3. Florida panthers used to range throughout the Southeast United States, but hunting and habitat destruction have reduced their numbers to only a few hundred individuals. Florida panthers have a number of genetic conditions, including heart defects and poor sperm quality. Pufferfish, blue-ringed octopus, and some species of salamanders all produce tetrodotoxin, a molecule that binds to Na+channels and inhibits the nervous systems of animals. However, scientists have found that the DNA in some species of garter snakes (which eat salamanders) have a different sequence of nucleotides in their Na+channel genes. These alternate alleles result in a slightly differently shaped Na+ channels, which don't bind well to tetrodotoxin. These alleles can be found in most garter snake populations, but are usually extremely uncommon. However, a new population of garter snakes has recently been established in habitat containing tetrodotoxin- producing salamanders..