Mongabay: Scientists have yet to conclusively explain the underlying cause of global declines in amphibian populations, according to a study published in the journal Proceedings of the National Academy of Sciences. The research says that two leading theories for the demise of amphibians — both related to the emergence and spread of the deadly chytrid fungus — are not supported by scientific data. The researchers don’t dispute that chytrid is killing amphibians but they say that data does not …