Ecologist Dr Melinda Moir has developed a tool to help conservationists decide whether they should move an endangered species' parasites.
As Australia relocates more and more of its endangered plants and animals to try to secure their survival in a changing climate, a difficult decision has arisen: should we also try to save their special parasites?
Ecologist Dr Melinda Moir of the ARC Centre of Excellence for Environmental Decisions (CEED) and University of Melbourne is well aware that parasites don’t enjoy the same public charisma as koalas or rare native flowers – but says they may still be important in subtle ways to the survival of their host species.
The issue of parasite conservation was highlighted for Dr Moir when working in a plant relocation programme in southwest Western Australia, where she found that two of the three plants to be relocated had bugs that were exclusively dependent on them.
“It was clear that if we took the plants and left the bugs behind, the bugs would become extinct if the plants failed to survive at their original location, as they were specially adapted to live on those plants and no others.
“This brings up the question of whether we are merely trying to salvage a few species that we think are important or attractive – or to preserve as much of the Earth’s biodiversity as possible through what many scientists now consider to be the Sixth Mass Extinction, driven by human activity.
“It also goes to the question: what is the real ‘value’ of a species?” she adds. “People may not have much time for parasites, especially ‘low-life’ bloodsuckers like ticks, but they may often play an important though largely invisible role, such as priming the immune system of their host or keeping its numbers under control.”
But it also raises the thorny question of whether the parasite might, in its new setting, start attacking some other species and become a pest – and this requires extensive testing.
In a New Zealand trial, where tuatara (native lizards) are being relocated to offshore islands to protect them from rats, it was recently decided to relocate their native ticks as well, as these were found to be exclusive to the tuatara and not to pose a risk to any other species. Left in its original location, the tick would probably have become extinct if the tuatara went locally extinct.
As a result of these early trials and investigations, Dr Moir and her colleagues are recommending that conservation programs for threatened plants – such as translocations, reintroductions and seedbanks – should also consider incorporating affiliated insect species.
This increases both the cost and complexity of conservation, so she and her colleagues have developed a decision support tool to assist conservation managers in reaching the right conclusions about whether to save dependent species along with their host.
However a major obstacle is that many dependent species are things like insects, nematodes and mites and remain unknown to science. Well-intentioned plans to translocate a few high-profile species to save them, but not their dependents, risk exacerbating extinction rates, she cautions.
“We are held back by bottlenecks of our own ignorance of the Earth’s biodiversity. Only a handful of these dependent species are being identified and described by science each year worldwide, and we know almost nothing of their relationship with their host or conservation status.”
Dr Moir suggests a practical approach may be to replace the focus on ‘saving species’ by instead concentrating on saving ‘threatened ecological communities’.
“Conserving most of the world’s biodiversity is a monumental task. But rather than be overwhelmed, we can begin to address the problem with small steps, like those outlined above.
“A world with no dependent species would be a biologically impoverished world. We ignore their fate at our own peril,” she says.
Editor's Note: Original news release can be found here.