Celebrating 500 generations of experimental evolution

It’s party time in the Centre for Geometric Biology: We’ve reached 500 generations of experimental evolution in our large and small algal cells!

Three and a half years ago Martino Malerba set up the first culture of the single-celled marine phytoplankton Dunaliella tertiolecta and begun to artificially select for large and small cells.  The selection process of separating the largest and the smallest cells has continued twice a week ever since.  Martino is now the proud ‘father’ of algal cells where the big cells are more than 10 times the size of the smaller cells.

The evolved algae lines have enabled Martino and his colleagues to look at the consequences of being a particular size without having to compare different species, which vary in many other ways than just size. This research directly supports the fundamental question the Centre for Geometric Biology seeks to understand “why do organisms grow to the size they do?”

The team has looked at the effects of size at both the level of the cell and the population. They have found that altering the size of a cell profoundly alters many fundamental traits of algal physiology and ecology. This affects how cells of different sizes will cope with fluctuating resources and, in turn, how those populations of cells use energy and grow.

Exciting research underway looks at community-level effects. What happens when grazers are only offered either large or small algal cells: does changing algal size have repercussions up the food chain?

Understanding how individuals grow and regulate their energy is critical in helping scientists predict how large-scale impacts, such as climate change, affect organisms.

Phytoplankton have critical roles in the ocean; they form the base of most food webs and fix large amounts of carbon.  So, while the research stemming from these artificially evolved algal cells is theoretically interesting, it also has a very direct and immediate application to how we understand and manage climate change.