Model Systems

The three-spined stickleback

Gasterosteus aculeatus

The three-spined stickleback is an all-round talent when it comes to being a research model: speciation, parasitology, behavioral ecology – stickles have

helped us in understanding many biological processes and are one of the most common model systems in evolutionary biology.

Its well described parasite fauna and ability to rapidly adapt to different ecological niches make it the perfect model species for investigating feedbacks between host-parasite interactions and host speciation.

Here are some of the many cool parasites you can find on three-spined sticklebacks:

Many thanks to Martin Kalbe for teaching me to identify these and helping with many of the pictures as well.

Daphnia magna


Crustaceans of the Daphnia genus are popular model organisms because they reproduce clonally most of the time, meaning that offspring are genetically identical to their parents. This allows for the separate study of genetic effects and non-genetic effects (phenotypic plasticity, epigenetics). In addition, Daphnia have a fast life cycle (from being born to having their first offspring in about 10 days at 21°C). This makes them amenable for transgenerational studies and general questions that involve life history evolution. What separates D. magna from other laboratory models is the vast knowledge that is available on its natural history and ecological impact. It is a ‘keystone species’ in  freshwater ecosystems, making it altogether an ideal study species for ecosystem level experiments.

Some examples showing Daphnia experiments from the individual level (in marmalade jars) over population level (small water tanks) to the ecosystem level (mesocosms):