The loss of photosynthesis in green algae: a case study for ecological transitions

We propose to investigate the physiological and ecological factors driving the loss of photosynthesis in green algae and their transition to a permanent heterotrophic lifestyle. Autotrophs produce organic molecules (such as carbohydrates) from inorganic compounds (CO2), and photoautotrophs are reliant on sunlight to do this. Photoautotrophs are the primary producers of most ecosystems. Most of all other life forms that rely on primary producers are called heterotrophs. There also exists a third class of organisms called mixotrophs, which switch between photoautotrophy and heterotrophy depending on environmental conditions. Interestingly, mixotrophy may facilitate the loss of photosynthesis in some environmental contexts. Chlamydomonadalean green algae are an exceptional system to study the transition from mixotrophy to heterotrophy, as Chlamydomonadalean algae boast various lineages that have independently transitioned from mixotrophy to free-living heterotrophy. The physiological advantages that facilitate the evolutionary transition from mixotrophy to heterotrophy (in green algae and other groups) are currently unknown. This proposed collaborative project will study the physiological costs and benefits of Chlamydomonadalean green algae with different trophic modes. By studying how previously photosynthetic lineages have eventually adapted to a non-photosynthetic lifestyle, we can provide fundamental knowledge to be mobilized into ecological models of future carbon sequestration.

Faculty Supervisor:

David Smith

Student:

Partner:

Purdue University

Discipline:

Life Sciences

Sector:

Life Sciences (not health); Biotechnology; Sustainability & the Environment

University:

The University of Western Ontario

Program: