Researchers from the University of Adelaide, New Zealand’s Manaaki Whenua-Landcare Research and the University of Auckland have released their findings after research over the past few years.
The project used microscopic techniques to sample fossilised faeces dating back more than 1500 years. Of the 16 original parasite taxa, nine disappeared before the 1990s, when the endangered parrot came under full-population management, and another four have been recorded as lost in the period since.
"Despite their sometimes negative portrayal, parasites are increasingly appreciated for their ecological importance," University of Adelaide’s Dr Jamie Wood, who contributed to the study, published in Current Biology, said.
"Parasites are among the planet’s most ubiquitous, successful and species-rich groups of organisms, and nearly all free-living species harbour some parasites. They may help with immune system development and compete to exclude foreign parasites that may be more harmful to their hosts," Dr Wood said.
"However, the dependence of parasites on living hosts may make them susceptible to extinction, especially as many parasites live with just one host species."
An extinction of a parasite that occurs in tandem with its host is known as a secondary extinction or a co-extinction, and it often happens at a faster rate than for the host animal.
"Predictive models indicate that parasites may go extinct before their hosts during the co-extinction process as opportunities to transmit between host individuals diminish.
"As a result, faunal declines may have a lasting impact on parasite communities, even if host populations eventually recover.
"Dependent species, like parasites, are rarely preserved or documented prior to their extinction, and so until now we have had few data to indicate the actual scale of the co-extinction process.
"Our new research indicates that parasite extinctions may be far more prevalent than previous estimates suggest, with unknown impacts on their hosts and their ecosystems."
Lead author Alexander Boast, from Manaaki Whenua-Landcare Research, was surprised at the degree of parasite loss.
"The level of parasite loss in kākāpō was greater than we had expected and very few parasite species were found in both ancient and modern kākāpō populations. Thus, it seems that endangered species everywhere may possess fractions of their original parasite communities," he said.
As the world looks at the effects of biodiversity loss, Dr Wood said due attention should also be given to parasitic life.
"Global rates of climate change, ecosystem modification and biodiversity decline continue to rise, which means there is an increasingly urgent need to recognise and understand the downstream impacts on dependent species, such as parasites, mutualists or predators," he said.
"Documenting parasite extinction, how quickly it can unfold, and estimating the number of presently threatened parasites are key first steps toward a ‘global parasite conservation plan’ and supporting informed predictions for past, present and future parasite losses." — Allied Media
