Eat or be eaten

Scoop a fishing net into one of the ponds at RMBLS’s Mexican Cut Nature Preserve, and you can easily come up with more than one tiger salamander. But there’s no guarantee that any two individuals will look the same. From the beginning of their lives, tiger salamanders — the only salamander native to Colorado — can choose different life journeys. In the first months of life, a hatchling can transition from a typical morphology into a wide-mouthed cannibal morphology and eat other hatchlings. Then, as it matures, it can either metamorphose into a terrestrial adult, or, in ponds that don’t dry up, stay in the water and mature as a gilled aquatic adult, or paedomorph. What’s more, this paedomorph will feed on hatchlings if given the chance.

It’s this variation in lifestyles — aquatic, terrestrial, cannibalistic, or not — that has kept biologists entranced with these salamanders for decades. Dr. Howard Whiteman of Murray State University in Kentucky has studied RMBL’s tiger salamanders for 31 years. In the summer of 2018, he collaborated with Scott Thomas, then a PhD student at The University of Akron in Ohio, on some experiments to study how the cannibalism of adults on hatchlings varied with things like body size and food availability. Scott returned the following summer, completed his PhD, and then received a postdoctoral fellowship from the National Science Foundation. He’s thoroughly smitten with salamanders.