Dietary source for skin alkaloids of dendrobatid poison frogs

Baškiera, Senka (2010) Dietary source for skin alkaloids of dendrobatid poison frogs. Bachelor's thesis, Faculty of Science > Department of Biology.

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Abstract

Dendrobatid frogs contain a variety of poisonous alkaloids in the skin glands. These alkaloids were initially considered to be synthesized by these frogs, but later studies showed they were actually of dietary origin. There were many research efforts to test the dietary hypothesis. Such work included placing frogs into outdoor cage with a diet of only fruit flies. The occurrence of alkaloids in skin extracts from these captive-raised frogs was very low. Another group of captive-raised frogs placed in outdoor screened cage, but provided with fresh leaf litter gathered from the area where these frogs were common, showed different alkaloid profile. And as expected, wild-caught frogs contained all alkaloids known to that species. Frogs raised in large glass terrarium, isolated entirely from natural surroundings, had no detectable alkaloids in the skin extracts. All of the results were as expected from previous studies and consistent with a given hypothesis. Dendrobatid frogs consume a high proportion of ants as part of their diet in the wild. Using gas chromatographic-mass spectral analysis, many tests were made on a variety of dendrobatid frog species to find a connection between formicine ants and these frogs. That connection was found in the presence of pumiliotoxins in both groups. Pumiliotoxins were detected in ants of the genera Brachymyrmex and Paratrechina. The presence of pumiliotoxins in these ants as well as in skin extracts of the dendrobatid frog Dendrobates pumilio, coupled with the presence of these ants in stomach contents of Dendrobates pumilio, strongly suggests that these ants represent a dietary source for pumiliotoxins in these populations of frogs. Based on results of all research it can be said that arthropods are the source of poison alkaloids in dendrobatid frogs and that their amount and variety is determined only by the availability of those arthropods in their environment. A comparative approach was used to test a prediction of the hypothesis of aposematism: coloration will evolve in tandem with toxicity. And it's the combination of two that allows them to have a diurnal lifestyle and to live carelessly, freed from any fear of predation. This made them to be very successful and well adapted species.

Item Type: Thesis (Bachelor's thesis)
Supervisor: Mrakovčić, Milorad
Date: 2010
Number of Pages: 19
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 03 Dec 2014 10:07
Last Modified: 03 Dec 2014 10:07
URI: http://digre.pmf.unizg.hr/id/eprint/3422

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