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Preferential Plastid Retention by the Acquired Phototroph Mesodinium chamaeleon
Author(s) -
Moeller Holly V.,
Johnson Matthew D.
Publication year - 2017
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/jeu.12446
Subject(s) - phototroph , biology , mixotroph , botany , predation , ciliate , plastid , generalist and specialist species , photosynthesis , ecology , heterotroph , chloroplast , bacteria , biochemistry , genetics , habitat , gene
The ciliate genus Mesodinium contains species that rely to varying degrees on photosynthetic machinery stolen from cryptophyte algal prey. Prey specificity appears to scales inversely with this reliance: The predominantly phototrophic M. major/rubrum species complex exhibits high prey specificity, while the heterotrophic lineages M. pulex and pupula are generalists. Here, we test the hypothesis that the recently described mixotroph M. chamaeleon , which is phylogenetically intermediate between M. major/rubrum and M. pulex/pupula , exhibits intermediate prey preferences. Using a series of feeding and starvation experiments, we demonstrate that M. chamaeleon grazes and retains plastids at rates which often exceed those observed in M. rubrum , and retains plastids from at least five genera of cryptophyte algae. Despite this relative generality, M. chamaeleon exhibits distinct prey preferences, with higher plastid retention, mixotrophic growth rates and efficiencies, and starvation tolerance when offered Storeatula major , a cryptophyte that M. rubrum does not appear to ingest. These results suggest that niche partitioning between the two acquired phototrophs may be mediated by prey identity. M. chamaeleon appears to represent an intermediate step in the transition to strict reliance on acquired phototrophy, indicating that prey specificity may evolve alongside degree of phototrophy.