| Popis: |
Hybridizing species of the Daphnia longispina complex are key taxa in plankton communities of many European lakes. In several of these lakes, it has been documented that the taxonomic structure of the complex during the 20th century has substantially changed following human-mediated environmental changes, particularly eutrophication and re-oligotrophication and fish stock changes. We characterize these changes in Lago Maggiore (Italy/Switzerland), a southern pre-alpine lake, which also passed through the human-mediated environmental changes. Lago Maggiore is one of best and longest studied European lakes so a large number of historical Daphnia samples from regular monitoring are available. Because local Daphnia do not form dormant egg banks suitable for genetic analysis (being able to overwinter in the water column), we used a combination of morphology and geometric morphometrics (elliptic Fourier analysis) to evaluate the taxonomic and phenotypic changes in the Daphnia longispina complex in Lago Maggiore since the mid-20th century (1948-2012), and attampted to characterize the impact of environmental changes over the respective period on Daphnia body shape and size. Examination of Daphnia phenotype indicates indeed the prevailing presence of D. longispina (hyalina morph) in the 1940s, dominance of... |
