After conducting a series of controlled reproduction experiments in the laboratory with 131 specimens of adult Australian bearded dragons ( Pogona vitticeps ), they have determined that global warming produces sexual reversion in these species.
According to molecular analyzes, 11 of the studied animals located in the warmest range of their habitat – originating from the desert and semi-desert regions of Australia – had a set of male chromosomes despite being female. They have also tried to prove that these specimens can go from a genetically controlled reproduction system to another controlled by temperature.
According to Arthur Georges, a co-author of the research, the increase in environmental temperature due to climate change means that a greater number of nests of these reptiles are exposed to solar radiation, which can cause sex reversals. Bearded dragons appear to have a number of ways to determine the sex of their offspring. Some have sex chromosomes, and the father determines the sex of the offspring (XY systems) as in humans. In others, sex is established by the mother (ZW systems), as in birds, and in other cases, they are parthenogenetic (there are no males and the unfertilized ovum is segmented).
According to the researchers, when the females with the reversed sex mated with males, none of the resulting offspring had sex chromosomes and their sex was determined by the incubation temperature of the eggs. The children of these mothers with reversed sex, who lay almost twice as many eggs as the rest, are also more prone to sexual reversal. All of this results in more feminized populations. It also proves that evolutionary responses and some drastic changes in sex determination in offspring can happen very quickly.
The study underscores the potential role of climatic extremes in altering the biology and genome of climate-sensitive reptiles. According to experts, this greater flexibility in sex determination mode could be a useful evolutionary weapon in the face of unpredictable weather. The Australian bearded dragon population is widespread in the sandy areas of the semi-arid regions of eastern Australia. It occupies open forests and is visible when perching high to warm up early in the morning from sunlight.
