New York Times: In the scientific equivalent of the board game Clue, teams of biologists have been sifting spotty evidence and pointing to various culprits in the widespread vanishing of harlequin frogs. The amphibians, of the genus Atelopus – actually toads despite their common name – once hopped in great numbers along stream banks on misty slopes from the Andes to Costa Rica. After 20 years of die-offs, they are listed as critically endangered by conservation groups and are mainly seen in …