Post by Ceratodromeus on Jul 5, 2016 8:08:40 GMT 5
Desert iguana - Dipsosaurus dorsalis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Lacertilia
Infraorder: Iguania
Family: Iguanidae
Genus: Dipsosaurus
Species: D.dorsalis
Description
The desert iguana is mid sized species of desert dwelling lizard, with adaptations to help it survive and thrive perfectly in these environments. They are drab colored animals, with a typically dark brown dorsal coloration with ocellated spots running down the animal's back. The tail shares a similar color pattern but instead a white and brown barred pattern. Dark pigmentation can be found around the eye but this, as well as the body coloration of adult animals, varies between poplations. Sexual dimorphism does not appear to be present in regards to body size, with adults of both sexes attaining similar lengths and weights overall. A study published in 1984{1}showed that animals from 31-44 months in age averaged a snout ventral length of 110-112mm(4.3-4.4in), and ranged from 85-126mm(3.3-4.9in) in snout-ventral length. Another study on the dietary habits and sexual dimorphism of the species based in Sonora gave the mean snout-vent length for males as 98mm(3.8in) and 90mm(3.54in) for females{2}.
Geographic range & habitat use
This species can be found from southern Nevada down into north/ central Mexico, where they are well studied. Since these lizards live in environments where rainfall is typically scarce, the desert iguana gets most of its water from the plants it eats -- they are especially fond of areas where there are creosote bushes. They can most commonly be found near semi dense vegetation and areas with loose rocks. Desert iguanas construct their own intricate burrows as a way to escape the extreme temperatures of their environment{5}.
One study on Californian desert iguanas showed that home ranges between the sexes did not significantly differ in size, with those of males being around 1,462m2 and that of females being around 1,558m2{3}.
Desert iguanas also go into Brumation("hibernation") in mid September or October, and emerge from Burrows some time in March{5}.
Dietary habits
D.dorsalis is primarily herbivorous, with as much as 95% of its food intake being vegetation in one study location, but in others only ~54% of the dietary intake is vegetation{2}. An ontogenic change in diet is present -- immature animals showing a preference for insects, while the adults, though they also eat a considerable amount of insect life, have a more flora oriented diet{4}. Insects eaten include ants, wasps,mantids, beetles, and Coeloptera larvae{2,4}.
Reproduction & growth
After desert iguanas emerge from their brumation period in March, they begin their reproductive season. Breeding size is attained in the first 20-32 months of life, at a snout-ventral length of approximately 104mm(4in){1}. Mating occurs between March and July, with a singular clutch of 3-8 eggs being laid{1,4,6}. The young animals emerge from their eggs approximately four weeks after being laid. In the first year of life, desert iguanas typically grow 22mm(0.8in), and after that growth is around 2mm(0.78in) per month{6}.
Survivorship & Mortality
Despite being moderately large lizards, mortality in populations is still ever present whether it be predator induced or environment induced. Annual survival amongst a study population of Californian desert iguanas is around 42% and not dependant on the age class of the animals{1}. Small, immature animals are susceptible to a wider away of predators than the adults, but even the big lizards fall prey to other animals. Snakes(Crotalus,Arizona), hawks(Buteo), and large predatory lizards(Gambelia, Crotaphytus) are all potential/confirmed predators of desert iguanas{4}. Laboratory studies have shown that this species shows behavioral plasticity in the regard that when a predatory snake(C.cerastes) is present, they will sleep very little or remain awake even if the snake in question is not moving{6}. In a study published in 2002, It was shown that desert iguanas are able to acknowledge the presence of lizard eating snakes via chemosensory, and in response to the scent of these snakes, will flatten out in a bid to blend in with the substrate{7}.
References
{1}Krekorian, CO'Neil. "Life history of the desert iguana, Dipsosaurus dorsalis." Herpetologica (1984): 415-424.
{2}Dibble, Christopher J., Geoffrey R. Smith, and Julio A. Lemos-Espinal. "Diet and sexual dimorphism of the desert iguana, Dipsosaurus dorsalis, from Sonora, Mexico." Western North American Naturalist 68.4 (2008): 521-523.
{3}Krekorian, CO'Neil. "Home range size and overlap and their relationship to food abundance in the desert iguana, Dipsosaurus dorsalis." Herpetologica (1976): 405-412.
{4}Pianka, Eric R. "Comparative ecology of two lizards." Copeia (1971): 129-138.
{5}Moberly, Walter R. "Hibernation in the desert iguana, Dipsosaurus dorsalis." Physiological Zoology 36.2 (1963): 152-160.
{6} Revell, Timothy K., and William K. Hayes. "Desert iguanas (Dipsosaurus dorsalis) sleep less when in close proximity to a rattlesnake predator (Crotalus cerastes)." Journal of Herpetology 43.1 (2009): 29-37.
{7}Bealor, Matthew T., and C. O'Neil Krekorian. "Chemosensory identification of lizard-eating snakes in the desert iguana, Dipsosaurus dorsalis (Squamata: Iguanidae)." Journal of Herpetology 36.1 (2002): 9-15.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Lacertilia
Infraorder: Iguania
Family: Iguanidae
Genus: Dipsosaurus
Species: D.dorsalis
Description
The desert iguana is mid sized species of desert dwelling lizard, with adaptations to help it survive and thrive perfectly in these environments. They are drab colored animals, with a typically dark brown dorsal coloration with ocellated spots running down the animal's back. The tail shares a similar color pattern but instead a white and brown barred pattern. Dark pigmentation can be found around the eye but this, as well as the body coloration of adult animals, varies between poplations. Sexual dimorphism does not appear to be present in regards to body size, with adults of both sexes attaining similar lengths and weights overall. A study published in 1984{1}showed that animals from 31-44 months in age averaged a snout ventral length of 110-112mm(4.3-4.4in), and ranged from 85-126mm(3.3-4.9in) in snout-ventral length. Another study on the dietary habits and sexual dimorphism of the species based in Sonora gave the mean snout-vent length for males as 98mm(3.8in) and 90mm(3.54in) for females{2}.
Geographic range & habitat use
This species can be found from southern Nevada down into north/ central Mexico, where they are well studied. Since these lizards live in environments where rainfall is typically scarce, the desert iguana gets most of its water from the plants it eats -- they are especially fond of areas where there are creosote bushes. They can most commonly be found near semi dense vegetation and areas with loose rocks. Desert iguanas construct their own intricate burrows as a way to escape the extreme temperatures of their environment{5}.
One study on Californian desert iguanas showed that home ranges between the sexes did not significantly differ in size, with those of males being around 1,462m2 and that of females being around 1,558m2{3}.
Desert iguanas also go into Brumation("hibernation") in mid September or October, and emerge from Burrows some time in March{5}.
Dietary habits
D.dorsalis is primarily herbivorous, with as much as 95% of its food intake being vegetation in one study location, but in others only ~54% of the dietary intake is vegetation{2}. An ontogenic change in diet is present -- immature animals showing a preference for insects, while the adults, though they also eat a considerable amount of insect life, have a more flora oriented diet{4}. Insects eaten include ants, wasps,mantids, beetles, and Coeloptera larvae{2,4}.
Reproduction & growth
After desert iguanas emerge from their brumation period in March, they begin their reproductive season. Breeding size is attained in the first 20-32 months of life, at a snout-ventral length of approximately 104mm(4in){1}. Mating occurs between March and July, with a singular clutch of 3-8 eggs being laid{1,4,6}. The young animals emerge from their eggs approximately four weeks after being laid. In the first year of life, desert iguanas typically grow 22mm(0.8in), and after that growth is around 2mm(0.78in) per month{6}.
Survivorship & Mortality
Despite being moderately large lizards, mortality in populations is still ever present whether it be predator induced or environment induced. Annual survival amongst a study population of Californian desert iguanas is around 42% and not dependant on the age class of the animals{1}. Small, immature animals are susceptible to a wider away of predators than the adults, but even the big lizards fall prey to other animals. Snakes(Crotalus,Arizona), hawks(Buteo), and large predatory lizards(Gambelia, Crotaphytus) are all potential/confirmed predators of desert iguanas{4}. Laboratory studies have shown that this species shows behavioral plasticity in the regard that when a predatory snake(C.cerastes) is present, they will sleep very little or remain awake even if the snake in question is not moving{6}. In a study published in 2002, It was shown that desert iguanas are able to acknowledge the presence of lizard eating snakes via chemosensory, and in response to the scent of these snakes, will flatten out in a bid to blend in with the substrate{7}.
References
{1}Krekorian, CO'Neil. "Life history of the desert iguana, Dipsosaurus dorsalis." Herpetologica (1984): 415-424.
{2}Dibble, Christopher J., Geoffrey R. Smith, and Julio A. Lemos-Espinal. "Diet and sexual dimorphism of the desert iguana, Dipsosaurus dorsalis, from Sonora, Mexico." Western North American Naturalist 68.4 (2008): 521-523.
{3}Krekorian, CO'Neil. "Home range size and overlap and their relationship to food abundance in the desert iguana, Dipsosaurus dorsalis." Herpetologica (1976): 405-412.
{4}Pianka, Eric R. "Comparative ecology of two lizards." Copeia (1971): 129-138.
{5}Moberly, Walter R. "Hibernation in the desert iguana, Dipsosaurus dorsalis." Physiological Zoology 36.2 (1963): 152-160.
{6} Revell, Timothy K., and William K. Hayes. "Desert iguanas (Dipsosaurus dorsalis) sleep less when in close proximity to a rattlesnake predator (Crotalus cerastes)." Journal of Herpetology 43.1 (2009): 29-37.
{7}Bealor, Matthew T., and C. O'Neil Krekorian. "Chemosensory identification of lizard-eating snakes in the desert iguana, Dipsosaurus dorsalis (Squamata: Iguanidae)." Journal of Herpetology 36.1 (2002): 9-15.
