Anna Karenina meets Spongebob's microbiome

“All happy families are alike; each unhappy family is unhappy in its own way.” In other words, we tend to differentiate people in their misery. And not only people. A very important part of research is understanding how organisms respond to unfavourable conditions. This has evolved from running around and poking them with a stick to putting their whole environment under stress. The quote from the renowned Anna Karenina is now being transferred to Biology books: the Anna Karenina principle predicts that in a host-associated microbiome certain stressors have stochastic rather than deterministic effects on community composition. Translating Tolstoy in Microbiology: “all healthy microbiomes are similar; each dysbiotic microbiome is dysbiotic in its own way” (Zaneveld et al. 2017). As ecologically important filter feeders with well-established microbial partnerships, sponges are a relevant target for microbial based monitoring studies.

Glasl et al. (2018) investigated how the diversity of the sponge microbiome influences community stability upon acute salinity fluctuations (ranging from 36 psu to 25 psu) under controlled experimental conditions. They used sponges with high and with low microbial abundance, testing the general ecological principle that increased biodiversity enhances the stability of an ecosystem (the stability-diversity concept). The sponges were highly tolerant of short-term acute salinity fluctuations, as they exhibited no signs of stress following salinity amendments. The microbiomes showed compositional resistance irrespective of their microbial diversity, as there was no shift in the compositional stability of the microbiome for both high and low diversity species. This lead to the conclusion that the stability-diversity concept does not apply to sponge microbiomes. The Anna Karenina principle also didn’t appear to hold here, as the dispersion of microbial communities remained consistent across both high and low diversity species, irrespective of experimental treatment. The study provides further evidence that sponge microbiomes exhibit strong genotype-specificity, suggesting that genotype-specific microbiome variations shoud be taken into account in future research. The high stability of the sponge holobiont upon salinity fluctuations and the resistance of sponge microbiomes against stressors support the evidence for the widely recognized environmental tolerance of sponges.

Reviewed article:

Glasl, B., Smith, C. E., Bourne, D. G. & Webster, N. S. (2018). Exploring the diversity-stability paradigm using sponge microbial communities. Sci. Rep.8, 1–9. doi: 10.1038/s41598-018-26641-9

References:

Zaneveld, J., Mcminds, R., Vega, R. (2017). Stress and stability: applying the Anna Karenina principle to animal microbiomes. Nature Microbiology, 2(9), 17121. doi: 10.1038/nmicrobiol.2017.121