PhD ceremony Ms. C. Burger: Local adaptation or dispersal? How pied flycatchers cope with climate change

PhD ceremony: Ms. C. Burger

Dissertation: Local adaptation or dispersal? How pied flycatchers cope with climate change

Promotor(s): prof. C. Bot, prof. J.M. Tinbergen

Faculty: Mathematics and Natural Sciences

In the thesis of Claudia Burger it was found that breeding early results in higher amounts of caterpillars in the nestling diet of pied flycatchers, but only in oak habitats. However, there was no clear experimental evidence for food-limitation in late-breeding pied flycatchers, regardless of habitat. Thus, birds seem currently rather well-adapted to the environmental circumstances. Adaptation through dispersal could become an increasingly important mechanism in the future, with ongoing climate change, as pied flycatchers don't seem to pay high fitness costs when breeding at a new location.

Burger investigated the ecological links between timing of avian breeding and food abundance in temperate forests. Fitness consequences of asynchronous changes between trophic levels, resulting from climate warming, are experimentally studied, and the possibilities for adaptation through dispersal. In the migratory pied flycatcher, climate change resulted in an increased mismatch between brood rearing time and the food peak. As a consequence, fitness is expected to decline and birds need to adapt, either locally by advancing the timing of breeding, or through dispersal to a more suitable location. The main finding in this thesis is that, currently, pied flycatchers in this Dutch population cope relatively well with the environmental changes. Furthermore, it was shown that breeding early results in higher amounts of caterpillars in the nestling diet, but only in oak habitats and not in other forest habitats. However, the experimental studies indicated that synchrony with caterpillars is generally less important for the birds’ fitness than previously reported. It was found, by experimentally translocating flycatchers to Sweden, that dispersing individuals could contribute with their genes and phenotypes to another population. Hence, long-distance dispersal could potentially speed up evolutionary change towards earlier breeding. In the future, dispersal might be an increasingly important process by which mobile species can successfully adapt to on-going climatic changes.