Randolph-Macon College Biology Professor Stephanie Coster is the author of two recently published articles, both of which highlight her research on a species of bird known as a rail.

“With this research, I’ve been involved in a range of experiences—from midnight runs on an airboat zooming through marshes and using special infrared cameras to see the warm bodies of sleeping birds to capture for feather sampling, through long hours in the lab and at the computer analyzing their DNA,” she says.

Connected Populations
The first article, “Gene flow connects coastal populations of a habitat specialist, the Clapper Rail Rallus Crepitans,” was published in IBIS: The International Journal of Avian Science.
The paper focuses on different populations of clapper rails across the Atlantic coast and uses genetic techniques to explore how connected these populations are.

“Clapper rails are habitat specialists that only live in brackish or salt water marshes, and they are hard to see or capture, which makes them hard to monitor,” explains Coster. “Because marshes are patchily distributed and make up a small portion of the coastline, we were interested to see whether the populations are isolated enough to make them genetically distinct and therefore potentially vulnerable to decline in the face of climate change, or if the populations are mixing freely and perhaps more resilient in the face of climate change.”

After sampling individuals from New Jersey through Georgia (including two Virginia populations), Coster found that the populations are highly connected through gene flow.

“I hypothesize that this connectivity is due to their high mobility (in that they can fly) and behavior that promotes limited mixing between marshes,” she says. “Ultimately this analysis bodes well for the conservation of clapper rails, in that although their habitat may be under threat, their genetic make-up is well poised for resilience.”

Evidence of Hybridization
Coster’s second paper, “Genetic analyses reveal cryptic introgression in secretive marsh bird populations,” was published in Ecology and Evolution. The paper explores whether there is hybridization between two related and difficult-to-distinguish rail species (the king and clapper rail) in coastal Virginia.

“While clapper rails are common in Virginia, king rails are in decline and identified by the state as a ‘species of greater conservation need,'” says Coster. “It is well known that the king and the clapper rail can hybridize, which makes it challenging to protect the declining species. My research looked at two clapper rail populations in Virginia to see if there was genetic evidence of hybridization. We found there was evidence of hybridization, and the genetic signature in combination with ecological records suggest that clapper rails may be displacing king rails in the area because they do better in saltier environments. This suggests that continued monitoring is needed to track these populations and inform possible management strategies.”

Stephanie Coster
Coster, who joined the RMC faculty in 2016, earned her B.S. at Trinity University and her M.S. and Ph.D. at University of New Hampshire. A molecular ecologist, Coster uses genetic approaches to help answer ecological questions and facilitate the conservation and management of wildlife populations. She teaches two courses at RMC: Integrative Biology I; and Evolution.