The application of mass spectrometry to the study of evolutionary trends in amphibians

Abstract

The glandular secretions of the skin of Litoria rubella specimens collected from five locations on the eastern seaboard of Queensland (Australia) contain the three tryptophyllin peptides Phe Pro Trp Leu (NH₂), Phe Pro Trp Pro (NH₂) and Phe Pro Phe Pro Trp Leu (NH₂). The relative proportions of these peptides in the glandular secretion are associated with geographic location, i.e. Phe Pro Trp Pro (NH₂) is a minor component of the peptide mixture in frogs from southern Queensland, but becomes significantly more abundant as the location becomes more northerly. This trend indicates an evolutionary change in the animal, but for what reason, and over what timescale is not known at this time.