Evolution of Microalgae and Their Adaptations in Different Marine Ecosystems


Microalgae are unicellular eukaryotic organisms that are predominantly photosynthetic. They are found in a wide range of habitats, particularly marine ecosystems, and are responsible for a significant portion of the oceans biogeochemical cycling. Microalgae have a varied evolutionary history with genes derived from photosynthetic organisms, heterotrophic eukaryotes and bacteria. This has led to a wide range of adaptations, allowing them to thrive in a variety of conditions. Microalgae in coastal regions are adapted to turbulence, high nutrients and low light whilst open ocean microalgae have to contend with high irradiance and low nutrient concentrations. Polar microalgae are adapted to freezing temperatures, high nutrients and long periods of light and darkness. Microalgae genomes and transcriptomes uncover and interpret these adaptations, providing information on how microalgae have become a dominant force within marine ecosystems.

Key Concepts

  • Microalgae are very diverse and species rich
  • Microalgae are adapted to diverse environments
  • Microalgae have complex evolutionary origins
  • Microalgae significantly contribute to the global carbon cycle on Earth
  • Marine microalgae are the base of the marine food web

Keywords: marine; microalgae; evolution; adaptation; genomics; phytoplankton; diversity

Figure 1. Average sea surface chlorophyll a concentration from 1998 to 2006. Chlorophyll a is used as an indicator of phytoplankton biomass.
Figure 2. Emiliania huxleyi bloom off the coast of South West England.
Figure 3. Evolution of algae according to primary, secondary and tertiary endosymbiotic events. EGT, endosymbiotic gene transfer.
Figure 4. Major differences between nutrient, light and turbulance in marine coastal and open‐ocean ecosystems.
Figure 5. Melosira sp. chain illustrating the advantages of a silica frustule: rigidity in microalgae chains can increase nutrient uptake in turbulent conditions. Images of diatoms collected during the Tara Oceans expedition 2009–2012. Courtesy of Christian Sardet and Chris Bowler.


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Further Reading

Bork P, Bowler C, de Vargas C, et al. (2015) Tara Oceans studies plankton at planetary scale. Science (Special Issue) 348: 873.

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Worden AZ, Follows MJ, Giovannoni SJ, et al. (2015) Rethinking the marine carbon cycle: factoring in the multifarious lifestyles of microbes. Science 347 1257594.

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Hopes, Amanda, and Mock, Thomas(Oct 2015) Evolution of Microalgae and Their Adaptations in Different Marine Ecosystems. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0023744]