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Data from: Cell size, photosynthesis and the package effect: an artificial selection approach

Cite this dataset

Malerba, Martino E. et al. (2023). Data from: Cell size, photosynthesis and the package effect: an artificial selection approach [Dataset]. Dryad.


Cell size correlates with most traits among phytoplankton species. Theory predicts that larger cells should show poorer photosynthetic performance, perhaps due to reduced intracellular self‐shading (i.e. package effect). Yet current theory relies heavily on interspecific correlational approaches and causal relationships between size and photosynthetic machinery have remained untested. As a more direct test, we applied 250 generations of artificial selection (c. 20 months) to evolve the green microalga Dunaliella teriolecta (Chlorophyta) toward different mean cell sizes, while monitoring all major photosynthetic parameters. Evolving larger sizes (> 1500% difference in volume) resulted in reduced oxygen production per chlorophyll molecule – as predicted by the package effect. However, large‐evolved cells showed substantially higher rates of oxygen production – a finding unanticipated by current theory. In addition, volume‐specific photosynthetic pigments increased with size (Chla+b), while photo‐protectant pigments decreased (β‐carotene). Finally, larger cells displayed higher growth performances and Fv/Fm, steeper slopes of rapid light curves (α) and smaller light‐harvesting antennae (σPSII) with higher connectivity (ρ). Overall, evolving a common ancestor into different sizes showed that the photosynthetic characteristics of a species coevolves with cell volume. Moreover, our experiment revealed a trade‐off between chlorophyll‐specific (decreasing with size) and volume‐specific (increasing with size) oxygen production in a cell.

Usage notes

The data include physiological measurements of photosynthetic characteristics of cells of Dunaliella tertiolecta as we were evolving their cell volumes toward smaller or larger sizes, using artificial selection. Also in the data, scanning electron microscopy photos and optical microscopy photos of the size-evolved cells. Please refer to the "READ ME_Instructions" file hosted on Zenodo for more information on the data files and R scripts included.