On the Evolution of Harming and Recognition in Finite Panmictic and Infinite Structured Populations

Abstract

Natural selection may favor two very different types of social behaviors that have costs in vital rates (fecundity and/or survival)to the actor: helping behaviors, which increase the vital rates of recipients, and harming behaviors, which reduce the vital rates of recipients. Although social evolutionary theory has mainly dealt with helping behaviors, competition for limited resources creates ecological conditions in which an actor may benefit from expressing behaviors that reduce the vital rates of neighbors. This may occur if the reduction in vital rates decreases the intensity of competition experienced by the actor or that experiencedby its offspring. Here, we explore the joint evolution of neutral recognition markers and marker-based costly conditional harming whereby actors express harming, conditional on actor and recipient bearing different conspicuous markers. We do so for two complementary demographic scenarios: finite panmictic and infinite structured populations. We find that marker-based conditional harming can evolve under a large range of recombination rates and group sizes under both finite panmictic and infinite structured populations. A direct comparison with results for the evolution of marker-based conditional helping reveals that, if everything else is equal, marker-based conditional harming is often more likely to evolve than marker-based conditional helping. K E Y W O R D S :Competition, fixation probabilities, genetic diversity, genetic relationship, harming, helping, marker recognition, spite, two-locus models.Helping behaviors, by which individuals in a population provide fitness benefits to others, are more likely to evolve in the presence of mechanisms that allow discrimination against defectors (Hamilton 1964; Hamilton 1971;Axelrod and Hamilton 1981;Eshel and Cavalli-Sforza 1982). Discrimination may occur if helpers can recognize each other by using conspicuous phenotypic cues, tags, or markers, and provide benefits to other individuals carrying the gene(s) underlying helping, instead of providing benefits to defectors. Both genetic kin-recognition and the so-called green-beard mechanism may involve the expression of helping conditional on actor and recipient bearing identical recognition markers (Hamilton 1964;Dawkins 1982;Grafen 1990). Such conditional helping relies on a tight linkage between the genes underlying helping and those producing the conspicuous markers. If genes for helping and markers were loosely coupled, defectors could acquire the markers expressed by helpers and then receive the benefits of helping without paying the cost. This would ultimately prevent the evolution of marker-based conditional helping.Genetic kin-recognition based on actor and recipient bearing identical marker alleles might evolve in spatially structured populations (Axelrod et al. 2004;Jansen and van Baalen 2006;Rousset and Roze 2007). Two individuals from the same group (or spatial location) are more likely to have inherited both helping and recognition marker alleles from the same recent commo...

Evolutionary dynamics ofn-player games played by relatives

“…One of the mechanisms of such assortment is via kin recognition [45,46,73], where individuals discriminate others by using genetic or phenotypic markers. Understanding the interplay between social interaction and kin recognition is important, and extending the current model in such a direction should further enrich our understanding of social evolution based on nepotism.…”

The evolution of fairness through spite

“…Negative assortment generated from small populations in this way, or by other external ecological factors, fits well in our model with a constant r 2 . However, other mechanisms of negative assortment, such as conditional behaviour or partner choice, can be frequency-dependent or may themselves evolve over time [33,37]. How to extend our model to capture these nuanced mechanisms, and explore the evolutionary dynamics when negative assortment coevolves with spiteful behaviour, are open questions for future research.…”

“…There are a number of mechanisms that can generate positive or negative assortment of strategies: spatial structure [29,30], population structure [31] and conditional strategies based on kinship [13], greenbeards [32] or co-evolving neutral markers [33]. Finite population size also generates some degree of negative assortment [34,35].…”

Evolution and the classification of social behavior

“…However, in both cases, it is also possible for defection to evolve and the prospects for cooperation depend on the specific conditions and parameters of the model. Lehmann et al (2009) provide an another example. They investigate the coevolution of conditional helping and harming behavior with neutral markers using two-locus population genetics, allowing the interaction 13 It is important to note that this contrast between interaction type and interaction structure may collapse at higher levels of abstraction.…”