AUTHOR=Hsu Veronica , Moeller Holly V. 

TITLE=Metabolic Symbiosis Facilitates Species Coexistence and Generates Light-Dependent Priority Effects

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2020.614367

DOI=10.3389/fevo.2020.614367

ISSN=2296-701X

ABSTRACT=<p>Metabolic symbiosis is a form of symbiosis in which organisms exchange metabolites, typically for mutual benefit. For example, acquired phototrophs like <italic>Paramecium bursaria</italic> obtain photosynthate from endosymbiotic green algae called <italic>Chlorella.</italic> In addition to facilitating the persistence of <italic>P. bursaria</italic> by providing a carbon source that supplements <italic>P. bursaria</italic>’s heterotrophic digestion of bacteria, symbiotic <italic>Chlorella</italic> may impact competitive interactions between <italic>P. bursaria</italic> and other bacterivores, with cascading effects on community composition and overall diversity. Here, we tested the effects of metabolic symbiosis on coexistence by assessing the impacts of acquired phototrophy on priority effects, or the effect of species arrival order on species interactions, between <italic>P. bursaria</italic> and its competitor <italic>Colpidium</italic>. Our results suggest light-dependent priority effects. The acquired phototroph benefited from metabolic symbiosis during sequential arrival of each organism in competition, and led to increased growth of late-arriving <italic>Colpidium</italic>. These findings demonstrate that understanding the consequences of priority effects for species coexistence requires consideration of metabolic symbiosis.</p>