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The study of group selection has developed along two autonomous lines. One approach, which we refer to as the adaptationist school, seeks to understand the evolution of existing traits by examining plausible mechanisms for their evolution and persistence. The other approach, which we refer to as the genetic school, seeks to examine how currently acting(More)
We describe an experiment exploring the effects of coexistence and population differentiation on the competitive outcome of two species of Tribolium flour beetles, T. castaneum and T. confusum. The only manipulation was whether the populations used in the competitive phase of the study were raised initially in mixed-species communities, single-species(More)
Wild et al. argue that the evolution of reduced virulence can be understood from the perspective of inclusive fitness, obviating the need to evoke group selection as a contributing causal factor. Although they acknowledge the mathematical equivalence of the inclusive fitness and multilevel selection approaches, they conclude that reduced virulence can be(More)
Genetic population differentiation is typically viewed as differentiation of population means. However, several theories of evolution and speciation postulate that populations differentiate not only with respect to the population means, but also with respect to the effects of alleles within these populations. I develop herein a measure of population(More)
Central to Wright's shifting-balance theory is the idea that genetic drift and selection in systems with gene interaction can lead to the formation of "adaptive gene complexes." The theory of genetic drift has been well developed over the last 60 years; however, nearly all of this theory is based on the assumption that only additive gene effects are acting.(More)
Coevolution generally refers to the process of two or more organisms adapting to each other as a result of individual selection. Another possibility, however, is that coevolution may result from selection acting directly at the community level. Certain types of multispecies associations, such as lichens, which are a symbiotic association between an alga and(More)
Community selection, defined as the differential proliferation and/or extinction of communities, can bring about a response that may be qualitatively different from the response to selection acting at lower levels. This is because community selection can result in genetic changes in all of the species within the community by acting on the interaction among(More)
Given the complexity of host-microbiota symbioses, scientists and philosophers are asking questions at new biological levels of hierarchical organization-what is a holobiont and hologenome? When should this vocabulary be applied? Are these concepts a null hypothesis for host-microbe systems or limited to a certain spectrum of symbiotic interactions such as(More)
A central assumption of quantitative genetic theory is that the breeder's equation (R=GP(-1)S) accurately predicts the evolutionary response to selection. Recent studies highlight the fact that the additive genetic variance-covariance matrix (G) may change over time, rendering the breeder's equation incapable of predicting evolutionary change over more than(More)
We investigate the generation and decay of interspecific disequilibrium (ID) between organelle and symbiont genomes as a function of the rate of horizontal transmission. We show that rare horizontal transmission greatly diminishes the covariance between organelle and symbiont genomes. This result has two important implications. First, a low level of ID does(More)