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Announcing Sacred Mounds, a novel of Magical Realism and Historical Fantasy from Jim Metzner, with a foreword by Hutke Fields, principal chief of the Natchez Nation.
Cyclonic hordes of insects, a telepathic despot, body-swapping sex - just a few of the surprises Salvador Samuels encounters when he is swept back to pre-colonial times, walking in the moccasins of a blind Indian - who, in turn, has been transported into Salvador's body in present-day America. Sacred Mounds Book Cover Four hundred years apart, they are bound by a mission to rescue our world, aided by the mysterious presence of the mounds. Thousands of these ancient earthworks once dotted the landscape of North America. We still don't know why they were created. Sacred Mounds suggests they are as important today as when they were made over a thousand years ago. Sacred Mounds weaves the stories of two men, each a stranger in a strange land. With the help of two remarkable women, they must find a way to save our planet and return home.
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NILE CROCODILE: Temperature Dependent Sex Determination: The Pulse of the Planet daily radio program offers free legal online mp3 downloads, exploring the world of sound in nature, culture and science, with audio adventures, world music, extraordinary sound portraits, science diaries, and nature ring-tones; an amazing sonic experience.

Airdate: Feb 11, 2000
Scientist: Dr. Alison Leslie

NILE CROCODILE: Temperature Dependent Sex Determination

NILE CROCODILE: Temperature Dependent Sex Determination
Believe it or not, the sex of baby crocodiles is determined by the temperature of the eggs in the nest.

We're listening to the sounds of baby crocodiles, freshly hatched from their eggs. You might think that there'd be a fifty-fifty chance that a particular hatchling would be male or a female. But that's not the case, and we'll find out why in a moment. I'm Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.

Believe it or not, the sex of baby crocodiles is determined by the temperature of the eggs when they were in the nest -- it's called temperature dependent sex determination.

"Temperature dependent sex determination or what is also known as TSD is a phenomenon that has been studied in a number of reptilian species. And what this means is that the sex of the hatchling is not determined genetically, as it is with human beings and with a lot of other mammalian species, but it actually determined by the average incubation temperature during the middle third of the developmental period."

Dr. Alison Leslie is a physiological ecologist with the University of Stellenbosch in South Africa. She's spent the last 4 years studying the Nile crocodile in South Africa's Lake St. Lucia. Dr. Leslie has observed that St. Lucia's crocodiles exhibit an unusual form of TSD.

"Turns out that temperatures below 31.7 degrees Celsius produce females. Any temperature above that, in other words, above 31.7, right up until 34.5 degrees Celsius, produce males and then temperatures above 34.5 degrees produce female hatchlings once again. So we have a female, male, female ratio for Nile Crocodiles. Which is pretty interesting."

So, there's only about a 3 degree range in which males will occur, which has a major impact on the long-term survival of crocodiles. We'll hear more in future programs. Pulse of the Planet is presented by the American Museum of Natural History. I'm Jim Metzner.