When Sophia Zaslow taps a tiny salamander with a paintbrush on a wooden track in the New Hampshire forest, she's asking a deceptively simple question: Does color predict speed?
The Binghamton University doctoral student has spent years pursuing this puzzle, conducting sprint trials on eastern red-backed salamanders to understand whether the vibrant stripe running along their backs—or lack thereof—correlates with how fast they can escape danger. It's a question that matters because it gets at something fundamental about how animals evolve: whether the traits we see on the outside tell us something true about what's happening on the inside.
Eastern red-backed salamanders come in three visually distinct varieties, or "morphs." There's the standard form with that signature red stripe running head to tail, a "lead" variant that's uniformly slate gray without any stripe, and a rare fully red-orange form. Within the red-striped morph, Zaslow noticed something intriguing: the stripe color varied considerably from individual to individual. If those color differences carried any physiological advantage, sprint speed would reveal it.
Her undergraduate research, which appears in the Canadian Journal of Zoology and was co-authored with Lindsey Swierk of Binghamton University and David S. Steinberg of the University of New Hampshire, describes a meticulous process. Zaslow gathered salamanders from three New Hampshire locations: the Binghamton campus nature preserve, another woodland site two hours north, and a third site two hours west. She placed each salamander on the end of her wooden performance track, tapped it gently with a paintbrush, and let it run to the best of its ability. A damp piece of paper kept the creatures from drying out. Distance markers on the track allowed her to measure exactly how far each animal sprinted before stopping.
What she found was surprising in its nuance. On the campus site, color and speed showed no correlation whatsoever. But at the northern location, salamanders with brighter red stripes were significantly faster. At the western site, the relationship reversed—the pattern went in the opposite direction entirely. Rather than suggesting that coloration drives speed, these results hint at something more complex: the salamanders' environment shapes the rules.
Zaslow and her team speculate that resource availability or predation pressure at each site may determine how much it matters to sprint quickly. In one habitat, speed pays off; in another, a different strategy wins. This reveals something profound about evolution: the same trait can be advantageous or disadvantageous depending on where you live.
Now pursuing her doctoral research in the Broome County area, Zaslow continues to study the red-backed salamander. She's planning behavioral trials that track not just sprint speed but respiration rates as a proxy for metabolism. She's also curious about something few researchers have examined: how these salamanders change as they age. Newly hatched salamanders have solid, bright red stripes, but Zaslow wonders whether color fades as the animals mature—and whether physiology changes in tandem. After all, red-backed salamanders are surprisingly long-lived for such tiny creatures, reaching eight or nine years old, and like all animals, they slow down with age.
In pursuing these questions, Zaslow is learning that even a creature small enough to fit in your palm holds secrets worth uncovering.