Cooperation in organisms, whether bacteria or primates, has been a difficulty for evolutionary theory since Darwin. On the assumption that interactions between pairs of individuals occur on a probabilistic basis, a model is developed based on the concept of an evolutionarily stable strategy in the context of the Prisoner's Dilemma game. Deductions from the model, and the results of a computer tournament show how cooperation based on reciprocity can get started in an asocial world, can thrive while interacting with a wide range of other strategies, and can resist invasion once fully established. Potential applications include specific aspects of territoriality, mating, and disease.

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The Evolution of Cooperation

Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another. But natural selection implies competition and therefore opposes cooperation unless a specific mechanism is at work. Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

/pdf/five-rules-for-the-evolution-of-cooperation-2bpocasc6i.pdf

Five Rules for the Evolution of Cooperation

http://osenberglab.ecology.uga.edu/wp-content/uploads/2015/09/Charnov-1976-TPB.pdf

Optimal foraging, the marginal value theorem.

Every form of behavior is shaped by trial and error. Such stepwise adaptation can occur through individual learning or through natural selection, the basis of evolution. Since the work of Maynard Smith and others, it has been realized how game theory can model this process. Evolutionary game theory replaces the static solutions of classical game theory by a dynamical approach centered not on the concept of rational players but on the population dynamics of behavioral programs. In this book the authors investigate the nonlinear dynamics of the self-regulation of social and economic behavior, and of the closely related interactions among species in ecological communities. Replicator equations describe how successful strategies spread and thereby create new conditions that can alter the basis of their success, i.e., to enable us to understand the strategic and genetic foundations of the endless chronicle of invasions and extinctions that punctuate evolution. In short, evolutionary game theory describes when to escalate a conflict, how to elicit cooperation, why to expect a balance of the sexes, and how to understand natural selection in mathematical terms.

 Comprehensive treatment of ecological and game theoretic dynamics
 Invasion dynamics and permanence as key concepts
 Explanation in terms of games of things like competition between species

/pdf/evolutionary-games-and-population-dynamics-pax1uk4ywa.pdf

Evolutionary games and population dynamics

Parasitic worms (helminths) frequently have complex life cycles in which they are transmitted trophically between two or more successive hosts. Sexual reproduction often takes place in high trophic-level (TL) vertebrates, where parasites can grow to large sizes with high fecundity. Direct infection of high TL hosts, while advantageous, may be unachievable for parasites constrained to transmit trophically, because helminth propagules are unlikely to be ingested by large predators. Lack of niche overlap between propagule and definitive host (the trophic transmission vacuum) may explain the origin and/or maintenance of intermediate hosts, which overcome this transmission barrier. We show that nematodes infecting high TL definitive hosts tend to have more successive hosts in their life cycles. This relationship was modest, though, driven mainly by the minimum TL of hosts, suggesting that the shortest trophic chains leading to a host define the boundaries of the transmission vacuum. We also show that alternative modes of transmission, like host penetration, allow nematodes to reach high TLs without intermediate hosts. We suggest that widespread omnivory as well as parasite adaptations to increase transmission probably reduce, but do not eliminate, the barriers to the transmission of helminths through the food web.

/pdf/the-trophic-vacuum-and-the-evolution-of-complex-life-cycles-8qnmvyvu9l.pdf

The trophic vacuum and the evolution of complex life cycles in trophically transmitted helminths

In recent years, the field of sexual selection has exploded, with advances in theoretical and empirical research complementing each other in exciting ways. This perspective piece is the product of ...

Endless forms of sexual selection

The interference ideal free distribution (IFD) model of Sutherland makes a number of predictions that have yet to be tested and that have implications for the validity of subsequent extensions to the theory. We tested these predictions in a study using different densities of the parasitoid wasp, Venturia canescens, foraging on patches containing different densities of its host, Plodia interpunctella. Our results support a number of the interference IFD model's general predictions. Gain rate decreased because of increased interference at higher density. Although gain rates on the two patches differed slighdy, this would be expected allowing for some sampling behavior and perceptual constraints. Early in each experiment when patch assessment is likely to occur, wasp movement was higher and gain rates lower. However, die more specific prediction of Sudierland's model, that proportional patch use should be constant and independent of density, was not upheld. Contemporary IFD models use only one of several equally valid potential relationships between gain rate, interference, and competitor density. The results of this study provide support for the additive model developed by Tregenza et al. (companion article). Key words: competition, foraging, ideal free distribution, interference, parasitoid, Venturia canescens. [Behav Ecol 7:387—394 (1996)]

http://www.selfishgene.org/Tom/Papers/TTetal_BE96b.pdf

Interference and the ideal free distribution: oviposition in a parasitoid wasp

Switching from one host to the next is a critical life-history transition in parasites with complex life cycles. Growth and mortality rates are thought to influence the optimal time and size at transmission, but these rates are difficult to measure in parasites. The parasite life cycle, in particular the trophic link along which transmission occurs, may be a reasonable proxy for these rates, leading to the hypothesis that life cycle should shape life-history strategy. We compiled data on the size and age at infectivity for trophically transmitted helminths (i.e., acanthocephalans, cestodes, and nematodes), and then categorized species into trophic links (e.g., planktonic crustaceans to fish, insects to terrestrial vertebrates, etc.). Comparative analyses that explicitly included stabilizing selection within trophic links fit the data significantly better than random walk models, indicating that parasites with different life cycles have different optimal times/sizes for host switching. The major helminth groups have often independently evolved similar life cycles, and we show that this has frequently led to convergent and/or parallel evolution of size and age at infectivity. This suggests that for particular life cycles there are universal optimal transmission strategies, applicable to widely divergent taxa, although the cases of parallelism might indicate that lineage-specific constraints sometimes prevent evolution to a single adaptive peak.

https://www.jstor.org/stable/pdfplus/41240819.pdf

Geoff A. Parker

Papers

The trophic vacuum and the evolution of complex life cycles in trophically transmitted helminths

Endless forms of sexual selection

Interference and the ideal free distribution: oviposition in a parasitoid wasp

Exploitation of the same trophic link favors convergence of larval life‐history strategies in complex life cycle helminths

Conflicts between and within the sexes in sexual selection: group report