Timing of growth and reproduction

Ultimate functions and proximate mechanisms

                                     

For many species, there is only a short period in the annual cycle in which conditions are suitable for reproduction or growth. This period is often determined by other species, at a lower trophic level: the timing of herbivore growth is constrained by the phenology of the vegetation, predator reproduction, by herbivore abundance, etc.

Spring temperatures have increased over the past 35 years, and this has affected the phenology of many species. An important question is whether all levels in multi-trophic interactions are affected at the same rate, i.e. whether synchronization in maintained under large-scale climate change.

Winter Moth, Great Tit & Pied Flycatcher

Our group currently concentrates on three model systems. Winter Moth eggs need to hatch at the time of Oak bud burst so that the small caterpillars can feed on the fresh leaves. Both Oak (Quercus robur) bud burst and Winter Moth (Operophtera brumata) egg hatching advance with warmer spring temperatures, but the Winter Moth does so much stronger, leading to severe mistiming. Mistiming also occurs in the Great Tits (Parus major), which do not advance their laying date as much as the phenology of the abundance of prey for their nestlings, which now peaks 9 days earlier than 20 years ago. Finally, advancement of Pied Flycatcher (Ficedula hypoleuca) timing of breeding is hampered by their arrival date from Central Africa. This date has not advanced while spring on their breeding grounds has. In all three of these model systems we aim to understand why mistiming occurs, whether natural selection will lead to a better synchronisation, and what the population consequences are of the mistiming.

Our Work

We collect field data and analyse long-term data sets (for the Great Tit on a European wide scale), carry out field experiments (for the Great Tit to manipulate laying date), carry out controlled environment experiments in the laboratory (for the Great Tit in temperature controlled aviaries, for the Pied Flycatcher to estimate heritability of the onset of migration, for the Winter Moth to estimate heritability of the timing mechanism), study the underlying physiology and use modeling to answer these questions. Finally, we are currently constructing a high density SNP map for the great tit to locate the genes underlying the plasticity in laying dates.