Q. Is an alligator`s sex really determined by the climate in which it is hatched?

A. Temperature is the deciding factor in an alligator`s gender, according to Dr. Paul Cardeilhac, a professor of veterinary medicine at the University of Florida.

He cited studies in which alligator eggs were incubated at 30 degrees centigrade (86 degrees Fahrenheit) from the 7th through the 21st days after they were laid. All of these eggs hatched female offspring. Eggs incubated at 34 degrees centigrade (93.2 degrees Fahrenheit) in the same period resulted in all male offspring.

The reason, Cardeilhac said, is that alligators lack sex-determined chromosomes, so temperature determines their gender. Temperatures 34 degrees centigrade and above produce androgenic hormones inside the egg, which form male sex organs.

If the nest is laid on a riverbank in the sunlight, the offspring will probably be male; if it is laid in a cool, shady place, the eggs will yield females. The sex of some lizards and turtles is determined in the same manner.