1) Evolution only applies if the frog goes on to successfully reproduce.
2) I think natural selection would favor frogs who are smart enough not to get trapped in a walk-in freezer.
3) There is a protist called
mixotricha paradoxa that is found only in the digestive system of a species of termites in Darwin, Australia (
mastotermes darwiniensis), that is a far cooler example of evolution (and specifically endosymbiosis, the process by means of which mitochondria and cellular nuclei are believed to have evolved). On the cell membrane of this protist, you can find three types of single-celled organisms that are only known to occur on the cell membranes of this protist. Altogether,
M. paradoxa incorporates four distinct species of bacteria into its physiology. Unlike animals (who have a measly two genomes) and plants (who have only three),
M. paradoxa has five genomes.