Only female turtles have recently hatched in the Keys.
The afternoon newspaper Lööp is already a kind of concept for sex. Science has now shown that it is also for gender reassignment. Its limit, at least for turtles, is 31 degrees.
Global warming is changing the gender distribution of organisms in an interesting way. In Florida, for example, it has been observed that in recent years, in some areas, no male turtles have hatched at all.
The topic was reported last week, among other things news channel CNN.
At our house in humans, gender is determined based on, among other things, sex chromosomes. However, some reptiles, such as turtles, do not have separate male and female chromosomes. They become girls or boys based on how warm their eggs hatch.
In some sea turtles, all the hatchlings turn into dogs if the eggs hatch in beach sand at a temperature slightly below 28 degrees.
If, on the other hand, the hatching temperature is constantly above 31 degrees, all will become females. The sex distribution of hatchlings then varies between these extremes.
In the Florida Keys, in the last four years, not a single small dog turtle has hit the wounds of the researchers. The last four summers have also been the hottest in recorded history in Florida. If things continue like this, populations may collapse.
Temperature determines the gender also with the bearded dragon, which is also popular as a pet. But they also have sex chromosomes. The Texas rock trio ZZ Top is known for their beards, and quite aptly, the male bearded agama has ZZ chromosomes.
However, the female also has a beard! Regardless of chromosomes, temperature makes sex. The ZZ embryo also turns into a female in extreme heat. Interestingly, according to research, these females produce more eggs than chromosomally “normal” females.
With some Australian skinks, it’s the other way around: a female with XX chromosomes hatches a male if it’s cooler.