Chameleons Reveal How Life Takes Shape
11/24/2025
Despite 300 million years of evolution between them, humans and chameleons share similarities in the genetic and developmental programs that shape their bodies. Evolutionary developmental biologist Natasha Shylo, who holds a doctorate in genetics, studies how these conserved processes have been modified over time to give rise to diverse forms of amniotes.
When Shylo talks about chameleons, she’s not referring to color-changing skin or swiveling eyes; she’s talking about embryos. A graduate of the Society for Developmental Biology’s GetHIRED! program—which provided structured deadlines, critical feedback on application materials, and a lasting peer community—she recently started her own lab at Rowan University. At Rowan, she aims to understand why early developmental processes are so deeply conserved across amniotes and how subtle changes in these shared programs lead to new traits. Studying those mechanisms requires close examination of the embryos themselves. “I don’t, on a day-to-day, study with [adult] chameleons,” says Shylo. “I work with their embryos. The stuff I do most is actually this stage where they look like a little donut. They’re round, and they have a blastopore in the center, and that’s my favorite stage.” At this point in development, humans and chameleons look quite similar.
But how deep do these embryonic similarities really go? During her postdoctoral training at the Stowers Institute for Medical Research, Shylo helped establish veiled chameleon as a model organism. She sequenced and annotated its genome, comparing developmental genes across species from starfish to humans, to understand how the genetic instructions for forming animal bodies have evolved. In particular, she studied the epidermal growth factor-cryptic (EGF-CFC) family of genes, which guide gastrulation and body axis formation. Shylo found that this gene family arose from a single ancestral gene in early deuterostomes. Over time, the gene duplicated and eventually created a family of gene copies in which individual genes underwent specialization. Later, gene loss and translocation in mammals helped shape vertebrate body plans. “I was looking at the left-right patterning genes,” Shylo recalls, “and I was like, oh, the genome for these genes looks very different in mammals than frogs and zebrafish ... chameleons were sort of that perfect in-between.” Her work fills a gap in understanding how early developmental steps differ between classic mammalian models, such as mice and rats, and more distant relatives like frogs and zebrafish. “Chickens alone can’t represent 25,000 species of reptiles,” she adds. “That’s where chameleons come in.”
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Veiled chameleon embryo, which is about the size of a peanut, at 120 days post-oviposition. Image provided by Natasha Shylo. |
Early embryonic stages are difficult to study in many vertebrates. Chickens and reptiles tend to lay small clutches, limiting sample size, while in many reptiles and mammals, embryos develop internally, making them hard to access. Veiled chameleons, by contrast, lay large clutches of 50-90 eggs, and gastrulation occurs more slowly after the eggs are laid, offering a rare opportunity to capture early development.
“When veiled chameleons lay their eggs, the embryos are at early gastrulation stages of development, which turns out is very different from other reptiles,” Shylo says. “That makes them super exciting to work with, because we now have an organism where the embryo is at these early stages of development.”
Beyond their research value, Shylo sees veiled chameleons as a way to engage students and the public in science. She finds them an engaging model for people less familiar with evolutionary or developmental biology. “Chameleons make a great conversation starter,” she says. “People get excited when they hear I study them, and that gives me a chance to talk about the biomedical questions we can answer using reptiles … things like how organs form and what happens when those processes go wrong.” By introducing chameleons as a model organism, Shylo hopes to make complex biological concepts more accessible and to spark curiosity that extends beyond her lab.
Shylo’s long-term goal is to use this model to investigate human congenital disorders. Many genes involved in these conditions are present in reptiles. “That means we could start testing some of those truly human mutations in our system,” she explains. By bridging evolutionary and biomedical research, Shylo aims to show how studying reptiles can inform our understanding of human development.
Last Updated 11/24/2025
