In the article... it is a challenging read unless you are scientifically inclined. I am to a certain extent.


Paraphrased from for the article:


Basically the argument is this...


the current line of thinking is the two types of sex determination types are thought to be mutually exclusive unto themselves.


Like you either have to have TSD (temp *environmental* sex determining) reptiles.

Or...

You have genetic sex determining found in a certain type of reptile.


The article argues that these two things are not mutually exclusive.

The genetic type of sex determining is thought to be the older form of the two.


But in some reptiles the TempSD has begun to really play more of a noticeable effect when studied.


However the article argues that there are other factors at play...

The males testosterone and how the androstetidone is transferred and estrogen synthesis etc etc. Gonad factors come to play into the equation. Male testosterone levels in other words factor in.


But as I was saying they are not thought to be mutually exclusive. You actually have TSD and GSD (temp % gene sex determining) factors at play simultaneously.


Males are found the extreme typically:


lots of warms or lots of colds

more males



Intermediate temps more females.


So this is counter to what some claim as either just hot: more females or cold more males


Intermediate temps: more females

Extreme temps: more males


The article states that TSD and GSD are closely related in reptiles. And some/most have incorporated both albeit with a few exceptions where one type of determining factor presides over the other.


See here from the article:



More recent work by Shine provides the strongest evidence yet that TSD and GSD may coexist in reptiles. They incubated eggs from the montane and chromosomally heteromorphic three-lined skink, Bassiana duperreyi, under temperature regimes that mimicked natural temperature variation. When temperatures were similar to those in the field at high altitudes in cool summers, sex ratios were significantly skewed. Approximately 70% of eggs produced males, a result that could not be explained by differential mortality. This suggests that, at the lower extremes of the natural range of temperatures experienced during incubation, sex in this species is temperature sensitive resulting in temperature
over-riding the underlying genotypic sex that prevails at other temperatures.




Read the article you will see. I would say that BDs are both TSD and GSD. Maybe a bit more toward the GSD side but the temp does play a minor factor to a small extent as it does with most other reptiles also.

Alligators and sea turtles have more specific TSD or GSD tendencies.

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