUAL cycle , *SPECIES hybridization , *MATE selection , *SEXUAL psychology , *BREEDING , *BIOLOGY - Abstract
Although reinforcement is ostensibly driven by selection against hybrids, there are often other components in empirical cases and theoretical models of reinforcement that may contribute to premating isolation. One of these components is local adaptation of a trait used in mate choice. I use several different comparisons to assess the roles that local adaptation and selection against hybrids may play in reinforcement models. Both numerical simulations of exact recursion equations and analytical weak selection approximations are employed. I find that selection against hybrids may play a small role in driving preference evolution in a reinforcement model where the mating cue is separate from loci causing hybrid incompatibilities. When females have preferences directly for purebreds of their own population, however, selection against hybrids can play a large role in premating isolation evolution. I present some situations in which this type of selection is likely to exist. This work also illustrates shortfalls of using a weak selection approach to address questions about reinforcement. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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19. WAITING FOR SYMPATRIC SPECIATION.
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Bolnick, Daniel I. and Gavrilets, S.
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SPECIES , *POPULATION , *BIOLOGICAL evolution , *ANIMAL sexual behavior , *GENETICS , *BIOLOGICAL variation - Abstract
While it now appears likely that sympatric speciation is possible, its generality remains contentious. If it really is rare, then most natural populations must not fit the assumptions of sympatric speciation theory. A better understanding of these assumptions may help identify when sympatric speciation is or is not likely. This paper investigates two such assumptions: that genetic variation for stringent assortative mating is not limiting and that females are not penalized for mating assortatively. Simulations demonstrate that the speed of sympatric speciation is very sensitive to the population's capacity for stringent assortative mating and is potentially extremely slow. The rapid divergence often thought to be a hallmark of sympatric speciation may only occur in a restricted area of parameter space. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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20. LEARNING AND COLONIZATION OF NEW NICHES: A FIRST STEP TOWARD SPECIATION.
- Author
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Beltman, Joost B., Haccou, Patsy, Cate, Carel Ten, and Gavrilets, S.
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SPECIES ,BIOLOGICAL classification ,GENETICS ,LEARNING ,GENETIC polymorphisms - Abstract
Learning processes potentially play a role in speciation but are often ignored in speciation models. Learning may, for instance, play a role when a new niche is being colonized, because the learning of niche features may cause niche-specific assortative mating and a tendency to produce young in this niche. Several animal species learn about their environmental features that may be important in finding or attracting mates. We use a gene-culture coevolutionary model to look into the effect of such learning on the colonization of new niches and on the genetic divergence between groups using different niches, which are steps necessary in achieving speciation. We assume that density is regulated separately in each of the two niches and that the viability of an individual depends on its genotype as well as on which niche it exploits. Our results show that genetic adaptation to the new niche is enhanced by a high female fecundity and a low viability selection against heterozygotes. Furthermore, when initial colonization (without genetic adaptation) fails, genetic divergence is more difficult when the mating preference is stronger. In contrast, when colonization without genetic adaptation is successful, a stronger mating preference makes genetic divergence easier. An increase in the number of egg-laying mistakes by females can have a positive or negative effect on the success of genetic adaptation depending on other parameters. We show that genetic divergence can be prevented by a niche shift, which can occur only if viabilities in the two niches are asymmetrical. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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21. THE EVOLUTION OF ENVIRONMENTAL AND GENETIC SEX DETERMINATION IN FLUCTUATING ENVIRONMENTS.
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Van Dooren, Tom J. M., Leimar, Olof, and Gavrilets, S.
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GENETIC sex determination ,COMPUTER simulation ,BIOLOGICAL evolution ,GENETIC polymorphisms ,GENETICS - Abstract
Twenty years ago, Bulmer and Bull suggested that disruptive selection, produced by environmental fluctuations, can result in an evolutionary transition from environmental sex determination (ESD) to genetic sex determination (GSD). We investigated the feasibility of such a process, using mutation-limited adaptive dynamics and individual-based computer simulations. Our model describes the evolution of a reaction norm for sex determination in a metapopulation setting with partial migration and variation in an environmental variable both within and between local patches. The reaction norm represents the probability of becoming a female as a function of environmental state and was modeled as a sigmoid function with two parameters, one giving the location (i.e., the value of the environmental variable for which an individual has equal chance of becoming either sex) and the other giving the slope of the reaction norm for that environment. The slope can be interpreted as being set by the level of developmental noise in morph determination, with less noise giving a steeper slope and a more switchlike reaction norm. We found convergence stable reaction norms with intermediate to large amounts of developmental noise for conditions characterized by low migration rates, small differential competitive advantages between the sexes over environments, and little variation between individual environments within patches compared to variation between patches. We also considered reaction norms with the slope parameter constrained to a high value, corresponding to little developmental noise. For these we found evolutionary branching in the location parameter and a transition from ESD toward GSD, analogous to the original analysis by Bulmer and Bull. Further evolutionary change, including dominance evolution, produced a polymorphism acting as a GSD system with heterogamety. Our results point to the role of developmental noise in the evolution of sex determination. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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22. REINFORCEMENT AND SEX LINKAGE
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Hall, Kirkpatrick, David W., Mark, Hall and Gavrilets, S.
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- 2006
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23. THE EFFECT OF WOLBACHIA VERSUS GENETIC INCOMPATIBILITIES ON REINFORCEMENT AND SPECIATION
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Telschow, Hammerstein, Werren, Arndt, Peter, John H., Telschow and Gavrilets, S.
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- 2005
- Full Text
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24. CONFOUNDING ASYMMETRIES IN EVOLUTIONARY DIVERSIFICATION AND CHARACTER CHANGE
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Maddison, Wayne P. and Gavrilets, S.
- Published
- 2006
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25. ADAPTIVE CHANGE IN THE RESOURCE-EXPLOITATION TRAITS OF A GENERALIST CONSUMER: THE EVOLUTION AND COEXISTENCE OF GENERALISTS AND SPECIALISTS
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Abrams, Peter A. and Gavrilets, S.
- Published
- 2006
- Full Text
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26. STOCHASTICITY, COMPLEX SPATIAL STRUCTURE, AND THE FEASIBILITY OF THE SHIFTING BALANCE THEORY
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O'Fallon, Adler, Brendan, Frederick R., O'Fallon and Gavrilets, S.
- Published
- 2006
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27. PROTECTED POLYMORPHISM AND EVOLUTIONARY STABILITY IN PLEIOTROPIC MODELS WITH TRAIT-SPECIFIC DOMINANCE
- Author
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Van Dooren, Tom J. M. and Gavrilets, S.
- Published
- 2006
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28. INTRAPARENTAL GAMETE COMPETITION PROVIDES A SELECTIVE ADVANTAGE FOR THE DEVELOPMENT OF HYBRID STERILITY VIA MEIOTIC DRIVE
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Adams, Curtis S. and Gavrilets, S.
- Published
- 2005
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29. LEAKY PREZYGOTIC ISOLATION AND POROUS GENOMES: RAPID INTROGRESSION OF MATERNALLY INHERITED DNA
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Chan, Levin, Kai M. A., Simon A., Chan and Gavrilets, S.
- Published
- 2005
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30. MULTILEVEL SELECTION AND THE PARTITIONING OF COVARIANCE: A COMPARISON OF THREE APPROACHES
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Okasha, Samir and Gavrilets, S.
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- 2004
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31. THE DIFFUSIVE SPREAD OF ALLELES IN HETEROGENEOUS POPULATIONS
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Skalski, Garrick T. and Gavrilets, S.
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- 2004
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32. Modelling social norms: an integration of the norm-utility approach with beliefs dynamics.
- Author
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Gavrilets S, Tverskoi D, and Sánchez A
- Subjects
- Social Norms, Social Behavior
- Abstract
We review theoretical approaches for modelling the origin, persistence and change of social norms. The most comprehensive models describe the coevolution of behaviours, personal, descriptive and injunctive norms while considering influences of various authorities and accounting for cognitive processes and between-individual differences. Models show that social norms can improve individual and group well-being. Under some conditions though, deleterious norms can persist in the population through conformity, preference falsification and pluralistic ignorance. Polarization in behaviour and beliefs can be maintained, even when societal advantages of particular behaviours or belief systems over alternatives are clear. Attempts to change social norms can backfire through cognitive processes including cognitive dissonance and psychological reactance. Under some conditions social norms can change rapidly via tipping point dynamics. Norms can be highly susceptible to manipulation, and network structure influences their propagation. Future models should incorporate network structure more thoroughly, explicitly study online norms, consider cultural variations and be applied to real-world processes. This article is part of the theme issue 'Social norm change: drivers and consequences'.
- Published
- 2024
- Full Text
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33. Social norm change: drivers and consequences.
- Author
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Andrighetto G, Gavrilets S, Gelfand M, Mace R, and Vriens E
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- Humans, Group Processes, Social Norms, Social Behavior
- Abstract
Social norms research is booming. In recent years, several experts have recommended using social norms (unwritten rules that prescribe what people ought or ought not to do) to confront the societal, environmental and health challenges our societies face. If we are to do so, a better understanding is required of how social norms themselves emerge, evolve and respond to these challenges. Social norms have long been used as post hoc explanations of behaviour or are seen as stable social constructs. Yet norms evolve dynamically with the changing group processes (e.g. political polarization, kinship structures) and societal challenges (e.g. pandemics, climate change) for which they are presented as solutions. The Theme Issue 'Social norm change: drivers and consequences' contains 14 contributions that present state-of-the-art approaches to understand what generates social norm change and how this impacts our societies. Contributions give insight into (i) the identification of norms, norm change and their effect on behaviour; (ii) drivers and consequences of spontaneous norm change; and (iii) how norm change can be engineered to promote desired behavioural change. This article is part of the theme issue 'Social norm change: drivers and consequences'.
- Published
- 2024
- Full Text
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34. A broader cultural view is necessary to study the evolution of sexual orientation.
- Author
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Savolainen V, Bailey NW, Diamond L, Swift-Gallant A, Gavrilets S, Raymond M, and Verweij KJH
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- Humans, Female, Male, Sexual Behavior
- Published
- 2024
- Full Text
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35. Norm Dynamics: Interdisciplinary Perspectives on Social Norm Emergence, Persistence, and Change.
- Author
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Gelfand MJ, Gavrilets S, and Nunn N
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- Humans, Learning, Social Networking, Social Norms, Cultural Evolution
- Abstract
Social norms are the glue that holds society together, yet our knowledge of them remains heavily intellectually siloed. This article provides an interdisciplinary review of the emerging field of norm dynamics by integrating research across the social sciences through a cultural-evolutionary lens. After reviewing key distinctions in theory and method, we discuss research on norm psychology-the neural and cognitive underpinnings of social norm learning and acquisition. We then overview how norms emerge and spread through intergenerational transmission, social networks, and group-level ecological and historical factors. Next, we discuss multilevel factors that lead norms to persist, change, or erode over time. We also consider cultural mismatches that can arise when a changing environment leads once-beneficial norms to become maladaptive. Finally, we discuss potential future research directions and the implications of norm dynamics for theory and policy.
- Published
- 2024
- Full Text
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36. The Field of Evolutionary Neuroscience: A Commentary on "Rethinking Norm Psychology" by Cecilia Heyes.
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Richerson PJ and Gavrilets S
- Subjects
- Humans, Biological Evolution, Neurosciences
- Published
- 2024
- Full Text
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37. Reproductive inequality in humans and other mammals.
- Author
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Ross CT, Hooper PL, Smith JE, Jaeggi AV, Smith EA, Gavrilets S, Zohora FT, Ziker J, Xygalatas D, Wroblewski EE, Wood B, Winterhalder B, Willführ KP, Willard AK, Walker K, von Rueden C, Voland E, Valeggia C, Vaitla B, Urlacher S, Towner M, Sum CY, Sugiyama LS, Strier KB, Starkweather K, Major-Smith D, Shenk M, Sear R, Seabright E, Schacht R, Scelza B, Scaggs S, Salerno J, Revilla-Minaya C, Redhead D, Pusey A, Purzycki BG, Power EA, Pisor A, Pettay J, Perry S, Page AE, Pacheco-Cobos L, Oths K, Oh SY, Nolin D, Nettle D, Moya C, Migliano AB, Mertens KJ, McNamara RA, McElreath R, Mattison S, Massengill E, Marlowe F, Madimenos F, Macfarlan S, Lummaa V, Lizarralde R, Liu R, Liebert MA, Lew-Levy S, Leslie P, Lanning J, Kramer K, Koster J, Kaplan HS, Jamsranjav B, Hurtado AM, Hill K, Hewlett B, Helle S, Headland T, Headland J, Gurven M, Grimalda G, Greaves R, Golden CD, Godoy I, Gibson M, Mouden CE, Dyble M, Draper P, Downey S, DeMarco AL, Davis HE, Crabtree S, Cortez C, Colleran H, Cohen E, Clark G, Clark J, Caudell MA, Carminito CE, Bunce J, Boyette A, Bowles S, Blumenfield T, Beheim B, Beckerman S, Atkinson Q, Apicella C, Alam N, and Mulder MB
- Subjects
- Animals, Humans, Female, Male, Marriage, Mammals, Sexual Behavior, Animal, Reproduction, Sex Characteristics
- Abstract
To address claims of human exceptionalism, we determine where humans fit within the greater mammalian distribution of reproductive inequality. We show that humans exhibit lower reproductive skew (i.e., inequality in the number of surviving offspring) among males and smaller sex differences in reproductive skew than most other mammals, while nevertheless falling within the mammalian range. Additionally, female reproductive skew is higher in polygynous human populations than in polygynous nonhumans mammals on average. This patterning of skew can be attributed in part to the prevalence of monogamy in humans compared to the predominance of polygyny in nonhuman mammals, to the limited degree of polygyny in the human societies that practice it, and to the importance of unequally held rival resources to women's fitness. The muted reproductive inequality observed in humans appears to be linked to several unusual characteristics of our species-including high levels of cooperation among males, high dependence on unequally held rival resources, complementarities between maternal and paternal investment, as well as social and legal institutions that enforce monogamous norms.
- Published
- 2023
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38. Authority matters: propaganda and the coevolution of behaviour and attitudes.
- Author
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Gavrilets S and Richerson PJ
- Abstract
Human decision-making is controlled by various factors including material cost-benefit considerations, values and beliefs, social influences, cognitive factors and errors. Among social influences, those by external authorities (e.g. educational, cultural, religious, political, administrative, etc.) are particularly important owing to their potential reach and power. To better understand the effects of 'soft' power of authorities we develop a unifying theoretical framework integrating material, cognitive and social forces controlling the joint dynamics of individual actions and beliefs. We apply our approach to three different phenomena: evolution of food sharing in small-scale societies, participation in political protests and effects of priming social identity in behavioural experiments. For each of these applications, we show that our approach leads to different (or simpler) explanations of human behaviour than alternatives. We highlight the type of measurements which can be helpful in developing practical applications of our approach. We identify and explicitly characterise the degree of mismatch between individual actions and attitudes. We assert that the effects of external authorities, of changing beliefs and of differences between people must be studied empirically, included in mathematical models, and accounted for when developing different policies aiming to modify or sustain human behaviour., Competing Interests: There are no competing interests., (© The Author(s) 2022.)
- Published
- 2022
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39. Disentangling the evolutionary drivers of social complexity: A comprehensive test of hypotheses.
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Turchin P, Whitehouse H, Gavrilets S, Hoyer D, François P, Bennett JS, Feeney KC, Peregrine P, Feinman G, Korotayev A, Kradin N, Levine J, Reddish J, Cioni E, Wacziarg R, Mendel-Gleason G, and Benam M
- Abstract
During the Holocene, the scale and complexity of human societies increased markedly. Generations of scholars have proposed different theories explaining this expansion, which range from broadly functionalist explanations, focusing on the provision of public goods, to conflict theories, emphasizing the role of class struggle or warfare. To quantitatively test these theories, we develop a general dynamical model based on the theoretical framework of cultural macroevolution. Using this model and Seshat: Global History Databank, we test 17 potential predictor variables proxying mechanisms suggested by major theories of sociopolitical complexity (and >100,000 combinations of these predictors). The best-supported model indicates a strong causal role played by a combination of increasing agricultural productivity and invention/adoption of military technologies (most notably, iron weapons and cavalry in the first millennium BCE).
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- 2022
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40. The spread of technological innovations: effects of psychology, culture and policy interventions.
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Tverskoi D, Babu S, and Gavrilets S
- Abstract
Technological innovations drive the evolution of human societies. The success of innovations depends not only on their actual benefits but also on how potential adopters perceive them and how their beliefs are affected by their social and cultural environment. To deepen our understanding of socio-psychological processes affecting the new technology spread, we model the joint dynamics of three interlinked processes: individual learning and mastering the new technology, changes in individual attitudes towards it, and changes in individual adoption decisions. We assume that the new technology can potentially lead to a higher benefit but achieving it requires learning. We posit that individual decision-making process as well as their attitudes are affected by cognitive dissonance and conformity with peers and an external authority. Individuals vary in different psychological characteristics and in their attitudes. We investigate both transient dynamics and long-term equilibria observed in our model. We show that early adopters are usually individuals who are characterized by low cognitive dissonance and low conformity with peers but are sensitive to the effort of an external authority promoting the innovation. We examine the effectiveness of five different intervention strategies aiming to promote the diffusion of a new technology: training individuals, providing subsidies for early adopters, increasing the visibility of peer actions, simplifying the exchange of opinions between people, and increasing the effort of an external authority. We also discuss the effects of culture on the spread of innovations. Finally, we demonstrate that neglecting the cognitive forces and the dynamic nature of individual attitudes can lead to wrong conclusions about adoption of innovations. Our results can be useful in developing more efficient policies aiming to promote the spread of new technologies in different societies, cultures and countries., (© 2022 The Authors.)
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- 2022
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41. Inequality between identity groups and social unrest.
- Author
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Houle C, Ruck DJ, Bentley RA, and Gavrilets S
- Subjects
- Social Behavior
- Abstract
Economic, social and political inequality between different identity groups is an important contributor to violent conflicts within societies. To deepen our understanding of the underlying social dynamics, we develop a mathematical model describing cooperation and conflict in a society composed of multiple factions engaged in economic and political interactions. Our model predicts that growing economic and political inequality tends to lead to the collapse of cooperation between factions that were initially seeking to cooperate. Certain mechanisms can delay this process, including the decoupling of political and economic power through rule of law and allegiance to the state or dominant faction. Counterintuitively, anti-conformity (a social norm for independent action) can also stabilize society, by preventing initial defections from cooperation from cascading through society. However, the availability of certain material resources that can be acquired by the state without cooperation with other factions has the opposite effect. We test several of these predictions using a multivariate statistical analysis of data covering 75 countries worldwide. Using social unrest as a proxy for the breakdown of cooperation in society, we find support for many of the predictions from our theory.
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- 2022
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42. The evolution of germ-soma specialization under different genetic and environmental effects.
- Author
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Tverskoi D and Gavrilets S
- Subjects
- Cell Differentiation, Climate, Fertility, Humans, Biological Evolution, Models, Biological
- Abstract
Division of labor exists at different levels of biological organization - from cell colonies to human societies. One of the simplest examples of the division of labor in multicellular organisms is germ-soma specialization, which plays a key role in the evolution of organismal complexity. Here we formulate and study a general mathematical model exploring the emergence of germ-soma specialization in colonies of cells. We consider a finite population of colonies competing for resources. Colonies are of the same size and are composed by asexually reproducing haploid cells. Each cell can contribute to activity and fecundity of the colony, these contributions are traded-off. We assume that all cells within a colony are genetically identical but gene effects on fecundity and activity are influenced by variation in the microenvironment experienced by individual cells. Through analytical theory and evolutionary agent-based modeling we show that the shape of the trade-off relation between somatic and reproductive functions, the type and extent of variation in within-colony microenvironment, and, in some cases, the number of genes involved, are important predictors of the extent of germ-soma specialization. Specifically, increasing convexity of the trade-off relation, the number of different environmental gradients acting within a colony, and the number of genes (in the case of random microenvironmental effects) promote the emergence of germ-soma specialization. Overall our results contribute towards a better understanding of the role of genetic, environmental, and microenvironmental factors in the evolution of germ-soma specialization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)
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- 2022
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43. Tempo and Mode in Cultural Macroevolution.
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Turchin P and Gavrilets S
- Subjects
- Biological Evolution, Humans, Phenotype, Cultural Evolution
- Abstract
Evolutionary scientists studying social and cultural evolution have proposed a multitude of mechanisms by which cultural change can be effected. In this article we discuss two influential ideas from the theory of biological evolution that can inform this debate: the contrast between the micro- and macro-evolution, and the distinction between the tempo and mode of evolution. We add the empirical depth to these ideas by summarizing recent results from the analyses of data on past societies in Seshat: Global History Databank . Our review of these results suggests that the tempo (rates of change, including their acceleration and deceleration) of cultural macroevolution is characterized by periods of apparent stasis interspersed by rapid change. Furthermore, when we focus on large-scale changes in cultural traits of whole groups, the most important macroevolutionary mode involves inter-polity interactions, including competition and warfare, but also cultural exchange and selective imitation; mechanisms that are key components of cultural multilevel selection (CMLS) theory.
- Published
- 2021
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44. The dynamics of cooperation, power, and inequality in a group-structured society.
- Author
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Tverskoi D, Senthilnathan A, and Gavrilets S
- Abstract
Most human societies are characterized by the presence of different identity groups which cooperate but also compete for resources and power. To deepen our understanding of the underlying social dynamics, we model a society subdivided into groups with constant sizes and dynamically changing powers. Both individuals within groups and groups themselves participate in collective actions. The groups are also engaged in political contests over power which determines how jointly produced resources are divided. Using analytical approximations and agent-based simulations, we show that the model exhibits rich behavior characterized by multiple stable equilibria and, under some conditions, non-equilibrium dynamics. We demonstrate that societies in which individuals act independently are more stable than those in which actions of individuals are completely synchronized. We show that mechanisms preventing politically powerful groups from bending the rules of competition in their favor play a key role in promoting between-group cooperation and reducing inequality between groups. We also show that small groups can be more successful in competition than large groups if the jointly-produced goods are rivalrous and the potential benefit of cooperation is relatively small. Otherwise large groups dominate. Overall our model contributes towards a better understanding of the causes of variation between societies in terms of the economic and political inequality within them., (© 2021. The Author(s).)
- Published
- 2021
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45. Coevolution of actions, personal norms and beliefs about others in social dilemmas.
- Author
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Gavrilets S
- Abstract
Human decision-making is affected by a diversity of factors including material cost-benefit considerations, normative and cultural influences, learning and conformity with peers and external authorities (e.g. cultural, religious, political, organisational). Also important are dynamically changing personal perceptions of the situation and beliefs about actions and expectations of others as well as psychological phenomena such as cognitive dissonance and social projection. To better understand these processes, I develop a unifying modelling framework describing the joint dynamics of actions and attitudes of individuals and their beliefs about the actions and attitudes of their groupmates. I consider which norms get internalised and which factors control beliefs about others. I predict that the long-term average characteristics of groups are largely determined by a balance between material payoffs and the values promoted by the external authority. Variation around these averages largely reflects variation in individual costs and benefits mediated by individual psychological characteristics. The efforts of an external authority to change the group behaviour in a certain direction can, counter-intuitively, have an opposite effect on individual behaviour. I consider how various factors can affect differences between groups and societies in the tightness/looseness of their social norms. I show that the most important factors are social heterogeneity, societal threat, effects of authority, cultural variation in the degree of collectivism/individualism, the population size and the subsistence style. My results can be useful for achieving a better understanding of human social behaviour and historical and current social processes, and in developing more efficient policies aiming to modify social behaviour., (© The Author(s) 2021.)
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- 2021
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46. Modern theories of human evolution foreshadowed by Darwin's Descent of Man .
- Author
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Richerson PJ, Gavrilets S, and de Waal FBM
- Subjects
- Animals, Brain anatomy & histology, Brain growth & development, Gorilla gorilla, Humans, Organ Size, Primates anatomy & histology, Primates growth & development, Primates physiology, Social Norms, Biological Evolution, Cultural Evolution, Social Evolution
- Abstract
Charles Darwin's The Descent of Man , published 150 years ago, laid the grounds for scientific studies into human origins and evolution. Three of his insights have been reinforced by modern science. The first is that we share many characteristics (genetic, developmental, physiological, morphological, cognitive, and psychological) with our closest relatives, the anthropoid apes. The second is that humans have a talent for high-level cooperation reinforced by morality and social norms. The third is that we have greatly expanded the social learning capacity that we see already in other primates. Darwin's emphasis on the role of culture deserves special attention because during an increasingly unstable Pleistocene environment, cultural accumulation allowed changes in life history; increased cognition; and the appearance of language, social norms, and institutions., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
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- 2021
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47. Celebrating the 150th anniversary of the Descent of Man .
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Gavrilets S, Richerson PJ, and de Waal FBM
- Abstract
Competing Interests: The authors declare no conflict of interests.
- Published
- 2021
- Full Text
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48. Ecological Consequences of Intraspecific Variation in Coevolutionary Systems.
- Author
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Senthilnathan A and Gavrilets S
- Subjects
- Models, Theoretical, Phenotype, Symbiosis, Biological Evolution, Ecosystem
- Abstract
AbstractThe patterns and outcomes of coevolution are expected to depend on intraspecific trait variation. Various evolutionary factors can change this variation in time. As a result, modeling coevolutionary processes solely in terms of mean trait values may not be sufficient; one may need to study the dynamics of the whole trait distribution. Here, we develop a theoretical framework for studying the effects of evolving intraspecific variation in two-species coevolutionary systems. In particular, we build and study mathematical models of competition, exploiter-victim interactions, and mutualism in which the strength of within- and between-species interactions depends on the difference in continuously varying traits between individuals reproducing asexually. We use analytical approximations based on the invasion analysis and supplement them with numerical results. We find that intraspecific variation can be maintained if stabilizing selection is weak in at least one species. When intraspecific variation is maintained under competition or mutualism, coexistence in a stable equilibrium is promoted when between-species interactions mostly happen between individuals similar in trait values. In contrast, in exploiter-victim systems coexistence typically requires strong interactions between dissimilar exploiters and victims. We show that trait distributions can become multimodal. Our approach and results contribute to the understanding of the ecological consequences of intraspecific variation in coevolutionary systems by exploring its effects on population densities and trait distributions.
- Published
- 2021
- Full Text
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49. The dynamics of injunctive social norms.
- Author
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Gavrilets S
- Abstract
Injunctive social norms are behaviours that one is expected to follow and expects others to follow in a given social situation; they are maintained by the threat of disapproval or punishment and by the process of internalization. Injunctive norms govern all aspects of our social life but the understanding of their effects on individual and group behaviour is currently rather incomplete. Here I develop a general mathematical approach describing the dynamics of injunctive norms in heterogeneous groups. My approach captures various costs and benefits, both material and normative, associated with norm-related behaviours including punishment and disapproval by others. It also allows for errors in decision-making and explicitly accounts for differences between individuals in their values, beliefs about the population state, and sensitivity to the actions of others. In addition, it enables one to study the consequences of mixing populations with different normative values and the effects of persuasive interventions. I describe how interactions of these factors affect individual and group behaviour. As an illustration, I consider policies developed by practitioners to abolish the norms of footbinding and female genital cutting, to decrease college students' drinking, and to increase pro-environmental behaviours. The theory developed here can be used for achieving a better understanding of historical and current social processes as well as for developing practical policies better accounting for human social behaviour., (© The Author(s) 2020.)
- Published
- 2020
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50. The multinomial index: a robust measure of reproductive skew.
- Author
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Ross CT, Jaeggi AV, Borgerhoff Mulder M, Smith JE, Smith EA, Gavrilets S, and Hooper PL
- Subjects
- Animals, Biological Evolution, Social Behavior, Reproduction, Sexual Behavior, Animal
- Abstract
Inequality or skew in reproductive success (RS) is common across many animal species and is of long-standing interest to the study of social evolution. However, the measurement of inequality in RS in natural populations has been challenging because existing quantitative measures are highly sensitive to variation in group/sample size, mean RS, and age-structure. This makes comparisons across multiple groups and/or species vulnerable to statistical artefacts and hinders empirical and theoretical progress. Here, we present a new measure of reproductive skew, the multinomial index, M , that is unaffected by many of the structural biases affecting existing indices. M is analytically related to Nonacs' binomial index, B , and comparably accounts for heterogeneity in age across individuals; in addition, M allows for the possibility of diminishing or even highly nonlinear RS returns to age. Unlike B , however, M is not biased by differences in sample/group size. To demonstrate the value of our index for cross-population comparisons, we conduct a reanalysis of male reproductive skew in 31 primate species. We show that a previously reported negative effect of group size on mating skew was an artefact of structural biases in existing skew measures, which inevitably decline with group size; this bias disappears when using M . Applying phylogenetically controlled, mixed-effects models to the same dataset, we identify key similarities and differences in the inferred within- and between-species predictors of reproductive skew across metrics. Finally, we provide an R package, SkewCalc, to estimate M from empirical data.
- Published
- 2020
- Full Text
- View/download PDF
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