What is dart frog toxin, which is said to have been used to kill Alexei Navalny?

Epibatidine is about 100 times more potent than morphine, and derived from frogs native to South America

• Russia killed Alexei Navalny with frog toxin, UK and four European allies say

Epibatidine, the dart frog toxin Britain says was used to kill Alexei Navalny, is about 100 times more potent than morphine.

The extremely toxic, nicotine-like substance was first derived from the Epipedobates genus of poison dart frogs native to northern South America - which are not found naturally in Russia.