Research

Individual heterogeneity in Escherichia coli bacteria

Are we all equal? What happens to reproduction and survival among individuals if we take away variability in genotypes and environments? How do senescence patterns differ in different environments and among different genotypes?

To study such questions we use a highly automated microfluidic system that produces large quantities of demographic data for individual bacteria. Please watch the movie illustrating the microfluidic chip and how the system works under the  microscope. This system provides a multitude of excellent opportunities to seriously confront theory with empirical data. We have for instance shown that classical senescence patterns of an early exponential increase in mortality followed by late age mortality plateau is not driven by age, but rather by stage dynamics that are independent of age. We also study stochastic processes at different levels of biological organization and evaluate their influence on demographic patterns.

Age-stage-structured Demographic Models

The prevailing biological understanding of aging and senescence, based on classical theories of aging, and an impressive literature describing underlying mechanisms, cannot explain the senescence patterns observed in many systems. Therefore we expand and explore population matrix models that go beyond age only by including stage dynamics. One of the nice features of such models is that they are inherently stochastic (Markovian) and therefore provide easy ways of investigating variances in fitness components and stage dynamics, two characteristics selection should act upon. We parameterize the models with individual level data from either the bacteria system, or with longitudinal data from field studies, such as an experimental field site on Plantago lanceolata, an island population of macaques, or similar high quality long term data sets.

Evolution of Phenotypic plasticity

What is the role of phenotypic plasticity for evolutionary processes. It is controversially debated, whether phenotypic plasticity promotes or inhibits adaptation to novel environment such as expected under climate change scenarios. We are interested to what degree phenotypic plasticity is adaptive and how common cryptic genetic variation is across many study systems. We mainly use meta analyses to aim for more general answers how organisms deal with fluctuating environments.