It’s the day before Christmas, and Barbara Shields has just wrapped up the last of five grant proposals she is writing. The OSU professor is busy cobbling together funding to study the genetics of bulltrout, a species of special concern in Oregon’s mountain streams.
This is just one of many directions Shields’s research has taken her since she joined the OSU faculty four years ago.
Barbara Shields collects fish near Corvallis with students Benjamin Dotson, left, and Joseph Feldhaus. Photo: Steve Dodrill
As a fisheries geneticist, Shields is interested in understanding how nature and nurture interact in native fish populations. Why do some species fail and others thrive? Is it genetics or environment?
"The answer," says Shields, "is…yes."
Her work has led her to the pioneering edge of genetics. But it was fish that were her first love. Back home in Nebraska, Shields grew up with a fascination for the cool, slithery things of nature. As a child, she raised garter snakes in a cage her grandfather built for her. She dug gallons of earthworms and captured frogs for her snakes.
But most fondly she remembers fishing with her father, who introduced her to the rich diversity of fish in the rivers and lakes of the Midwest.
"I had an old cane pole, and he showed me how to catch bluegills and sunfish," she remembers. "And he taught me the names of all the fish. There were the everyday minnows and such. And then there were paddlefish, bowfins and garfish, ancient species that lived at the same time as the dinosaurs and have not changed since."
From the beginning, Shields noticed that some species thrive while others disappear.
As an undergraduate at University of Nebraska, Shields had been discouraged from studying fish, an academic interest that was considered just too messy for women. So Shields’s questions about genetics and environment had to be tested with plants. As an undergraduate, she published papers on plant physiology, and she went on to study plant genetics as a Fulbright Scholar in Switzerland. As a post-doc at the University of South Florida, she applied her skill as a geneticist in a study of mice, linking nutrition, genetics and cancer.
However, fish remained her true love. Pursuing her Ph.D. at the University of Minnesota, Shields met Ann Kapuscinski, professor of fisheries and one of the first women to earn a Ph.D. in fisheries from Oregon State University. Kapuscinski encouraged Shields to examine the differences in whitefish populations in Minnesota’s lakes, where some fish grew large and others remained tiny.
Was it genetics or environment? Through close examination of genetic minutiae within the fish’s DNA, Shields detected big differences among the populations. But in examining the extent of variables within the vast lake ecosystems, Shields recognized a universe of triggers that could foster or inhibit particular genetic potential.
"The study of genetics demonstrates that living things are much more than machines," says Shields, "and management that assumes machine-like predictability in natural populations can lead to faulty conclusions and management actions that do more harm than good."
This is the lesson that Shields most wants to teach her students at OSU. She teaches four classes during the school year, including a class she developed called "Genetics for Fish and Wildlife Management."
In this class, Shields introduces genetics to future natural resource managers, as a tool to measure the status of natural populations. Just as DNA can be used to unravel evidence at a crime scene, so it can be used to track alien invasions, disease outbreaks and other mysteries of the natural world. And the study of genetics can help fish and wildlife managers understand the consequences of their actions and why some species thrive while others fail.
"You can provide a great environment for fish and wildlife," says Shields, " but if the individuals lack adaptive genetic diversity, the population will not thrive. Conversely, you can have a diverse natural population, but with a poor environment the species will not thrive."
One of the many studies currently under Shields’ microscope is an examination of how alterations to the fish’s environment can alter the fortunes of fish parasites. Few environments have been more altered than the Columbia River, where hundreds of miles of free-flowing river have been rebuilt into a series of large reservoirs. The change has devastated native salmon populations, but has been ideal for American shad, a species introduced from lakes and rivers back East. Shad now range from the Columbia estuary to Priest Rapids Dam, 400 miles upstream, and throughout other altered river systems in the West. The shad carry marine parasites known as seal worms, a nematode that infects the flesh of fish and can be passed to humans.
Shad, in their native freshwater habitats back East, did not carry seal worms. But introduced into the altered environments of western rivers, shad have become an easy ride for this potentially deadly parasite. Shields’s research examines how the introduction of new species can extend the reach of naturally occurring parasites, and put other species at risk.
Like her father before her, Shields has included her children in the world she loves. Michael, 9, and Becca, 6, have grown up with an eye for nature’s mysteries. It was Michael, in fact, who first noticed differences in some of the tiny sticklebacks he caught during a family vacation. His observation led Shields to examine parasite abundance in central Oregon reservoirs, another altered environment for native fish. And Becca raises Siberian dwarf hamsters, selectively breeding them to produce sweet-natured cuddly pets through the mysterious combination of environment and genetics.