Bocas del Toro Research Station

Research Projects

Molly Cummings and Martine Maan

Molly and Martine

University of Texas at Austin; Section of Integrative Biology

Poison or passion: warning and attraction in a color polymorphic frog

Poison frogs are among the most colorful animals known. These colors make it easy for predators to remember that they are toxic and should be avoided. To enhance this message, toxic animals often use the same color; thereby making predator learning easy. The strawberry poison frog, Dendrobates pumilio, forms a spectacular exception to this rule: in the Bocas del Toro archipelago, this frog shows extreme color variation, ranging from red to orange to yellow to blue. Sometimes this variation exists between islands, and sometimes within islands. Such polymorphism is unusual for an aposematic species, and we are investigating the roles of natural and sexual selection in the evolution and maintenance of this variation.

Earlier research, by former STRI fellow Dr. Kyle Summers, suggested that colors are important in mate choice in this system. We are currently examining the possibility that sexual selection plays an important role in the divergence of morphs by testing female preferences in several populations. Are females selecting for brighter males? Or have specific color preferences? Or do they tolerate novel color morphs? We are also examining the underlying mechanism behind any potential biases by measuring the visual pigment expression across the populations.

Female color preferences may differ between islands because of sensory biases, microhabitat differences, or variation in predator communities. To distinguish these possibilities, we analyze predator distribution, ambient light spectra, vegetation, microhabitat selection and frog visual properties in the different populations. We are also studying the relationship between color pattern and toxicity across islands.

Finally, we study the extent to which color divergence is facilitated by predator avoidance behavior: when predators are familiar with one toxic color morph, they may generalize their avoidance to other color morphs as well. This mechanism would greatly facilitate the evolution of different color morphologies. We study this phenomenon by exposing chickens from different islands, familiar with their local frog phenotype, to color morphs that they have never seen before.

Frog Photos: Clockwise from Top Right: Dr. Martine Maan and assistant Ashley Lamb measuring D. pumilio in the lab, Angie Estrada (STRI intern) conducting predator surveys in the field, Light measurement equipment, Dr. Molly Cummings in the chicken coop, Dendrobates pumilio color morphs in the Bocas del Toro Archipelago: Isla Popa, Aguacate, and Isla Bastimentos.

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