Curriculum Vitae
I studied biology at the University of Bremen, Germany, and the University of Otago, New Zealand and graduated in 2006 with specializations in ecology, zoology and marine biology. For my German Diploma thesis I run a field experiment ‘effects of root herbivory on the attraction of aboveground insects on Brassica nigra plants’. This fieldwork was based at the NIOO Centre for Terrestrial Ecology, workgroup Multitrophic Interactions. After my graduation and a short employment as research assistant at the NIOO I worked as a freelancer for the Northwest Nature Trust. Besides conceptual work on the Water Framework Directive and Natura 2000 projects I collected avifaunistic data in the nature reserve Borgfelder Wuemmewiesen. In January 2008 I started as a PhD student at the Animal Population Biology department. The project is part of the NWO-VICI grant of Marcel Visser: ‘Adapting to a warmer world: phenology, physiology and fitness.’
Projects
The mechanism underlying plasticity: photoperiod and temperature as cues
I am interested in the effects of a changing climatic environment on bird physiology and behaviour. More precisely, I am looking at how great tits regulate cycles of reproduction and plumage moult by environmental factors.
Two aspects make timing a challenge for great tits: laying of eggs is the outcome of a chain of physiological processes that start in winter with gonadal development, so reproduction is initiated weeks before the peak of food abundance that is essential for feeding their nestlings.
Furthermore, there is extensive year-to-year variation in the timing of food availability. What matters is not to be on time in just a single year but to respond adaptively to between-year variation. That is, timing has to be ‘phenotypically plastic’.
Animals use cues in early spring, such as photoperiod and temperature, which predict the later phenology of their food. These cues may play a role over a period of several months and it is likely that different cues play a role in different processes in the physiological chain.
To identify what allows birds to regulate the crucial timing of reproduction I set up experiments in our 36 climatized aviaries, where I can control photoperiod and temperature for every pair of great tits individually. As the endocrine system provides a mechanism by which animals can respond to environmental changes, I investigate the hormonal changes that take place over the course of the year. Besides breeding, I also record song activity and moulting. To assess the genetic component of variation in the sensitivity to cues I use genetically related birds from our long-term population in the Hoge Veluwe National Park, which are hand-raised in our facilities.
In spring I also record nestbox temperatures in our wild population, as well as ambient temperatures in different habitats, to examine if birds prefer to breed in a warmer or colder environment. This could be linked to energy requirements or the abundance of invertebrate prey.
Links
Marcel Visser’s personal webpage
Luc te Marvelde’s personal webpage
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