Friday, 11 July 2014

Amphibians 'Learn' to Avoid Pathogenic Fungi

There is some data that supports the impression that fungi are causing increasing numbers of fatal infections in the wild over a large part of the world. Worryingly many completely different groups of organisms seem to be in decline e.g. bats, corals (Aspergillus sydowii), bees, snakes and amphibians but also plants. Some of this has been suggested to be a result of global warming - environments are changing as temperatures shift and those organisms trapped in a warmer environment are stressed to such an extent that they are more vulnerable to infection or predation. Some is being suggested to be a result of human activity spreading pathogens to parts of the world that they had not reached before now.

Aside from the importance of each species with respect to itself and the global diversity of living organisms, many of these species are of fundamental economic importance to us all so we need to understand why these populations are declining so as to be able to stop and reverse the decline.

Osteopilus septentrionalis
This new paper in the highly important journal Nature offers us one clue on how amphibians may be helped to start to resist pathogenic fungi. This particular group of frogs are living in an environment that has become infested with a pathogenic fungus (Batrachochytrium dendrobatidis). Conservationalists have taken frogs away from the infested areas and bred them successfully in captivity, however when they re-introduce them to the infected areas they fail to thrive - after all the fungus is still there so we might predict this outcome.

How can we help?

It turns out that if you expose the frogs to the fungus two things happen to enable resistance: they quickly learn to avoid it, and gradually become immune. This happens whether or not the fungus is alive. If then we carefully expose the frogs to dead fungus prior to re-release into the wild they should be able to avoid the fungus and thus thrive more readily. Perhaps other organisms have similar survival strategies we can use to help protect them?

The authors put it like this:
these results offer hope that other wild animal taxa threatened by invasive fungi might be rescued by management approaches based on herd immunity.

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