"Hydra Effect": The Advantage of Wiping Out a Population of Animals

Khryss | Published 2017-09-08 04:41

Here's a bright side to mass deaths.

Some animals tend to not all live together. They split up and have several small populations that are almost independent--almost. A collection of this populations is called "metapopulation".

Now while each small population live on their own, the survival of the entire group (metapopulation) still has something to do with the occasional migrations of one population to another. This seems really harmless for migration has its own set of benefits. One is the re-population in an area wherein such species become extinct.

However, the problem here is that this also synchronises breeding and death. There's a rotation between small and large numbers in all populations but with very frequent migrations, the cycle just seem to sync up. This harmonious relationship is dangerous for this means that when “one group crashes, they [just] all crash," says Jeremy Fox at the University of Calgary, Canada. This affects greatly the survival of metapopulations.

So, to find a way to de-sync such and possibly help these populations, Fox and colleagues simulated a model of them. Result showed a very counter-intuitive approach: rapidly and completely wiping out a population can avoid the global extinction of a metapopulation and help the species persist in the long run!

They tested this in another 27 metapopulations of two protist species. Results were similar--higher levels of migration on those that experienced mass death survived 50% longer. Fox dubbed this ironic phenomenon “the spatial hydra effect". (Yes, like that serpent in Greek mythology that appears to double its head every after one was chopped off.)

While this doesn't actually have much implications on species conservation given that the setting in the experiment is controlled and too specific, this can instead help control diseases. For instance, trying to vaccinate everyone in a "measles-infested" country would just create an "extinction event" that de-syncs the measles population, consequently helping it survive.

Now this article's journey just had an unexpected ending, don't you think?


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