The effects of climate on reptiles
Climate has shown to have different effects on the environment, plants, and animals. Climatic change can make the environment dry or wet, causing an impact on the adaptation of animals and even the plants. For instance, we have seen some plant shading leaves for it to adapt and survive the dry season. On the other hand, we have experience animals that migrate to other cooler places which .favour their conditions or even change in order to adapt to the change in climate conditions. However, in reptile, climate change has a different effect. The change in climate can cause a shift in the sex of the reptile, either from male to female or vice verse.
In other mammal and human beings, the sex chromosomes, Y and X, is used in determining the physical sex. Unlike other animals, the sex chromosomes of the reptiles sometimes do not correspond with the physical sex. This type of characteristic is called reversal sex. Factors such as change in temperature, low or high temperatures can cause sex reversal in the group of certain reptiles such as the lizards and crocodiles. Several studies show that this type of characteristic is a powerful and widespread evolutionary force in reptiles. With such a change in temperature, it raises some questions on how the reptiles such as the lizards can survive in warm or cooler conditions. This report provides an overview of factors that causes sex reversal and how common the characteristic is in reptiles. Don't use plagiarised sources.Get your custom essay just from $11/page
The sex chromosomes in human beings can be identified if the physical sex (an embryo) is either female which is indicated as XX, or male indicated as XY. With this, it is easy to identify sex in human beings, unlike reptiles that are complicated when it comes to sex determination. However, certain species, such as the snakes, have sex chromosome similar to that of human beings. But other species, including the marine turtles and crocodiles, their sex can be determined by the conditions in which the eggs get raised in. Research indicates that certain species depicts combinations of both sexes. With this, the temperature causes a shift in sex. When temperatures do not favor certain sex, an opposite signals get sent to the embryo containing sex chromosomes causing a sex reversal. For instance, the sex chromosomes in lizards do not correspond with the reproductive function and the physical appearance.
One of the best examples of reptile, which describes clearly sex reversal is pogona vitticeps (bearded dragon). The sex chromosome of this reptile are names W and Z, unlike that of human being, which is XX for female or XY for male. A dragon, which is male, carries two Z chromosomes (ZZ) while the female carries W chromosome and Z chromosome (ZW). A female dragon produces almost the same number of female (ZW) and the male (ZZ) offspring. However, during the incubation period of the eggs in a hotter condition (more than 320C), a larger number of females get hatch than the number of young male ones. This is because some of the female offspring undergo sex reversal in a hotter condition changing their sex from male to female. This shows that a hotter condition favors the female chromosomes. From this, it is clear that sex reversal is a fully functional condition. Whenever there is a female sex reversal, many eggs with female chromosomes get laid, unlike the eggs with male chromosomes. This shows that sex reversal can be an added advantage to certain species.
Another reptile species which get affect by the climate conditions is bassiana duperreyi, also known as eastern three-lined skink from Australia. This type of reptile, the chromosomes of the male are XY, and the chromosomes of the female are XX almost same to that of human being, but shows a change in chromosomes and the host. Also, the depicted chromosomes in this type of species have the same name. The chromosomes rise independently, and genes used to trigger female and male development are different. With this type of species (skink), the XX chromosomes of a female skink can be reversed to XY chromosomes showing a male skink but only when exposed at a cool temperature.
With these two provided examples, it is clear that the species with similar sex chromosomes (female skink–XX chromosomes and male dragon- ZZ chromosomes) experiences sex reversal. However, the reversal of sex occurs in two different climatic conditions. For instance, the reversal in dragon occurs when the temperature is higher while reversal in skink happens when the temperatures are low. These are two conditions that cause sex reversal in reptiles and the affected chromosomes in relation to the stated conditions.
In addition, research and various studies clearly indicate that hotter temperature causes a change of gender in lizards. This indicates the sex chromosomes cannot be used to determine gender in certain species but the condition of the climate where they are incubated. However, biologically converted lizards, from male to female, due to hotter temperatures forming a new female lizard, are considered to be better mothers compared to the female lizards that had the female chromosomes initially.
Reasons for sex reversal
Once a sex reversal occurs, it can cause significant impacts regarding the behavior of the hosting species. With the bearded dragon, the transformed male species to females are much bolder compared to the female and male, which carries the same sex chromosomes. This characteristic is helpful to this newly formed species when finding mate and food. However, this characteristic can be a disadvantage to them as it exposes the species to other predators.
Research also indicates that some lizards do not lay eggs. The reversal or shift in sex due to change in temperature can also affect this kind of species, which are considered to give birth to offspring. An example of this species includes niveoscincus ocellatus (Tasmania’s snow skink). With such species, the reversal in sex occurs due to environmental temperature experienced by a mother during the pregnancy period. This shows that a shift in sex is a widespread characteristic in reptiles. However, emerging studies indicate that environmental changes causing sex reversal can be a common characteristic in amphibians and fish, causing emergence of new species and carries severe effects in the quick changing of the environment.
Most of the researchers have focused on sex reversal in birds and mammals, whereby reversal is caused by mutations affecting the expression of genes during the development of embryo reason why sex shift in reptiles has not been fully appreciated. Sex reversal in birds and mammals has indicated by several studies had developed a wrong impression indicating that sex reversal causes harm to the individual species. However, more studies have not been done on reptiles because some of the sex chromosomes in certain reptile species are difficult to define and to differentiate. This makes sex reversal in this species very hard to spot.
Several concerns have risen due to the effects of sex reversal, especially on reptiles. Several people and researchers question if this could be the end of certain sex in species after its extinction in the entire population. This can also cause the extinction of species due to lack of fertilization as only one sex will be existing in the whole population. For the species which are sensitive to temperatures such as the marine turtles, crocodiles, and the bearded dragon, if the future becomes warmer, does it mean that the world will exist without males? These are the type of questions which majority of the people consider and more research is needed to ascertain the real truth concerning this statement. This question carries more weight, considering the current condition of global warming. This condition (global warming) is deemed to affect the world as it causes a rise in temperatures, and if nothing is done about it, the world can become warmer than the current condition. What is not known is if this condition will cause the extinction of certain species considering the fact that extension was experienced on certain species due to climatic change such as the dinosaurs as climate affected its food chain. This event occurred over 65 million years ago in a period called cretaceous tertiary.
The answer to these questions will differ in each species. The survival of the reptiles due to change in climate depends on the answers provided to several questions such as, how rapid are the change in climatic conditions? If the species can control where and when they nest? Can the climatic condition which caused a reversal in sex change? This shows that each type of species will experience a different route as people continue to experience changing environment and uncertainty. By answering these questions, it is clear that a certain path will lead to extinction, while other species will utilize flexibility using sex determination as a strategy to survive.