Altitudinal Variation in Digestive Tract Length in Yunnan Pond Frog (Pelophylax pleuraden)

Abstract The digestive tract plays an important role in digestion and the acquisition of food energy. Understanding the impact of abiotic environments on digestive tract morphology is especially important for evolution of digestive tract across different environments. Here, we investigated altitudinal variation in digestive tract length in the Yunnan Pond Frog ( Pelophylax pleuraden ) across five populations ranging from 1413 m to 1935 m a.s.l. in Ningnan County, Sichuan province in western China. Frogs were collected during the breeding season, from 1–5 June 2012. Our results revealed that females had longer digestive tract and relative digestive tract ( i.e. digestive tract length / body size) lengths in com-parison to males, on average, but the differences between them decreased with increasing altitude. Digestive tract and relative digestive tract lengths increased with increasing altitude suggesting that a higher proportion of indigestible ma-terials may be consumed at high-altitude sites and result in a relative increase in digestive tract dimensions.