Barbara Mizumo Tomotani
Researcher in Chronobiology
I am a researcher at the Arctic Seasonal Timekeeping Initiative (ASTI) interested in the evolution of biological clocks and calendars.
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I am interested in the evolution of clocks and calendars in wild organisms and how the timing of daily and seasonal events is affected by global environmental change. My research strategy involves a combination of field and laboratory experiments and analyses of long-term datasets, mostly using songbirds.
Most organisms organize their activities through circadian (i.e. day/night) clocks, which in turn are entrained to environmental information such as light. Circadian clocks allow organisms to anticipate daily events and are ubiquitous in nature. They “tick” at different rates in different individuals, thus showing variation in their properties, such as period length, which is highly heritable. But the evolution of clocks is only possible if this variation is also associated with fitness differences. Currently, however, the selection of clocks under natural conditions remain poorly understood, for this, we need to study ‘wild clocks’ and connect the clock properties measured in the lab with fitness measures in the wild.
The light/dark cycle is the most important synchronizer of the biological clocks. Cities remarkably change the environment and one of the obvious impacts is the amount of artificial light at night present in the urban environment. I study the process of urbanization as a natural experiment to test the prediction that by dramatically changing the environment, cities expose organisms to profoundly distinct selective pressures compared to their natural environment and select different clock properties. Using the great tit (Parus major) as a model species, I measure the clock of individuals in cities and forests and carry out a large-scale common-garden study to separate genetic and environmental effects. I am particularly interested in possible differences in the clock's sensitivity to light.
Following up on the urban clock project, I am interested in exploring the latitudinal adaptation of circadian clocks. When they move to the arctic, organisms are exposed to more extreme conditions of light, what would be the effects of artificial light at night on the clock in such environments? I am also using the great tits in this project and I hope to expand the common garden protocol to include birds from distinct latitudes.
Calendars in a changing world:
Animals need to time their daily and seasonal activities so they match favourable conditions in the environment. To do so, they use predictive environmental cues, with the photoperiodic and temperature variation being the most important ones for seasonal rhythms. Climate change is a major challenge that organisms face because by disrupting those important cues, they interfere with the animals' abilities to make predictions and may impact survival and reproductive success. I studied the effects of climate change on the timing of annual-cycle stages of a migratory bird: the pied flycatcher (Ficedula hypoleuca). Long-distance migrants, such as flycatchers, have complex annual cycles comprising several events, like breeding and migration, that need to be fitted into one year. Climate change advances annual-cycle stages, but, because not all stages respond to changes in temperatures, the shifts may vary depending on the stage (e.g. reproduction advances faster than migration). This could lead to a mismatch across the entire annual cycle because it modifies the time available for each stage.
External collaborators: Marcel E. Visser, Kees van Oers (NIOO, Netherlands Institute of Ecology)