Nathan Hanna and Dr. Jack Sites, Biology Department
Liolaemus is a genus of lizards that is very common in South America, particularly the southern regions. Distinguishing differences between separate species within the Liolaemus genus has been an ongoing pursuit, one in which Jack Sites and his lab have been extensively engaged. Liolaemus chehuachekenk is a species that is very similar to Liolaemus fitzingerii. Both are found throughout central regions of Patagonia. The purpose of this project has been to provide data to help in distinguishing boundaries, gene flow, historical divergence, and population structure between the two species.
I worked on this project with the help of Doug Brown, Luciano J. Avila, Jack W. Sites Jr., Mariana Morando, and Frank M. Fontanella. We began this project by finding and analyzing microsatellites within the DNA of samples from both species. Microsatellites are useful for this type of analysis because they are convenient to work with but behave similarly to other genes with respect to gene flow throughout a population. A microsatellite is a repeating pattern of nucleotides (the subunits of DNA: Adenine, Guanine, Cytosine, and Thymine).
The Site’s lab had previously developed primers for many common microsatellites in the Liolaemus genus. A primer is a molecule that binds to a particular microsatellite with which it has a complementary sequence and that allows it to be copied.
The first step we took was to find several primers that resulted in replicated DNA. This was done by iterative experiments testing each of the available primers. If the DNA sample did not produce replicated DNA then we knew that the sample did not contain the microsatellite associated with that primer. We found 10 primers that produced results: DI-7938, DI-159, TET-3500, DI-1570, TET-2216, DI-3138, TET-3105, TET-1177, TET 1501, and TET-1102. We searched for these microsatellites in our L. fitzingerii samples first. We then tried each of these primers in samples from L. chehuachekenk. Nine of the 10 microsatellites were also found in L.
chehuachekenk After identifying the presence of these microsatellites in each species, we began the process of identifying how many unique versions of each microsatellite existed in each set of samples. To do this we used a primer that uses a fluorescent marker in conjunction with a DNA sequencing machine. After running each sample through the sequencer, we received an output of data that we used to identify the microsatellite in question and to calculate the length of that particular version of the microsatellite. We found between 7 and 24 versions of each microsatellite in L. fitzingerii. We found between 3 and 11 versions of each microsatellite in L. chehuachekenk.
The data that we found in this experiment was published in Conservation Genetics Resources. We were successful in generating data that can be used for further analysis of the two species L. fitzingerii and L. chehuachekenk. This data can be used to provide greater detail concerning boundaries, gene flow, historical divergence, and population structure between the two species.