Inclusive fitness
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Superorganismality and caste differentiation as points of no return: how the major evolutionary transitions were lost in translation Open
More than a century ago, William Morton Wheeler proposed that social insect colonies can be regarded as superorganisms when they have morphologically differentiated reproductive and nursing castes that are analogous to the metazoan germ‐li…
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Social complexity and kinship in animal societies Open
Studies of eusocial invertebrates regard complex societies as those where there is a clear division of labour and extensive cooperation between breeders and helpers. In contrast, studies of social mammals identify complex societies as thos…
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Epistasis and Adaptation on Fitness Landscapes Open
Epistasis occurs when the effect of a mutation depends on its carrier's genetic background. Despite increasing evidence that epistasis for fitness is common, its role during evolution is contentious. Fitness landscapes, which are mappings …
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Chimpanzee fathers bias their behaviour towards their offspring Open
Promiscuous mating was traditionally thought to curtail paternal investment owing to the potential costs of providing care to unrelated infants. However, mounting evidence suggests that males in some promiscuous species can recognize offsp…
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Kin Recognition in Bacteria Open
The ability of bacteria to recognize kin provides a means to form social groups. In turn these groups can lead to cooperative behaviors that surpass the ability of the individual. Kin recognition involves specific biochemical interactions …
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Correlates and Consequences of Worker Polymorphism in Ants Open
Body size is a key life-history trait influencing all aspects of an organism's biology. Ants provide an interesting model for examining body-size variation because of the high degree of worker polymorphism seen in many taxa. We review work…
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Toward a metabolic theory of life history Open
Significance Data and theory reveal how organisms allocate metabolic energy to components of the life history that determine fitness. In each generation, animals take up biomass energy from the environment and expend it on survival, growth…
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The evolution of altruism and the serial rediscovery of the role of relatedness Open
Significance The canonical explanation for the evolution of altruism (“kin selection”)—which was mathematically derived in the 1960s by W. D. Hamilton—emphasizes the importance of genetic relatedness. Over the past three decades, numerous …
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The role of physiological traits in assortment among and within fish shoals Open
Individuals of gregarious species often group with conspecifics to which they are phenotypically similar. This among-group assortment has been studied for body size, sex and relatedness. However, the role of physiological traits has been l…
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Kin-directed food sharing promotes lifetime natal philopatry of both sexes in a population of fish-eating killer whales, Orcinus orca Open
The vast majority of social animals exhibit sex-biased dispersal as a strategy to reduce kin competition and avoid inbreeding. Piscivorous 'resident' killer whales, Orcinus orca, of the eastern North Pacific, however, are unusual in that b…
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Evolution of cooperation with asymmetric social interactions Open
Significance Humans have a remarkable, but not ubiquitous, tendency toward altruism. This behavior reflects a classic enigma in evolutionary theory: When and why would individuals forgo selfish interests to help strangers? Population struc…
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Stable social relationships between unrelated females increase individual fitness in a cooperative bird Open
Social animals often form long-lasting relationships with fellow group members, usually with close kin. In primates, strong social bonds have been associated with increased longevity, offspring survival and reproductive success. However, l…
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The evolution of infanticide by females in mammals Open
In most mammalian species, females regularly interact with kin, which is expected to reduce aggressive competitive behaviour among females. It may thus be difficult to understand why infanticide by females has been reported in numerous spe…
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Inclusive fitness is an indispensable approximation for understanding organismal design Open
For some decades most biologists interested in design have agreed that natural selection leads to organisms acting as if they are maximizing a quantity known as "inclusive fitness." This maximization principle has been criticized on the (u…
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Deep evolutionary conservation of autism-related genes Open
Significance Sociobiological theory proposed that similarities between human and animal societies reflect similar evolutionary origins. We used comparative genomics to test this controversial idea by determining whether superficial behavio…
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Postreproductive killer whale grandmothers improve the survival of their grandoffspring Open
Understanding why females of some mammalian species cease ovulation prior to the end of life is a long-standing interdisciplinary and evolutionary challenge. In humans and some species of toothed whales, females can live for decades after …
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Kin and multilevel selection in social evolution: a never-ending controversy? Open
Kin selection and multilevel selection are two major frameworks in evolutionary biology that aim at explaining the evolution of social behaviors. However, the relationship between these two theories has been plagued by controversy for almo…
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Explaining negative kin discrimination in a cooperative mammal society Open
Significance Kin selection theory predicts that animals will direct altruism toward closer genetic relatives and aggression toward more distantly related individuals. Our 18-y study of wild banded mongooses reveals that, unusually, dominan…
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Understanding the links between social ties and fitness over the life cycle in primates Open
Many studies highlight the correlation between social ties and fitness, yet often cannot reveal how ties influence fitness. This review is aimed to facilitate the formulation and testing of hypotheses in this area on non-human primates. I …
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Social traits, social networks and evolutionary biology Open
The social environment is both an important agent of selection for most organisms, and an emergent property of their interactions. As an aggregation of interactions among members of a population, the social environment is a product of many…
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Invasion fitness, inclusive fitness, and reproductive numbers in heterogeneous populations Open
How should fitness be measured to determine which phenotype or "strategy" is uninvadable when evolution occurs in a group-structured population subject to local demographic and environmental heterogeneity? Several fitness measures, such as…
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Genetic signatures of microbial altruism and cheating in social amoebas in the wild Open
Significance Microbes are surprisingly social organisms and are providing model systems for the study of the evolution of cooperation and conflict. Despite their many advantages in the laboratory, such as experimental evolution, it is rare…
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Mobility can promote the evolution of cooperation via emergent self-assortment dynamics Open
The evolution of costly cooperation, where cooperators pay a personal cost to benefit others, requires that cooperators interact more frequently with other cooperators. This condition, called positive assortment, is known to occur in spati…
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Allopreening in birds is associated with parental cooperation over offspring care and stable pair bonds across years Open
Individuals of many species form bonds with their breeding partners, yet the mechanisms maintaining these bonds are poorly understood. In birds, allopreening is a conspicuous feature of interactions between breeding partners and has been h…
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Sibling conflict and dishonest signaling in birds Open
Significance Should a chick beg for food even if it isn’t struggling to grow? Does it have anything to lose? The answer could be “yes” if it risks losing indirect fitness through the starvation of siblings. Evolutionary theory suggests tha…
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The evolution of sex peptide: sexual conflict, cooperation, and coevolution Open
A central paradigm in evolutionary biology is that the fundamental divergence in the fitness interests of the sexes (‘sexual conflict’) can lead to both the evolution of sex‐specific traits that reduce fitness for individuals of the opposi…
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There is no fitness but fitness, and the lineage is its bearer Open
Inclusive fitness has been the cornerstone of social evolution theory for more than a half-century and has matured as a mathematical theory in the past 20 years. Yet surprisingly for a theory so central to an entire field, some of its conn…
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Kinship and familiarity mitigate costs of social conflict between Seychelles warbler neighbors Open
Significance In nature, animals must compete with their neighbors for access to limited resources. Since conflict over resources can be extremely costly in terms of time, energy, and reproductive success, investigating how individuals reso…
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Mother's little helpers: What we know (and don't know) about cooperative infant care in callitrichines Open
Since Darwin ( ), scientists have been puzzled by how behaviors that impose fitness costs on helpers while benefiting their competitors could evolve through natural selection. Hamilton's ( ) theory of inclusive fitness provided an explanat…
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The stagnation paradox: the ever-improving but (more or less) stationary population fitness Open
Fisher's fundamental theorem states that natural selection improves mean fitness. Fitness, in turn, is often equated with population growth. This leads to an absurd prediction that life evolves to ever-faster growth rates, yet no one serio…