Timing of growth and reproduction: ultimate functions and proximate mechanisms


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.
We are currently concentrating 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 (PhD project of Lucia Salis). 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 (post-docs Phillip Gienapp and Veronika Laine and PhD projects of Irene Verhagen en Jip Ramakers). Finally, the timing of the different parts of the life cycle of the Pied Flycatcher (Ficedula hypoleuca)  - timing of breeding, moult, migration, etc -  are affected differently by climate change, which may lead to mismatches between life cycle events (PhD project of Barbara Tomotani).
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. 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) and 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). Using these data, we study the ecology, the evolution and the underlying physiology of timing.
More recently, we have started to work on geneomic variation - using the sequences Great tit and Wintermoth genomes, and the 650 kSNP chip for the Great tit - and have collected RNA data from Great tits and Wintermoths from experimental set ups. We will start unraveling the molecular genetic architecture underlying seasonal timing to get more insight in the links between genotypes and phenotypes, and how there are shaped by environmental conditions.


An important part of this research has funded by a NWO-VICI grant (2007-2013) and is curently funded by an ERC Advanced grant (2014-2019).