Reptile & Amphibian Forums

SCIENCE DAILY (Rockville, Maryland) 02 July 08 Malagasy Chameleon Spends Most Of Its Short Life In An Egg
There is a newly discovered life history among the 28,300 species of known tetrapods, or four-legged animals with backbones. A chameleon from arid southwestern Madagascar spends up to three-quarters of its life in an egg. Even more unusual, life after hatching is a mere 4 to 5 months. No other known four-legged animal has such a rapid growth rate and such a short life span.
"It really is a huge surprise," says Christopher Raxworthy, Associate Curator in the Department of Herpetology at the American Museum of Natural History. "Adding to that, until now, the short life span of chameleons in captivity has always been considered as a failure to thrive. We need to rethink this."
Most mammals, reptiles, birds, and amphibians (all tetrapods) typically live 2 to 10 years, an average bracketed at the upper end by some long-lived animals (for example, turtles and humans that can live for a century) and at the lower end by a handful of animals that only live for about a year.
The males in nine species of marsupials die off after a year, for example, as do most adults in about twelve species of lizards. But the chameleon described here, Furcifer labordi, not only has a brief, yearly life cycle, but the bulk of that time is spent incubating inside an egg. Once outside of the egg, all individuals in the population die within 4 to 5 months.
Kristopher Karsten, a graduate student from the Department of Zoology at Oklahoma State University, discovered the unusual life cycle almost by accident. "I showed up late in the season and found something weird," recalls Karsten. "There were no juveniles. But by February, I found carcasses all over with no signs of mutilation or predation. The population plummeted--we've never seen this with other lizards."
Now, after five seasons of data and sightings of nearly 400 individuals, the life cycle of F. labordi can be described. Hatching begins with the rains in November, and, once emerged, the chameleons develop rapidly, growing up to 2.6 mm (0.1 inches) a day--up to two orders of magnitude greater than other known lizard growth rate. In less than 60 days, for example, there can be a 300%-400% increase in body size for males to reach adulthood. After reaching maturity, the population reproduces, and females burrow through about 138 mm (5.4 inches) of sand to lay their eggs. Once covered, the eggs wait out the dry season for the next 8 to 9 months, and all adults die.
"It is amazing to think that for most of the year, this chameleon species is represented only by developing eggs buried in the ground," says Raxworthy. "This species really illustrates just how much there is still to discover about the natural history of Madagascar." Karsten agrees, adding: "We've identified a species that does something really different from the others, but what is driving this system? One bad year could wipe out these chameleons."
The new research is reported in the June 30 issue of Proceedings of the National Academy of Sciences. The research was carried out by Karsten and Laza Andriamandimbiarisoa of the Département de Biologie Animale, Université d'Antananarivo in Madagascar. Raxworthy and Stanley Fox of the Department of Zoology at Oklahoma State University helped design the study and write the research paper. The project was funded by a National Science Foundation grant to Raxworthy.
Chameleon Spends Most Of Its Short Life In An Egg

TULSA WORLD (Oklahoma) 06 July 08 OSU researcher's lizard theory feted
Oklahoma City (AP): Confused and frustrated that the lizards he was trying to study all suddenly died, an Oklahoma State University researcher, Kris Karsten, came to a conclusion that's earned him national acclaim.
As it turns out, the chameleon he'd been researching lives a brisk life and might just be better off in its egg than after it has hatched.
Karsten published his doctorate research on the tiny chameleon species Furcifer labordi last week in the Proceedings of the National Academy of Sciences. The chameleon, which lives in the desert in southwestern Madagascar, had been known to scientists for more than 100 years, but no one had ever realized that the lizards' life cycle lasts less than a year.
"It really exemplifies how little we know about a lot of the world," said Karsten, who is from Kansas City, Mo.
Karsten said a one-year life span is common among plants and insects but almost unheard of in four-legged vertebrates.
The chameleons are trapped in their eggs for about the first four or five months of their lives, growing to full size, about 4 inches long. Upon hatching, they mate furiously, using extensions on their noses and skulls to fight each other and attract attention.
"There's not a lot of room for error," Karsten said. "If you're a male chameleon of this species and you can't find a female to convince to mate, you've got no offspring in the next generation."
The strange mating habits attracted Karsten's attention, and he visited Madagascar — an island on the Indian Ocean side of southern Africa — to study the chameleons. Not long after Karsten arrived, however, all of the individuals he'd set out to observe died.
His chance to observe the chameleons and collect information about them seemed finished.
But over four years, Karsten and colleagues in Madagascar and the U.S. returned to observe about 400 individuals to discover what he believes may be an evolutionary strategy.
Karsten, who received his doctorate from OSU in May, said he hoped his discovery would inspire young scientists who may believe everything interesting about science has been figured out.
OSU researcher's lizard theory feted