Emerging Model Organism

The Veiled Chameleon (Chamaeleo calyptratus Duméril and Duméril 1851): A Model for Studying Reptile Body Plan Development and Evolution

  1. Paul A. Trainor4,6
  1. 1Department of Biology, La Sierra University, Riverside, California 92515;
  2. 2Natural History Museum of Los Angeles County, Los Angeles, California 90007;
  3. 3Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912;
  4. 4Stowers Institute for Medical Research, Kansas City, Missouri 64110;
  5. 5Instituto de Biomedicina y Biotechnologia de Cantabria-CSIC-Universidad de Cantabria-Sodercan, Santander, Spain 39012;
  6. 6Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas 66160

    Abstract

    Vertebrate model organisms have facilitated the discovery and exploration of morphogenetic events and developmental pathways that underpin normal and pathological embryological events. In contrast to amniotes such as Mus musculus (Mammalia) and Gallus gallus (Aves), our understanding of early patterning and developmental events in reptiles (particularly nonavians) remains weak. Squamate reptiles (lizards, snakes, and amphisbaenians) comprise approximately one-third of all living amniotes. But studies of early squamate development have been limited because, in most members of this lineage, embryo development at the time of oviposition is very advanced (limb bud stages and older). In many cases, squamates give birth to fully developed offspring. However, in the veiled chameleon (Chamaeleo calyptratus), embryos have progressed only to a primitive pregastrula stage at the time of oviposition. Furthermore, the body plan of the veiled chameleon is highly specialized for climbing in an arboreal environment. It possesses an entire suite of skeletal and soft anatomical modifications, including cranioskeletal ornamentation, lingual anatomy and biomechanics for projection, autopodial clefting for grasping, adaptations for rapid integumental color changes, a prehensile tail with a lack of caudal autotomy, the loss of the tympanum in the middle ear, and the acquisition of turreted eyes. Thus, C. calyptratus is an important model organism for studying the role of ecological niche specialization, as well as genetic and morphological evolution within an adaptive framework. More importantly, this species is easily bred in captivity, with only a small colony (<10 individuals) needed to obtain hundreds of embryos every year.

    Footnotes

    • 7 Correspondence: lissamphibia{at}gmail.com

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