| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Habitats Amphibians Rock the High Sierra
The clouds of stars are vivid enough to touch. If I weren’t so tired and cold I’d like to stay up all night watching them swirl around the sky and move among the cragged peaks and cliffs that ring the horizon. But the evening’s insanity has worn me out. Hours ago, right after dinner and a couple of shots of scotch, I was limping toward my sleeping bag when University of California at Berkeley herpetologist Vance Vredenburg asked me if I’d like to join him and four of his field assistants on a search for the nocturnal Mt. Lyell salamander (Hydromantes latycephalus), probably the most extreme and peculiar amphibian on Earth. My body screamed “No!” so I was both relieved and horrified to hear my mouth say, ”Of course.” I put on all available layers and stuffed my sleeping bag, flashlight, and water bottle into my pack. The six of us set out into the late dusk. It was early June, but at 11,000 feet in King’s Canyon National Park much of the ground was still covered with snow. I’d already been in the High Sierra for two days, but I had not yet acclimated to the altitude. I couldn’t get a lungful of air, my head ached, I was woozy, and my thighs burned. The day’s sun had softened the snow enough that every dozen delicate steps or so my boot punched through the frozen crust, filling my pant leg with snow. Few creatures can survive these conditions, but it’s a real accomplishment for a cold-blooded, lungless amphibian without access to polar fleece. Little is known about just how it pulls off the feat. We do know that H. platycephalus has both the longest and the fastest tongue of any salamander on Earth. It sits in wait, camouflaged by its mottled, granite-like coloration, often clinging to vertical roc faces with its peculiar, webbed feet and sticky epidermal secretions, until an insect comes within range. Bam! The hapless prey vanishes. Slow-motion footage shows the cool killer completely still, except for its mouth and tongue. Even a small body movement could result in a long and deadly fall from its perch. We also know that H. platycephalus secretes a poison capable of blinding humans. A photographer lost his vision for three days after handling one and then rubbing his eyes during a photo shoot. And we know that, unlike other salamanders, Hydromantes uses its walking-stick tail as a fifth leg, sort of like a kangaroo. After a dizzying hour’s walk, the group stood at the bottom of Tate Falls, a 300-foot-tall granite waterfall at the foot of a glacier. The Mt. Lyell salamander was found here in 1999 by Vredenburg and two field assistants. Because there were so few known populations of the salamander, says Vredenburg, it radically revised the distribution maps for the species and, at 11,550 feet, it was one of the highest elevation records for the creature. Even more importantly, though, the high-altitude discovery may provide key evidence to an emerging theory that would rewrite our assumptions about the geology of the Sierra Nevada and the evolutionary history of the animals that live here. H. platycephalus was first found by a University of California at Berkeley undergraduate in 1914. Charles Lewis Camp, who later became a renowned herpetologist, geologist, and historian, had set a trap line while doing a survey of the fauna on Mt. Lyell in Yosemite. The trap was intended for mammals, but two salamanders, engaged in what was probably a mating dance, wandered into it. A romantic tragedy for the pair, but great luck for Camp. He immediately recognized it as a new animal and, back at the museum in Berkeley, classified it with the other known species in the genus at the time, all of which are European and four of which are found only on the Italian island of Sardinia in the Mediterranean Sea. “It seems so unlikely,” says David Wake, UC Berkeley
herpetologist, Academy Fellow, and authority on North American amphibians.
“They are each other’s closest relatives,” he says. “Why would there be
a handful of relictual salamanders in California, and some in Italy, but
none in-between? Hydromantes was then, and remains, a complete
zoogeographic enigma.” I want to remind everybody what’s at stake here,” Vredenburg said. “If you get hurt, it’s going to be a long time before we can get a helicopter in here. This is about as dangerous as it gets.” “Yeah.” “Right.” “Okay, Vance,” came the humbly mumbled responses in an uncharacteristically solemn moment. I silently considered my beautiful family ...and my lack of life insurance. Then we all were climbing the waterfall’s icy rock face in every direction, looking for salamanders in the fissures between the huge granite chunks. The sound of the melt from the glacier above us dripping and streaming over the precipice filled the moonless night. The crisscrossing beams from our headlamps danced over the cliffs and boulders, creating an eerie light show in the ultimate planetarium. My adrenal glands must have finally choked to a start because climbing suddenly seemed effortless. My fingers and toes felt confident and strong on the narrow and often invisible holds. I don’t know how long it was before a human word broke the trance-like spell of the search. “Here!” Tunstall yelled. We scrambled and climbed to the site like ants making their way toward a cookie crumb, and focused our flashlights on the salamander. Freezing water rained down, but no one noticed. It tilted its funny, squarish head (platycephalus means “flat head”) slightly to look at us with its bulging eyes, or perhaps to smell us with supersensitive chemoreceptors. Its mottled black and green-gray skin almost perfectly matched the granite, and its body was dense, rocklike, and looked incredibly durable for an amphibian. Photographer David Liittschwager and I had followed Vredenburg to this remote part of the High Sierra mainly to see another animal: the beleaguered mountain yellow-legged frog (Rana muscosa). Vredenburg had studied the frog here for six years and had shown its precipitous decline, at least here in 60 Lake Basin, to be caused by introduced trout. Various land management agencies had been airlifting the fish into the area for decades. (It’s hard to believe now, but ten years ago most biologists insisted that the introduced trout had minimal impact, if any, on Rana muscosa populations.) Vredenburg had also shown that by eliminating fish from at least some of the higher and more isolated lakes, it was possible to restore populations of the frog. He did this so elegantly and definitively that he managed, while still a grad student, to convince the National Park Service and the California Department of Fish and Game to begin eradicating fish from many highland lakes in King’s Canyon, Yosemite, and Sequoia national parks. Three years ago, David Wake, Vredenburg’s Ph.D. advisor, urged him to do genetic studies of the frog in addition to the population and migration field studies he was already doing. The results were intriguing...and potentially earthshaking. “The DNA work showed a huge [genetic] divide somewhere in the center of the Sierra Nevada,” Vredenburg says. This frog exists in the Sierra Nevada and the mountaintops surrounding Los Angeles—two areas separated by a wide desert barrier. There were four distinct evolutionary lineages, with three groups in the Sierra Nevada and one isolated far to the south. The strangest finding was that one of the northern groups was much more closely related to the southern group than it was to its northern neighbors. And while the geographic obstacle between the two mountainous areas is a desert, formidable for a frog to cross, the divide between the three northern lineages in the Sierra Nevada appeared negligible. Furthermore, the deepest genetic division passes right through the northern portion of 60 Lake Basin. When Vredenburg and his colleagues found the salamander population in the 60 Lake area, the Park Service gave them a grant to look for still more, which they quickly found. “Researchers who had previously been thinking about Hydromantes suddenly got the idea that the same pattern [as that present for Rana muscosa] may be visible in their genes and morphology,” says Vredenburg. Sure enough, when Ted Papenfuss from the UC Berkeley Museum of Vertebrate Zoology sifted through old genetic data on the lizard, he noticed a sharp north-south break. He’s now following up on the study. “I would not be surprised if there were a new Hydromantes described in the next nine months due to all of this,” says Vredenburg. Meanwhile, other scientists started to notice a similar, equally surprising north-south break among populations of other animals near 60 Lake Basin. “It’s weird,” says Wake, “because you think you’re in the High Sierra and that the divisions should be east-west. But there is a Hydromantes break there.” The same pattern is seen among populations of Yosemite toads, wood rats, a shrew, the mountain king snake, and the sharp-tailed snake. “We don’t detect this at the morphological level,” says Wake, “but when you see the genetic data it just smacks you in the face.” Whatever led to this unexpected split remains a mystery. But the abundance of examples hints that it was a giant geological event—one that current theory doesn’t explain, Wake says. “Maybe the glaciations occurred over a much larger time than we’d thought. Or maybe the mountains formed long before the Pleistocene, when they were believed to have formed. I don’t know.” The effects of these findings are rippling into other disciplines as well. “When I tell geologists about these findings in biology, they talk about taking a closer look and maybe revising their theories, too,” Wake says. We found five H. platycephalus tucked between the rocks that night before hoisting ourselves over the waterfall and onto the glacier that feeds it. It was late and I suddenly realized how tired, wet, and cold I was. Now, as I lie here watching the stars, safely shivering in my sleeping bag, I keep wondering about the salamander: what secrets it holds about the history of these spectacular mountains; about its shared past with the Hydromantes in Sardinia; about how to survive subzero nights with a damp, porous skin. As I drift off to sleep, Vredenburg is sawing wood nearby. I learn later that he is dreaming about H. platycephalus, too. He sees a female burrowing through the snow and laying her eggs right there in the snow, though in reality no one yet knows how the salamander reproduces. But this is certain: If I come up here again to watch Vredenburg find out, I’ll buy life insurance first. Gordy Slack is a freelance science writer and contributing editor of California Wild. |
