The droppings of ancient kakapos revealed a startling fact: More than 80 percent of the parasites in the birds have disappeared. This "co-extinction" suggests that as endangered animals struggle to survive, their tiny parasitic companions are often the first to disappear.
Researchers found that more than 80% of the parasites detected in kakapo feces before the 1990s are no longer present in contemporary kakapo populations. Photo credit: Chris Birmingham
Researchers from the University of Adelaide, New Zealand's Manaaki Whenua-Landcare Research Center and the University of Auckland found that more than 80 per cent of parasites detected in kakapo faeces before the 1990s are no longer present in contemporary kakapo populations.
The project, which used ancient DNA and microscopy techniques to sample feces dating back more than 1,500 years, found that nine of the 16 original parasite taxa disappeared before the endangered parrots came under comprehensive population management in the 1990s, and four more were recorded disappearing during this period.
"Although parasites are sometimes portrayed in a negative light, their ecological importance is increasingly recognized," said Dr Jamie Wood of the University of Adelaide, who was involved in the study published in Current Biology.
Parasites are one of the most ubiquitous, successful, and species-rich groups of organisms on Earth, with nearly all free-living species harboring some parasite. They may contribute to the development of the immune system and compete to exclude foreign parasites that may be more harmful to the host.
"However, parasites' dependence on living hosts may leave them vulnerable to extinction, especially as many parasites live with only one host species."
The extinction of a parasite that occurs simultaneously with its host is known as secondary extinction or co-extinction, and often occurs at a faster rate than the host animal.
Dr Wood said: "Predictive models suggest that in a co-extinction process, parasites may become extinct before their hosts because the opportunities for transmission between host individuals are reduced."
"Thus, even if host populations eventually recover, animal declines may have lasting effects on parasite communities. Dependent species, such as parasites, are rarely preserved or documented prior to extinction, so until now we have little data to indicate the actual scale of the co-extinction process. Our new study suggests that parasite extinctions may be more common than previously estimated, and the effects on their hosts and their ecosystems are unclear."
Lead author Alexander Boast from Manaaki Whenua-Landcare Research was surprised by the extent of parasite losses.
"The disappearance of internal parasites in kakapos is greater than we expected, with very few parasite species found in both ancient and modern kakapo populations. Therefore, endangered species around the world may retain only a small fraction of their original parasite communities," he said.
Dr Wood said that when we consider the impacts of biodiversity loss, parasites should also be given their due attention: "Global climate change, ecosystem modifications and rates of biodiversity decline continue to increase, meaning we increasingly need to recognize and understand the downstream impacts on dependent species such as parasites, mutualists or predators." Documenting the rate of parasite extinction and estimating the current numbers of threatened parasites is a critical first step in developing a Global Parasite Conservation Plan, and also supports informed predictions of past, present and future parasite losses. "
Compiled from /scitechdaily