Measuring competition coefficients in an ant community: Implications for intraspecific adaptation load

Area of Science:

• Community Ecology
• Behavioral Ecology
• Evolutionary Biology

Background:

• Stable species coexistence despite resource competition is a key ecological question.
• Ant communities exhibit complex coexistence patterns, challenging ecological theories.
• Measuring interspecific and intraspecific competition in ants is difficult due to their life history.

Purpose of the Study:

• To rigorously measure competition coefficients in ants using non-invasive field methods.
• To investigate the role of intraspecific competition and aggression in ant community structure.
• To test the predictions of the intraspecific adaptation load theory.

Main Methods:

• Non-invasive mark-recapture of Diacamma cf. indicum colonies.
• Baiting experiments and stable isotope analysis to assess food niche overlap.
• Population dynamic and inclusive fitness modeling to estimate competition coefficients and aggression impacts.

Main Results:

• Intraspecific competition was significantly stronger than interspecific competition for Diacamma.
• Diacamma worker survival was negatively correlated with conspecific colony density, indicating interference competition.
• Aggression towards conspecifics, not heterospecifics, was observed, supporting the intraspecific adaptation load theory.

Conclusions:

• Intraspecific competition, intensified by density-dependent aggression, suppresses dominant species, facilitating coexistence.
• The intraspecific adaptation load theory provides a framework for understanding how adaptation and population dynamics shape communities.
• Behavioral adaptations like territorial aggression play a crucial role in structuring ant communities and promoting species coexistence.