Thursday, January 3, 2013

Frogs in peril

Pristimantis museosus (credit Brad Wilson)
one of three out of ten species showing cryptic diversity
There is no doubt that amphibians currently are among the most endangered groups of animals on our planet. 41% of the species throughout the world are threatened. The most insidious and as yet unstoppable agent of amphibian decline is a pathogenic chytrid fungus, Batrachochytrium dendrobatidis.

It infects epidermal cells of its host and often causes death by inhibition of the electrolyte transport. In Central America, this fungus advances in an easterly-moving wave, with the most severe consequences at higher elevation. For example the highland frog faunas of western and central Panama have declined dramatically whereas eastern Panama faunas still seem to be abundant and diverse.

For critically endangered species, captive breeding seems to be a reasonable intervention and represents a short-term attempt to prevent extinction. As a consequence an international consortium of zoos and conservation organizations started an effort to begin captive breeding of many species of frogs from Central Panama. Despite the fact that the number and the rate of new species descriptions per year has been increasing in the past years, the current taxonomic knowledge of amphibians does not represent the true diversity of independent evolutionary lineages. As a result, species’ endangerment may be underestimated and management efforts may unknowingly overlook cryptic species. Frogs that were collected from various locations in an effort to capture a representative sample of genetic diversity of a species may harbor cryptic lineages. 

In a recent study a group of researchers from Columbia, Panama and the US used DNA Barcoding to survey variation in captive populations of 10 species of Neotropical amphibians maintained in a captive breeding program.They found that three of ten species showed substantial cryptic genetic diversity within the breeding program. But as this wasn't enough an additional three species showed cryptic diversity among wild populations, but not in captivity. As careful scientists they did not call these lineages species yet but this study shows that such conservation efforts are vulnerable to incomplete taxonomy. They recommend DNA Barcoding as simple tool to identify cryptic diversity and thereby improving conservation efforts.

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