Side-blotched lizard

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Side-blotched lizards
Male common side-blotched lizard
Uta stansburiana
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Phrynosomatidae
Genus: Uta
Baird & Girard, 1852

Several, see text

Side-blotched lizards are lizards of the genus Uta. They are some of the most abundant and commonly observed lizards in the deserts of western North America, known for cycling between three colorized breeding patterns[1] and is best described in the common side-blotched lizard. They commonly grow to six inches including the tail, with the males normally being the larger sex. Males often have bright throat colors.

These lizards are prey for many desert species. Snakes, larger lizards, and birds all make formidable predators to side-blotched lizards. Larger lizard species, such as collared, leopard, and spiny lizards, and roadrunners are the main predators. In turn, the side-blotched lizards eat arthropods, such as insects, spiders, and occasionally scorpions.

As a result of their high predation rate, these lizards are very prolific breeders. From April to June they breed, with the young emerging as early as late May. These inch-long young appear all through the summer, and into September.

The diploid chromosome number in most if not all species is 34, consisting of 12 macro- and 22 microchromosomes.[2]


Side-blotched lizards are notable for having the highest number of distinct male and female morphs within a species: three male and two female. They show a diversity of behaviors associated with reproduction, which are often referred to as "alternative reproductive tactics".[3]

Orange-throated males are "ultra-dominant, high testosterone", who establish large territories and control areas that contain multiple females. Yellow stripe-throated males ("sneakers") do not defend a territory, but cluster on the fringes of orange-throated lizard territories, and mate with the females on those territories while the orange-throat is absent, as the territory to defend is large. Blue-throated males are less aggressive and guard only one female; they can fend off the yellow stripe-throated males but cannot withstand attacks by orange-throated males.

Orange-throated females lay many small eggs and are very territorial. Yellow-throated females lay fewer, larger eggs, and are more tolerant of each other.[4]

This is called the rock paper scissors effect,[5] borrowed from the name of the playground game, because the outcome of the mating success shows that one morph of the lizard takes advantage over another but not over the third.[6]

The orange and blue-throated males can sometimes be seen approaching a human "intruder". One speculation is that he could be giving the female(s) a chance to escape, but whether he is defending the female has not been documented. Another speculation is that he is highly motivated to engage whenever he sees movement on his territory, which he may be interpreting as a possible intruding male, or another female.


The systematics and phylogeny of the side-blotched lizards is very confusing, with many local forms and morphs having been described as full species.[7] Following the 1997 review of Upton & Murphy which included new data from mtDNA cytochrome b and ATPase 6 sequences, the following species can be recognized pending further research:

Uta stellata and U. concinna are now usually considered subspecies of U. stansburiana. U. encantadae, U. lowei, and U. tumidarostra might be subspecies of a distinct species (Las Encantadas side-blotched lizard), instead. Similarly, U. auriculata and U. clarionensis might be subspecies of a single species, the Revillagigedo side-blotched lizard.


The specific name, lowei, is in honor of American herpetologist Charles Herbert Lowe.[8]


  1. ^ Sinervo, B.; C.M. Lively (1996). "The rock–paper–scissors game and the evolution of alternative male strategies". Nature 380 (6571): 240–243. doi:10.1038/380240a0.
  2. ^ Pennock et al. (1968)
  3. ^ Taborsky,M & Brockmann HJ (2010) Alternative reproductive tactics and life history phenotypes. pp 537-586, In P. Kappeler, Ed. Animal Behaviour: Evolution and Mechanisms. Springer Berlin Heidelberg
  4. ^ Roughgarden, Joan (2004). Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press. ISBN 0-520-24073-1 Especially chapter 6, Multiple Gender Families, pp. 90-93.
  5. ^ Sinervo, B & Lively C.M. (1996) The rock-scissors-paper game and the evolution of alternative male strategies. Nature 340: 240-246
  6. ^ Goodenough, J (2010). Perspectives on Animal Behaviour. p. 70.
  7. ^ See e.g. Oliver (1943)
  8. ^ 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. (Uta lowei, p. 161).


  • Collins JT (1991). "Viewpoint: a new taxonomic arrangement for some North American amphibians and reptiles". Herpetological Review 22(2): 42-43. PDF fulltext
  • Grismer LL (1994). "Three new species of intertidal side-blotched lizards (Genus Uta) from the Gulf of California, Mexico". Herpetologica 50: 451–474.
  • Murphy, Robert W.; Aguirre-León, Gustavo (2002). "The Nonavian Reptiles: Origins and Evolution". pp. 181-220. In: Case, Ted J.; Cody, Martin L.; Ezcurra, Exequiel (editors) (2002). A New Island Biogeography of the Sea of Cortés. New York: Oxford University Press. 690 pp. ISBN 0-19-513346-3. PDF fulltext Appendices 2-4
  • Oliver JA (1943). "The Status of Uta ornata lateralis Boulenger". Copeia 1943(2): 97-107. doi:10.2307/1437774 (First page image)
  • Pennock, Lewis A.; Tinkle, Donald W.; Shaw, Margery W. (1968). "Chromosome Number in the Lizard Genus Uta (Family Iguanidae)". Chromosoma 24 (4): 467-476. doi:10.1007/BF00285020 PDF fulltext
  • Upton, Darlene E.; Murphy, Robert W. (1997). "Phylogeny of the Side-Blotched Lizards (Phrynosomatidae: Uta) Based on mtDNA Sequences: Support for a Midpeninsular Seaway in Baja California". Mol. Phyl. Evol. 8 (1): 104-113. doi:10.1006/mpev.1996.0392 PDF fulltext