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Research

Click here to see my publications and grants

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Limbs, Genitals, and Gene Regulation

Although limbs and external genitalia differ dramatically in their form and function, these appendage types use many of the same genes and signaling molecules during development. It is thought that the external genitalia in amniotes (mammals, birds, and reptiles) evolved partly through re-purposing of genes important for limb development.

During my Ph.D., I explored how genes instruct cells during early development to build the tissues that become limbs and external genitalia.
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  • How are genes turned on in different cells of the embryo?

  • How similar is gene regulation in limbs and external genitalia?
     

I wrote a 172-page dissertation that reviews the literature and reports my findings.

Alligator_stages_AaronEvoDevo_2.jpg

Life stages of the American alligator

Not shown: Adult alligator chasing Aaron

Many of the genes important for limb and genital development are shared in distantly related species of amniotes. To investigate how these genes are regulated in diverse species, I am comparing the DNA sequences of their genomes. Regions of DNA that are shared between these very distantly related species may also be present in the human genome (conserved), and play a role in the development of these structures in humans.

tetrapod phylogenetic tree black-01.png

Simplified phylogenetic tree of amniotes

Phylogeny and dates adapted from Pyron, R. A. (2010).
DOI: 10.1093/sysbio/syp090

Limb EvoDevo in the Anole Lizard

Anolis lizards are well-known for their striking patterns of convergent evolution on different Caribbean islands. Although the ecology and evolution of these lizards has been extensively studied, we know relatively little about the underlying mechanisms that have contributed to the evolution of different phenotypes within this genus.

 

One of the most striking phenotypic differences among Anolis species is limb size, which is adapted for the particular microhabitat that each Anolis species resides within. Differences in adult limb length between anole species are due to changes that occur early in embryonic development.

 

To determine whether gene regulation plays a role in shaping the differences in short-limbed and long-limbed anoles, I performed a genome-wide analysis of regulatory elements in different anole species during limb development.

 

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DSC00593.jpg

Green anole (Anolis carolinensis)

Photo by Aaron at the UGA State Botanical Garden

Our lab has recently published a method to perform CRISPR-Cas9 gene editing in the brown anole, the first report of gene editing in any reptile.
 
Using this newly developed tool, I collaborated on projects investigating the gene regulatory networks that control the evolution and development of the Anolis limb.

AA_paired_edit_edited.jpg

Brown anole hatchlings

 Left- Albino mutant

Right - wild type lizard

From Rasys et al. (2019).

DOI: 10.1016/j.celrep.2019.07.089  

Photo by Aaron

Publications and Grants

Publications

  • Garcia-Elfring A, Sabin CE, Iouchmanov AL, ..., Alcala AJ, Osman RS, Lauderdale JD, Hendry AP, Menke DB, Barrett RDH (2023). 
    Piebaldism and chromatophore development in reptiles are linked to the tfec gene.
    Current Biology. https://doi.org/10.1016/j.cub.2023.01.004
     

  • Geneva AJ, Park S, Bock D, de Mello P, ... , Alcala AJ, Infante CR, Kolbe JJ, Schluter D, Menke DB, Losos JB (2022). 
    Chromosome-scale genome assembly of the brown anole (Anolis sagrei), a model species for evolution and ecology. Communications Biology.
    https://doi.org/10.1038/s42003-022-04074-5
     

  • Rasys AM, Park S, Ball RE, Alcala AJ, Lauderdale JD, & Menke DB. (2019).
    CRISPR-Cas9 Gene Editing in Lizards through Microinjection of Unfertilized Oocytes.
    Cell Reports, 28(9), 2288–2292.e3. doi:10.1016/j.celrep.2019.07.089

Lizard_print_cover.jpg

Cover photo by Aaron Alcala

Grants

Funding

I wrote the following successfully funded grants:

Title
Year
Amount
R.C. Lewontin Early Award – Society for Study of Evolution
2018
$2500
Robin Hightower Genetics Graduate Support Fund - UGA
2018
$667
Patricia and Doyle Mote Award for Biomedical Research
2020
$1000
UGA Genetics Graduate Student Association Travel Award
2019-20
$2000
research-posters

Posters

I have presented my various research projects at 8 scientific conferences and received recognition for Best Poster Semi-Finalist at the 2020 Society for Developmental Biology Meeting.

See below for an example poster I designed about my research.

Aaron Alcala - Research Poster - TBX5 Limbs Genitalia
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