In today’s Academic Minute, Dr. Matthew Heard of Winthrop University discusses the threat diseases pose to endangered species.
Matthew Heard is an assistant professor of biology at Winthrop University where his research is focused on understanding the drivers of extinction for plants and animals across the world. In recent projects, he has examined how species invasions impact native plants, the role infectious disease plays in driving extinctions, and the ecological and evolutionary consequences of global climate change. He earned his Ph.D. at Brown University.
Dr. Matthew Heard - Infectious Disease and Species Extinctions
While infectious diseases are thought to pose a significant threat to animals, they have infrequently been linked to the actual extinction of a species. Since the year 1500, infectious diseases have been a contributing factor in less than 4% of known animal extinctions that have occurred worldwide. This number seems surprisingly low given how much we hear about infectious diseases, but work that my colleagues and I recently completed provides reasons why this number might increase in the future.
We conducted a detailed examination of threatened animal species around the world and found two interesting things. First, infectious diseases are rarely the sole reason that an animal is threatened with extinction. This makes sense, as the loss of a host species that a disease infects could also mean the loss of life for the disease itself. However, it also shows that many animals are likely to be simultaneously affected by multiple threats, which could increase the impact that a disease outbreak has on an animal.
Our other key finding was that the threat posed by infectious disease is increasing as animals move closer to extinction. What this indicates is that as an animal decreases in population size or in its distribution, they are more likely to be threatened by infectious disease. This implies that a threatened animal has the potential to be wiped out by a disease outbreak that normally would have just reduced their population size.
So what does this mean for the future of animals? Well it’s hard to say definitively, but it seems clear that things will probably get worse. In the case of vertebrates, approximately one fifth of all species across the world are threatened with extinction and this number is thought to be increasing. Additionally, many infectious diseases such as Ranaviruses, Chytridiomycosis, and White Nose Syndrome, which are driving mass die-offs in amphibians, reptiles, and mammals are increasing in frequency and occurrence.
Ultimately, these findings beg the question of whether the threat posed by disease is likely to increase in the future and whether disease could be the final nail in the coffin for threatened animal species around the world.