Waking Up In Eden Part 5

Getting dressed here meant throwing on a pair of khaki pants, a white linen s.h.i.+rt, and a pair of sandals. My hair dried itself. Makeup now consisted of a few swipes of color. I went out to the front porch. James put down his rake and sputtered with anger.

"The pigs are back," he said indignantly. "Ten of them - momma, poppa, and eight little piggies. They're rooting around, ruining the gra.s.s. Digging up my plants," he snorted. "Making a mess."

I only half-believed him. Oh, I had heard about the wild pigs that roamed the interior mountains of Kauai. Hunters stalked the tusked boar as big sport. Some carry only a knife and a sewing kit - the knife to slit the pig's throat and a sewing kit to sew up their dogs if they got gored. But surely the wild pigs didn't dare come so close to civilization.

Just after sunset that night I drove to the end of the cottage drive. Under the big mango tree stood what looked like a large German shepherd. Then a pack of smaller animals appeared, some coal black, others slate gray. The pigs. I counted seven little ones, as well as the big he-boar. He looked more wolf than barnyard pig, standing on tall legs, staring at me from tiny eyes that glittered devil-red in the headlights. I steered the car over the lip of the driveway and onto the lawn, stepped on the gas pedal, and charged, honking the horn. The pigs scurried around in a panicked circle, then disappeared down the ravine.

The next morning I found signs of their rooting in the newly seeded gra.s.s, not ten feet from my parked car - practically on the doorstep! Over the next weeks, I saw the pigs from time to time as they grew older and bolder. Their manes ran stiffly down their spines just like a razor. Pigs are mean, a new friend Diego the Texan warned. "They can kill you. Then they'll eat you, too," he said. "They're meat eaters." Some people like the pigs, which reputedly make good pets. One Garden employee confided that he and his ex-wife used to sleep with their pet pig, all two hundred pounds. The pig had her own pillow.

I had grown oblivious to the countless roosters, hens, and broods of chicks that wandered in and out of the yard. But I'd be d.a.m.ned if I would share the place with pigs. James also grew more and more infuriated. Finally, I gave him the okay to invite his friends in to hunt. I didn't see the pigs anymore, although once or twice I heard a far-off gun crack.

CHAPTER TWELVE.

Alien Species

PIGS WEREN'T THE only pests on Kauai. For the past week, Kauai's radio stations broadcast public announcements seeking volunteers for "Operation Sweep." About fifty of us mustered in the Anahola Valley. Our mission: to repel a vicious invader, the ivy gourd plant. This innocent-appearing vine had crept across Oahu and the Big Island, consumed hundreds of acres, smothered utility poles, and buried whole valleys. It stole sunlight and ground s.p.a.ce from other plants, until all that remained was a thick carpet of pale green ivy. Ivy gourd could grow a foot a day. And now it threatened Kauai.

Many volunteers showed up outfitted in heavy footgear, protective hats, and T-s.h.i.+rts with yellow letters stenciled across the backs: Pest Action Control Team. Thirteen young sailors from the frigate USS Crommelin had volunteered a day of sh.o.r.e leave to pull weeds while their s.h.i.+p was docked in Nawiliwili Harbor. "There would have been more of us," explained the s.h.i.+p's recreational officer, "but last night they went ash.o.r.e and some didn't feel too good this morning."

The idea of weeding the jungle seemed impossible. But the crowd reverberated with hope that they could take back the island from the eight thousand or so invading alien plant species that were ruining it. Jimmy Nakatani, Hawaii's chairman of agriculture, flew in from Honolulu for the sweep to see if, for once, his soldiers could make a dent. "There's a good chance we can wipe out ivy gourd," he boomed over a portable sound system. "In the case of Miconia," he explained, "we waited too long to do something. In this case, we decided to do it. Just do it." The megalomaniac Miconia, an invasive tree from South America introduced to Hawaii in 1969 as an ornamental species, was Public Enemy Number One. So far nothing could stop its explosive growth, not biological warfare with imported insects or fungi, nor weeding, nor pesticides.

A short man with a canvas duck-hunting hat pulled low over thick gla.s.ses milled around the fringes of the crowd, throwing off energy even in repose. He introduced himself as Guy Nagai, the Agriculture Department's noxious weed specialist. He had been patrolling Kauai's backwoods when he discovered a wall of ivy gourd behind a hollow of houses - the first sighting of it on the island. "Today's objective is not complete eradication," Nagai said as he took the mike. "We're looking for annihilation of the plant at its one-acre core."

Most enterprises in Hawaii begin with an appeal to the G.o.ds, so we gathered in a circle, locked hands, and bowed our heads. A burly volunteer dressed in a sleeveless T-s.h.i.+rt gave a long, lyrical blessing: "Thank you, Lord, for helping us to do this work for the good of the community and to get rid of this noxious weed that we don't need. Thank you for the people who came from land and sea. Let them work in safety as they go into uncharted territory in the valley."

My team headed down a road walled with giant, spiky agave and morning glory, another pest vine that long ago had spread over Kauai. Our division leader, a volunteer named Ed, stopped and pulled back a green leaf curtain. "This is what we're looking for," he said, tugging on an inch-thick vine dangling from a host tree. He pointed to another gnarled vine, as thick as a man's forearm. "And this is what we call the mother of all mother vines."

"We're at ground zero," Ed announced when we reached a settlement of three wood houses, built in a vaguely hip, California style. Our man Nagai had discovered that a woman from Thailand had occupied the third house. She had apparently bought some shoots at an outdoor farmers' market and planted them in her garden. Thai grow ivy gourd for its sweet, young leaves, which when steamed taste like a tender spinach. The woman moved back to Thailand three years ago, but her garden continued to flourish. The ivy vines produced thousands of little gourds, which spilled open, releasing untold millions of seeds into the immediate vicinity and beyond.

We broke open boxes of sawtooth machetes, quart bottles of pesticide spray, and cases of burlap gunnysacks. Our team spread out along the base of the hill and started pulling. So delicate, so harmless seemed the tendril-like shoots. Larger vines with thick, woody stalks put up more resistance. We felt as if we were trying to uproot small trees bare-handed. In a few minutes I had filled my gunnysack. It was dirty work. The troops revolted. Too many vines, too few gunny sacks. We resorted to a new tactic, which was just to cut at the root and spray the stump.

By lunchtime, we quit. But our commanders were happy. Nagai estimated that we had killed 70 percent of the plants in the one-acre core. "We did a lot of damage," he announced happily. Agriculture and Fish and Wildlife personnel would later arrive for serious spraying. Nagai planned to rappel down cliffs at the far end of the valley to clean out the ivy there. In another three months, he predicted, all known ivy gourd on Kauai would be dead. He and his troops would continue their monitoring, quickly zapping any new growth.

STATE BIOLOGISTS HAVE no real hope of ever eradicating most alien species. Since European and American colonists arrived in the early 1800s, importations of foreign plants, animals, and insects have been both deliberate and accidental. A woman who wanted berries for pie, for instance, probably transplanted blackberry brambles in innocence. Barnyard goats and pigs burrowed into the hills, but without larger predators they quickly bred out of control, now responsible for much of the devastation of island vegetation. Stowaway ants on colonists' s.h.i.+ps crawled ash.o.r.e and have been decimating the local insect kingdom ever since. Due largely to alien invasions, 70 percent of the Hawaiian bird species are now extinct; 10 percent of the native flora is gone. Most of the flora's habitat was the islands' dry, or mesic, forestland, plowed under over the last century for pineapple and cane. Less than 10 percent of that fragile habitat remains.

All over the world, the extinction rate has accelerated. The great biologist E. O. Wilson conservatively estimates that every year, 27,000 plant or animal species - three per hour - are extinguished, never to be seen again. Scientists predict that by the year 2050, two-thirds of the planet's plant species could disappear entirely.

Some argue that nothing can really be done to stop the onslaught of imported plants. After all, they argue, people have been transporting slips, seeds, and roots from one corner of the earth to another since Marco Polo. These people point out that Hitler's Third Reich tried to enforce a native-plants-only policy.

In truth, plant introductions have immeasurably enriched our landscapes and diets. The yellow iris and rugosa roses that flourish in New England, as well as the cherry trees in Was.h.i.+ngton, D.C., are all introductions. Only three native American fruits are still in commercial production - blueberries, cranberries, and Concord grapes. Our wide array of citrus, peaches, melon, plums, and other vegetables and fruits - even the apple - come from elsewhere, thanks to Johnny Appleseed, exploring botanists, and nurserymen. So the problem isn't just imported species; it's the unknown Pandora's box factor. Which of the imports will be useful to man and which will explode into monster plants?

For almost as long as imported species have been causing problems people have been trying to undo the damage. One of the most famously misguided experiments in Hawaii was the turn-of-the-century introduction of the mongoose onto the larger islands, to hunt the rats that ate through acres of sugarcane. Only after the mongooses had bred themselves out of control did the farmers observe that mongooses hunt in daylight, rats at night, and never the twain shall meet.

Rats still flourish to this day in Hawaii. The Garden's botanists have found that even on remote cliffs and atolls, the rodents eat the seeds from some of the rarest plants. Mongooses overran Oahu and Maui long ago, raiding so many birds' nests that the seabird and wetland bird populations have almost completely disappeared. Only Kauai and Lanai remain mongoose-free. Inhabitants are determined to keep it that way. A few days ago, I picked up a flyer in my driveway printed in old Wild West lettering, with a black silhouette of a mongoose:

WANTED: Mongoose Sighting Reports

I called up the state wildlife biologist, who told me that a tourist had reported spotting a mongoose at the banana plantation right around the corner from my cottage. Usually such a report spurs state officials to saturate the area with traps. But the biologist expressed skepticism. Foresters suspected that the last purported mongoose found on Kauai twenty-five years ago was merely a hoax - somebody probably had imported a dead carca.s.s. The recent tourist may have actually seen a cat, he speculated.

I worried. My cat, Sam, was just the right shade of brindled brown and gray. Sam could have easily been over at the banana farm, sneaking around like a mongoose. I had a vision of Sam trussed up as an alien species.

While the specter of mongooses causes alarm, residents fear brown tree snakes even more. These snakes ate the entire native bird population of Guam. Honolulu Airport personnel have discovered frozen brown tree snakes in the wheel wells of planes arriving from Guam. So far no live snakes. Authorities, however, are pessimistic. The state biologist confided, "The snakes are here. If we've found one dead one, it means there are dozens alive that we just haven't found."

Last week, Agriculture Department officials convened a brown tree snake SWAT team training session, attended by fifteen eager Kauai citizens. Instructors hid plastic snakes in trees to train volunteers to hunt and trap them at night.

There's something sweet about the idea of trying to keep serpents off the Garden Isle. But I fear that locals have as much chance as Adam had in Eden.

IN A CHAPTER ent.i.tled "Evils of an Exotic Civilization," Isabella Bird regretfully noted that small-mindedness and the inability to band together for a common good plagued the Hawaiian populace. The island peoples were so divided into nationalist and ethnic origins that they exhibited "an absence of larger interests shared in common," she wrote. "Except sugar and dollars, one rarely hears any subject spoken about with general interest. . . . Those intellectual movements of the West which might provoke discussion and conversation are not cordially entered into, partly owing to the difference in theological beliefs, and partly from an indolence born of the climate, and the lack of mental stimulus."

That observation, made in 1873, seemed still valid today when it came to plant rescue in the face of impending disaster. Perhaps more than any other place on the planet, the Hawaiian botanists had a mandate for staging a concerted, organized effort to study and preserve the native plants before they disappeared. Yet many botanists here wasted much of their energy arguing. The Garden's botanists were mad at the Nature Conservancy for grabbing credit for discovering species; other botanists were annoyed at the Hawaii Department of Land and Natural Resources for proposing regulations governing propagation of endangered species. Rearranging deck chairs on the t.i.tanic, I called it. Botanists couldn't even agree on counting the species, much less saving them.

Nowhere was this more evident than in the feud between Harold St. John, Hawaii's botanical t.i.tan of the twentieth century, and upstart Warren Wagner. St. John was a little guy, short and wiry with a crew cut, who marched into the field on plant collection expeditions wearing his World War Iera b.u.t.toned spats over high boots. A cutthroat tennis player, his motto was "If I can't win, I won't play." He stayed on the courts until age ninety-eight. St. John spent most of his long life in Hawaii, roosting at Honolulu's Bishop Museum, dominating the islands' botanical studies.

Some taxonomists are lumpers, lumping together different variations of one plant into one species. Others are splitters, who consider each and every distinction, no matter how minute, to const.i.tute a separate species. St. John became the biggest splitter of all time, dividing what he had earlier cla.s.sified as one species into two or three, or in some cases, two dozen or more.

St. John epitomized botanists of his era, thrilled with the dramatic speciation in Hawaii, the formation of multiple species from a single ancestor. Nowadays, botanists are trained to look for hybrids - crossing of species resulting in what appear to be new species but are really just variations. As St. John grew older, he continued to split and subdivide, claiming more and more new discoveries.

Starting in the 1960s, biologists' interests s.h.i.+fted away from the pure revelatory amazement at the diverse speciation on islands to a concern for determining the why and how of evolution. What factors drive a species to diverge, mutate, and adapt? What are the underlying mechanisms that allow for this divergence? When Warren Wagner arrived in Hawaii he embodied this new approach. Another small, intense man, Wagner had straight, dark, lank hair and a big walrus mustache that lent him a slight chipmunk appearance. Bright, aggressive, with a newly minted Ph.D. and full of the know-it-all obnoxiousness of youth, he eagerly flaunted his newfangled thinking. Wagner was more balanced, and sometimes lumped and sometimes split. He examined all available specimens, identified general characteristics, but allowed for some variation.

Honolulu's Bishop Museum hired Wagner in 1982 to produce a new, comprehensive Hawaiian flora. It was to be the most complete list of flowering species ever compiled. The first and, up until Wagner, the only flora of the Hawaiian Islands was published in 1888 by William Hillebrand, a German doctor who spent twenty years in Hawaii studying the vegetation. Wagner was charged with creating the definitive record of Hawaiian plants for the twentieth century and well beyond. It would consume him and nearly sixty collaborators for a decade.

Warren concluded early on that St. John was just an old coot, and so deliberately left him out of the flora project. Wagner and St. John had a daily opportunity to sort out their disagreements but did not. During Wagner's tenure at the Bishop Museum, he, St. John, and the rest of the botany staff lunched together every day, seated at a picnic table outside the herbarium. They got along cordially but didn't talk about Wagner's book.

As Wagner neared completion of his project he had identified 2,270 plant species growing in Hawaii, including 988 native Hawaiian species. St. John apparently grew more and more furious. He seethed quietly, like a spider in waiting. And then he struck. Just after Wagner sent the final galleys of his book to the printer with his last revisions, St. John let loose a flurry of publications in tiny, obscure botanical journals. He claimed to identify a total of 800 more Hawaiian native species, nearly doubling the number reported by Wagner.

St. John succeeded in casting doubts on the accuracy of Wagner's new flora before it was even reviewed. The old man died a few months later, just a few months shy of one hundred years. He left a tangled, spiteful legacy of disputed cla.s.sifications that has taken Wagner and other Hawaii botanists more than a decade to sort out. How silly. This was just the sort of petty malice that wasted time. Why couldn't they have joined forces and sorted out the cla.s.sifications together? Perhaps it was the island effect of confined s.p.a.ces; it seemed to drive people to stake out a small patch of turf and defend it to the end.

CHAPTER THIRTEEN.

The Rosetta Stone of Evolution

WHEN WARREN WAGNER was still a graduate student at Was.h.i.+ngton University in St. Louis, he received some valuable advice from G. Ledyard Stebbins, the landmark geneticist and evolutionary biologist who was among the first to apply modern evolutionary theory to plants. By all means, study the Hawaiian endemics, Stebbins said, but if you really want to study evolution, study the new weeds. They're the future of the archipelago.

After completing the Hawaii flora, Wagner became a leading voice in the new field of plant evolutionary genetics on oceanic islands. He's still studying the weeds, now as chairman of the botany department at the Smithsonian Inst.i.tution in Was.h.i.+ngton, D.C. Every few years or so he flies to Nuku Hiva, then sails to the small outer Marquesas Islands, made famous by Paul Gauguin and Herman Melville. For three to six weeks, he treks up mountains and through rain forests to collect plant samples for DNA extractions. Wagner's work shows an ancestral genetic link between the Marquesas Islands and the waif plants that settled in Hawaii, 2,800 miles to the northeast.

Some scientists call Hawaii the Rosetta stone of evolution: the perfect place to decode the formation of new species, that elusive process that Charles Darwin called "the mystery of mysteries."

Geography dictated evolutionary fate. As most of the Hawaiian Islands lie within the earth's tropical zone between the lat.i.tudes of the Tropic of Cancer and Tropic of Capricorn, sun rays. .h.i.t them directly, at times perpendicularly, creating a hot zone. The higher temperatures warm the ocean and increase evaporation, which allows trade winds to vacuum up enormous amounts of water, then disgorge it in seasonal monsoons that made the islands habitable.

Because the Hawaiian Islands are the most isolated in their distance from continents, very few plants or animals could travel the vast distances over open water to reach the archipelago. Once on the islands, the colonists met an onslaught of varied climates and ecologies, all packed into a tiny area smaller than Rhode Island. It was adapt or fail to survive. This superheated, supercharged evolutionary crucible caused the few colonists to evolve new traits in a shorter time compared to elsewhere. It produced Hawaiian plant and animal species so diverse, so multiformed and adaptive as to represent one of the natural wonders of the world.

The central questions for evolutionary scientists are, When did adaptation occur, and why? Many of the Hawaiian species exhibit affinities with continental species, yet how were they transported such great distances? Where did each of the immigrant lines come from? Did they evolve here, or exist unchanged from their original form, perhaps from now-disappeared land ma.s.ses?

These puzzles have consumed scientists for centuries and drove Darwin to formulate his theory of natural selection. Now, however, new techniques using computer programs and DNA a.n.a.lysis are beginning to provide real answers.

What Darwin suspected and could only postulate based on careful observations, Wagner now proves.

As I dug deeper into scientific papers and tomes, I found that the story has been revealed in odd places - in the giant chromosomes and many-shaped p.e.n.i.ses of the Hawaiian fruit fly, in a remote Arctic violet, and in a common California weed.

WHEN HAWAII AND ALASKA were admitted to the union in 1959, my fourth grade cla.s.s at Oak Knoll Elementary School in Hopkins, Minnesota, celebrated by constructing relief maps of the mountainous terrains of the forty-ninth and fiftieth states. Sculpting the continental Alaskan landma.s.s out of a crumbly mixture of salt, flour, cream-of-tartar, and water was easy compared to trying to make the Hawaiian archipelago. We created a Pacific Ocean by painting a box lid blue, then formed islands from little blobs of homemade Play-Doh. We learned that a long, undersea fissure in the earth's crust created escape hatches for molten lava lurking at the center of the earth. Each leak erupted into its own volcano that grew and grew until it parted the sea waters above. When cooled, the lava spire became an island. The explanation could almost have come from the Book of Genesis: Let the dry land appear, and it was so.

The story has changed dramatically.

That very year, Princeton Geology professor Harry Hess informally presented his hypothesis that the seafloor was in constant motion, slowly spreading apart. Three years later, in his 1962 paper "History of Ocean Basins," one of the most important contributions in the development of plate tectonics, Hess outlined the basics: molten rock (magma) oozes up from the earth's interior along mid-oceanic ridges, forming new seafloor that spreads away from the active ridge crest and, eventually, sinks into deep oceanic trenches. The earth's hard crust floats over a slippery core, propelling continents to move in ma.s.sive plates - similar to the way a cracked sh.e.l.l slides over a hard-boiled egg. Subsequent testing of the ocean floor showed Hess was right in his estimate that ocean sediment had acc.u.mulated only for three hundred million years or so, a very short time compared to what it would have been if the sea bottom had rested undisturbed since the oceans first formed.

Hess's work soon led to an explanation for the Hawaiian Islands. Canadian geophysicist J. Tuzo Wilson postulated in 1963 that the islands formed successively over a fixed hot spot, then slowly moved, conveyer-belt style, to the north and west. The eight current high Hawaiian islands occupy the southeast end of a much longer submerged archipelago that extends 3,616 miles north and west, culminating in Meiji Seamount (an underwater mountain) up near the Bering Strait. Those ancient underwater islands resulted from initial volcanic activity about seventy-five to eighty million years ago. Thus, over a compacted span, islands formed some of the highest mountains in the world, then eroded or broke off in great slumps into the ocean until they dwindled to mere atolls or slips of sand barely a few yards high. And then many of them disappeared under the ocean's surface.

The southernmost volcano, Kilauea on the Big Island, has flowed more or less continuously since missionaries first sighted its red-hot spouts and belches in 1823. Farther south, the underwater seamount of Loihi is currently forming, although scientists project it won't poke above water for another million years or so.

Tectonic movement is slow: three and a half inches per year.

The end result of these scientific advances is that we know that many of the Hawaiian Islands were quickly created and then disappeared, all in neat and tidy order, which now can be almost precisely dated.

Back at Oak Knoll Elementary, we also learned that Hawaii was called the melting pot. The islands attracted peoples from around the Pacific Rim and North and South America, and they lived together peaceably.

As I investigated island biology further, I found that the melting pot metaphor also serves well to explain the truly exceptional fauna and flora of Hawaii.

ALTHOUGH DARWIN BECAME the world's most famous naturalist, it didn't always look like he, or his theories, would amount to much. Captain Robert FitzRoy hired the twenty-two-year-old genteel Darwin as company for a two-year surveying voyage to Tierra del Fuego and the East Indies. Loneliness and isolation had been known to drive sea captains insane, and Captain FitzRoy wanted diversion. The voyage of the HMS Beagle stretched into a fifty-seven-month journey through the Pacific islands and around the South American continent. It turned Darwin into an acute observer. Although dazzled by the Galapagos Islands fauna, it was the birds that inspired his eureka moment.

He noticed that the Galapagos finches all resembled the common finch on mainland Ecuador but varied slightly from island to island. Seed-eating finches cracked open nuts with gross, heavy beaks. Others developed straight, narrow, chisel-like bills to pry insects from trees. Still other species' beaks grew thin and curved, all the better to sip nectar from flowers. Perhaps, Darwin theorized, they had somehow descended from the same parental lineage. "The most curious fact is the perfect gradation in the size of the beaks," he wrote in his journal. "There are no less than six species with insensibly graduated beaks. . . . Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."

Fascinated by the way that plants and animals moved around the globe, Darwin sensed that long-distance dispersal might be key to how and why species evolved, or what he called "radiated," into different forms. He reasoned that Galapagos animals must have traveled the six hundred miles from South America over water, as no evidence of a land bridge existed. After his return to England, he mounted experiments for several years, to test whether plants and animals were capable of long-distance travel. He put seeds into salt.w.a.ter tanks in the bas.e.m.e.nt of his house in Downe, happily reporting later, "I found that out of 87 kinds, 64 germinated after an immersion of 28 days and a few survived an immersion of 137 days." He hung a pair of chopped-off duck's feet in an aquarium and with satisfaction observed that freshwater snails clung to them, evidence that the mollusks could have traveled as stowaways. He shot partridge after a heavy rainfall, then counted the seeds in the mud stuck to the birds' feet.

He finally published his five-hundred-page tome, On the Origin of Species, in 1859, twenty-three years after the return of the Beagle. b.u.t.tressing his theories was an impressive array of evidence, including a growing fossil record, new estimates of the geological age of the earth's strata, and his own experiments. He postulated that species evolved slowly by a process he called "natural selection." Traits that contributed to successful survival tended to be reproduced through the next generations in greater proportion. Eventually a trait mutated, or evolved, into a different species or even split into several directions of mutation, in response to new surroundings.

Darwin noted even then that endemism was a byproduct of evolution - the creation of species that exist in only one place and nowhere else.

What would have happened if Darwin had visited Hawaii and seen its honeycreepers, regarded as perhaps the most spectacular example of adaptive radiation in the world, even greater than that of the Galapagos finches? All thirty-three known Hawaiian honeycreeper species and another fourteen known from fossil records share similar bodies. But the honeycreeper bills vary in astounding directions, from a short chisel to a long, curved scimitar. Tongues also grew, some like Pinocchio's nose, in astonis.h.i.+ng lengths and directions. Would the differences be so startling that Darwin would have missed their commonality?

He based his studies on morphology - the examination of form and structure. He put forth the idea of drawing evolutionary trees - grouping species that exhibit the same characteristics and branching into ever-more refined, distinct features. In the old days, botanists such as Harold St. John manually sketched family trees to diagram familial relations.h.i.+ps; these sketches were called "cladograms." The new evolutionists like Warren Wagner use such structural study only as a starting point. Sophisticated computer programs now spew out faster and more complex cladograms.

But only DNA molecular a.n.a.lysis provides rock-solid evidence of genetic links. New techniques have led to the discovery of an almost unlimited amount of data, locked up in DNA molecules that can be extracted from fossils millions of years later.

By measuring one lineage of Hawaiian honeycreepers, such data suggests evolution produced about a 2 percent divergence every million years. a.s.suming a constant molecular clock, that puts arrival of the original honeycreeper ancestor in Hawaii at about 3.5 million years ago.

Rapid evolution is not only possible, but frequent. Change after arrival on the islands appears inevitable. Five species of endemic banana moths in Hawaii have evolved in the approximately one thousand years since humans introduced the banana to the islands. In Lake Lanao in the Philippines, four endemic genera of cyprinid fish evolved in ten thousand years or less. And new plant species have been discovered in the newly formed lava islands just over a century after the 1883 eruption of Krakatoa in Indonesia.

While scientists have studied birds, animals, and plants to decipher the secrets of evolutionary magic, evolutionary biologists regard the Hawaiian fruit fly - Drosophila - as supreme, the Mount Everest of DNA a.n.a.lysis for island biology. More than seventy-two scientists joined together in 1962 to form the Drosophila Genome Project to study this amazing insect over the next decades.

In part this is because there are so d.a.m.n many species - more than one thousand, and still counting - of these tiny flies, which have evolved into so many different ecologies. Before you wonder how even enthralled scientists observe differences between flies no bigger than a speck, it's helpful to know that there are two distinguis.h.i.+ng physical attributes. Even closely related fruit fly species are distinguished by the shape of the male p.e.n.i.s, so distinctive an identifying mark that it has been likened to a fingerprint in individual humans. Complex courts.h.i.+p behaviors also offer clues. Some species of males court females in the hopes of being chosen. Other Drosophila males aggressively jump on females from the get-go, in a more wham, bam, thank you, ma'am, style. Fruit fly DNA a.n.a.lysis is easy, compared to other organisms. The fruit fly develops giant chromosomes in its salivary glands and other parts of its larvae. Different-colored bands on each chromosome can be read like road maps into its genetic history.

These genetic maps show that the thousand-plus fruit fly species all descended from a single colonist, or at most two. Using DNA trapped by amber fossils, scientists found evidence that two distinct Hawaiian fruit fly lineages began to split 30 million years ago. Kauai, the oldest surviving high Hawaiian island with the kind of rain forest habitat favored by fruit flies, is only about 5.1 million years old. Thus, the fascinating implication: The original fruit fly colonization occurred on older, more northern islands in the chain that have since disappeared. As one island degraded and lost its wet mountain habitat, the flies moved south to greener pastures.

JUST AS DNA TESTING has been used to settle human paternity cases, it has turned up some surprising relatives in the plant world as well. The genus Viola, for instance, is a moderate-sized and largely herbaceous group of about 550 species worldwide. Wagner identified seven Hawaiian species (and three subspecies) in his 1990 Manual of the Flowering Plants of Hawaii. For years, botanists thought that the original violet colonist in Hawaii must have come from South America, as they shared a similar appearance. Wrong, according to chromosome data. DNA showed the Hawaiian violets to be closely related to those in Alaska and along the Bering Strait: Viola langsdorfii. They don't look alike. The Arctic violets grow cla.s.sic pansy-like flowers and circular leaves that we would all recognize as similar to common violet houseplants, while the Hawaiian violets sometimes grow into shrubs as tall as twelve feet.

The evolutionists only briefly puzzled over how a violet from the Arctic region could get to Hawaii. Obvious. By air. More than fifty species of migrating birds breed in the Arctic but winter in Hawaii. Conducting their own Darwin-like experiments, modern-day scientists trapped birds to examine their feathers, finding plentiful evidence of seed stowaways.

Not all new arrivals in Hawaii built dynasties. Wagner showed that 10 of the original 291 original plant colonists radiated into multiple new adaptations, so many that they account for about half of Hawaii's plant diversity of about one thousand native species. Of native birds, only the Hawaiian honeycreepers diverged into radiations. The 19 other native Hawaiian bird lineages exist in only one form.

Once established in their new tropical habitats, many of the newly evolved species lost their compet.i.tive edge. Plants discarded the ability to emit toxins, or the armament to deter herbivores with oils, resins, stinging hairs, or coa.r.s.e textures. It's as if they expended all their energy into fitting into the new surroundings, and then kicked back, luxuriating in paradise. Under rapid, though irreversible, adaptation, some Hawaiian plant and animal species became excessively specialized to their niche environments, some no larger than a single valley. They lost whatever immunities and resistances they once had, becoming vulnerable to any import of disease or parasite. While this loss of compet.i.tive ability is exhibited in endemic island species around the world, nowhere are the native plants so poorly equipped for compet.i.tion than in Hawaii. There is no easy explanation, but it means that almost any continental species of plant seems capable of moving in and annihilating the native inhabitants. Grazing by human-imported cattle and goats and rooting by pigs aids the death marches of these alien species, as weeds thrive on newly disturbed soil. Moreover, the native Hawaiian species show poor ability to replace themselves after disturbance.

This pernicious habit of alien invaders to move into newly plowed ground provides a particularly dismal outlook for conservation efforts. We can work like h.e.l.l to weed the aliens by pulling up roots, but it only disturbs the soil and thus welcomes more intruders. And many of the invaders are spread by birds that eat their seeds and then widely excrete them like crop dusters. "Not only are weeds well-entrenched in many areas of the Hawaiian islands, but efforts to remove them would very likely only renew and widen the areas of disturbance and encourage more weedy growth than before," noted Sherwin Carlquist in his 1974 landmark book, Island Biology.

But all this genetic theory is difficult. When I came to the case of the Hawaiian silversword, I had a better sense of how the miracle of evolution can turn a lowly weed into a majestic tower of a plant.

Tourists come from continents away to trek up the cindercovered dry slopes of the dead volcano of Haleakala on Maui. Many travel an hour and a half up the winding mountain road in the dark to watch dawn creep up over the crater's 10,023-foothigh summit. Others come to see the great silversword, Argyroxiphium sandwichense. As it nears death, it produces a spire of upward-turned, silvery bayonet-type spears. From its center rises one stem, up to six feet tall and covered by hundreds of purplish rosette flowers. And while its royal appearance is truly remarkable, its story is what draws the crowds.

Most likely birds carried sticky, resin-coated seeds from a now-extinct tarweed that was growing in coastal California. The avian carriers flew across the ocean, unknowingly delivering seeds and depositing them into the evolutionary cauldron of Hawaii, where they underwent a rapid transformation into the dramatic Hawaiian silverswords, greenswords, and some twenty-eight other island species in what is called "the silversword alliance." Originally in the sunflower family, in Hawaii tarweeds grew tall. And low. Leaf anatomy developed into varied shapes.

One species grows on Kauai's rainy Mount Waialeale. Another Kauai silversword cousin grows into a ten-foot-tall onestem tree. Dryland species on Hawaii and Maui sprout hairs, thick leaves, and different internal tissues to cope with drought. Some of the dry land relatives form matlike clumps in lava fields. One wetland silversword species evolved into a vine. Other silverswords adapted to wet, poorly drained bogs. Or Alpine desert. Midlevel forest. Species moved back and forth between such niche climates at least five, and likely more, times over the last few million years, suggesting that a change of ecologies was fundamental to its diversification.

While the silversword exemplifies the drama of evolution, its near extinction ill.u.s.trates both human destruction and human rescue.

Climbers to the Haleakala Volcano summit used to prove they had reached the summit by plucking a silversword flower and taking it home. Although the volcano was declared a National Park in 1916, park rangers didn't crack down on this vandalism until the 1930s. The first official count of silversword, in 1935, estimated that the total population had dwindled to four thousand individual plants.

Thanks to intensive replanting projects, the population swelled to 64,800 silverswords by 1991. Using Steve Perlman's paintbrush breeding techniques, Hawaiian Silversword Foundation volunteers and state foresters pollinated a cliff-dwelling variety, then collected seeds and grew thousands of seedlings in the University of Hawaii's Center for Conservation Research.