Population Genetics - what's the best aproach to save frogs?

Batrachochytrium dendrobatidis (frog chytrid fungus) is a parasitic fungus associated with the major decline in amphibian populations in Australia (and the world). First reported in 1998, it’s the only known chytrid to be parasitic to vertebrates. It grows in keratinised cells.
The fungus is thought to be transferred by direct
contact between frogs and tadpoles. Chytrid spread is considered a major environmental disaster for Australian and world frog populations.

Appropriate and effective response requires understanding if the spread of the fungus is due to emergence of pathogenic clones or environmentally determined increase in fungus populations. Determining genetic structure of the fungus and environmental variables will provide direction to the predominant hypothesis and therefore targeted response.

Genetic sequencing provides both framework and answers in international studies that have been struggling with this pathogen, its speed of spread and how it kills frogs. Thirty-five strains of the fungus from 19 species were DNA harvested and a (incomplete) genomic library was established representing 3 continents and including 33 clone sequences.

Low level genetic variation within intercontinental samples was determined where strains evaluated have the genetic signature of a newly emerged pathogen. There is an implication that coalescence time of the entire sample is relatively recent and few mutations have occurred. The study on the affect of the fungus on frogs indicates the recent introduction of the pathogen. Genotypes of frogs are similar in populations where the fungus does and dosen’t spread.

Neither epidemic spread nor endemism explains the problem which means complicated global fungus control problems in the future.



Primary Reference:
Morehouse, E.A., James, T.Y., Ganley, A.R.D., Vilgalys, R., Berger, L., Murphey, P.J. and Longcore, J.E.. (2003) Multilocus sequence typing suggests the chytrid pathogen of amphibians is a recently emerged clone. Molecular Biology 12, 395-403

http://www.blackwell-synergy.com.ezproxy.library.uq.edu.au/doi/pdf/10.1046/j.1365-294X.2003.01732.x
Secondary References:
Laurance, W.F.. (2008) Global warming and amphibian extinctions in eastern Australia. Austral Ecology 33, 1-9
Rachowicz, L.J., Hero, J.M., Alford, R.A., Taylor, J.W., Morgan, J.A.T., Vredenburg, V.T., Collins, J.P. and Briggs, C.. (2005) The Novel and Endemic Pathogen Hypotheses: Competing Explanations for the Origin of Emerging Infectious Diseases of Wildlife. Conservation Biology 19, 5. 1441-1448
Background:
http://en.wikipedia.org/wiki/Population_genetics
http://en.wikipedia.org/wiki/Ecological_genetics
Graphic:
http://www.e-pond.info/green_tree_frog_pictures.html M. Avery