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Genetic Basis of Butterflies524 words

Sea Monsters861 words

The Comeback991 words

Who Speaks for the Animals?782 words

Gentle Giants915 words

The Origin of Species913 words

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Genetic Basis of Butterflies

Genetic Basis of Butterfliesby ReadWorks

If you've ever been in a park during the summer, you may have seen butterflies flitting from flower to flower. They are quite beautiful, and like humans, seem to have individual traits. There are orange butterflies with big brown eyes, blue butterflies with black markings on their wings, and white butterflies with small black antennae. According to some butterfly experts, there are approximately 20,000 kinds of butterflies in the world. Each species (or type) of butterfly has its own genetic information that dictates what characteristics it will have and distinguishes it from other butterflies.

Inherited genetic information explains why certain species look different from others. Monarch butterflies, orange butterflies with black markings and white spots on their wings, are most common in Mexico and the United States. Their bright color makes them easily noticeable to predators, but also acts as a warning that they are poisonous if eaten.

The poison of monarch butterflies can be traced back to a plant they feed on during an earlier stage in their lives. What we think of as butterflies are the adult versions of caterpillars. As caterpillars, monarchs feed on milkweed, which contains a toxin that is poisonous to most vertebrates but not to monarch caterpillars. When the caterpillars become adult monarch butterflies, the milkweed in their bodies is poisonous to any predators that might try to eat them.

An unsuspecting predator that did not know the monarch butterfly was poisonous would soon realize its mistake. After tasting the poisonous bug, most predators quickly spit out the monarch and learn not to eat them again. Unlike other butterflies, whose genetic information (and therefore their coloration) helps them blend into their habitats in order to defend themselves from predators,

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Genetic Basis of Butterflies

monarch butterflies rely on their bright coloration to keep them safe. An interesting fact: another species of butterfly, the viceroy, mimics the coloration of the monarch in order to keep predators from eating it!

Even though there are many kinds of butterflies that look very different, all butterflies share a certain number of traits, which are also determined by their genetic information. They all have the same life cycle. First a caterpillar hatches from an egg. The caterpillar eats plants and grows bigger. Then it covers itself in a hard case called a chrysalis, and it enters a stage of transformation. During this stage, the insect is called a pupa. Inside the chrysalis, the pupa grows the legs, wings, and other parts of an adult butterfly. Once the butterfly is fully developed, the chrysalis splits apart, and the butterfly emerges. All butterflies have four wings-two upper, two lower-that are covered in tiny colored scales. A butterfly's genes determine the color of its scales, and more-they dictate the insect's size and shape as well.

Colorful decorations are key to the survival of the monarch butterfly. Vivid colors signal danger to the predators which might otherwise eat the butterfly. Other species of butterfly, with different genes, rely on different survival strategies, and have their own distinctive designs. But no matter the pattern, the blueprints for each of the 20,000 different species' development are written in their genetic codes.


Sea Monsters

Sea Monstersby Stephen Fraser

A new wave of fossils reveals the oceans' prehistoric giants.

Way back when Tyrannosaurus rex shook the ground, another giant reptile lurked in the prehistoric oceans. A 50-foot predator, Mosasaurus was a real sea monster.

Mosasaurus and T. rex never battled or even met. But the marine giant is now stealing some of the spotlight that T. rex and its fellow dinosaurs have enjoyed for so many years. A new wave of findings has drawn some amazing portraits of the aquatic denizens of the Age of Reptiles.

"Over the last 10 to 20 years, we have begun to look more closely at fossils found in marine sediments," says Mike Everhart, a paleontologist at the Sternberg Museum of Natural History in Hays, Kan. "In doing so, we've discovered that some of these creatures were very large, very scary predators-something you wouldn't want to share your ocean with!"

From Land To Sea

Only a few reptiles-turtles, sea snakes, and saltwater crocodiles-inhabit today's oceans, which are dominated by mammals and fish. But the seas of the Mesozoic Era (251 million to 65 million years ago) swarmed with reptiles, some of them as big as whales. Marine reptiles were actually the first big prehistoric reptiles discovered by fossil hunters.

The earliest marine reptiles evolved from land reptiles roughly 240 million years ago (mya). Earth's climate was getting warmer then, and so were the oceans, which favored the evolution and spread of the ectothermic (cold-blooded) reptiles.

Unlike most of today's reptiles, the prehistoric marine reptiles were viviparous-the females produced live offspring instead of eggs. "The reason is simple," says Mike Caldwell, a paleontologist at the University of Alberta in Canada. "If you give live birth you can live anywhere in oceanic environments and are not bound to come ashore to lay eggs." One fossil of a prehistoric marine reptile, now on view in a German museum, shows the animal giving birth.

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Sea Monsters

Simon Danaher

Mosasaur

No longer tied to the land, the marine reptiles could fully adapt to living in the ocean and compete with sharks and other big fish. "The interesting fact is that just about every animal in the ocean is a predator-from the smallest minnow to the biggest mosasaur-while almost all land animals are herbivores [plant eaters]," says Everhart.

Three Groups

Paleontologists have sorted the prehistoric marine reptiles into three main groups.



Sea Monsters

Thomas Miller

Ichthyosaurs

Ichthyosaurs. The first group was the ichthyosaurs. The earliest ones had long, supple bodies and probably rippled through the water like eels. Later ichthyosaurs evolved fins and tails and "looked like our present-day dolphins," says Caldwell. Ichthyosaurs were built for speed.

The largest known marine reptile was a whalelike ichthyosaur, Shonisaurus. It was as long as two school buses.

Chris Butler/Photo Researchers, Inc

Pliosaur

Plesiosaurs. Next to evolve, about 200 mya, were the plesiosaurs. Plesiosaurs moved like turtles: They flapped their paddle-like limbs to propel themselves through the water.

Plesiosaurs had small heads, broad bodies, and short tails. Over time, many of them evolved fantastically long necks. One of them, the 14-meter (46-foot) Elasmosaurus, had a neck that was half the length of its entire body and contained 72 vertebrae (bony segments). Today's mammals-even giraffes-have just seven neck vertebrae.

The long-necked plesiosaurs were slow swimmers. They probably cruised just below the ocean surface, swinging their long necks to angle their heads beneath unsuspecting fish and snap them up.

Another group of plesiosaurs, the pliosaurs, evolved in a whole different direction. Their necks remained short, but their bodies grew bulkier with heads like those of crocodiles. "These guys were the big, hulking monsters of the group, with huge teeth and a bonecrushing bite," says Everhart. They preyed on fish, ichthyosaurs, and other plesiosaurs.



Sea Monsters

Mosasaurs. The ichthyosaurs and pliosaurs disappeared about 90 mya. Replacing them at the top of the food chain were the mosasaurs, huge lizards related to today's Komodo dragons. Mosasaurs had long heads, short necks, and long, sinuous tails, which they used to propel themselves like snakes. "More than likely, mosasaurs were very aggressive animals, capable of pursuing and killing all kinds of prey," says Everhart.

If mosasaurs were still alive, "ocean travel would be safe in larger vessels," he adds. "But you wouldn't want to go fishing, sailing, surfboarding, windsurfing, or just plain swimming anywhere mosasaurs lived."

Endless Questions

Along with the dinosaurs, the giant marine reptiles became extinct 65 mya. But their fossilized remains are abundant around the world.

"Mosasaurs were first discovered in Europe, but the most and some of the best have been found here in Kansas, which used to lie under a prehistoric sea," says Everhart. "The first major fossil I ever collected turned out to be a mosasaur that I named Tylosaurus kansasensis in 2005."

What remains to be learned about the prehistoric ocean-goers? "Did they have a four-chambered heart like a crocodile or a three-chambered one like a lizard? Did they live together in family groups like whales or porpoises? Did they care for their young? How long did they live?" says Everhart.

"It is an endless list of biological questions," adds Caldwell.



The Comeback

The Comebackby Stephen Fraser

A major conservation project has brought puffins back home to the United States.Stephen Kress will never forget the first time he saw Atlantic puffins in the wild. The year was 1967. Wow! he thought at the sight of thousands of the toy-like creatures on a shoreline of the Canadian province of New Brunswick. These birds are amazing!

Two years later, while working as an instructor at an Audubon camp on Hog Island off the coast of Maine, Kress learned he was in a place where Atlantic puffins had flourished more than 100 years previously. Now they were all gone.

Kress knew a local treasure had been lost. He has since made it his life's work to return that treasure. His efforts have become a model for seabird conservation efforts worldwide.

Land and SeaAtlantic puffins are short, stocky birds with black and white feathers, orange legs, orange feet, and large, triangular, orange-red beaks. An adult puffin stands only about 25 centimeters (10 inches) tall.

Atlantic puffins are "all-purpose birds," says Kress; they live on land and at sea. On northern shores of the Atlantic Ocean, they scamper over the rocky ground and burrow like groundhogs. At sea, their abilities to drink salt water and dive more than 60 meters (200 feet) allow them to live in the open water for years at a time.

In the ocean and the air, puffins are mostly silent. On land, they growl. The noise "sounds like a chain saw," says Kress.

Bill Coster/Alamy



The Comeback

In its beak a puffin parent carries fish that it will feed to its chick.

The coastal burrows that Atlantic puffins inhabit are built for breeding. Before that happens, though, a male and a female puffin go on a series of "dates," says Kress, which may stretch out to a yearlong "engagement" of nest building.

Once they've mated, a puffin couple, which may remain together for life, raises one chick at a time, caring for it equally. Puffins eat fish, such as hake, herring, and sand eels, in summer and zooplankton (tiny marine animals) in winter. But chicks are fed mainly fish, which is higher in protein than zooplankton.

Oxford Scientific/Photo Library

A puffin emerges from the burrow that the bird and its mate dug for their family.

To feed their young, some seabirds, such as albatross and penguins, eat fish and then regurgitate the partially digested meal into the mouths of their offspring. By contrast, puffin parents provide their chicks with whole fish they've carried crosswise in their bills, sometimes five or six at a time. The most fish that a single puffin has been observed carrying is 61.

When a puffin chick matures, it heads out to sea, where it spends about two or three years before returning to land to find a mate and breed in a colony. The first nesting usually happens when the birds are about 5 years old. Puffins live to about 20 years of age, though some live to 30 or more.

AP Images

Wooden decoys like the one at right were used to lure puffins to Eastern Egg Rock island off the coast of Maine.

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The Comeback

During his stay on Maine's Hog Island in 1969, Kress learned that puffins had been hunted to extinction there. At one time, in fact, only a single pair lived in all of Maine. By 1969, the island had been overrun by the puffins' enemies-gulls. Still, Kress couldn't help but wonder whether the puffins might be transplanted from elsewhere and reestablished on the island. No one had ever attempted anything like that before.

In 1972, Kress began his restoration project by digging burrows and shooing away gulls on Eastern Egg Rock Island. Then he made a series of trips to one of the biggest puffin colonies in Canada. Helped by two assistants, he extracted puffin chicks from their burrows, enduring occasional bites from distressed parents. With the chicks stored safely in soup cans, Kress and his crew carried them back to the United States, where they deposited one into each hand-dug burrow. For the next year, the researchers looked after the chicks, feeding them every day.

When the chicks eventually fledged-developed feathers and wing muscles that enabled them to fly-they did what young puffins naturally do: They left home for the open sea. From then on, Kress could only wait for the birds to return. One, two, three, four, five years went by.

Courtesy of Bill Scholtz

Stephen Kress and island supervisor Ellen Peterson attach a band to a puffin on Eastern Egg Rock.

Finally, on July 4, 1981, Kress sighted what he had long been hoping for: a pair of puffins caring for a chick on Eastern Egg Rock. "After 100 years of absence and nine years of working toward this," Kress wrote in his journal that evening, "puffins are again nesting at Eastern Egg Rock-a Fourth of July celebration I'll never forget."

Model ProgramToday, Kress is vice president for bird conservation for the National Audubon Society. Thanks to his Project Puffin, Eastern Egg Rock is now home to more than 100 pairs of nesting puffins. Altogether, about 1,000 pairs live in Maine.



The Comeback

Steve Allen/Getty Images

A puffin flaps its wings 400 times a minute-a very high number for a bird of its size.

Kress's translocation techniques have involved more than digging burrows and transporting chicks. Puffins are social animals-they live in groups. So Kress set up wooden puffin decoys and broadcast puffin calls to lure puffins to the Maine islands. When the birds began arriving, he erected mirrors to create the illusion of bigger, more enticing colonies.

Countless seabirds have since benefited from Kress's ingenuity. Seabird conservationists around the globe have adopted his techniques to reestablish almost 50 species in 14 countries, including petrels in New Zealand and albatross in Japan. "That was always my hope," says Kress, "to extend this beyond the puffin."



Who Speaks for the Animals?

Who Speaks for the Animals?by Rachel Howard

It was just another hot day during a humid summer in New York City. The beaches were crowded with families, and the air-conditioned subways promised a welcome respite from the heat, that is, until a woman entered a northbound train just after midnight and was confronted by an odd smell. When she looked around the train, she noticed something lying on the floor under one of the seat banks. "I board a car that's not terribly full," she is reported by the publication Gothamist as saying, "and as soon as I enter, a stench hits my nose. It's not the typical...urine/trash smell...it's...fishy? I look down to the end of the car to see a dead shark on the floor."

Questions swirled online and in the news: Where did this shark come from? How had it gotten onto the subway? How had it died? It was a curiosity that stumped anyone who'd heard about the strange incident. Photographs popped up online of the gray creature, which was about four feet long. Spectators posed the shark in a variety of ways: one of the more popular images that circulated online was a photo of a MetroCard-a card allowing entrance to the subway-on the floor next to the shark, as if it had entered the subway voluntarily.

The Metropolitan Transit Authority (MTA), responsible for the care and maintenance of the New York City subway system, was luckily equipped to deal with the deceased shark. It is reported that at Queensboro Plaza, a major transportation hub, the MTA authorities ordered everyone off the train in order to handle the situation at hand. What to do with a dead shark? The MTA authorities disposed of the body.

Still, the questions remained unanswered. Even though the subway train was clean and fishy stench-free, many in New York continued to wonder what had happened to the shark and how it ended up on a subway. Due to the amount of attention the story received online and on television news, someone was sure to come forward with the story of how the shark ended up taking a ride on the N train.


Who Speaks for the Animals?

Some questions were finally answered when a woman recognized the shark in pictures from the subway as the same shark her kids had taken pictures of that same day, after it had washed ashore on Coney Island, a beach at the bottom tip of Brooklyn. Her neighbor's daughter had even picked up the corpse for a photograph. Images of the shark hanging in the air, held by a brown-haired girl in sunglasses, began to appear online, corroborating the woman's story.

Apparently the shark had washed ashore sometime in the afternoon, and it was already deceased. Beachgoers showed intense interest in the small shark, taking pictures and congregating around it for a time. After a while, someone picked it up and took it to Luna Park, the amusement park located just north of the beach at Coney Island. It was left on the ground by the old wooden roller coaster, when apparently someone else decided to take it home and instead, left it on the subway.

This incident brings a number of issues to light, not only about the shark and its death, but about the way city dwellers think of and act toward wildlife. To a certain extent, the appearance of a wild animal, even a dead one, is an exciting and unusual occurrence in a city. The desire to photograph it, play with it, even to take it home is, on some level, understandable-where else in a city of millions of people can one experience a creature from the marine wild in a similar way? Aquariums and zoos, in protecting the animals that live in their sanctuaries, rarely, if ever, allow visitors to handle the animals.

At issue too is the sad disregard for an animal's death that was exhibited by the people who played with its corpse. The question, "What would you do?" begs to be asked. We are told not to approach or ever touch a wild animal, even if it looks friendly. It could be carrying disease or ready to attack, no matter how sweet it appears to be. Why do we not have a similar approach to dead animals? When does it become okay to disturb wildlife? Even the photographs that were posted on the Internet in some way disturbed the death of the shark, who was taken all over the city rather than left on the beach and in the ocean where it belonged.

What remains to be seen is whether there will be any public outcry about the situation: who will speak for the animals?


Gentle Giants

Gentle Giantsby Stephen Fraser

Would you stick your head into the mouth of a shark as big as a whale?Several years ago, Robert Hueter found himself with his head all the way inside a shark's mouth. The fish was about 22 feet long and weighed more than 3,000 pounds. "I put my whole head and shoulders into it," he says.

Hueter is a biologist at the Mote Marine Laboratory in Sarasota, Fla. He and a colleague, Phil Motta, of the University of South Florida, were conducting research at the Georgia Aquarium. The big shark had been safely anesthetized-put in a sleeplike state. "At no time did we feel we were in any danger," says Hueter. "It was more of a feeling of 'Let's not hurt the shark; let's be very careful.'

Mote Marine Laboratory

"Afterwards, Phil said to me, 'Boy, we sure do some crazy things together!'"

The animal that the two men examined was a juvenile whale shark, the biggest species of fish in the world. An adult whale shark can weigh 14 tons and be 14 meters (45 feet) long. Despite their size and abundance, whale sharks are a mystery in many ways.

Filter FeedersHueter saw his first whale shark when he was a college student. "I was amazed at its size and power when it swam," he recalls. "But I wasn't frightened, because the animal was so gentle."

Gentle isn't a word you would expect to see in an article about sharks, especially giant ones. Sharks have fearsome reputations. But though they're carnivores (flesh eaters), sharks rarely attack people.



Gentle Giants

"There are only a dozen or so species that have ever bitten a human," says Hueter, "and none of them actively hunt humans as prey."

The whale shark got its name because it's as big as some whales. And, like many whales, it's a filter feeder, an animal that strains food from the water it swallows. The food that whale sharks filter is mainly zooplankton (tiny marine animals and fish eggs). "We actually call whale sharks planktivorous, which means 'plankton-eating,'" says Hueter.

A whale shark eats on the run. As it cruises through the ocean, water flows continuously into its mouth. Filter pads in its throat strain out the zooplankton, and the filtered water is expelled through the shark's gills. The trapped food gathers in a big ball at the back of the animal's throat before being swallowed.

Filter feeding mechanisms are what Hueter and Motta were studying when they stuck their heads inside the whale shark at the Georgia Aquarium. "We used a waterproof camera and photographed the inside of the animal's mouth," says Motta. "We were trying to figure out how the animal could gulp so much zooplankton without clogging its gills. We still are not sure."

Rasp TeethAlthough whale sharks don't bite or chew, they have thousands of tiny teeth, each the size of a match tip, arranged in hundreds of rows. The rows resemble rasps-woodworking tools that have tiny bumps arranged along a metal blade. The whale shark's Latin name, Rhincodon typus, means "rasp tooth type." Hueter believes the teeth are vestigial, an evolutionary leftover from the whale shark's ancestor.

That ancestor was probably a creature similar to today's nurse shark, a 135-kilogram (300-pound) species that often rests on the seabed and feeds on fish and other marine animals there. Hueter guesses that the whale shark's ancestor originally ate fish eggs but eventually took advantage of the nutritional benefits of zooplankton in the open sea.



Gentle Giants

Shawn Heinrichs; Bob Cranston/Animals Animals

A tourist swims with a whale shark. Whale shark tourism is a multimillion-dollar industry around the world.

Zooplankton can be so abundant in the whale shark's feeding grounds, adds Motta, that visibility in the water is limited to 3 to 4.5 meters (10 to 15 feet). "When a whale shark suddenly appears ahead, it's like confronting a school bus underwater," he says.

Shutterstock

A head-on view of a whale shark's open mouth

Whale sharks are also distinctive for being aplacentally viviparous. Their pups hatch from eggs inside the mother's body and continue to develop there, feeding on yolk and nutritional liquid, until they are born alive. By contrast, some sharks have a placenta, an organ that provides oxygen and nourishment to the pups inside the mother's body. Other, less advanced shark species lay eggs on the ocean floor, and the fetuses develop for weeks before hatching.



Gentle Giants

Shutterstock

Gill slits on the flank of a whale shark's body

"There is no parental care in any shark species," says Hueter. "The offspring are strictly on their own after they are born."

Mystery ListHundreds of thousands of whale sharks are thought to populate the oceans in a band of tropical waters that circles the globe. In 2007, Hueter and his colleagues attached a tracking device to an adult whale shark that they had named Rio Lady. In 150 days, she traveled nearly 8,000 kilometers (5,000 miles) from Mexico's Yucatán Peninsula southeast to a point halfway between Brazil and Africa. Hueter suspects that whale sharks give birth there.



Gentle Giants

Shutterstock

The largest known whale sharks are roughly the length of a school bus.

That's one mystery among many that scientists are investigating. "Whale sharks dive deeper than a mile," adds Hueter. "We don't know why they do that, or where they mate, or how long they live. And then there's the question of how they ingest so much zooplankton without clogging their gills. The list goes on."



The Origin of Species

The Origin of Speciesby Kirsten Weir

Is it time to scale back the war on alien plants and animals?The cane toad is the Darth Vader of the amphibian world. A native of Central and South America, the lumpy toad was turned loose in Australia in the 1930s. Farmers hoped it would eat the beetles that were damaging sugarcane crops. The toad made itself at home, spreading steadily across the land.

As the toad multiplied, though, conservationists started to worry. The toad secretes a goo that can be toxic when eaten. Some feared that the imported amphibian would kill off snakes, crocodiles, and other local predators.

Minden Pictures/SuperStock

For years the cane toad has been the poster child of invasive species. An invasive species is a plant or an animal that settles in a new region, where it does harm to the environment, the economy, or human health. Conservationists regularly take up arms against plant and animal invaders by trapping, hunting, poisoning, or bulldozing them.

A growing number of scientists have now begun to argue, however, that conservationists are too hung up on the native versus nonnative distinction. "The public has embraced the idea of hating nonnative species," says Mark Davis, a biologist at Macalester College in St. Paul, Minn. "There's no scientific basis for that."

Hitching A RideIt's easier than ever for people to move around the planet, often bringing other species along for the ride. Sometimes that's done on purpose. Gardeners have been moving desirable plants from




continent to continent for centuries. Other times, nonnative species are accidental tourists. Zebra mussels arrived in the Great Lakes after being inadvertently toted across the ocean in the ballasts of ships.

Scientists estimate that some 50,000 foreign species have settled in the U.S. Among them is the python, a 6-meter (20-foot) Asian constrictor. Florida pet owners dumped pythons into the wild and they're now spreading across Everglades National Park. Another is kudzu, a vine from Japan that grows as much as a foot in one day and is running rampant across the southeastern U.S. Then there's the zebra mussel, which clogs water pipes and has done hundreds of millions of dollars in damage to power plants and water utilities around the Great Lakes.

Jack Dermid/Photo Researchers, Inc.

Kudzu, an invasive Japanese vine, has spread across the United States. Here it is seen engulfing an old home in North Carolina.

Billions of dollars are spent in the U.S. alone to control invasive species each year. Tim Male, vice president of conservation policy at Defenders of Wildlife, says the country should do even more to fight nonnative species. "It's rarer than it should be that people are going out and trying to control nonnative species in some of our most special habitats," he says.

Male and his colleagues are engaged in the preservation of the country's ecological niches. An ecological niche is a unique position that a species fills in an ecosystem-the species' habitat, the food it eats, and the predators that eat it. If nonnative species are allowed to invade local niches, Male says, "we're affecting the species that are present now, and we're also significantly affecting the future web of life, forever."

Toad HypeDavis agrees that some nonnative species are harmful. And he agrees that vigorous efforts should be made to prevent the accidental introduction of foreign species to new habitats. But too many biologists assume nonnative means harmful, he says. He and 18 other ecologists made that case in the scientific journal Nature this past summer. "It is time for scientists, land managers, and policy makers to ditch this preoccupation" with nonnative species, they wrote.

Some nonnative species aren't as bad as they're made out to be, say the ecologists. Take the cane ReadWorks.org

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toad, the horror of which hasn't lived up to the hype. While the toad's presence led to a decline in some predator populations in Australia, most species weren't impacted at all, scientists reported recently. Some species actually benefited from the toad's arrival.

And consider the salt cedar, a shrub brought from Africa and Eurasia to the western U.S. in the 1800s. Between 2005 and 2009, the U.S. government spent $80 million fighting the shrub because it's suspected of soaking up too much valuable groundwater from its desert habitat. But, notes Davis, the shrub is now the favorite nesting site for the southwestern willow flycatcher, an endangered bird. The shrub may be doing more good than harm.

Keith Douglas/All Canada Photos/Corbis

Honeybee

Some nonnative species do nothing but good. Honeybees are an example. They pollinate more than 100 crops in the U.S., providing an estimated value of more than $9 billion a year. Honeybees are an import from Europe, but nobody's suggesting they buzz off.

Native species, on the other hand, aren't always helpful. Mountain pine beetle outbreaks occur periodically in the forests of western North America. Millions of trees perish as the beetle larvae eat their way through the trees' trunks. The mountain pine beetle is currently killing more North American trees than any other bug. It's a homegrown hazard.




Claude Jardel/Biosphoto

Mountain Pine Beetle

Land ManagementInstead of waging war on foreign species, Davis says, conservationists should figure out how to include them in land management plans. In general, he notes, the introduction of nonnative species results in more species in a given habitat, not fewer.

Claude Jardel/Biosphoto

Python

To Davis, the lesson is clear: "Don't judge species on where they came from. Judge them on what they are doing."



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