Salinity tolerance in <Emphasis Type="Italic">Daphnia magna</Emphasis>: characteristics of genotypes hatching from mixed sediments |
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Authors: | Email author" target="_blank">Raquel?OrtellsEmail author Thorsten?B?H?Reusch Winfried?Lampert |
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Institution: | (1) Department of Physiological Ecology, Max Planck Institute of Limnology, Postfach 165, Plon, 24302, Germany;(2) Present address: Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, A.O. 2085, Valencia, 46071, Spain |
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Abstract: | The hatching of diapausing eggs is a means of temporal dispersal that can provide populations with genotypes adapted to different
environments. In a salinity-variable shallow lake, we predicted that the mixing of different age-classes of eggs in the sediment
may yield genotypes with different salinity optima. The alternative would be the absence of local adaptation and the presence
of a homogenous population of salt-tolerant genotypes with high phenotypic plasticity. We tested these alternatives by isolating
Daphnia magna resting eggs from different sediment depths, exposing them to hatching cues at different salinity levels and measuring the
performance of hatched individuals. Results revealed a homogeneous sediment with generally broad-tolerance genotypes and some
genotypes with low salt tolerance, which supports the second hypothesis. However, the disturbed character of the sediment
hampered historical reconstruction. The absence of local adaptation in the diapausing egg bank may be the result of various
scenarios in the response of D. magna populations to severe salinity changes in the lake. |
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Keywords: | Cladocerans Microsatellites Resting egg banks Shallow lakes Zooplankton |
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