Fae Neto, Wladimir A., Dosselli, Ryan, Kennington, W. Jason, and Tomkins, Joseph L. (2023) Correlated responses to selection for different cell size in Chlamydomonas reinhardtii using divergent evolutionary pathways. Journal of Applied Phycology, 35. pp. 1621-1634.

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Abstract

Cell size is an important trait that is often correlated with organisms’ survival under different thermal environments, and in the case of phytoplankton, it is also related to survival under different light irradiance. While smaller phytoplankton thrive under warm and high light (summer conditions), larger cells seem to be more efficient under cool and low light conditions (winter conditions). In this study, we used different evolutionary pathways, nitrogen depletion and size selection, to select for differences in average cell diameter in the single-celled alga Chlamydomonas reinhardtii. We tested whether there was a size-related fitness (growth rate) advantage across two light intensities and two temperatures; environmental effects that have dramatic effects on algal growth. Under these environmental conditions we then tested how the evolutionary pathway to reduced cell size affected fitness and photophysiology. The results suggest that the relationship between size and growth rate in C. reinhardtii is strongly correlated with changes in the photosynthetic apparatus in different sized cells. Large-selected cells evolved to have smaller light-harvesting antennae, making them less susceptible to photodamage. However, they accumulate larger amounts of reactive oxygen species, potentially due to their lack of antioxidant carotenoids. In addition, the maximum growth rate was reduced, potentially due to their reduced ability to repair PSII due to lower metabolic rates. Similar responses were observed in lines that evolved to have smaller cells under nitrogen depletion. The results demonstrate that different evolutionary pathways to reduced cell size result in different changes in metabolism, with N-depleted and Small-selected cell lineages having similar sizes, but thriving differently under winter/summer conditions. With large production systems in mind, it is possible to assume that the choice of strains selected using adaptative laboratory evolution or direct selection on size can affect the overall production yield and carbon capture according to the seasons and possibly other abiotic parameters.

Item ID:	89286
Item Type:	Article (Research - C1)
ISSN:	1573-5176
Copyright Information:	© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funders:	Australian Research Council (ARC)
Projects and Grants:	ARC grant DP170100554
Date Deposited:	21 Oct 2025 21:28
FoR Codes:	31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310403 Biological adaptation @ 50% 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310801 Phycology (incl. marine grasses) @ 50%
SEO Codes:	28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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