Scientists have found that a newly identified and highly infectious
tadpole1 disease is found in a diverse range of frog populations across the world. The discovery sheds new light on some of the threats facing fragile frog populations, which are in decline worldwide. The study, published in the
Proceedings2 of the National Academy of Sciences journal, led by the University of Exeter and the Natural History Museum, describes the
molecular3 methods used to test frog
tadpoles4 for a newly identified infectious agent.
Tadpoles from six countries across three continents were tested for 'protists' - single celled microbes with complex cells which store their
DNA5 in a
nucleus6, like human cells. The
previously7 unidentified
parasite8 was present in tadpole livers in both tropical and
temperate9 sites, and across all continents tested. The infectious agent was identified as a distant relative of Perkinsea sp., a
marine10 parasites11 found in animals and
algae12.
Professor Thomas Richards from the University of Exeter said: "Global frog populations are suffering serious declines and infectious disease has been shown to be a significant factor. Our work has revealed a previously unidentified microbial group that infects tadpole livers in frog populations across the globe."
"We now need to figure out if this novel microbe - a distant relative of
oyster13 parasites - causes significant disease and could be contributing to the frog population declines."
It is widely recognised that
amphibians15 are among the most threatened animal groups: for example, in 2008, 32% of species were listed as 'threatened or extinct' and 42% were listed as in decline. The decline of
amphibian14 populations, particularly frogs, is thought to suggest that Earth is currently undergoing a sixth mass
extinction16 event.