In vitro competition between two transmissible cancers and potential implications for their host, the Tasmanian devil

Area of Science:

• Conservation biology
• Cancer research
• Evolutionary biology

Background:

• Tasmanian devil populations are declining due to devil facial tumour disease (DFT1).
• A second transmissible cancer, DFT2, emerged in 2016, increasing concerns for species survival.

Purpose of the Study:

• To investigate the competition dynamics between DFT1 and DFT2 transmissible cancers in vitro.
• To understand how these two cancers interact and potentially compete in the Tasmanian devil population.

Main Methods:

• Utilized cell lines for DFT1 and DFT2 in monoculture and co-culture experiments.
• Employed logistic and Lotka-Volterra competition models to analyze growth curves.
• Assessed competition with and without a semi-permeable membrane to test for mechanical stress.

Main Results:

• DFT2 exhibited faster growth than DFT1 in monoculture but reached lower maximum cell densities.
• In co-culture, DFT2 outcompeted DFT1, leading to a decline in DFT1 cell numbers.
• Mechanical stress from DFT2 appeared to inhibit DFT1 growth, a phenomenon not observed when cells were separated.

Conclusions:

• DFT2 demonstrates superior competitive ability compared to DFT1 in vitro.
• Initial cell numbers may influence competition outcomes in laboratory settings.
• DFT2 has the potential to outcompete DFT1 in the wild, despite its current smaller geographic range, informing future disease management strategies.