Does within‐population variation in egg size reduce intraspecific competition in Atlantic Salmon, Salmo salar?

• Published in: Functional Ecology
• Main Authors: Einum, S., Fleming, I. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2004
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1111/j.1365-2435.2004.00824.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2435.2004.00824.x; https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2435.2004.00824.x

Summary If phenotypes differ in habitat preferences there may be a decrease in intraspecific competition with increasing phenotypic variation, causing heterogeneous populations to perform better than homogeneous ones. Furthermore, if the relative performance of different phenotypes depends on environmental conditions, population heterogeneity may buffer populations against temporal environmental variation. Here these hypotheses are tested using 10 experimental populations of juvenile Atlantic Salmon ( Salmo salar L.) reared across a range of five different water discharges. Each population consisted of fish of identical parental origins to control for genetic differences among populations, but differed in body size heterogeneity owing to differences in egg size distributions. No effect of population heterogeneity on final body size or dispersal rates was detected. Thus, egg size heterogeneity does not appear to influence the average level of intraspecific competition in Atlantic Salmon. There was a strong positive effect of water discharge on body size, but no effects of phenotypic heterogeneity on variation in final body size among discharge levels. Thus, the relative growth performance of juveniles arising from different egg sizes may not change sufficiently with environmental changes for egg size variation to create a strong buffering effect against year‐to‐year variation in environmental conditions.