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Joakim Svensson

MSc Student

I am doing my master thesis in the PACE Lab with Bo Ebenman as my supervisor. The first three years I studied in Norrköping on the Environmental Science Program which is a quite broad program based mainly on sustainable development. Since biology always has been one of my main interests I started at the master program "Ecology and the Environment" in 2009, aiming to be finished in spring 2011.

Master Thesis: Reintroducing captive bred species – the effects on ecological communities

Through history species has disappeared from their natural ranges due to anthropogenic activities, but for the last 100 years conservationists have reintroduced species to their historical natural habitat in an effort to “undo” the damages caused by mankind. The IUCN (1998) defines a reintroduction as; “An attempt to establish a species in an area which was once part of its historical range, but from which it has been extirpated or become extinct”. The loss of a single species can affect and change the structure of an entire ecosystem and its processes. So how do we know if the system has changed? Is there some way to predict how a system reacts to an extinction of a species, and then to its reintroduction? How do you know that the reintroduction is successful? The few concrete examples we get from nature today is in most cases not monitored and analyzed since there often is lack of funds in studying e.g. an extinction or a reintroduction after it has occurred. Hence science has turned to mathematical modeling of ecosystems through computer programs to get answers on how the dynamics in it can change.

This study aims to understand how an ecological food-web reacts when a species disappears from it and then later return to it from captivity. There are four different main types of scenarios that is the most probable outcome when reintroducing a species (these will be used as a response variable in the thesis):

I will model an ecological food web and take out species from different trophic levels (one level at a time), let the system stabilize itself and then return the species “modified” (changed attributes due to the time in captivity) to see what happens to the food web. Two different sized food webs (12 and 50 species) will be used to see if the size and complexity of the ecological community matters to a reintroduction.

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Last updated: 08/26/10