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Raul
Diaz Kevin de Queiroz, Ph.D.
"Learn science, meet cool scientists, large IMAX® screens, and an even larger federal triangle; the RTP 2003 program has shown me that science is not just a lot of work, but it is also a lot of fun." |
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Phylogenetic
relationships among corytophanine iguanid lizards inferred from morphological
characters A group of lizards known to science as the corytophanine lizards is composed of nine species which are distributed amongst three genera (Laemanctus, Basiliscus, and Corytophanes). These lizards live in north america, and more specifically can be found in forests and along streams from northwestern Mexico, concentrated in Central America, and down to northwestern South America. What sets these lizards apart is a strange “crest” of bone and cartilage which extends upwards and back off the top of their skulls (different genera and species have different looking “crests”). Although found in all three genera, only in the genus Basiliscus do they only occur in males (termed in biology as “sexual dimorphism”). Two of the three general differ from Basiliscus in that they mainly live on trees, or spend most of their time climbing above the ground in the forests. The genus Basiliscus on the other hand, have become specialized to living along streams by taking on an extended flap of skin running the length of their toes. This makes them wider. Because of this extra skin, they can spread their weight over a greater area and are able to run quickly across the surface of water to run away from a predator (this is why this genus is known as the “Jesus Christ lzards”). This group of three genera belong to a larger group called the “iguanidae”. In systematic biology, one conducts studies to see how different organisms are related to one another evolutionarily. This systematic study is part of a larger project attempting to resolve relationships within the “iguanidae”. In order to better understand the greater group, we must make sure the smaller relationships are well resolved. Previous studies have been made on this smaller group called the corytophaninae and led to a clarification in relationships within two out of the three genera represented. This study was conducted to test whether his previous resolutions were in fact supported by my own, as well as finding resolution within the Basiliscus, which had not yet been done completely. Specimens for this study were studied from the collections from the Smithsonian’s Natural History collection of reptiles and amphibians. Skeletal and “wet” (alcohol preserved) specimens were used. Relationships were found based on comparing scales and bone structures and taking note of differences and similarities among all the species. These were analysed through a computer program. Our results clarified the genus Basiliscus and supported the previously known relationships among all the genera, but was contradicted within Basiliscus for the relationship of B. galeritus and B. vittatus by a DNA study which had been concurrently conducted by another group of scientists. This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-02435123. |