Slow-living animals could be the source of more diseases

Slow-living animals could be the source of more diseases Animals that live longer, slower lives may be “reservoirs” of diseases that could jump to humans and other species, according to a new study from the University of Exeter. The research was focused on endemic diseases that are carried by host species for long periods of time.

Some species live fast and die young, dedicating an enormous amount of energy to reproduction and breeding, while other animals devote most of their energy to survival. 

“We introduce the concept of demographic competence to describe the ability of host populations to sustain endemic infectious disease,” said the researchers. They explained that hosts with high demographic competence are more likely to carry infections that can spill over into other species. 

“We propose that the pace of host life history will interact with pathogen life history to influence demographic,” said the study authors. 

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

“Diseases of wildlife pose a threat to the survival of endangered species worldwide, and we know there is risk of spillover of disease between closely related species of wildlife, livestock and humans,” said Professor Dave Hodgson.

“These spillover 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.”

The team used mathematical models to explore what kinds of animals and diseases are most likely to coexist for a long time. 

“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,” said Dr. Matthew Silk.

“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 behavior 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.”

The study is published in the journal Nature Ecology and Evolution.

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By Chrissy Sexton, Earth.com Staff Writer