Cheating (biology)
If individuals who cheat are able to gain survivorship and reproductive benefits while incurring no costs, natural selection should favor cheaters.
[7] Thus, cheaters can persist in a population because their exploitative behavior gives them an advantage when they exist at low frequencies but these benefits are diminished when they are greater in number.
One study shows that a small influx of immigrants with a tendency to cooperate less can generate enough genetic variability to stabilize selection for mutualism.
Models that provide insight on cheating include the social amoeba Dictyostelium discoideum;[10][11][12] eusocial insects, such as ants, bees, and wasps;[13] and inter-specific interactions found in cleaning mutualisms.
This species of amoeba is most commonly found in a haploid, single-celled state that feeds independently and undergoes asexual reproduction.
This makes chimeric aggregates of Dictyostelium discoideum susceptible to cheating individuals that take advantage of the reproductive behavior without paying the fair price.
In other words, if certain individuals tend to become a part of the sorus more frequently, they can gain increased benefit from the fruiting body system without sacrificing their own opportunities to reproduce.
Having a 34Mb genome that is completely sequenced and well annotated makes D. discoideum a useful model in studying the genetic bases and molecular mechanisms of cheating, and in a broader sense, social evolution.
Eusocial insects behave cooperatively, where members of the community forgo reproduction to assist a few individuals to reproduce.
[13] If workers sought to pass their own genes by laying eggs, foraging activities would diminish, leading to decreased resources for the entire colony.
This, in turn, can cause a tragedy of the commons,[18] where selfish behavior lead to the depletion of resources, with long-term negative consequences for the group.
However, in natural bee and wasp societies, only 0.01–0.1% and 1%, respectively, of the workers lay eggs, suggesting that strategies exist to combat cheating to prevent tragedy of the commons.
In some ant species and yellowjackets, policing may occur via aggression towards or killing egg-laying individuals to minimize cheating.
[13] Cleaning symbiosis that develop between small and larger marine organisms often represent models useful for studying the evolution of stable social interactions and cheating.
[15][16][17] Studies on cleaning mutualisms generally suggest that cheating behavior is often adjusted depending on the species of the client.
[16] Studies have found that cleaner species can strategically adjust cheating behavior according to the potential associated risk.
[16][17] Some evidence suggest that physiological processes can mediate the cleaners' decision to switch from cooperating to cheating in mutualistic interactions.
In this instance, the males can gain access to females without having to defend territories or acquiring additional resources (which often serve as the basis for attractiveness).
[19] Models such as this provide valuable tools for research aimed at energetic constraints and environmental cues involved in cheating.
Studies find that mating strategies are highly adaptable and depend on a variety of factors, such as competitiveness, energetic costs involved in defending territory or acquiring resources.
Under low-iron conditions, P. fluorescens produces siderophores, specifically pyoverdine, to retrieve the iron necessary for survival.
One study showed that when P. fluorescens grew in association with Streptomyces ambofaciens, another bacterium that produces the siderophore coelichelin, no pyoverdine was detected.
In a study by Dandekar et al., the researchers examined the survival rates of cheating and non-cheating bacteria populations (Pseudomonas aeruginosa) under varying environmental conditions.
[24] These microorganisms, like many species of bacteria, use a cell-cell communication system called quorum sensing that detect their population density and prompt the transcription of various resources when needed.
The problem arises when some individuals ("cheaters") do not respond to these quorum sensing signals and therefore do not contribute to the costly protease production yet enjoy the benefits of the broken down resources.
When P. aeruginosa populations are placed into growth conditions where cooperation (and responding to the quorum signal) is costly, the number of cheaters increases, and the public resources are depleted, which can lead to a tragedy of the commons.
Further studies revealed that in a lab setting, the cleaner fish undergoes behavioral change in face of deterrents against eating their preferential food.
[33] In several trials, the plate of their preferential food source was immediately removed when they eat it, to mimic "client fleeing" in natural settings.
In a series of experiments, researchers forced non-cooperation between the bacteria and the plants by placing various nodules in nitrogen-free atmosphere.
[35] West et al. created a model for legume sanctioning the bacteria and hypothesizes that these behaviors exist to stabilize mutualistic interactions.
