Telomeres are DNA/protein structures at the ends of chromosomes that shorten with age. Evidence is accumulating that telomere length is a biomarker of aging, providing a possible key towards understanding the enigma of aging, but the evidence is largely non-experimental. We will study telomeres in relation to aging and life history using an experimental approach in wild birds (jackdaws), which are exposed to natural selection pressures absent from laboratory settings. We have successfully modulated actuarial senescence (=increase of mortality rate with age) by inducing a change in reproductive effort through brood size manipulation, i.e. decreasing or increasing the number of young in the nest. This experiment also affected nestling development, but in a sex-dependent way: growth of daughters was more affected than growth of sons, but only in sons was there an effect on telomeres. Furthermore, the telomere shortening in nestlings was fast enough to allow longitudinal comparisons within weeks, while in humans this takes years. These findings create a unique opportunity to simultaneously test: (i) Whether the induced acceleration of actuarial senescence can be attributed to accelerated physiological aging, using telomere shortening as biomarker. (ii) Whether telomere dynamics in nestlings constitutes a biomarker that links developmental conditions to success later in life, and how this depends on sex. (iii) Candidate physiological causes of telomere shortening, exploiting the high rate of telomere shortening in nestlings. Through this experimental work in an ecologically relevant setting we will make a unique contribution to our understanding of telomeres, life histories and aging.

The battle of the sexes in the brain Couples come into conflict when one of the partners cheats. In fruit flies, when females mate with other males, it makes the paternity of her offspring uncertain. In response, males produce chemicals that act on the female brain and decrease her sexual interest - a chastity belt for the brain. The womans brain, on the other hand, "learns" to resist this chemical. Like an arms race, men and women continue to develop strategies to get their way. Here we study how this arms race has turned the brain into a complex organ.

We aim to unravel the molecular basis of plant embryo development without fertilization (Parthenogenesis) and apply it in protocols for breeding line production and maintenance. Gametic embryogenesis has high potential for the instant production of homozygous lines from haploid gametes (doubled haploids, DHs), and breeding lines from (un)reduced gametes obtained by modifying steps in meiosis. Parthenogenesis in combination with the omission of meiosis is of great interest to maintain vigorous F1-hybrids via clonal seed production. Parthenogenesis occurs naturally in a variety of species, mainly in combination with apomeiosis (unreduced gametes), known as Apomixis. We will perform a single cell comparative transcriptome analysis of eggs, embryo sacs and zygotes from apomictic versus sexual dandelions (Taraxacum), characterize the differentially expressed transcripts, and develop their application in crops.

The timing of light exposure, physical activity, and food intake are important cues for synchronising the biological clock. Disruption of the biological clock is a clear threat to both public health and vulnerable ecosystems. Especially in a highly industrialised country such as The Netherlands there is a mismatch between biological clocks and social demands. However, these cues have drastically – and abruptly - changed in our modern society due to the widespread use of artificial light and the round-the-clock demand for goods and services. Fundamental research has shown that precisely these conditions cause desynchrony among clock cells.

Phenotypic plasticity is a key determinant of organismal performance, allowing rapid adjustment to environmental variation. However, its evolutionary impact is in dispute. On the one hand, plasticity facilitates range expansion and thereby increases the opportunity for evolutionary differentiation. On the other hand, plastic responses will weaken selection for genetic change, hampering adaptive evolution. We currently lack the empirical data to verify either scenario, limiting our ability to predict how biodiversity responds to environmental change. Here, we aim to resolve this ambiguity by determining the role of visual plasticity in the evolution of cichlid fish species diversity. Colour vision has a relatively simple genetic basis, exhibits plasticity, affects both reproduction and survival, and is often associated with species divergence. The species-rich cichlid family provides a well-resolved comparative framework. Focusing on the African cichlids (600+ species), we will quantify plasticity by 1) documenting visual niche breadth in nature and 2) measuring environment-induced changes in visual gene expression in the laboratory. We then use phylogenetic analysis to test whether more plastic lineages are more species-rich than less plastic ones. Subsequently, we experimentally address the underlying mechanism by quantifying the effects of visual plasticity on individual behaviour and fitness. This will establish the causal relationship between visual plasticity and ecological niche expansion. Together, these approaches will reveal whether and how visual plasticity can promote or inhibit speciation. By integrating developmental genetics and evolutionary ecology, this project will generate fundamental insights into the contribution of plasticity to biodiversity dynamics in a changing world.