Hollants J., Leliaert F., Verbruggen H., Willems A. & De Clerck O. (2013)
Permanent residents or temporary lodgers: characterizing intracellular bacterial communities of siphonous green algae
Proceedings of the Royal Society B: Biological Sciences 280: 20122659


The ecological success of giant celled, siphonous green algae has repeatedly been linked to endophytic bacteria living within the cytoplasm of the hosts. Yet, virtually nothing is known about the relative importance of evolutionary and ecological factors controlling the intracellular bacterial flora of these seaweeds. Using the siphonous alga Bryopsis as a model, we explore the diversity of the intracellular bacterial communities and investigate whether their composition is controlled by ecological and biogeographical factors rather than the evolutionary history of the host. Using a combination of 16S rDNA clone libraries and DGGE analyses, we show that siphonous algae harbor a diverse and complex mixture of generalist and specialist bacteria. Variation partitioning analyses show a strong impact of local environmental factors on bacterial community composition for generalist species, while specialists reflect a predominant imprint of evolutionary history. The results highlight the importance of interpreting the presence of individual bacterial phylotypes in the light of ecological and evolutionary principles such as phylogenetic niche conservatism to understand complex endobiotic communities and the parameters shaping them.

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