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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Alkaloid Variation and its Relationship to Dietary Arthropods in Dendrobates pumilio on Isla Bastimentos, Bocas del Toro Province, Panama

EPA Grant Number: U916080
Title: Alkaloid Variation and its Relationship to Dietary Arthropods in Dendrobates pumilio on Isla Bastimentos, Bocas del Toro Province, Panama
Investigators: Saporito, Ralph A.
Institution: Florida International University
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 2002 through January 1, 2004
Project Amount: $53,687
RFA: Minority Academic Institutions (MAI) Fellowships for Graduate Environmental Study (2002)
Research Category: Biology/Life Sciences , Academic Fellowships , Fellowship - Natural and Life Sciences

Description:

Objective:

A remarkable diversity of lipophilic alkaloids are present in the skin of poisonous frogs and toads worldwide. Originally discovered in neotropical dendrobatid frogs, these alkaloids are now known from mantellid frogs of Madagascar, certain myobatrachid frogs of Australia, and several bufonid toads of South America. These alkaloids appear to be sequestered from a variety of alkaloid-containing arthropods, and they presumably are active as a passive chemical defense against predation and/or microorganisms. The objective of this research project is to examine the degree of spatial and temporal variation in alkaloid profiles in Dendrobates pumilio.

Approach:

Alkaloid profiles are known to vary significantly in the species D. pumilio on Isla Bastimentos, Bocas del Toro Province, Panama. Although alkaloid variability has been shown to exist in this species, relatively few studies have specifically addressed the degree of spatial and temporal variation in alkaloid profiles. To assess the level of alkaloid variation in dendrobatid frogs, alkaloid profiles were constructed for D. pumilio from 13 different sites on the northwestern coast of Isla Bastimentos in 2003, for comparison with the same sites examined in 2000. Furthermore, to accurately evaluate the extent of alkaloid variation within a single site, alkaloid profiles were created for individual frogs within these same 13 sites during 2003.

Temporal and spatial variation in populations of leaf-litter arthropods is known to exist in neotropical forests, and population sizes are known to vary seasonally. Given that diet is related to toxicity in dendrobatid frogs, differences in alkaloid profiles on such small spatial and temporal scales may suggest that the availability of alkaloid-containing arthropod prey items is responsible for the variability observed in alkaloid profiles. To assess the role of dietary variation as it relates to alkaloid variation, stomach contents of D. pumilio will be identified and compared among 4 of the 13 sites in which alkaloid variation is greatest. To provide a biological link between the alkaloids present in D. pumilio and those present in potential arthropod prey items, frog alkaloid profiles will be compared to alkaloids found in leaf-litter arthropods at the same 13 sites. From past data, I expect that alkaloid profiles will vary among all sites, both within and between years. In addition, I anticipate that alkaloid variation within a single site will be lower than the variation among all sites.

Supplemental Keywords:

fellowship, alkaloid variation, dietary arthropods, Dendrobates pumilio, spatial and temporal variation, Panama, alkaloid profiles.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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