Mutualistic effects of the nematode Gyrinicola batrachiensis on the development and gut morphology of Green frog, Rana clamitans, tadpoles

Abstract

The nematode Gyrinicola batrachiensis (order Oxyuroidea) is known to infect the posterior end of the gastrointestinal tract of tadpoles of eight North American anurans, including bull frogs (Rana catesbeiana) and green frogs (Rana clamitans) (Bolek and Rhoden, 2011). Gregory Pryor and Karen Bjorndal describe a novel mutualistic relationship between G. batrachiensis and host bull frog tadpoles. Infection of G. batrachiensis has been shown to increase development rate and decrease time taken to reach metamorphosis in bull frog tadpoles. The increase in development rate is attributed to an alteration of gut morphology and gut fermentation rates in the gut of bull frog tadpoles (Bjorndal and Pryor, 2005). This study investigates the relationship between G. batrachiensis and host green frog tadpoles to see if they share a similar mutualistic relationship as bull frogs and the nematode. Green frog tadpoles were raised in an enclosed setting in Source Pond at the Kalamazoo Nature Center and comparisons of development rate, body size, and gut morphology were made between uninfected tadpoles and tadpoles infected with G. batrachiensis. Infected tadpoles developed at a faster rate than their uninfected counterparts. Infected tadpoles also had wider colons than uninfected tadpoles which is congruent with the effects of G. batrachiensis on bull frog tadpoles. These findings show that green frog tadpoles reap similar ecological and evolutionary advantages from harboring G. batrachiensis as bull frog tadpoles. The novel mutualism described by Gregory Pryor and Karen Bjorndal furthers our understanding of the diversity and physiological contributions of fermentative gut symbionts (Bjomdal and Pryor, 2005). This study confirms that the mechanism of the mutualistic relationship is consistent between ranid species with tadpoles that harbor the nematode and nulls the hypothesis that one species may have an advantage over another.