Publication Date



Northern leopard frog; Animals--Abnormalities; Natural selection


In a population of immature leopard frogs (Rana pipiens) at Mud Lake, Washington County, Minnesota, a high frequency of unilateral deformity of the hind legs was observed in 1965. Metamorphosis from tadpole to frog took place during July, and samples in late July averaged 14.8% deformed frogs. By late September, the frequency of deformed frogs had decreased to 3.6%, presumably as the result of natural selection.

First Page


Last Page


Included in

Zoology Commons



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.