Slow-living animal species could be disease reservoirs – study


Animals that live slowly – breeding less rapidly and living longer – could be reservoirs of diseases that jump to other species including humans, a new study suggests.

Some species live fast and die young, devoting effort to reproduction, while others conserve more energy for survival, researchers say.

While the coronavirus pandemic has drawn attention to fast-spreading infectious diseases, the new study by the University of Exeter focuses on endemic diseases that co-exist with host species for long periods of time.

Researchers measured what they called demographic competence – the ability of a host species to survive in large numbers while sustaining high levels of infection.

The study found that slow-lived species often have higher demographic competence for persistent infections.

They are therefore more likely to act as reservoirs of infection that can spill over into other species, the study suggests.

Professor Dave Hodgson, director of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall, said: “Diseases of wildlife pose a threat to the survival of endangered species worldwide, and we know there is risk of spill-over of disease between closely related species of wildlife, livestock and humans.

“These spill-over events are known to be influenced by similarities in immune systems, and by increasing levels of contact between humans and wildlife caused by exploitation of natural ecosystems like rainforests.

“Our findings highlight the potential to use other, more ecological, characteristics like lifespan, reproductive capacity and population size to identify and predict the wildlife reservoirs from which new diseases could emerge.”

In the study published in the journal Nature Ecology and Evolution, researchers used mathematical models to explore what kinds of animal species and pathogens – diseases – are likely to co-exist for long periods.

Dr Matthew Silk, of the University of Exeter, said: “As well as finding that slow-living species may be reservoirs of infectious disease, we show a ‘flip-side’ whereby species with low demographic competence may not be able to co-exist with new diseases and might therefore suffer local or complete extinction.

“It is important to note that pace-of-life in the host species isn’t the only important factor affecting ‘demographic competence’.

“Traits of the pathogen itself – such as how easily it is transmitted and how likely it is to kill a host – will also play a key role, as will the social behaviour of the host species.

“We must also consider the role of immunity.

“Differences in immune systems that we know exist between fast and slow hosts can influence how long individuals are ill and whether they can be re-infected.”