The relative influence of abundance and priority effects on colonization success in a coral-reef fish
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The sequence of species colonization is increasingly recognized as an important determinant of community structure, yet the significance of sequence of arrival relative to colonizer abundance is seldom assessed. We manipulated the magnitude and timing of coral-reef fish settlement to investigate whether the competitive dominance of early-arriving Ambon damselfish (i.e., a priority effect) decreased in strength with increasing abundance of late-arriving lemon damselfish. Sequence of arrival had a stronger effect on survival than the number of competing individuals. Relative to when both species arrived simultaneously, lemon damselfish were less aggressive, avoided competitive interactions more frequently and experienced depressed survival when they arrived later than Ambon damselfish, with these effects occurring independently of lemon damselfish abundance. These results suggest priority effects are more important than colonizer abundance and should motivate the integration of priority effects into future studies of density dependence to determine their relative importance.
KeywordsCompetition Coral-reef fish Damselfish Density dependence Pomacentrus Settlement
We would like to thank staff at the Lizard Island Research Station and B. Allan, C. Mirbach and C. Thompson for field assistance. Three anonymous reviewers provided many helpful comments on versions of this manuscript. This study was funded by the Ian Potter Foundation (D. E. Poulos) and an Australian Research Council Grant (M. I. McCormick). All applicable institutional and/or national guidelines for the care and use of animals were followed. Research was undertaken under the James Cook University Animal Ethics guidelines (Animal Ethics Approvals: A2080).
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