Description
Pogona vitticeps was first described by Ernst Ahl in 1926, who placed it in the genus Amphibolurus.[3][4]
A studied conducted in 2014 established the existence of endogenous circadian rhythm in pigmentation changes in Pogona vitticeps. In other words, light and dark can influence the color changes of this kind of lizards. If exposed to light, the dorsal skin of the lizard becomes darker, and if exposed to darkness, it becomes lighter. Under constant darkness (i.e. in the subjective night), the lizards’ dorsal skin becomes the lightest.[5]
Ecology and behaviour
Bearded dragons do not vocalize, except to hiss softly when threatened. Instead, they communicate through colour displays, posture, and physical gestures, such as leg waving and head bobbing. Bearded dragons are not social animals, but will sometimes gather in groups, especially in popular feeding or basking areas. At these times, a distinct hierarchy will emerge: the highest-ranking animals will take the best - usually the highest or sunniest - basking spots, and all other individuals arrange themselves lower down. If a low-ranking animal tries to challenge one of the dominant dragons, the dominant animal will demonstrate its superiority by bobbing its head and inflating its beard, at which point the challenger may signal submission by waving one of its front legs in a slow or fast circle. If the low-ranking dragon does not submit, it will return the head bob, and a standoff or fight may ensue.
The several different kinds of head bob gestures are:
- Slow bowing motion - often used by adult females to signal submission to a male
- Fast bob - used by males to signal dominance (often accompanied by an inflated and/or blackened beard)
- Violent bob - used by males just before mating, much more vigorous, and usually sets the animal's whole body in motion
- Females also do fast and violent head bobs as it shows us that they are stressed out and need some alone time. This also applies for the males.
When under direct attack, the central bearded dragon opens its mouth to display its yellow membranes and extend its beard.[6] It darkens the colour of its skin and flattens its body, and will hiss and make small jumps towards the attacker. Bearded dragons are not known to attack humans.[7]
Bearded dragons have been shown to be able to learn from watching the behaviour of conspecifics. An experiment demonstrated that after one individual was trained to open a door to reach a food item, most other bearded dragons watching this action were able to perform it as well.[8]
Reproduction
Courtship involves the male "head bobbing" to display dominance. If the female displays submissive behaviour, the male will use its mouth to grab the back of the female's head and the male will also wrap its front legs around the female's upper torso to keep her from moving. Copulation and insemination are quick. The gestation period averages about a month and a half.
Thermally induced sex reversal
A 2016 study showed that high-temperature incubation of eggs transforms genetically male individuals into functional females.[11]
Normally their sex is determined genetically. Males have ZZ sex chromosomes, females ZW. However, when their eggs are incubated at temperatures above 32 °C (90 °F) some genetic males are born female. These females are fertile, sometimes producing more eggs than the ZW females. [12]
Captive breeding
Captives worldwide are threatened by Agamid adenovirus, a virus that compromises the immune system of the dragon, and leads to death from other diseases. However, the majority of the infections are subclinical. Subclinically infected animals show no symptoms, but are active carriers of the disease and will infect other bearded dragons.
When the female is ready to lay eggs, she will generally stop eating and spend most of her time trying to dig.[citation needed]