Climate change devastating lizards worldwide: 20 percent estimated to face extinction

 

Lizards have evolved a variety of methods to escape predators: some will drop their tail if caught, many have coloring and patterning that blends in with their environment, a few have the ability to change their colors as their background changes, while a lot of them depend on bursts of speed to skitter away, but how does a lizard escape climate change? According to a new study in Science they don't.

The study finds that lizards are suffering local extinctions worldwide due exclusively to warmer temperatures. The researchers conclude that climate change could push 20 percent of the world's lizards to extinction within 70 years. Some places like Madagascar—with 210 species of lizards and half of the world's chameleons—appear particularly susceptible to a mass extinction of lizards.

The story begins Mexico in the 1970s when study co-author Jack Sites, a biology professor at Brigham Young University, began surveying populations of Sceloporus (i.e. spiny) lizards.

"I had provided a baseline data set with precise localities where the lizards were common," Sites explained. "But Mexican ecologists were going back every few years, and pretty soon the lizards were hard to find, and then they weren't seeing any. These are protected areas, so the habitat's still there. So you start to think there is something else going on."

Madagascar is a hotspot of predicted extinction for lizards and members of the Chamaeleonidae family like this Furcifer lateralis are currently going extinct. Photo by: Ignacio De la Riva.

Intrigued by the data professor of ecology and evolutionary biology at the University of California, Santa Cruz, Barry Sinervo, went to Mexico and surveyed 48 species of the spiny lizards in 200 sites in Mexico. Disturbingly, Sinervo found that 12 percent of the local populations had disappeared entirely.

But was this warmer temperatures or something regional that the team hadn't noticed? The researchers then turned to other research projects in South America, Africa, Australia, and Europe. On all five continents the story was similar: lizard populations were dropping even in protected area.

"To get this kind of pattern, on five continents in 34 different groups of lizards, that's not random, that's a correlated response to something big," Sites says. The researchers were especially careful to ensure that other factors, especially habitat degradation, weren't causing the decline.

"We did a lot of work on the ground to validate the model and show that the extinctions are the result of climate change," Sinervo said. "None of these are due to habitat loss. These sites are not disturbed in any way, and most of them are in national parks or other protected areas."

The researchers believe that temperatures are simply rising too fast for lizards to adapt. For one thing on hot days, lizards must spend their day cooling off in the shade and so are unable, due to their cold-bloodedness, to seek out food.

"There are periods of the day when lizards can't be out, and essentially have to retreat to cooler places," Sinervo explains. "When they're not out and about, lizards aren't foraging for food."

Many species have yet to be discovered and named across the world, as exemplified by this unnamed Liolaemus species from Bolivia. Many of these species could disappear before they are formally described. Photo by: Ignacio De la Riva.

In addition, if temperatures are particularly hot during the reproductive cycle, lizard mothers aren't able to get their energy-requirements to support eggs or embryos.

"The heat doesn't kill them, they just don't reproduce," Sites said. "It doesn't take too much of that and the population starts to crash."

In fact, lizards that bear live young rather than eggs appear to be more negatively affected by climate change.

"Live-bearers experience almost twice the risk of egg-layers largely because live-bearers have evolved lower body temperatures that heighten extinction risk," Sinervo said. "We are literally watching these species disappear before our eyes."

The researchers also found evidence of lizard migrations due to a changing climate, a phenomenon that has been shown in a wide-variety of species from birds to mammals to trees.

"We are actually seeing lowland [lizard] species moving upward in elevation, slowly driving upland species extinct, and if the upland species can't evolve fast enough then they're going to continue to go extinct," Sinervo explains.

Researchers say that the prediction of a 20 percent extinction rate could decline if humans effectively slow anthropogenic climate change. However they expect lizard populations to decline significantly over the next few decades regardless: in fact they estimate that approximately 6 percent of lizard species will vanish by 2050 whether emissions are lowered or not, since carbon dioxide stays in the atmosphere for decades.

Lizards play important ecological roles in the world's environments since they are a vital prey source for a variety of species, including birds and snakes. Dropping lizard populations is likely to hit lizard-eaters hard. In addition, lizards prey heavily on insects.

"We could see other species collapse on the upper end of the food chain, and a release on insect populations," Sinervo says.

For researchers who have spent their life studying lizards, the news that the small reptiles are far acutely susceptible to warming temperatures—and already disappearing—is disheartening to say the least.

"It's a terrible sinking feeling," Sites says of the study's dire conclusions. "When I first saw the data, I thought, 'Can this really be happening?'"

"If the governments of the world can implement a concerted change to limit our carbon dioxide emissions, then we could bend the curve and hold levels of extinction to the 2050 scenarios," Sinervo concludes. "But it has to be a global push… I don't want to tell my child that we once had a chance to save these lizards, but we didn't. I want to do my best to save them while I can."




Global maps of observed local extinctions in 2009, and projections for 2050 and 2080 based on geographic distributions of lizard families of the world. Map by: Barry Sinervo.

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One man's mission to save Cambodia's elephants

Since winning the prestigious 2010 Goldman Environmental Prize in Asia, Tuy Sereivathana has visited the US and Britain, even shaking hands with US President Barack Obama, yet in his home country of Cambodia he remains simply 'Uncle Elephant'. A lifelong advocate for elephants in the Southeast Asian country, Sereivathana's work has allowed villagers and elephants to live side-by-side. Working with Fauna and Flora International (FFI) he has successfully brought elephant-killing in Cambodia to an end. As if this were not enough, Sereivathana has helped curb the destruction of forests in his native country and built four schools for children who didn't previously have formal education opportunities.

Mongabay.com recently reached Sereivathana while he was in London for the Elephant Parade—a showcase of Asian Elephants statues around the city to help raise conservation funds to save the species (to read more about the parade: Elephants march in London, trumpeting conservation).

When asked how he felt on hearing the news that he had won this year's Goldman Environmental Prize (often dubbed the 'Nobel Prize' for the environment), Sereivathana said, "my wife and I dropped tears from surprise and excitement. I sat down and remembered my childhood till the day that I started working with elephant conservation."

Tuy Sereivathana with an Asian elephant. Photo by: Tom Dusenbery.

Like Cambodia's recent history, Sereivathana's path has not been easy. Sereivathana was born in 1970—the very year King Sihanouk of Cambodia was overthrown. From the ensuing power struggle rose the Khmer Rouge and its head, genocidal dictator Pol Pot. Fearing the new order, Sereivathana's parents escaped from the city of Phnom Penh to a small village deep in the countryside of Cambodia.

It was there, living a decidedly rural life, that Sereivathana had his first encounter with the Asian elephant. Visiting the village, two mahouts and their domestic elephants allowed young Sereivathana to pummel them with questions. Seeing an elephant for the first time changed the course of his life.

"That night, all members of my family were sleeping deeply well except me. I imagined large groups of wild elephants with their babies in large forest. I wanted to work as an elephant protector (in that time we didn’t know the word 'conservationist' yet)," writes Sereivathana.

Years later Sereivathana received a government scholarship and studied in Minsk, Belarus. On returning to Cambodia after a seven year absence, Sereivathana worked in forestry, but eventually began his lifelong dream of working with elephants when FFI granted him the opportunity.

"In 2003, two elephant experts from FFI Cambridge went to meet my boss, Mr.Chey Samith, director of department of Nature Conservation and Protection (DNCP)," Sereivathana explains. "They needed a government officer who has strong commitment on elephant conservation to cooperate with an elephant project. My chance came. I became involved with elephant conservation from that time on."

Before Sereivathana's involvement elephants were killed regularly in southwest Cambodia amid the Cardamom Mountains because they were viewed as a pest who increasingly raided farmers' crops.

Tuy Sereivathana providing crop seeds to farmers affected by human-elephant conflict. Photo courtesy of: Tuy Sereivathana

Sereivathana says the conflict was exacerbated by habitat loss which forced many elephants out of the forest and into agricultural areas. New villages and new crops encroached on elephant habitat and even their long-trodden corridors.

After working to gain the farmers' trust, Sereivathana implemented several low-cost measures to keep elephants away from farmers' fields, thereby mitigating conflict and ulimtately protectingthe 250 or so elephants that survived in the region.

Employing a variety of highly creative methods—including carbide explosions to scare marauding elephants, electric fences powered by solar panels, hanging hammocks and hats to confuse elephants into thinking people were there, placing chili in ropes and dung to keep elephants away, and encouraging farmers to switch to less elephant-friendly crops—Sereivathana successfully brought elephant mortalities from human conflict down to zero. In fact, not a single elephant has been killed in Cambodia since 2005, the year Sereivathana started working with FFI fulltime.

Even more than this, Sereivathana has become a local ambassador not just for elephants but for the tropical ecosystems of the Cardamom Mountains, which house a variety of rare and endangered species, including the Indochinese tiger, the pileated gibbon, the Siamese crocodile, and the wild cattle known as kouprey which may already be extinct.

"My project worked with people to stop going into the forest (where they cut trees or timbers) through providing training courses on agronomics and chicken farming," explains Sereivathana. "We also provided crop seeds, handle tractors, and made agreements with wildlife hunters and loggers."

Wild elephant raid in Vield Reahn village. Photo courtesy of: Tuy Sereivathana

Sereivathana attributes much of his success to working closely with the poor agraian communities, in other words he has paid as much attention to human needs as to the elephant's.

"We also build trust with local community and local authority. Conservation base with human needs is one of the most important," says Sereivathana.

Along this line, Sereivathana developed a program which built four community schools inside elephant areas.

"I knew villagers [were] concerned about future of their kids (who are illiterate). We helped to create the schools and provided teachers: these are indirect ways to improve elephant conservation in the areas. The teachers choose one day per week to do education on elephant conservation or value of forest to students such as read story books about wildlife, forests, and elephants," Sereivathana says, adding that by teaching children one also reaches adults.

"When the students return home, they talk positively about elephants. It can help villagers to change their mind on elephant conservation and also bring mainstream elephant conservation to a new generation."

Asian elephants, Sereivathana says, have always been important to Cambodians: "[they] played one of the main roles in building Angkor Wat [and] many Cambodian stories and songs show very deep relationship between elephant and our culture."

It has just taken a passionate advocate like Sereivathana to remind locals to see elephants differently: not as enemies, but more like eccentric five ton neighbors.

Tuy Sereivathana in a school he helped to create. Photo courtesy of: Tuy Sereivathana

"The elephant is a flagship species," says Sereivathana, who sees elephants as possessing a vital ecological niche in his nation's forests. "To conserve the elephant, we have to think about their habitat (they need large forest), so other species can survive in the habitat. In case of water sources during the dry season, elephants make water holes by trampling, so other wildlife also use the water source. Elephants spread out seeds of trees in forest."

Even the dung of Asian elephants has been recently discovered to provide an important link between elephants and other forest species. Researchers have found life blooming amid the dung: fungi, insects, and even tiny frogs.

When asked what advice Sereivathana would give future Cambodian conservationists, he had this to say: "We must join as strong friends and try to improve our capacity day to day, support each other. Hopefully, many of us can show face in global community. Please don’t hesitate or be shy to show our effort and achievement; especially don’t feel negative about your future."

Sereivathana has proven just how much one person's dedication and passion can impact the future of one of the world's most beloved species, the Asian elephant, but more importantly he's achieved success by bettering the lives of the people who share the elephants' habitat.




Tuy Sereivathana receiving his award at the 2010 Goldman Prize ceremony. Photo courtesy of the Goldman Environmental Prize.

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