37 Result(s)
within
Life Sciences
Piet Spaak
Article
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Article
Cyclomorphosis as a factor explaining success of a Daphnia hybrid in Tjeukemeer
Recent studies have shown that Daphnia hybrids are intermediate to their parental species for several life history traits, and that they combine advantageous traits of the parental species, thereby decreasing the...
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Article
Sexual reproduction in Daphnia: interspecific differences in a hybrid species complex
To investigate whether reproductive variation in the Daphnia galeata-cucullata-hyalina hybrid species complex can explain the occurrence of hybrids and backcrosses, a total of 43 clones from three north German la...
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Article
Tail spine length in the Daphnia galeata complex: costs and benefits of induction by fish
We studied the combined effect of fish kairomones and food conditions on the relative tail spine length (RTL) of five Daphnia taxa, and the interaction of these factors with the vertical distribution of the da...
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Preface; Cladocera: the Biology of Model Organism
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Article
Hybridization in the Daphnia galeata complex: are hybrids locally produced?
Within the species complex of Daphnia galeata,D. cucullata and D. hyalina variouscombinations of hybrids and parental taxa occur inlakes throughout Europe. Since daphnids are cyclicparthenogens and mostly repr...
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Article
Differential behaviour and shifts in genotype composition during the beginning of a seasonal period of diel vertical migration
During the first few weeks of a recurring seasonalperiod of diel vertical migration in Lake Maarsseveen(The Netherlands), part of the hybrid Daphniagaleata × hyalina population migrated, whileanother part rema...
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Article
Genetic markers, genealogies and biogeographic patterns in the cladocera
Cladoceran crustaceans are an important component of zooplankton in a wide range of freshwater habitats. Although the ecological characteristics of several cladoceran species have been well studied, biogeograp...
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Does trimethylamine induce life-history reactions in Daphnia?
Laboratory experiments were carried out to investigate life-history reactions of Daphnia to trimethylamine (TMA), a substance, which has recently been found to induce a similar phototactic reaction in Daphnia as ...
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Article
Carbon as an indicator of Daphnia condition in an alpine lake
Carbon–length relationships can be used to indicate the condition of daphnids in natural situations. We examined the Daphnia galeata population of an alpine lake (Oberer, Arosasee, Switzerland), where most indivi...
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The influence of fish kairomones on the induction and vertical distribution of sexual individuals of the Daphnia galeata species complex
To assess the potential production of hybrids and backcrosses in a semi-natural environment, we studied the combined effect of fish kairomone, and food level on the production of males and ephippial females in...
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Article
Chemically induced anti-predator defences in plankton: a review
Planktonic organisms exhibit diverse morphological, behavioural and life-history responses to the chemical presence of potential predators. Prey organisms have been found to sense such predators via predator-d...
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Article
No Evidence for Adaptive Micro-Evolution to a Decrease in Phosphorus-Loading of a Daphnia Population Inhabiting A Pre-Alpine Lake
Many polluted lakes in Europe are being restored and phosphorus concentrations have dropped dramatically in these lakes. We studied the genetic structure of Daphnia galeata over the past 30 years in Lake Greifens...
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Amplified Fragment Length Polymorphism (AFLP) Reveals Species-Specific Markers in the Daphnia Galeata–HyalinaSpecies Complex
Daphnia often occur in species complexes that consist of two or more co-occurring species and their hybrids. Hybrid individuals are often capable of sexual reproduction and so backcrossing with introgression occ...
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Article
Hatching with the enemy: Daphnia diapausing eggs hatch in the presence of fish kairomones
Infochemicals are known to play a key role in mediating predator-prey interactions, both in aquatic and terrestrial communities. However, state-dependent variation may exist in how effectively individuals can ...
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Article
Macroinvertebrate diversity in fragmented Alpine streams: implications for freshwater conservation
Lakes and reservoirs disrupt the longitudinal connectivity of streams, considerably affecting benthic macroinvertebrate assemblages and diversity. Changes in assemblage composition within fragments can result ...
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Article
Temporary collapse of the Daphnia population in turbid and ultra-oligotrophic Lake Brienz
The cyclical parthenogen Daphnia is a key species in aquatic food webs. Its abundance is influenced by environmental factors like food quantity and quality, predation, diseases, temperature and washout by dischar...
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Article
Epidemiology of a Daphnia brood parasite and its implications on host life-history traits
Parasites influence host life-history traits and therefore might crucially shape host populations in natural systems. In a series of laboratory experiments, we studied the impact of an oomycete brood parasite ...
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Preface
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Article
Starving with a full gut? Effect of suspended particles on the fitness of Daphnia hyalina
Suspended particles are abiotic factors that can affect the abundance of cladocerans such as daphnids. Ultra-oligotrophic Lake Brienz, situated in the front ranges of the Swiss Alps, is dominated by two major ...
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Article
Intra-specific rDNA-ITS restriction site variation and an improved protocol to distinguish species and hybrids in the Daphnia longispina complex
A collaborative research effort was undertaken to evaluate the robustness of a recently developed genetic tool for species identification of members in the morphologically variable Daphnia longispina species comp...
