Researchers discover leopard gecko produces females at cooler incubation temperatures and mostly males at warmer ones. This clear sex-determination pattern of leopard gecko has established it as a key model for studying environmental effects on development.
Credit: Professor Shinichi Miyagawa from Tokyo University of Science, Japan.
Bible literalists insist that every word in the Bible is true and without error, yet the text itself contains statements that cannot all be true at the same time, so at least one of them must be false*. The Bible also contains factually incorrect statements, such as the assertion in Genesis 6:19 and 7:15–16 that males and females of every ‘kind’ were brought onto the Ark, reflecting the same assumption found in Genesis 1:27 that living creatures were created as male and female.
We now know, unlike the authors of Genesis, that not all species exist as fixed male–female pairs. There are many examples of hermaphrodite creatures that are both male and female; some species that are entirely female, such as the New Mexico whiptail lizard and the marbled crayfish; many aphids and some beetles such as the vine weevil; and species that can change sex during their lifetime, such as certain fish. And, as a recent paper in the journal Developmental Biology by a team of researchers led by Professor Shinichi Miyagawa from the Department of Biological Science and Technology, Tokyo University of Science, Japan, shows, there are also species such as the leopard gecko, Eublepharis macularius, in which sex is not determined by inherited chromosomes at all but by the temperature at which the embryo develops in the egg.
In other words, in some species the difference between male and female is not fixed at conception at all, but depends on something as mundane as the temperature of the nest.
The team showed that there is a discrete window, known as the temperature-sensitive period, during which temperature triggers temperature-dependent sex determination (TSD), activating specific sets of genes that control the development of either testes or ovaries, thereby determining the sex of the developing embryo.





































