Distribution of colour and pattern polymorphism in montane frogs of Sri Lanka

Abstract

Amphibian body colouration and pigment patterns play a vital role on their survival in the environment. Anuran polymorphism were studied in and around the five lentic water bodies of within and outside the Horton Plains National Park from January 2017 to November 2017 on three consecutive days per month. A total number of 694 amphibians, belonging to 3 families and 11 species were recorded during the study. Colour polymorphism were recorded only in Taruga eques, in this species six and three dorsal colours were recorded respectively within and outside the park. The most prevalent dorsal colourations of Taruga eques were Green and Dark brown. Distinct hour glass pattern was the highest prevalent pattern polymorphism of Taruga eques irrespective to the locality type. Moreover, three different dorsal patterns were recorded in Minervarya greenii. The present study indicated that endemic Taruga eques possess diverse colour and pattern polymorphism as other tree frogs in the world. Most of the recorded polymorphism in the present study were not previously recorded in Taruga eques and Minervarya greenii. Presence of dorsal pigment patterns may be a selective advantage for amphibians, specifically for tree frogs which may disrupt the expression of bright dorsal colouration for visually oriented predators. However, further field studies are warranted to understand the selective advantages of polymorphism in amphibians