Saturday, October 3, 2015

Color my world

It’s one thing to read about something in from a textbook, and another to see it unfold before your very eyes. Indeed, the past month spent in Costa Rica can be summarized as a first-hand journey of exploring the encyclopedia of life.
Step into the forest and perhaps what strikes you immediately is a tapestry of various hues and shades of green. Yet, if one takes a closer look, a wide spectrum of different colors begins to emerge beyond the sea of green – a dot of red here, a line of yellow there, a flash of blue in the distance. Nature has an interesting way of playing with colors, especially so in the rain forest. For some organisms, it is part of a fashion show, attracting attention from potential mates, pollinators and dispersers. For others, it becomes part of their camouflage, allowing them to blend seamlessly with the background, evading the watchful eyes of predators. Yet for a group of somewhat eccentric creatures, evolution has enabled them to use coloration as a warning signal, a beacon that says – don’t try to mess with me or you’ll be in for a bad time.
            A classic example of warning coloration or aposematism is the Poison Dart Frog. Fortunately for us, two species of dart frogs call La Selva home – the Strawberry Poison Dart Frog (Oophaga pumilio), and the Green and Black Poison Dart Frog (Denbrobates auratus). Intrigued by these beautiful amphibians, two of my course mates (Jeanne & Mackenzie) and I were interested to know how aposematic coloration, and to a larger extent novel phenotypes and coloration, may affect predation on and consequently establishment of an organism in a community. With a constraint on time, we decided to work with a simpler model that employed similar anti-predatory techniques and settled on Lepidopteran larvae. Following predation experiment protocols in scientific literature, we manufactured 600 model caterpillars of three different designs, stepped out of the comforts of our air-conditioned computer room into the warm and humid forest, and exposed them to the predators of La Selva. 24 hours later, we collected the models and analyzed impressions left on them to identify the predators. After hours of looking for bite marks, and recording predation rates of the different designs, we were surprised to find similar predation rates across the different designs, contrary to our hypothesis. This confounded us until a discussion with faculty highlighted that we did not account for how different the designs were in terms of conspicuousness. After making this correction, we finally saw evidences of predators avoiding novel and aposematic prey – a biological phenomenon learned in books transpiring right before our very eyes.  

Field experience under the belt, interesting results collected, and watching one of nature’s secrets unfold, I can’t think of a better way to wrap up our time in La Selva. I am definitely looking forward to the remainder of the semester that lies ahead.
Donovan Loh
Duke University

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