Tumors (re)shape biotic interactions: evidence from the freshwater
While it is often assumed that oncogenic process in metazoans can
influence biotic interactions, empirical evidence for that is lacking.
Here, we use the cnidarian Hydra oligactis to experimentally explore the
consequences of tumor associated phenotypic alterations for the hydra’s
predation efficiency, the relationship with commensal ciliates and the
vulnerability to predators. Unexpectedly, the efficiency of hydra
predation on prey was higher in tumorous polyps compared to non-tumorous
ones. Commensal ciliates colonized preferentially tumorous hydras than
non-tumorous ones, and had a higher replication rate on the former.
Finally, in a choice experiment, tumorous hydras were preferentially
eaten by a fish predator. This study, for the first time, provides
evidence that neoplastic growth has the potential, through effect(s) on
host phenotype, to alter biotic interactions within ecosystems and
should thus be necessarily taken into account by ecologists.