As today is Earth Day (April 22, 2012), I decided to focus this post on the importance of amphibians to people today. Historically, amphibians are significant in that they are believed to have been among the first vertebrates to leave the water. The evidence for this can be seen in the fact that many amphibians are still completely dependent on water sources for life and reproduction. Today there is still a lot of work to be done on figuring out the evolutionary relationships between the vast diversity of amphibians. For example, a frog known as the Hourglass Treefrog (Dendropsophus ebraccatus) was found by Justin Touchon of the Smithsonian Tropical Research Institute to be able to lay its gelatinous eggs both in water and on land. This demonstrates a phenotypic plasticity in this species as far as reproduction, meaning that the female frog may deposit her eggs in different locations depending on the environmental conditions. Many species of amphibians are also able to reproduce entirely independently of water, such as the lungless plethodontid salamanders. The factors going into the evolution of terrestrial breeding are still being actively investigated.
Traditionally frogs have been important to human society as a food source in some indigenous diets. Today frog legs are eaten as a delicacy in countries such as France and the United States. Frogs are also ecologically useful in their own eating habits, since many amphibians feed on pest insects such as mosquitoes and flies. However, one of the most important contributions that frogs make for people today is in the medical field. Many amphibians naturally produce antimicrobial or antifungal peptides in their skin that can be isolated to provide new antibiotics. Frogs such as the African Clawed Frog (Xenopus laevis) also provide a good organismal model for studying developmental or hormonal processes.
However, probably the most current way in which frogs are important to human society is as environmental indicators. Malformed frogs can serve as a warning that there is something contaminating the environment that might be harmful to people. Malformations in frogs are known to be caused by either trematodes, retinoids, chemical contaminants or UV-B radiation. Sex changes in frogs may also be induced by harmful chemicals, such as the herbicide “Atrazine”, which has been shown to be able to change genetic male Xenopus laevis into females.
Ending this post, I would like to remind everyone that this Saturday (April 28th) is Save the Frogs Day. If anyone is in Blacksburg, VA this weekend, I would encourage you to come out to the Price House Blacksburg Nature Center on Saturday for some fun activities such as origami frogs and a live animal presentation on amphibian conservation. There will also be a raffle for some small handknit frogs, with proceeds going to benefit the Panama Amphibian Rescue and Conservation project. You can also enter or donate to the raffle on Thursday, April 26th from 2-4 p.m. in front of Pamplin Hall on Virginia Tech campus. Thanks, and Happy Earth Day!