Scientists know that temperature determines sex in certain reptiles—alligators, lizards, turtles, and possibly dinosaurs. In many turtles, warm temperatures during incubation, create females; cold temperatures, males. This is one hypothesis that explains dinosaur extinction: a meteor hit, cooling the Earth, producing an all-male population.
Identifying the gender of a turtle is not a simple task to do. Unlike other mammals, turtles do not have any distinct sign that declares its gender such as external genitalia. It makes identifying the sex of a turtle much more challenging, but not impossible.
The aptly-name red-eared slider is an easily recognizable semiaquatic turtle that's popular in the global pet trade. These animals are considered one of the top invasive species of the world, and it's really no wonder when you consider their mating habits. Red-eared sliders Trachemys scripta eleganswhich have a red stripe around their ears and are known to quickly "slide" off objects into the water, are native to the southern United States and northern Mexico.
The red-eared slider Trachemys scripta elegansalso known as the red-eared terrapinis a semiaquatic turtle belonging to the family Emydidae. It is a subspecies of the pond slider. It is the most popular pet turtle in the United States and is also popular as a pet in the rest of the world.
Description: Red-eared Sliders are brightly marked, and look similar to the painted turtle. The carapace top shell of the Red-eared Slider is higher domed than that of the Western Painted Turtle and is weakly keeled. Characteristics that most obviously distinguish the Slider include yellow marginal scutes, a yellow plastron covered in dark, blotchy markings, and a red ear mark located just behind the eye although this ear mark is not always visible in older specimens.
However, quite often curiosity strikes and people simply want to know. Some slider hobbyists, on the other hand, want to breed their turtles or house multiple turtles in one habitat. For these reasons, you definitely need to know whether your turtles are male or female.
It is often difficult to determine the gender of a pet turtle, especially if you did not purchase it from a breeder that hatched them from controlled temperature environments. The temperature during egg incubation is what determines whether an embryo will become a male or female; cooler incubation temperatures produce males and females develop in warmer temperatures. Thankfully there are some types of turtles that make it easier than others to distinguish a male from a female without knowing their incubation temperature.
In the red-eared slider turtle Trachemys scriptaa species with temperature-dependent sex determination TSDthe expression of the aromatase gene during gonad development is strictly limited to the female-producing temperature. The underlying mechanism remains unknown. A putative TATA box was located 31 bp upstream of the gonad-specific transcription start site. DNA methylation at the CpG sites between the putative binding sites of the fork head domain factor FOX and vertebrate steroidogenic factor 1 SF1 and adjacent TATA box in the promoter region were significantly lower in embryonic gonads at the female-producing temperature compared the male-producing temperature.
If you keep pet turtles, it's nice to know if you've got boys or girls. However, unlike many mammals, turtles have no external genitalia. This makes determining their sex much more difficult, but it's not impossible.
Many egg-laying reptiles lack sex chromosomes, depending instead upon the incubation temperature of the egg to determine the sex of their offspring, a process known as temperature-dependent sex determination TSD. How temperature both stimulates and inhibits genetic cascades to determine the type of gonad and direct sexual differentiation is the focus of this application. This investigator and his colleagues have developed the red-eared slider turtle Trachemys scripta elegans as an animal model system to study TSD.