The ability to acquire chemical defenses through the diet has evolved across several major taxa. Chemically defended organisms may need to balance chemical defense acquisition and nutritional quality of prey items. However, these dietary preferences and potential trade-offs are rarely considered in the framework of diet-derived defenses. Poison frogs (Family Dendrobatidae) acquire defensive alkaloids from their arthropod diet of ants and mites, although their dietary preferences have never been investigated. We conducted prey preference assays with the Dyeing Poison frog (Dendrobates tinctorius) to test the hypothesis that alkaloid load and prey traits influence frog dietary preferences. We tested size preferences (big versus small) within each of four prey groups (ants, beetles, flies, and fly larvae) and found that frogs preferred interacting with smaller prey items of the fly and beetle groups. Frog taxonomic prey preferences were also tested as we experimentally increased their chemical defense load by feeding frogs decahydroquinoline, an alkaloid compound similar to those naturally found in their diet. Contrary to our expectations, overall preferences did not change during alkaloid consumption, as frogs across groups preferred fly larvae over other prey. Finally, we assessed the protein and lipid content of prey items and found that small ants have the highest lipid content while large fly larvae have the highest protein content. Our results suggest that consideration of toxicity and prey nutritional value are important factors in understanding the evolution of acquired chemical defenses and niche partitioning as a whole.

All behavioral data were collected using a GoPro camera, and then analyzed in Boris behavioral software.

Lipid data from all arthropod groups were collected via ether-soluble lipid extraction. The differences between lipid-containing and lipid-free weight (post extraction) were converted to proportions in order to calculate an approximation of organismal lipid percentage.

Protein data from all arthropod groups were collected via a protein extraction and Bradford assay, which was done using a plate reader. These numbers were standardized by dividing sample weight in order to calculate an approximation of micrograms of protein per milliliter.

Alkaloid data from frogs was collected by using an electronic pulse stimulator on the ventral skin of live frogs for 30s. Skin secretions were wiped with a lint-free cloth and stored in methanol. These methanol alkaloid extracts were run using liquid chromatography/mass-spectrometry. Raw files can be opened using the software XCalibur. MSConvert was used to generate mzML files, a vendor-neutral, non-proprietary format.

Microsoft Excel can open the spreadsheets (.xlsx).

Many programs can open .csv files, like Microsoft Excel.

Mass spectrometry files can be opened with XCalibur (.raw files) or a program that can open XML files (.mzML).