In a Washington State University greenhouse, on the roof of Abelson Hall, dwells an orphan. Sheltered by a translucent plastic tent that diffuses the sunlight, drenched in water that keeps the air heavy with moisture, a semitropical plant called Gasteranthus atratus unfurls its crinkly, dark mahogany leaves. Once a year or so it puts forth cream-colored, vase-shaped flowers. It doesn’t seed, however. Whether it needs another member of its species or a particular insect or bird to pollinate it isn’t known. For now, it simply grows, and waits.
Gasteranthus atratus is an orphan, because its home no longer exists. The species was discovered in the mid-1970s in an isolated patch of forest in the high mountains of western Ecuador. A few years later, the forest—the only place the plant had ever been found—was leveled and converted to agricultural use.
“It may not have a place in the wild any more,” botanist and doctoral student John Clark says of the unfortunate plant.
The only reason Gasteranthus atratus survives at all is that the scientists who first found it brought back live cuttings in addition to their usual haul of dried specimens. With its unusual leaves and pretty flowers, it was a good prospect as an ornamental houseplant. WSU’s orphan grew from one of those original cuttings. Clark brought it with him when he came to Pullman four years ago from the Marie Selby Botanical Gardens in Florida, which has a vigorous research program focusing on orchids, bromeliads, and gesneriads, the family Gasteranthus belongs to.
Clark and his advisor, Eric Roalson, are exploring the genealogy of gesneriads all over the world. It’s a daunting task. The family is incredibly diverse, with about 3,400 species already identified. That’s almost as many species as in all the families of mammals combined (about 4,300). Along with diversity, the family has a high rate of endemism—many species have a small home range and are found nowhere else. They live on a single archipelago or island, or even a single mountaintop or river valley. Because such sites are usually isolated from similar sites nearby, the residents of neighboring places have evolved along their own paths over time, producing the stunning diversity we see today.
Much of that diversity is at risk, says Clark, because species with small home ranges are especially vulnerable to habitat loss. And despite their shared genetic history and similar habitats, different species of gesneriads are not interchangeable. If one species disappears, it can’t be replaced simply by transplanting a close relative from another site.
“This biodiversity came about over an incredibly long period of time, long before we were part of this ourselves, and because of that, it’s not something that we have the capacity to recreate,” says Clark.
He and Roalson tease out the genetic links among family members by comparing DNA 10 sequences of dozens of species from each of several geographic regions. They hope their analysis will reveal how the species are related, why they are where they are, and eventually, what the complex family tells us about the bigger picture of how life on earth evolved.
They already know that some gesneriads in Australia and nearby islands are more closely related to gesneriads in South America than to those in southeast Asia. That relationship can be traced to ancient times, when the continents now known as Australia and South America were close to the Antarctic land mass. The Asian land mass, thousands of miles to the north, had very different species of gesneriads. For the past 50 million years or so, the northward-drifting Australian continental plate has been bumping up against the Asian plate, bringing the two historically distinct life zones into close proximity. The interface zone where they meet is a dazzling natural laboratory of evolutionary processes.
In coming years, Clark hopes to survey islands in the region, most of which he expects to host their own endemic species of gesneriads. Time is short, though. Exploding human populations and development claim more of the specialized habitats and their native species every year.
“That interface zone can be better understood by looking at these organisms,” says Clark. “But if we don’t have those individuals, or as many of those individuals as possible, the puzzle becomes increasingly incomplete.”
He’s frustrated by the scarcity of funding for field surveys, which arguably cost less per unit of valuable information than almost any other form of research. Clark can mount a month-long biodiversity survey anywhere on earth, including travel, equipment, supplies, and field assistants, for $15-20,000. Even though he uses high-powered molecular techniques to work out the family’s history, Clark says he still needs information that can only come from “down and dirty” fieldwork—firsthand knowledge of the soil, setting, microclimate, neighboring plants, helpful and predatory animals, and everything else that comprises the ecosystem that is the natural context of the plant in question.
“If a species isn’t doing what it’s supposed to in its native habitat, what good is it? What does it serve?” says Clark. In its natural home, Gasteranthus atratus had been a key part of a unique ecosystem. Now, he says, it’s not extinct, exactly, but its place in the world has become metaphoric: it’s a puzzle piece, a clue to the history of its family.
Meanwhile, the orphan’s tale continues. In the 1990s a new survey team found Gasteranthus atratus living in a small forest near its original home. That might have been reason for hope, but unfortunately, the second forest was not protected from development and has likely been cleared. With the rarity of field surveys, says Clark, we may never know whether the species still survives in the wild, or fully appreciate what we’ve lost, if it and the natural communities it was part of have disappeared.
“Subtleties sometimes have a much greater impact than we once thought,” he says. “And that’s what these species are. They’re subtleties. But they’re important, because it’s an infinitely intricate puzzle that they’re a part of—and we don’t have all the pieces.”