For the first time, it has been shown that climate change It is capable of modifying the sex of some species of lizards in the wild. These male reptiles can transform into fertile females capable of reproducing, which could have profound implications for biodiversity and species survival in an increasingly warming environment.
The impact of climate change on the sex of lizards
The increase in temperatures caused by climate change is directly influencing sex determination in certain reptile species, such as Australia's bearded dragon lizards. One of the most significant studies, conducted by a team at the University of Canberra, has shown that genetically male lizards They can transform into females when exposed to high temperatures.
This process was initially observed in laboratory, when lizard eggs were incubated at extreme temperatures. It was discovered that genetically XY males could develop female anatomical features. The finding was, however, even more surprising when it was confirmed in field studies, showing that this change occurs naturally in the nature due to global warming.
Thus, the sex of lizards is no longer determined exclusively by genetics, but also by environmental conditions, such as temperature. This discovery highlights the vulnerability of species whose sex depends on the incubation temperature in the face of climate change.
The scientific importance of this discovery
From a scientific perspective, the discovery has raised crucial questions about other species of reptiles and sexual animalsThe ability of lizards to change sex in response to extreme temperatures suggests an evolutionary mechanism with profound implications for persistence of speciesThese types of evolutionary adaptations could be a response to accelerated changes in climate, but they could also represent a vulnerability if conditions continue to worsen.
To corroborate these changes, scientists took genetic and anatomical samples from 131 wild-caught lizards, finding that the changes in sex depended not only on chromosomes, but also on the environmental exposure at high temperatures. These molecular studies confirmed that many of the “reverted males” were genetically male but anatomically female.
This mechanism, known as temperature-dependent sex determination (TSD) has also been observed in other species such as turtles and crocodiles. In these species, the temperature at which the eggs are incubated determines whether the individuals will be male or female.
The effect on global biodiversity
One of the biggest fears among scientists is that if this phenomenon accelerates, it could drastically alter the sex ratio In many species, affecting their ability to reproduce sustainably. In some populations where males transform into females, reproduction could be severely compromised, leading to population declines.
An emblematic case is that of the sea turtles In Australia, where rising beach temperatures have led to up to 99% of hatchlings being female. If this trend continues, some species could face extinction if the effects of climate change in these key egg-incubation areas are not mitigated.
Why does this phenomenon occur?
Sex change in these reptiles is due to a temperature-sensitive period during which high heat levels trigger the production of an enzyme called aromataseThis enzyme converts testosterone into estrogen, which causes male embryos to develop into females. This process is irreversible and occurs during the later stages of embryonic development.
This phenomenon has been confirmed by research detailing how thermosensitive proteins They play a key role in the activation of aromatase. This production of estrogen directly influences the development of the reproductive organs of the embryo, modifying its sex despite its genetic code.
Evolutionary and long-term consequences
The long-term consequences should not be underestimated. The rapid change in sex determination due to rising temperatures raises questions about the species' ability to adapting to a rapidly changing climate environmentIf the rate of global warming continues to exceed the ability of these species to adapt, they could be subject to strong selective pressures.
Some scientists speculate that some species may develop genetic mechanisms that reduce the influence of temperature on sex determination. However, this evolutionary process is uncertain, and the speed at which it must occur may not be sufficient to save many species.
In addition, climate change is pushing some species to modify their reproductive behaviour patterns. For example, in some parts of the world, turtles have begun to lay their eggs in colder areas, as an adaptive response to balance the sex ratio in their offspring.
However, not all species can adapt to this change. For example, tuataras New Zealand's reptile species, an ancient species, are in serious danger due to rising temperatures. In this species, if eggs are incubated at temperatures above 21,5 °C, all the offspring are born male, which could lead to the extinction of the species.
Finally, this situation underlines the importance of mitigate the effects of global warming to preserve biodiversity. Species that depend on TSD are at particular risk if greenhouse gas emissions continue to increase.
It is crucial to increase efforts to reduce greenhouse gas emissions and protect habitats crucial for the reproduction of these and other species. From reducing emissions to conserving natural habitats, each action can have a significant impact on the preservation of biological diversity.