An evolutionary dynamics model adapted to eusocial insects.
Bottom Line: This study aims to better understand the evolutionary processes allowing species coexistence in eusocial insect communities.The interactions of colonies at the ecological timescale drive the evolution of strategies at the evolutionary timescale by natural selection.Our results illustrate that asymmetric competition underpins diversity in ant communities.
Affiliation: Université de Lyon, Lyon, France.
This study aims to better understand the evolutionary processes allowing species coexistence in eusocial insect communities. We develop a mathematical model that applies adaptive dynamics theory to the evolutionary dynamics of eusocial insects, focusing on the colony as the unit of selection. The model links long-term evolutionary processes to ecological interactions among colonies and seasonal worker production within the colony. Colony population dynamics is defined by both worker production and colony reproduction. Random mutations occur in strategies, and mutant colonies enter the community. The interactions of colonies at the ecological timescale drive the evolution of strategies at the evolutionary timescale by natural selection. This model is used to study two specific traits in ants: worker body size and the degree of collective foraging. For both traits, trade-offs in competitive ability and other fitness components allows to determine conditions in which selection becomes disruptive. Our results illustrate that asymmetric competition underpins diversity in ant communities.
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Mentions: The structure of the evolutionary isoclines allows us to determine the dynamics of the two strategies after the branching event. According to the arrows indicating the direction of evolution (Fig. 4.a), one of the strategies increases while the other decreases. The evolutionary isocline towards which the two strategies evolve loses its evolutionary stability (, in Fig. 4.a), thereby causing a second branching event. The community then reaches a higher degree of polymorphism.