Data from: Thermal response of freshwater ciliates: can they survive at elevated lake temperatures?

The response of the single-celled ciliates to increased temperature during
global warming is critical for the structure and functioning of freshwater
food webs. I conducted a meta-analysis of the literature from field
studies and experimental evidence to assess the parameters characterising
the thermal response of freshwater ciliates. The shape of the thermal
performance curve predicts the ciliates’ survival at supraoptimal
temperatures (i.e., the width of the thermal safety margin, TSM). The
ciliates’ typical TSM is ~5°C. One-third of the freshwater ciliates
dwelling permanently or occasionally in the pelagial cannot survive at
temperatures exceeding 30°C. Likewise, cold-stenothermic species, which
represent a significant fraction of euplanktonic ciliates, cannot survive
by evolutionary adaptation to rapidly warming environments. The
statistical analysis revealed that the ciliates’ thermal performance is
affected by their planktonic lifestyle (euplanktonic versus
tychoplanktonic), ability to form cysts, and nutritional ecology.
Bactivorous ciliates have the widest temperature niche, and algivorous
ciliates have the narrowest temperature niche. Phenotypic plasticity and
genetic variation, favouring the selection of pre-adapted species in a new
environment, are widespread among freshwater ciliates. However, the lack
of evidence for the temperature optima and imprecisely defined tolerance
limits of most species hamper the present analysis. The extent of
acclimation and adaptation requires further research with more ciliate
species than the few chosen thus far. Recent eco-evolutionary experimental
work and modelling approaches demonstrated that the ciliates’ thermal
responses follow general trends predicted by the metabolic theory of
ecology and mechanistic functions inherent in enzyme kinetics. The present
analysis identified current knowledge gaps and avenues for future research
that may serve as a model study for other biota. Thermal adaptation may
conflict with adaptation to other stressors (predators, food availability,
pH), making general predictions on the future role of freshwater ciliates
in a warmer environment difficult, if not impossible, at the moment.