Clarkson University Honors Program Thesis Proposal

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                  Clarkson University Honors Program Thesis Proposal

                Examining taxonomic differences in iguanian lizards.

Meghann Strain
Mentor: Dr. James Schulte
February 28th, 2006

       The superfamily Iguania is comprised of New World lizards. These lizards have

traditionally grouped into three categories, Agamidae, Chamaeleonidae, and Iguanidae.

Recently, these conventional have come under scrutiny. It has been proposed that due to

the many variations within Iguanidae, it would be better divided into individual families,

and the previous families Agamidae and Chamaeleonidae combined. The number of

subdivisions has been debated among researchers, however, leaving many opportunities

for taxonomic research to be conducted. (1)

       In the past, the majority of taxonomic data was gathered through morphological

data alone. Current studies utilize employ these observations, but now extend into

molecular and genetic testing as well (1). A number of sequencing techniques are

available to researchers, including the Promega fmol DNA system and the ABI Prism Big

Dye sequencing kit. The Promega system utilizes thermal cycle sequencing and DNA

polymerase to produce accurate results. The ABI Prism kit includes premixed materials

for DNA sequencing.

       The genetic testing will be performed by gathering DNA from either muscle or

liver tissue in the specimens. The genetic material will be amplified through

denaturation, annealing, and extension through heating. The products are then purified to

ensure that there is no contamination. This process will then be repeated.
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        The DNA will then be eluted from the solution using Maniatis elution buffer. The

eluted DNA was then sequenced using either the Promega fmol DNA system, or the ABI

Prism Big Dye sequencing kit. The sequences will then be compared to determine their

relative relationships.

        By evaluating the similarities between the DNA sequences, it will be possible to

estimate the evolutionary relationships between species. These relationships will also

help to determine approximate times of divergent evolution (2). One group that will be

put under special scrutiny will be the viviparous lizards. In future research, these lizards

may provide information regarding chemicals that can predict premature births. It is

hoped that this data can be extrapolated for use during human pregnancies.



Goal:
        The objective of this research is to re-evaluate the evolutionary distinctions

between members of the superfamily Iguania through morphological and molecular

techniques. If time and resources allow, research may also extend into evaluating the

evolution of viviparous iguanian lizards.


Timeline:
       The remainder of this semester will be spent examining previously obtained

specimens of a number of iguanian lizard species. The week following finals week will

be devoted to collecting new specimens in Arizona. The research will be completed by

February of 2007, and the rough draft of the thesis will be written concurrently. The final

draft will be finished by the end of March.
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References:

1. James A. Schulte II, John Pablo Valladares, & Allan Larson. (2003). Phylogenetic
Relationships within Iguanidae inferred using molecular and morphological data and a
phylogenetic taxonomy of Iguanian Lizards. Herpetologica. 59:3, 399-419.

2. Omar Torres-Carvajal, James A. Schulte II, & John E. Cadle. 2005. Phylogenetic
relationships of South American lizards of the genus Stenocercus (Squamata: Iguania): A
new approach using a general mixture model for gene sequencing data. Molecular
phylogenetics and Evolution.