Presenter Information

Ethan ElazeguiFollow

Major

Biology

Anticipated Graduation Year

2022

Access Type

Open Access

Abstract

What would happen if we re-wound and replayed the tape of life? Stephen J. Gould posed this now famous thought experiment. While Gould thought each tape of life would look different, the biological evidence is varied. Many examples of convergent evolution have shown different evolutionary lineages evolving the same traits. Like Gould, our research asks whether similar genetic architecture underlies pelvic reduction across the vertebrate tree. Reduction and even loss of these appendages is common across the phylogeny and has been frequently traced back to the loss of expression of the gene Pitx1. Notably, loss of Pitx1 leaves a phenotypic signature that can be detected without sequencing--pelvic vestiges tend to be larger on the left side than the right if Pitx1 is involved. Can phenotypic data implicate Pitx1 in the repeated loss of hindlimbs in squamate lizards? We landmarked micro-CT scans to measure pelvic and femur lengths of limb-reduced species, then exported them to the statistical software R to determine statistical significance of hindlimb and pelvic asymmetry. In this study, most of the species examined demonstrated statistically insignificant left-larger biases and one statistically insignificant right-larger bias. Thus, there is not strong evidence that squamate limb loss is underlain by loss of Pitx1 expression.

Community Partners

The Field Museum of Natural History, Museum of Comparative Zoology, American Museum of Natural History

Faculty Mentors & Instructors

Dr. Yoel Stuart, Assistant Professor, Department Biology; Samantha Swank, Lab Technician, Department Biology

Supported By

NSF grant DEB-1456462 to Y.E. Stuart

Comments

For more information, visit us at https://stuartlabloyola.org/ .

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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Assessing the Genetic Basis of Hindlimb and Pelvic Reduction in Squamate Reptiles

What would happen if we re-wound and replayed the tape of life? Stephen J. Gould posed this now famous thought experiment. While Gould thought each tape of life would look different, the biological evidence is varied. Many examples of convergent evolution have shown different evolutionary lineages evolving the same traits. Like Gould, our research asks whether similar genetic architecture underlies pelvic reduction across the vertebrate tree. Reduction and even loss of these appendages is common across the phylogeny and has been frequently traced back to the loss of expression of the gene Pitx1. Notably, loss of Pitx1 leaves a phenotypic signature that can be detected without sequencing--pelvic vestiges tend to be larger on the left side than the right if Pitx1 is involved. Can phenotypic data implicate Pitx1 in the repeated loss of hindlimbs in squamate lizards? We landmarked micro-CT scans to measure pelvic and femur lengths of limb-reduced species, then exported them to the statistical software R to determine statistical significance of hindlimb and pelvic asymmetry. In this study, most of the species examined demonstrated statistically insignificant left-larger biases and one statistically insignificant right-larger bias. Thus, there is not strong evidence that squamate limb loss is underlain by loss of Pitx1 expression.