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Rapid evolution of cooperation in group-living animals.

Franz M, Schülke O, Ostner J - BMC Evol. Biol. (2013)

Bottom Line: In contrast, at low frequencies of cooperators rapid evolutionary dynamics lead to a decrease in assortment, which acts against the evolution of cooperation.Rapid evolutionary dynamics can emerge in this case because sufficiently strong selective pressures allow evolutionary and demographic dynamics, and consequently also feedback between assortment and evolution, to occur on the same timescale.In particular, emerging positive frequency-dependent selection could be an important explanation for differences in cooperative behaviors among different species with similar population structures such as humans and chimpanzees.

View Article: PubMed Central - HTML - PubMed

Affiliation: Courant Research Center Evolution of Social Behavior, University of Göttingen, Kellnerweg 6, Göttingen 37077, Germany. mathias.franz@duke.edu.

ABSTRACT

Background: It is often assumed that evolution takes place on very large timescales. Countering this assumption, rapid evolutionary dynamics are increasingly documented in biological systems, e.g. in the context of predator-prey interactions, species coexistence and invasion. It has also been shown that rapid evolution can facilitate the evolution of cooperation. In this context often evolutionary dynamics influence population dynamics, but in spatial models rapid evolutionary dynamics also emerge with constant population sizes. Currently it is not clear how well these spatial models apply to species in which individuals are not embedded in fixed spatial structures. To address this issue we employ an agent-based model of group living individuals. We investigate how positive assortment between cooperators and defectors and pay-off differences between cooperators and defectors depend on the occurrence of evolutionary dynamics.

Results: We find that positive assortment and pay-off differences between cooperators and defectors differ when comparing scenarios with and without selection, which indicates that rapid evolutionary dynamics are occurring in the selection scenarios. Specifically, rapid evolution occurs because changes in positive assortment feed back on evolutionary dynamics, which crucially impacts the evolution of cooperation. At high frequencies of cooperators these feedback dynamics increase positive assortment facilitating the evolution of cooperation. In contrast, at low frequencies of cooperators rapid evolutionary dynamics lead to a decrease in assortment, which acts against the evolution of cooperation. The contrasting dynamics at low and high frequencies of cooperators create positive frequency-dependent selection.

Conclusions: Rapid evolutionary dynamics can influence the evolution of cooperation in group-living species and lead to positive frequency-dependent selection even if population size and maximum group-size are not affected by evolutionary dynamics. Rapid evolutionary dynamics can emerge in this case because sufficiently strong selective pressures allow evolutionary and demographic dynamics, and consequently also feedback between assortment and evolution, to occur on the same timescale. In particular, emerging positive frequency-dependent selection could be an important explanation for differences in cooperative behaviors among different species with similar population structures such as humans and chimpanzees.

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Differences of mean pay-offs of cooperators and defectors and assortment in the sexual reproduction model. (a, c) In blue areas cooperators receive greater average pay-offs and in red areas defectors receive greater average pay-offs. (b, d) Blue areas indicate high positive assortment and red values indicate low positive assortment cooperators. (a, b) Scenario without selection (s = 0). (c, d) Scenarios with selection (s = 0.5). Note that results are shown only for cost-benefit ratios up to 0.6.
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Figure 8: Differences of mean pay-offs of cooperators and defectors and assortment in the sexual reproduction model. (a, c) In blue areas cooperators receive greater average pay-offs and in red areas defectors receive greater average pay-offs. (b, d) Blue areas indicate high positive assortment and red values indicate low positive assortment cooperators. (a, b) Scenario without selection (s = 0). (c, d) Scenarios with selection (s = 0.5). Note that results are shown only for cost-benefit ratios up to 0.6.

Mentions: Analysis of the sexual reproduction model revealed similar results to those found in the asexual model (Figure 8). However, in the sexual reproduction model a much broader adaptive valley emerged. This happened because reproduction is directly connected to male migration. At low frequencies of cooperators most males carry one or two defector alleles. In this case, males introduce defector alleles into cooperator groups, which increases mixing of cooperator and defectors. Thus, compared to the asexual model it is much more difficult to maintain groups with many cooperators when the frequency of cooperators is low. The situation is very different at high frequencies of cooperators when males are more likely to carry cooperator alleles. In this case, it is less likely that males introduce defector alleles into cooperator groups. This makes it more likely that these groups grow and fission, which leads to an elevated level of positive assortment.


Rapid evolution of cooperation in group-living animals.

Franz M, Schülke O, Ostner J - BMC Evol. Biol. (2013)

Differences of mean pay-offs of cooperators and defectors and assortment in the sexual reproduction model. (a, c) In blue areas cooperators receive greater average pay-offs and in red areas defectors receive greater average pay-offs. (b, d) Blue areas indicate high positive assortment and red values indicate low positive assortment cooperators. (a, b) Scenario without selection (s = 0). (c, d) Scenarios with selection (s = 0.5). Note that results are shown only for cost-benefit ratios up to 0.6.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231370&req=5

Figure 8: Differences of mean pay-offs of cooperators and defectors and assortment in the sexual reproduction model. (a, c) In blue areas cooperators receive greater average pay-offs and in red areas defectors receive greater average pay-offs. (b, d) Blue areas indicate high positive assortment and red values indicate low positive assortment cooperators. (a, b) Scenario without selection (s = 0). (c, d) Scenarios with selection (s = 0.5). Note that results are shown only for cost-benefit ratios up to 0.6.
Mentions: Analysis of the sexual reproduction model revealed similar results to those found in the asexual model (Figure 8). However, in the sexual reproduction model a much broader adaptive valley emerged. This happened because reproduction is directly connected to male migration. At low frequencies of cooperators most males carry one or two defector alleles. In this case, males introduce defector alleles into cooperator groups, which increases mixing of cooperator and defectors. Thus, compared to the asexual model it is much more difficult to maintain groups with many cooperators when the frequency of cooperators is low. The situation is very different at high frequencies of cooperators when males are more likely to carry cooperator alleles. In this case, it is less likely that males introduce defector alleles into cooperator groups. This makes it more likely that these groups grow and fission, which leads to an elevated level of positive assortment.

Bottom Line: In contrast, at low frequencies of cooperators rapid evolutionary dynamics lead to a decrease in assortment, which acts against the evolution of cooperation.Rapid evolutionary dynamics can emerge in this case because sufficiently strong selective pressures allow evolutionary and demographic dynamics, and consequently also feedback between assortment and evolution, to occur on the same timescale.In particular, emerging positive frequency-dependent selection could be an important explanation for differences in cooperative behaviors among different species with similar population structures such as humans and chimpanzees.

View Article: PubMed Central - HTML - PubMed

Affiliation: Courant Research Center Evolution of Social Behavior, University of Göttingen, Kellnerweg 6, Göttingen 37077, Germany. mathias.franz@duke.edu.

ABSTRACT

Background: It is often assumed that evolution takes place on very large timescales. Countering this assumption, rapid evolutionary dynamics are increasingly documented in biological systems, e.g. in the context of predator-prey interactions, species coexistence and invasion. It has also been shown that rapid evolution can facilitate the evolution of cooperation. In this context often evolutionary dynamics influence population dynamics, but in spatial models rapid evolutionary dynamics also emerge with constant population sizes. Currently it is not clear how well these spatial models apply to species in which individuals are not embedded in fixed spatial structures. To address this issue we employ an agent-based model of group living individuals. We investigate how positive assortment between cooperators and defectors and pay-off differences between cooperators and defectors depend on the occurrence of evolutionary dynamics.

Results: We find that positive assortment and pay-off differences between cooperators and defectors differ when comparing scenarios with and without selection, which indicates that rapid evolutionary dynamics are occurring in the selection scenarios. Specifically, rapid evolution occurs because changes in positive assortment feed back on evolutionary dynamics, which crucially impacts the evolution of cooperation. At high frequencies of cooperators these feedback dynamics increase positive assortment facilitating the evolution of cooperation. In contrast, at low frequencies of cooperators rapid evolutionary dynamics lead to a decrease in assortment, which acts against the evolution of cooperation. The contrasting dynamics at low and high frequencies of cooperators create positive frequency-dependent selection.

Conclusions: Rapid evolutionary dynamics can influence the evolution of cooperation in group-living species and lead to positive frequency-dependent selection even if population size and maximum group-size are not affected by evolutionary dynamics. Rapid evolutionary dynamics can emerge in this case because sufficiently strong selective pressures allow evolutionary and demographic dynamics, and consequently also feedback between assortment and evolution, to occur on the same timescale. In particular, emerging positive frequency-dependent selection could be an important explanation for differences in cooperative behaviors among different species with similar population structures such as humans and chimpanzees.

Show MeSH
Related in: MedlinePlus