Genetic variation and phenotypic plasticity causes of morphological variation in Eurasian perch

Question: What is the importance of genetic variation and phenotypic plasticity in formingthe morphological difference between littoral and pelagic perch?Organism: Juveniles of Eurasian perch (Perca fluviatilis L.).Site: Enclosures (2 × 2 m) in a pond, Röbäcksdalen, Umeå, Sweden.Methods: Adults from the littoral and pelagic habitats were bred separately andtheir offspring were raised in enclosures with either open water or vegetation in an artificialpond.Results: Offspring from littoral parents had a higher proportion of littoral prey types in theirdiet than pelagic offspring even though there were no differences in prey community betweentreatments. Littoral offspring had a deeper body than pelagic offspring raised in the sameenvironment. However, most of the phenotypic variation in this experiment was explained byphenotypic plasticity: offspring from both parental types raised in open water displayedpelagic-type characteristics, whereas offspring raised in vegetation displayed littoral-typecharacteristics.Conclusion: Previous long-term studies on perch show that they experience a fluctuatingenvironment due to population dynamics. The plasticity in perch could therefore be importantas fluctuating environments favour plasticity.