User:Edickerson1/Ctenophorus decresii

Introduction
The average length of the lizard from snout-vent is 80.76 mm with larger individuals being around 89mm and smaller individuals around 72mm. [11]

The optimal time for mating in this species is 2-3 weeks after the females come from hibernations. Eggs are typically laid from September to October with most of them being laid earlier in the period. [7]

Description
It was thought that variations of color in these lizards was because of different levels in sexual maturity. These variations are most likely due to environmental conditions such as “maternal effects, incubation conditions or post-hatching conditions”. There is also a possibility that genetics are primarily responsible for the variations [1]. These lizards are often characterized by the color of their throats. The colors of these male lizards can vary, but they are usually orange only, yellow only, orange surrounded by yellow, or grey only throats. The colors can also vary in degree of intensity and are due to different lineages, northern and southern. [5] Males with orange throats tend to be more aggressive when it comes to defending their territory. It is still unclear how the lineages of females impact the expression of their colors especially since females from wither lineage tend to have the same coloration. [5] From this, it can be concluded that throat color in these lizards is polymorphic specifically in determining whether the phenotype is yellow or orange. Although both colors are polymorphic, the yellow color is also greatly influenced by environment and levels of testosterone present. Polymorphism and environmental factors play major roles in color expression, but it is impossible to say which one is more significant without genomic analysis and linkage mapping. [2]

Magnetic resonance imaging (MRI) has been used on the tawny dragon lizards to examine their brains. A study found that the brain had 224 structures that could be seen. The left hemisphere in the brain is associated with the optic system. This research was fundamental in the study of evolutionary neuroscience in lizards. By having the neuroanatomy of lizards, scientists are able to see how behavior and cognitive function are related to structures of the brain. [14]

Diet
C. decresii consume a wide variety of foods and are omnivores. Their main diet consists of invertebrates and vegetation. Invertebrates include crickets, moths, fly maggots, and locusts. [12]

Conservation: Habitat loss, conservation efforts

The effects of climate change, specifically rising temperatures, have caused significant declines in many species, and the tawny dragon lizard is not an exception. In high temperatures, the tawny dragon lizard has adapted effectively regulate their body temperature through a process called behavioral thermoregulation, but there is a cost. Because of this, water loss occurs at a much higher rate leading to desiccation, or drying, more quickly. The combination of high temperatures and decreased rainfall has had a severe impact on the not only survival of these lizards but also fecundity and growth rate. As these conditions continue to become more extreme, these problems will become increasingly more severe. [3]

Ctenophorus decresii are also threatened by habitat fragmentation and bush rock removal. These lizards already have specific habitat requirements, so any habitat loss can increase the risk of decline. The population size is trending downwards, because their habitat range is becoming so small in some areas. Although many of these problems are driven by humans, grazing animals impact the population as well. Constant grazing from animals like sheep, cattle, and feral goats reduce the areas where the lizards can hide and live. With fewer hiding places, they are more susceptible to predation. This, in conjunction with human land clearing, causes much less genetic variation within the species. [8]

Fertilization
Ctenophorus decresii are characterized by their ability to produce multiple clutches in a year but a short lifespan. Incubation temperature affects the hatchling tail length and sex. At intermediate incubation temperatures, the proportion of males to females was much higher compared to extreme incubation temperatures (very high or very low) where females were the only sex seen. This shows that the season in which the females lay the eggs is good indicator of which sex will be seen in the hatchlings and body size, also known as temperature-dependent sex determination. Very low incubation temperatures are often associated with slower, less developed hatchlings. If incubated at a suitable temperature, hatchlings will have a higher body mass. These individuals will also have a higher probability of reproductive success especially in terms of clutch size and offspring body mass. Studies suggest that body mass is also influenced by the length of incubation. Eggs laid closer to the beginning of the season have more time to develop thus giving them more of an opportunity to gain more body mass. On the other hand, those laid later in the season do not have the same opportunity. Larger body sizes provide an advantage to males and females. Males are better able to defend their territories, and females have higher fecundity. Males with more territory also had larger body masses.

Mate searching behavior
As mentioned in the description section, the coloration of the male tawny dragon lizards can vary, especially by region (northern and southern). For mating, southern females are more likely to mate with southern males however, they are much less selective in their mate preferences than northern females. Both southern and northern males are more likely to be rejected by northern females. Southern males also prefer to mate with southern females because they share the same lineage. This suggests that preferences by either sex are driven by behavioral differences regionally. These lizards primarily prefer to mate with partners that are in the same region geographically. Overall, it appears that speciation is primarily driven by sexual selection with neither sex being more selective than the other.

Male-male interactions
In these lizards, northern males are considered more aggressive than southern males. Orange, northern males are the most aggressive, and southern males are the least aggressive. [5] However, males, regardless of lineage, can differentiate their aggression. Aggression occurs at a higher rate when two males have not interacted with one another. When encountering a male that he had encountered before aggression was significantly lower. Repeated interactions were shown to more effective in limiting aggression between males. If there has already been a previous encounter, it is less likely that the individual will be a threat to the livelihood or territory of that male. [6] Being able to recognize which lizards they have already encountered gives lizards the opportunity to limit costly interactions. They are able to tell which individuals they have already won or lost to. To distinguish between individuals, the lizards use physical characteristics as opposed to chemical or behavioral cues. This species uses coloration of the throats to distinguish between lizards, similar to how scientist do in experiments. When researchers controlled for throat coloration, it was more difficult for lizards to determine if they had already encountered the lizard. There were similar levels of aggression for familiar and unfamiliar males. [15]

Another indicator of aggression is the presence of black chest patches. Males with these patches are not only more aggressive but also more likely to initiate and win fights. [10] Size and residency status also seem to be deciding factors in the winner of territories with size being a bit more important. Regardless of size, residents are more effective at defending their territories against non-residents. In these cases, larger males do not have the advantage. However, when both lizards are residents (or non-residents), the larger lizard has more success at defending their territory. [11]

A higher level of aggression is also associated greater number of encounters with other lizards, specifically those where they are the initiator of the fight. If a male is initiating more fights, it can be assumed that they are the more dominant individual. This also means these males reside in territories that are rich with resources that must be defended in order for them to maintain their dominance. High aggression is associated with a greater degree of territorialism. [15]

Cryptic behavior
The intensity of colors in these lizards indicates the amount predation they are susceptible to. As expected, individuals with more brightly colored bodies are at a higher risk of predation, because they are more easily spotted. In these habitats, the rocks in which the lizards bask are darker, so the bright oranges and yellows contrast greatly Individuals that are not as bright, or duller, are attacked significantly less than their brightly colored counterparts. The main predator of the tawny dragon lizard is birds. [9] C. decresii are a species that use crypsis as a defense mechanism, however females use this mechanism more than males. Although more prevalent in females, both sexes use the coloration to blend it with their surroundings. The exact colors depend on the environment, but the colorations are usually localized to the exposed body regions, so individuals can avoid predation. [13]