Competition-colonization trade-offs in a ciliate model community

Area of Science:

• Ecology
• Microbiology
• Evolutionary Biology

Background:

• Species coexistence is often explained by a competition-colonization (CC) trade-off.
• Empirical evidence for the CC trade-off's role in species coexistence remains mixed.
• Benthic ciliate communities provide a model for studying ecological trade-offs.

Purpose of the Study:

• To investigate the presence and importance of a CC trade-off in a microcosm experiment with six benthic ciliate species.
• To differentiate between dispersal and growth rates as components of colonization ability.
• To determine if competitive and colonization abilities are correlated in this community.

Main Methods:

• Microcosm experiment with six benthic ciliate species.
• Measured colonization time, dispersal rates, and growth rates.
• Assessed competitive ability through pairwise growth comparisons with and without competitors.

Main Results:

• Species exhibited significant variation in colonization abilities, influenced by dispersal and growth rates.
• A clear competitive hierarchy was observed, but competitive and colonization abilities were uncorrelated.
• The strongest competitor was an intermediate colonizer; weakest competitors were weakest colonizers.
• Some inferior competitors showed higher colonization abilities than the strongest competitor.

Conclusions:

• A community-wide CC trade-off was absent in this ciliate community.
• Coexistence for a subset of species may be facilitated by a CC trade-off.
• Temporal effects and differential resource use may serve as alternative coexistence mechanisms for poor competitors and slow colonizers.