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Daphnia : Model Herbivore, Predator and Prey by Lampert

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cynthia breuer

on 29 October 2013

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Transcript of Daphnia : Model Herbivore, Predator and Prey by Lampert

Daphnia :
Model Herbivore,
Predator and Prey

by Winfried Lampert

Properties making Daphnia suitable as a model organism
transparent --> inner organs are visible
carry eggs in brood pouch --> easy calculation of life history and population dynamic parameters
good size 0,03-5mm --> micro- and mesocosm
Properties making Daphnia suitable as a model organism
geographically widespread --> studies of dispersal and phylography
fast reproduction with direct development --> production of large populations and quick respondance to environmental changes
easy to culture
Properties making Daphnia suitable as a model organism
presented by Cynthia Breuer
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Branchiopoda
Order: Cladocera
Family: Daphniidae
Genus: Daphnia

Scientific Classification
mostly parthenogenetical reproduction --> study of clones
cyclic parthenogens --> study of sexual and asexual reproduction
phenogenetic and genotypic variabiltiy and their phylogeny are well described
Properties making Daphnia suitable as a model organism
central position in aquatic food web --> interactions between trophic levels --> makes them ideal objects to study adaption

accessible for mathematical modelling --> well studied
Daphnia as a model
A Physiological Model
physiological studies build a complete energy budget of zooplankton, serves as a model of ecosystem function--> energy budget models --> sophisticated mathematical models describing growth process, reproduction and survival
fast response to environmental factors
food and reproduction are coupled --> strong correlation between the juvenile growth rate and the instantaneous rate of population growth, often used as a proxy for fitness
A Model Herbivore
model filter feeder
availability of radioactively labelled algae and bacteria as food tracers

biochemical composition affects Daphnia
filters a broad range of paricle sizes

impact on seasonal events in phytoplancton of temperate lakes
--> model for intra- and interspecific competetion

size efficiency hypothesis --> model for herbivore competeive ineraction (large Daphnia have a lower threshold concentration
A Model Predator
they feed on all particles of appropriate size
swallow plants completely without letting them regenerate
plants use defence strategies
eg. colony formation of Scenedesmus in response to kairomone
model of top-down effects in microbial food webs --> Daphnia= small individual bacterial cells, no Daphnia= filaments and aggregates
A Model Prey
relatively large size range --> makes Daphnia vunerable
fish: conspiciuous prey eg adult Daphnia
fish larvae and invertebrates: gap-limited eg juvenile Daphnia
--> conflict to establish defence strategies, changing predator pressure

--> Daphnias respond to kairomone
Chaoborus kairomone: grow faster
fish kairomone: fosters reproduction
Other strategies: helmets, crests, tail pines neck teeth

Thanks for your attention!
Any questions left?
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