The conditional benefits of cannibalism for wood frog tadpoles (lithobates sylvaticus)

Abstract

Wood frog tadpoles have an incredible ability to rapidly adapt to changing conditions, and when population densities become high tadpoles often become cannibalistic. Cannibalism potentially represents an ideal diet by composition, and should be beneficial to the growth and development of cannibalistic individuals. To test the relative efficacy of cannibalism to growth and development we conducted multiple feeding experiments. Results indicate that cannibalism represents a better alternative to starvation and provides some benefit to development and survival of tadpoles over low quality diets. However, cannibalism can be detrimental to tadpole growth and/or develop­ment relative to diets of similar protein content. Additionally, tadpoles raised individually appear to initially avoid consuming the cannibalistic diet, and may continue to do so until they face the risk of starvation. Conversely, when tadpoles were raised in groups providing them with compe­tition, they immediately fed upon the cannibal diet. Our results suggest that competition, rather than dietary quality is likely the driving force behind cannibalistic behaviour unless tadpoles oth­erwise face the risk of starvation.