THE EFFECT OF COEXISTENCE ON COMPETITIVE OUTCOME IN TRIBOLIUM CASTANEUM AND TRIBOLIUM CONFUSUM

Area of Science:

• Ecology
• Evolutionary Biology
• Population Genetics

Background:

• Understanding interspecific competition is crucial for predicting species coexistence and community dynamics.
• The roles of prior coexistence and population differentiation in shaping competitive outcomes remain incompletely understood.

Purpose of the Study:

• To investigate how population differentiation and prior coexistence affect the competitive dynamics between two Tribolium flour beetle species.
• To determine if natural selection and genetic drift acting on populations influence competitive ability.

Main Methods:

• Populations of Tribolium castaneum and Tribolium confusum were initially reared in single-species, mixed-species, or standard laboratory conditions.
• Competitive outcomes were assessed in replicated mixed-species and single-species population trials.
• Measures included competitive success, time to extinction, and population census histories.

Main Results:

• Significant differentiation occurred among lineages for all measures of competitive outcome, including which species won, extinction timing, and population dynamics.
• High community-level heritabilities were observed for competitive outcomes, suggesting rapid evolution of competitive ability via group selection.
• Prior coexistence did not systematically alter the competitive outcome between the two species.

Conclusions:

• Population differentiation, driven by natural selection and genetic drift, plays a substantial role in determining competitive outcomes.
• Group or community-level selection can rapidly drive the evolution of competitive traits.
• The history of coexistence does not appear to be a primary factor influencing the outcome of competition in this system.