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Social Evolution (social + evolution)
Selected AbstractsMathematical Models of Social Evolution: A Guide for the Perplexed by Richard McElreath, Robert BoydINTERNATIONAL STATISTICAL REVIEW, Issue 3 2007Hanna Kokko No abstract is available for this article. [source] Proximate Determinants of Reproductive Skew in Polygyne Colonies of the Ant Formica fuscaETHOLOGY, Issue 11 2002Minttumaaria Hannonen Understanding the determinants of reproductive skew (the partitioning of reproduction among co-breeding individuals) is one of the major questions in social evolution. In ants, multiple-queen nests are common and reproductive skew among queens has been shown to vary tremendously both within and between species. Proximate determinants of skew may be related to both queen and worker behaviour. Queens may attempt to change their reproductive share through dominance interactions, egg eating and by changing individual fecundity. Conversely, workers are in a position to regulate the reproductive output of queens when rearing the brood. This paper investigates queen behaviour at the onset of egg laying and the effect of queen fecundity and worker behaviour on brood development and reproductive shares of multiple queens in the ant Formica fusca. The study was conducted in two-queen laboratory colonies where the queens produced only worker offspring. The results show that in this species reproductive apportionment among queens is not based on dominance behaviour and aggression, but rather on differences in queen fecundity. We also show that, although the queen fecundity at the onset of brood rearing is a good indicator of her final reproductive output, changes in brood composition occur during brood development. Our results highlight the importance of queen fecundity as a major determinant of her reproductive success. They furthermore suggest that in highly derived polygyne species, such as the Formica ants, direct interactions as a means for gaining reproductive dominance have lost their importance. [source] KIN-BASED RECOGNITION AND SOCIAL AGGREGATION IN A CILIATEEVOLUTION, Issue 5 2010Alexis S. Chaine Aggregative groups entail costs that must be overcome for the evolution of complex social interactions. Understanding the mechanisms that allow aggregations to form and restrict costs of cheating can provide a resolution to the instability of social evolution. Aggregation in Tetrahymena thermophila is associated with costs of reduced growth and benefits of improved survival through "growth factor" exchange. We investigated what mechanisms contribute to stable cooperative aggregation in the face of potential exploitation by less-cooperative lines using experimental microcosms. We found that kin recognition modulates aggregative behavior to exclude cheaters from social interactions. Long-distance kin recognition across patches modulates social structure by allowing recruitment of kin in aggregative lines and repulsion in asocial lines. Although previous studies have shown a clear benefit to social aggregation at low population densities, we found that social aggregation has very different effects at higher densities. Lower growth rates are a cost of aggregation, but also present potential benefits when restricted to kin aggregations: slow growth and crowd tolerance allow aggregations to form and permit longer persistence on ephemeral resources. Thus in highly dynamic metapopulations, kin recognition plays an important role in the formation and stability of social groups that increase persistence through cooperative consumptive restraint. [source] MATHEMATICS OF KIN- AND GROUP-SELECTION: FORMALLY EQUIVALENT?EVOLUTION, Issue 2 2010Arne Traulsen Evolutionary game theory is a general mathematical framework that describes the evolution of social traits. This framework forms the basis of many multilevel selection models and is also frequently used to model evolutionary dynamics on networks. Kin selection, which was initially restricted to describe social interactions between relatives, has also led to a broader mathematical approach, inclusive fitness, that can not only describe social evolution among relatives, but also in group structured populations or on social networks. It turns out that the underlying mathematics of game theory is fundamentally different from the approach of inclusive fitness. Thus, both approaches,evolutionary game theory and inclusive fitness,can be helpful to understand the evolution of social traits in group structured or spatially extended populations. [source] The sociobiology of biofilmsFEMS MICROBIOLOGY REVIEWS, Issue 1 2009Carey D. Nadell Abstract Biofilms are densely packed communities of microbial cells that grow on surfaces and surround themselves with secreted polymers. Many bacterial species form biofilms, and their study has revealed them to be complex and diverse. The structural and physiological complexity of biofilms has led to the idea that they are coordinated and cooperative groups, analogous to multicellular organisms. We evaluate this idea by addressing the findings of microbiologists from the perspective of sociobiology, including theories of collective behavior (self-organization) and social evolution. This yields two main conclusions. First, the appearance of organization in biofilms can emerge without active coordination. That is, biofilm properties such as phenotypic differentiation, species stratification and channel formation do not necessarily require that cells communicate with one another using specialized signaling molecules. Second, while local cooperation among bacteria may often occur, the evolution of cooperation among all cells is unlikely for most biofilms. Strong conflict can arise among multiple species and strains in a biofilm, and spontaneous mutation can generate conflict even within biofilms initiated by genetically identical cells. Biofilms will typically result from a balance between competition and cooperation, and we argue that understanding this balance is central to building a complete and predictive model of biofilm formation. [source] Social behavior and comparative genomics: new genes or new gene regulation?GENES, BRAIN AND BEHAVIOR, Issue 4 2002G. E. Robinson Molecular analyses of social behavior are distinguished by the use of an unusually broad array of animal models. This is advantageous for a number of reasons, including the opportunity for comparative genomic analyses that address fundamental issues in the molecular biology of social behavior. One issue relates to the kinds of changes in genome structure and function that occur to give rise to social behavior. This paper considers one aspect of this issue, whether social evolution involves new genes, new gene regulation, or both. This is accomplished by briefly reviewing findings from studies of the fish Haplochromis burtoni, the vole Microtus ochrogaster, and the honey bee Apis mellifera, with a more detailed and prospective consideration of the honey bee. [source] Budding dispersal and the sex ratioJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2009A. Gardner Abstract There is much interest in understanding how population demography impacts upon social evolution. Here, we consider the impact of rate and pattern of dispersal upon a classic social evolutionary trait , the sex ratio. We recover existing analytical results for individual dispersal, and we extend these to allow for budding dispersal. In particular, while a cancelling of relatedness and kin competition effects means that the sex ratio is unaffected by the rate of individual dispersal, we find that a decoupling of relatedness and kin competition means that budding dispersal favours increasingly female-biased sex ratios. More generally, our analysis illustrates the relative ease with which biological problems involving class structure can be solved using a kin selection approach to social evolution theory. [source] The joint effects of kin, multilevel selection and indirect genetic effects on response to genetic selectionJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2008P. BIJMA Abstract Kin and levels-of-selection models are common approaches for modelling social evolution. Indirect genetic effect (IGE) models represent a different approach, specifying social effects on trait values rather than fitness. We investigate the joint effect of relatedness, multilevel selection and IGEs on response to selection. We present a measure for the degree of multilevel selection, which is the natural partner of relatedness in expressions for response. Response depends on both relatedness and the degree of multilevel selection, rather than only one or the other factor. Moreover, response is symmetric in relatedness and the degree of multilevel selection, indicating that both factors have exactly the same effect. Without IGEs, the key parameter is the product of relatedness and the degree of multilevel selection. With IGEs, however, multilevel selection without relatedness can explain evolution of social traits. Thus, next to relatedness and multilevel selection, IGEs are a key element in the genetical theory of social evolution. [source] Polyandry and colony genetic structure in the primitive ant Nothomyrmecia macropsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2001M. Sanetra The Australian endemic ant Nothomyrmecia macrops is considered one of the most ,primitive' among living ants. We investigated the genetic structure of colonies to determine queen mating frequencies and nestmate relatedness. An average of 18.8 individuals from each of 32 colonies, and sperm extracted from 34 foraging queens, were genotyped using five highly variable microsatellite markers. Queens were typically singly (65%) or doubly mated (30%), but triple mating (5%) also occurred. The mean effective number of male mates for queens was 1.37. No relationship between colony size and queen mate number was found. Nestmate workers were related by b=0.61 ± 0.03, significantly above the threshold under Hamilton's rule over which, all else being equal, altruistic behaviour persists, but queens and their mates were unrelated. In 25% of the colonies we detected a few workers that could not have been produced by the resident queen, although there was no evidence for worker reproduction. Polyandry is for the first time recorded in a species with very small mature colonies, which is inconsistent with the sperm-limitation hypothesis for the mediation of polyandry levels. Facultative polyandry is therefore not confined to the highly advanced ant genera, but may have arisen at an early stage in ant social evolution. [source] Institutionalization of the Family and Marriage: Questioning Their Cognitive and Relational RealitiesJOURNAL OF FAMILY THEORY & REVIEW, Issue 1 2009Jetse Sprey This paper argues that to explain the institutionalization processes named the family and marriage, it is necessary to recognize the ontological distinction between their cognitive and relational realities. Institutionalization is an ordering process analogous to instinct in animal societies. In that capacity the human family and marriage collectively order the care and social placement of offspring. Given the biology of Homo sapiens, the family preceded the onset of the human race by millions of years, whereas marriage, the contract that legitimates the social placement of offspring, represents a strictly cultural aspect of human social evolution. The current state and uncertain future of the cognitive and relational components of the institutions of the family and marriage are addressed. [source] Medium molecular weight polar substances of the cuticle as tools in the study of the taxonomy, systematics and chemical ecology of tropical hover wasps (Hymenoptera: Stenogastrinae)JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2010David Baracchi Abstract The Stenogastrinae wasps have been proposed as a key group for an understanding of social evolution in insects, but the phylogeny of the group is still under discussion. The use of chemical characters, in particular cuticular hydrocarbons, for insect taxonomy is relatively recent and only a few studies have been conducted on the cuticular polar substances. In this work, we ascertain, by the matrix-assisted laser desorption ionization-time of flight mass spectrometry technique, that different species of primitively eusocial hover wasps have different compositions of the epicuticular polar compounds ranging from 900 to 3600 Da. General linear model analysis and discriminant analysis showed that the average spectral profiles of this fraction can be diagnostic for identification of the species. Moreover, for the first time we show population diversification in the medium MW polar cuticular mixtures in insects. In conclusion, the results demonstrate that the chemical characters are consistent with the physical characters and the study support the importance of medium MW polar substances as powerful tools for systematics (chemosystematics) and chemical ecology (fertility signal and population characterization) in a primitively social insect taxon. Riassunto Le vespe primitivamente eusociali della sottofamiglia delle Stenogastrinae sono state proposte come gruppo chiave per lo studio dell'evoluzione della socialità negli insetti. Ancora oggi, però, la filogenesi del gruppo rimane incerta e discussa. Sebbene l'uso dei caratteri chimici, e in particolare degli idrocarburi cuticolari, negli studi tassonomici sugli insetti sia ben noto, seppur di recente applicazione, sono ancora pochi gli studi condotti sulle sostanze cuticolari di natura polare. In questo lavoro abbiamo saggiato, mediante tecniche di spettrometria di massa (MALDI-TOF MS), la presenza di composti polari cuticolari di massa compresa tra i 900 e i 3600 (probabilmente provenienti dal veleno) sulla cuticola di alcune specie di vespe stenogastrine. Analisi statistiche multivariate hanno dimostrato che lo spettro medio dei profili chimici nel range da noi indagato può essere utilizzato per l'identificazione delle specie e la nostra ricerca propone questo metodo come un potente strumento non solo per studi di tassonomia (chemotassonomia) ma anche per studi di sistematica e di ecologia chimica (es. segnali di fertilità e differenze intra-popolazioni) nei taxon di insetti primitivamente eusociali. [source] Phylogenetic reconstruction of carnivore social organizationsJOURNAL OF ZOOLOGY, Issue 1 2007F. Dalerum Abstract It is generally assumed that carnivore social organizations evolved directionally from a solitary ancestor into progressively more advanced forms of group living. Although alternative explanations exist, this evolutionary hypothesis has never been tested. Here, I used literature data and maximum likelihood reconstruction on a complete carnivore phylogeny to test this hypothesis against two others: one assuming directional evolution from a non-solitary ancestor, and one assuming parallel evolutions from a socially flexible ancestor, that is, an ancestor with abilities to live in a variety of social organizations. The phylogenetic reconstructions did not support any of the three hypotheses of social evolution at the root of Carnivora. At the family level, however, there was support for a non-solitary and socially flexible ancestor to Canidae, a socially flexible or solitary ancestor to Mustelidae, a solitary or socially flexible ancestor to Mephitidae, a solitary or group living ancestor to Phocidae, a group living ancestor to Otariidae and a solitary ancestor to Ursidae, Felidae, Herpestidae and Viverridae. There was equivocal support for the ancestral state of Procyonidae and Hyaenidae. It is unclear whether the common occurrence of a solitary ancestry at the family level was caused by a solitary ancestor at the root of Carnivora or by multiple transitions into a solitary state. The failure to support a solitary ancestor to Carnivora calls for caution when using this hypothesis in an evolutionary framework, and I suggest continued investigations of the pathways of the evolution of carnivore social organizations. [source] Flexible social organization and high incidence of drifting in the sweat bee, Halictus scabiosaeMOLECULAR ECOLOGY, Issue 8 2009YUKO ULRICH Abstract The very diverse social systems of sweat bees make them interesting models to study social evolution. Here we focus on the dispersal behaviour and social organization of Halictus scabiosae, a common yet poorly known species of Europe. By combining field observations and genetic data, we show that females have multiple reproductive strategies, which generates a large diversity in the social structure of nests. A detailed microsatellite analysis of 60 nests revealed that 55% of the nests contained the offspring of a single female, whereas the rest had more complex social structures, with three clear cases of multiple females reproducing in the same nest and frequent occurrence of unrelated individuals. Drifting among nests was surprisingly common, as 16% of the 122 nests in the overall sample and 44% of the nests with complex social structure contained females that had genotypes consistent with being full-sisters of females sampled in other nests of the population. Drifters originated from nests with an above-average productivity and were unrelated to their nestmates, suggesting that drifting might be a strategy to avoid competition among related females. The sex-specific comparison of genetic differentiation indicated that dispersal was male-biased, which would reinforce local resource competition among females. The pattern of genetic differentiation among populations was consistent with a dynamic process of patch colonization and extinction, as expected from the unstable, anthropogenic habitat of this species. Overall, our data show that H. scabiosae varies greatly in dispersal behaviour and social organization. The surprisingly high frequency of drifters echoes recent findings in wasps and bees, calling for further investigation of the adaptive basis of drifting in the social insects. [source] Discovery of a large clonal patch of a social amoeba: implications for social evolutionMOLECULAR ECOLOGY, Issue 6 2009OWEN M GILBERT Abstract Studies of genetic population structures of clonally reproducing macro-organisms have revealed large areas where only one clone is found. These areas, referred to as clonal patches, have not been shown to occur in free-living microbes until now. In free-living microbes, high genetic diversity at local scales is usually maintained by high rates of dispersal. We report, however, a highly dense, 12-m clonal patch of the social amoeba Dictyostelium discoideum in a cattle pasture located in a Texas Gulf Coast prairie. We confirm the presence of only one clone by the analysis of 65 samples and amplification of 10 polymorphic microsatellite loci. Samplings of additional cattle pastures nearby showed higher clonal diversity, but with a density of D. discoideum isolates lower than in the clonal patch. These findings show that high rates of microbial dispersal do not always produce genetic diversity at local scales, contrary to the findings of previous studies. The existence of clonal patches may be particularly important for microbial social evolution. [source] Molecular ecology of social behaviour: analyses of breeding systems and genetic structureMOLECULAR ECOLOGY, Issue 2 2001Kenneth G. Ross Abstract Molecular genetic studies of group kin composition and local genetic structure in social organisms are becoming increasingly common. A conceptual and mathematical framework that links attributes of the breeding system to group composition and genetic structure is presented here, and recent empirical studies are reviewed in the context of this framework. Breeding system properties, including the number of breeders in a social group, their genetic relatedness, and skew in their parentage, determine group composition and the distribution of genetic variation within and between social units. This group genetic structure in turn influences the opportunities for conflict and cooperation to evolve within groups and for selection to occur among groups or clusters of groups. Thus, molecular studies of social groups provide the starting point for analyses of the selective forces involved in social evolution, as well as for analyses of other fundamental evolutionary problems related to sex allocation, reproductive skew, life history evolution, and the nature of selection in hierarchically structured populations. The framework presented here provides a standard system for interpreting and integrating genetic and natural history data from social organisms for application to a broad range of evolutionary questions. [source] Social trajectories and the evolution of social behaviorOIKOS, Issue 2 2002S. Helms Cahan Current research on the evolution of sociality seeks to integrate a wealth of species-specific studies to draw more generalized conclusions. Developing a unified theory of social evolution has been a challenging process, hampered by the inherent complexity of social systems. By viewing a species' social structure as the result of a series, or "trajectory", of decisions individuals make about whether or not to disperse from their natal territory, whether to co-breed or refrain from breeding, and whether or not to provide alloparental care, we can more easily evaluate whether selective factors influencing each social decision are similar across taxa. At the same time, the social trajectory framework highlights the interrelationships among different social decisions, both throughout the life of an individual and over evolutionary time. There are likely to be multiple unifying themes within sociality research; we hope that the simple framework outlined here will promote exchange between researchers across taxonomic disciplines to begin to identify common principles. [source] Schumpeter 1911: Farsighted Visions on Economic DevelopmentAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 2 2002Markus C. Becker This paper presents to the English-speaking reader a sample of material contained only in Schumpeter's first German edition (1911) of Theorie der wirtschaftlichen Entwicklung, material subsequently omitted from later German editions and from the English translation. The newly-translated material, presented here for the first time in English, comprises a substantial part of the second chapter, only available in a completely rewritten version, and fully half of the famous seventh chapter, which has not been previously available at all in English. This material merits attention today because it contains remarkable and farsighted visions on economic theory that may inspire current efforts to devise models of economic and social evolution. In order to better appreciate the original text, we briefly introduce the "background" to Theorie and its revisions, briefly describing the social and intellectual environment of the time. We then discuss how the entrepreneur evolved over the three editions of Theorie (from 1911 to 1934) in view of the shift in Schumpeter's personal and intellectual life and outline the most important implications raised by the first German edition of 1911. Finally, we use Schumpeter's own statements to settle the obstinate confusion on the publication year of Theorie in favour of the year 1911. [source] Host intrinsic determinants and potential consequences of parasite infection in free-ranging red-fronted lemurs (Eulemur fulvus rufus)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010Dagmar Clough Abstract Parasites and infectious diseases represent ecological forces shaping animal social evolution. Although empirical studies supporting this link abound in various vertebrate orders, both the study of the dynamics and impact of parasite infections and infectious diseases in strepsirrhine primates have received little empirical attention. We conducted a longitudinal parasitological study on four groups of wild red-fronted lemurs (Eulemur fulvus rufus) at Kirindy Forest, Madagascar, during two field seasons in consecutive years to investigate i) the degree of gastrointestinal parasite infection on population and individual levels and ii) factors potentially determining individual infection risk. Using a comprehensive dataset with multiple individually assignable parasite samples as well as information on age, sex, group size, social rank, and endocrine status (fecal androgen and glucocorticoid), we examined parasite infection patterns and host traits that may affect individual infection risk. In addition, we examined whether parasite infection affects mating and reproductive success. Our results indicated high variability in parasite infection on individual and population levels. Time of year and group size was important determinants of variability in parasite infection. Variation in hormone levels was also associated with parasite species richness and parasite infection intensity. Differences in parasite infection between years indicate a potential immune-enhancing function of steroid hormones on nematode infections, which has not been reported before from other vertebrates studied under natural conditions. Male mating and reproductive success were not correlated to any measure of parasite infection, which suggests a nonfunctional role of the parasites we examined in primate sexual selection. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source] Fashioning and Demarcation of the Danish Chemical Community in the 19th CenturyCENTAURUS, Issue 3 2007Anita Kildebæk Nielsen The development of Danish chemistry in the 19th century was a complex process involving the establishment of boundaries for chemistry, creation of professional identities, and institutional constructions. Many of these factors can be analysed through detailed studies of the media carrying chemical information. This paper explores the development process by studying three Danish chemical periodicals published in the vernacular. By analysing their contents, editorial lines, and intended audiences, these three periodicals give specific information on the social evolution of chemistry and the process of demarcation of chemistry from non-chemistry. The analysis is linked to the early history of the Danish Chemical Society in order to address the question of what it meant to be a chemist in second half of the 19th-century Denmark. Taken together, examination of specific aspects of the society and the three periodicals provide new perspectives on the relationships between the three most important groups of chemical practitioners: academics, engineers, and pharmacists. [source] | ||||||||||||||||||||||||||||