UNIVERSITY GRADUATE SCHOOL BULLETIN
Master’s Thesis Proposal Seminar
The Relationship Between
Diet and Toxicity in the Strawberry Poison Frog, Dendrobates pumilio
By
Ralph Saporito
Dendrobatids are endemic Neotropical frogs that have an enormous diversity of alkaloids in the skin. Used by frogs in chemical defense against predation and/or microorganisms, these alkaloids represent unique classes of substances whose use in biological research and medicine are unparalleled. Interestingly, most of these alkaloids, as yet, are not known to occur elsewhere in nature. Past research has shown that dendrobatids accumulate alkaloids through diet, and some of these alkaloids have been identified in arthropod prey items. Therefore, it seems likely that dendrobatids obtain these alkaloids from their natural arthropod prey. In addition to this phenomenon, variation in alkaloid profiles within and among populations of the same species of dendrobatid frogs are known to exist in the Bocas del Toro archipelago, Panama. Much of the variation in alkaloid profiles is concentrated in the dendrobatid species Dendrobates pumilio, however little quantitative data exists on the extent of this alkaloid variation in individual frogs, both within and among populations. Explanations for this unusual variation are purely theoretical. Arthropod distributions are known to vary spatially in tropical regions. Therefore, if dendrobatids obtain alkaloids from arthropods, and arthropod distributions vary in space, then the variation seen in alkaloid profiles of D. pumilio may be attributed to the spatial variation of arthropods.
To provide a biological link between alkaloids present in dendrobatid frogs and those present in potential arthropod prey items, alkaloid profiles of the Panamanian species Dendrobates pumilio will be compared to alkaloids found in leaf-litter arthropods at several sites on Isla Bastimentos. In addition, stomach contents will be identified to provide information on arthropods consumed. Variation in individual alkaloid profiles of D. pumilio will be compared within and among populations that are known to contain variation in alkaloid profiles. Alkaloid analysis will employ the use of gas chromatography in conjunction with mass spectrometry and infrared spectroscopy.
Date: May 30, 2002 Department: Biological Sciences
Time: 11:00 a.m. Major Professor: Dr. Maureen A. Donnelly
Place: Wertheim Conservatory