Effects of competition on fitness-related traits
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While interspecific competition is prevalent in natural systems, we do not yet understand how it can influence an individual’s phenotype within its lifetime and how this might affect performance. Morphology and swimming performance are two important fitness-related traits in fishes. Both traits are essential in acquiring and defending resources as well as avoiding predation. Here, we examined if interspecific competition could induce changes in morphology and affect the swimming performance of two strains of juvenile Atlantic salmon (Salmo salar). We imposed competitive scenarios on the fish using artificial streams containing different combinations of four interspecific competitors. Exposure to interspecific competitors induced morphological changes over time, through the development of deeper bodies, whereas controls free of interspecific competitors developed more fusiform body shapes. Furthermore, swimming performance was correlated to fusiform morphologies and was weaker for Atlantic salmon in competitive scenarios vs. controls. This implies that interspecific competition has direct effects on these fitness-related traits in Atlantic salmon. To the best of our knowledge, this is the first time that morphology, an important fitness-related trait linked to swimming performance, has been shown to be negatively impacted through interactions with an interspecific competitor.
KeywordsInterspecific competition Geometric morphometrics Swimming performance Atlantic salmon Salmo salar
We would like to thank Chris Wilson, Bill Sloan, and Scott Ferguson from the OMNR. We would also like to thank Hassen Allegue, Marie-Christine Bellemare, and Marie-Hélène Greffard for their assistance in the experiment. This work was supported by a Fonds nature et technologie du Québec (FQRNT) award to ADS and a Natural Sciences and Engineering Research Council of Canada (NSERC-Strategic) award to BDN and PRPN.
Author contribution statement
ADS carried out the data acquisition, data analysis, participated in the design of the study, and drafted the manuscript; ALSH participated in data acquisition and participated in the design of the study; BDN and PRPN both conceived and participated in the design of the study. All authors gave the final approval for publication.
Compliance with ethical standards
Conflict of interest
We have no competing interests.
This study was approved by Université du Québec à Montréal’s ethics committee.
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