Tonight I saw an excellent episode of PBS's Nature entitled Frogs: The Thin Green Line. It touched on how frogs, despite being on this planet for more than 250 million years (!) are now in decline - their adaptations failing them in the face of global warming and modern day chemicals infiltrating their habitat. Here is a link to the PBS website for the episode, which has a really informative written introduction of the episode. You can also watch it online.
Also, there are some interesting links posted therein about how chemicals from industrial agriculture affect the food chain, and ultimately us. In the episode several populations of frogs were mentioned that are becoming feminized from the chemicals in the water. One particular chemical used commonly in agriculture was found in concentrations three times LESS than what is allowed in drinking water and was still strong enough to cause male frogs to grow eggs in their testes.