News of the Wild
From the August/September 2010 issue
Roger Di Silvestro
Chameleons, the Champions of Breakfast
Because reptiles are cold-blooded, their muscles usually contract slowly during periods of low temperature, such as early morning. Not so for the tongue of the veiled chameleon, as biologists at the University of South Florida recently learned. The tongue shoots out to catch insects equally fast at cool and warm temperatures. Why? As muscles pull the tongue into the mouth, they stretch the tongue’s springy collagen, a protein-based connective tissue, much like pulling back on a bowstring. When released, the tongue snaps outward at maximum speed because the collagen isn’t slowed by cooling.
Riding on the Global Warming Express
For the first time, scientists have linked human-caused global warming definitively to the timing of a natural event. Researchers at Australia’s University of Melbourne used records dating to 1940 to determine that common brown butterflies (Heteronympha merope) have emerged from their chrysalises 1.6 days earlier per decade across the past 70 years. During the same period, Melbourne, Australia, warmed by about 0.25 degrees F per decade. “This rate of warming is extremely unlikely to be natural and is highly consistent with the expected effects of human greenhouse gas emissions,” says Michael Ray Kearney, one of the researchers. The butterflies now take wing 10.4 days earlier than they did in the 1940s. By raising the insects in temperature-controlled chambers, the researchers showed that the warming around Melbourne can explain the shift in emergence date. Such studies, the biologists reported in Biology Letters, “improve our ability to forecast future climate change impacts on biodiversity.”
Making Do with Tree Shrew Poo
Scientists believe that Borneo’s giant montane pitcher plant (Nepenthes rajah), an endangered highland species, stands out as the largest meat-eating plant in the world: Measuring up to 13 inches high and 7 wide, the “pitcher” in which it captures and digests food can hold more than a half-gallon of water. What scientists did not know until recently is just what it is eating. Carnivorous-plant expert Charles Clarke and his colleagues at Malaysia’s Monash University and British Columbia’s Royal Roads University have discovered that glands on the pitcher “lids” of these massive plants produce large quantities of nectar highly palatable to local tree shrews, rodentlike animals related to primates. To get the nectar, the tree shrews—which match closely in size the dimensions of the pitcher—have to perch on the plants in a way that places their rear ends over the pitcher mouths. While dining they also take a moment, apparently, to mark their territory by defecating. The droppings, the researchers believe, are absorbed by the plant and fulfill most of its nitrogen needs. “One-hundred-and-fifty years after the discovery of N. rajah, we finally have an explanation for why the largest carnivorous plant in the world produces such pitchers,” Clarke told the BBC. The researchers suspect that many other highland pitcher species also feed on mammal droppings, including one plant that often serves as a bat roost.