The phenotypic and fitness response to the combination of copper and thermal stressors strongly varies within the ciliate species, Tetrahymena thermophila

Copper pollution can alter biological and trophic functions. Organisms can set up different tolerance strategies, including accumulation mechanisms (intracellular vacuoles, external chelation, etc.) to maintain themselves in copper-polluted environments. Accumulation mechanisms can influence the expression of other phenotypic traits, allowing organisms to improve their fitness. Whether copper effects on accumulation strategies interact with other environmental stressors such as temperature and how this may differ within species are still unsolved questions. Here, we tested experimentally whether the combined effect of copper and temperature modulates traits linked to fitness, morphology, movement and accumulation in six strains of the ciliate Tetrahymena thermophila. We also explored whether copper accumulation might modulate environmental copper concentration effects on phenotypic and fitness traits. Results showed high intraspecific variability in the phenotypic and fitness response t...