Ctenophorus decresii

Ctenophorus decresii
	Photograph of a tawny dragon
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Iguania
Family:	Agamidae
Genus:	Ctenophorus
Species:	C. decresii
Binomial name
	Ctenophorus decresii; (A.M.C. Duméril & Bibron, 1837)
Synonyms[1]
	Grammatophora decresii ; A.M.C. Duméril & Bibron, 1837; Agama decresiensis ; Fitzinger, 1843; Ctenophorus decresii ; — Fitzinger, 1843; Amphibolurus decresii ; — Boulenger, 1885; Amphibolurus modestus ; Ahl, 1926; Ctenophorus decresii ; — Manthey & Schuster, 1999;

Ctenophorus decresii, also known commonly as the tawny crevice-dragon or the tawny dragon, is a species of lizard in the family Agamidae. The species is endemic to Australia.

Etymology

The specific name, decresii, refers to L'Île de Decrès, which was the French name for Kangaroo Island in 1837.[2]

Taxonomy

C. decresii is a member of the genus Ctenophorus, which is a very diverse group of lizards found throughout Australia. The entire genus of lizards is sexually dimorphic. Neck and overall coloration distinguishes male lizards from female and juvenile lizards.

Habitat and geographic range

Most often C. decresii is found in rocky areas throughout Australia. However, its habitat varies as it is found in a few distinct locations throughout Australia.[3] Scientists have identified the different populations of lizards as separate lineages due to geographic isolation.[3] The three lineages of C. decresii are the northern, southern, and NSW lineages. The entire genus Ctenophorus maintains a generally constant body shape, adapted for the Australian climate.[3]

Polymorphism

Ctenophorus decresii is known to display polymorphisms in throat coloration.[4] Within the species C. decresii, morphs can range from grey and white to a bright red.[4] Some of the variants include multi-colored, grey, yellow, orange, blue, and red-throated lizards.[5] This variation comes from the diverse geographic locations in which C. decresii can be found, such as South Australia, New South Wales, and other areas throughout Australia.[5] One geographic location may favor a certain throat color for C. decresii, while a different location may favor a different color.[5]

Although there is a lot of diversity in throat colors, the color variants in the throats are discrete, meaning the morphologies of individual lizards could be placed into specific categories [6] After using objective methods to identify the color morphs, statistical tests were run.[6] The tests analyzed variation based on granularity, segmentation, and comparison with visual background.[6] One group of lizards had similar granularity, segmentation, and coloration.[6] Another group also had similar granularity, segmentation, and coloration that differed from the first group. There were very few lizards with in-between phenotypes.[6] However, within the categories, there still is slight variation in the shades of colors of the lizards.[6] Because throat coloration is a discrete trait, it is highly heritable. This is a key reason that the discrete color variation has been maintained over multiple generations. The offspring will have similar or the same coloration as the parents, therefore making the coloration carry out over generations.

C. decresii's diversity in discrete throat color may be caused by a combination of sexual selection and natural selection.[4]

The C. decresii throat colors can be classified into two main, discrete categories—dull and bright-colored.[7] The dull-colored throats give lizards a fitness advantage because the lizards are harder for predators, like birds, to see.[7] The dull throats allow the lizards to avoid predators and survive longer; therefore, this trait became more prevalent in that population of lizards.[7]

However, bright-colored throats also give the lizards a fitness advantage because the bright-colored throats attract more females, and therefore those males are more likely to reproduce.[7] Although the bright-colored throats increase the likelihood of being eaten by predators, they also increase sexual success.[7] Therefore, the prevalence of bright-colored throats is maintained in this population of lizards.[7] Based on the conflicting benefits of dull and bright-colored throats, it is understandable that both morphs have been maintained in this species.[7] Each trait gives a lizard a different evolutionary advantage.

References

"Ctenophorus decresii ". The Reptile Database. www.reptile-database.org.
Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Ctenophorus decresii, p. 67).
McLean, Claire A.; Moussalli, Adnan; Sass, Steve; Stuart-Fox, Devi (2013). "Taxonomic assessment of the Ctenophorus decresii complex (Reptilia: Agamidae) reveals a new species of dragon lizard from western New South Wales". Records of the Australian Museum. 65 (3): 51–63. doi:10.3853/j.2201-4349.65.2013.1600.
Stuart-Fox, D.M.; Moussalli, A. (2004). "Evolution of Color Variation in Dragon Lizards: Quantitative Tests of the Role of Cryypsis and Local Adaptation". Evolution. 58 (7): 1549. doi:10.1554/03-448. PMID 15341157. S2CID 9060145.
McClean, Claire Alice (2014). "Geographic variation and speciation in the colour polymorphic tawny dragon lizard". hdl:11343/39946. Cite journal requires |journal= (help)
Teasdale, T.C.; Stevens, M (2013). "Discrete Color polymorphism in the tawny dragon lizard Ctenophorous descresii and differences in signal conspicuousness among morphs". Evolutionary Biology. 26 (5): 1035–1046. doi:10.1111/jeb.12115. PMID 23495663. S2CID 33168207.
Stuart-Fox, D.M.; Moussali, A. (2003). "Conspicuous Males Suffer Higher Predation Risk". Animal Behaviour. 66 (3): 541–550. doi:10.1006/anbe.2003.2235. S2CID 11691062.