About the Author
Sofia Prado-Irwin is currently a fourth-year Ph.D. student in the Organismal and Evolutionary Biology department and a resident tutor in Currier House. She is interested in the evolution, ecology, and natural history of reptiles and amphibians. When she’s not in the field or in the office, she enjoys chasing insects through the woods, watching Jeopardy, listening to podcasts, and baking.
Linking Lizards
Exploring the process of evolution
When most of us hear the word “island,” we picture a tropical paradise with palm trees, sunshine, and white sand beaches. When I hear the word “island,” however, I think of Anolis lizards, or anoles. Anoles are a diverse group of arboreal lizards found in the Caribbean, Central and South America, and even the southern United States. They are well-known in the field of evolutionary biology for their interesting patterns of diversification in the four Greater Antillean islands—on each of these islands, they have independently evolved forms (or ecomorphs) that look and behave similarly. Take the “trunk-ground” ecomorph as an example – these lizards spend most of their time perched low on tree trunks, jumping to the ground to catch prey. They have stocky, muscular bodies and long hind limbs to help them jump and run efficiently. And each island has its own “trunk-ground” species that has evolved independently. Caribbean anoles therefore provide a fascinating example of repeated evolution by natural selection.
However, anoles are not restricted to islands – in fact, there are more species of anole present in mainland Central and South America than there are on all the Caribbean islands combined. Interestingly, the mainland species do not show the same predictable patterns of diversity seen on the islands—with a few exceptions, ecomorphs have not evolved on the mainland. Why might this be the case? As of right now, we simply don’t know. Factors such as the diversity and abundance of predators, topographic and climatic complexity, and the presence of competitors all vary between mainland and island environments, and may have contributed to different evolutionary patterns between mainland and island anoles. However, such hypotheses are difficult to test because mainland anoles simply have not been well-studied. For most mainland species, even basic information about their ecology (for example diet, habitat use, behavior) is unknown.
For my Ph.D. thesis, I hope to fill in these gaps and provide some insight to the fundamental question: how and why does the process of evolution differ between island and mainland environments? To that end, I am studying the ecology and evolutionary history of anole populations in mainland Central America and in nearby Caribbean islands. In the summer of 2017, supported by the David Rockefeller Center for Latin American Studies, I began collecting data for this project in two locations: the island of Utila in Honduras (Photo 1) and La Selva Biological Station in Costa Rica (Photo 2). I spent time in the forest observing individual lizards, documenting their behavior, and measuring their habitat use (Photos 3-5, 9-12). I also quantified the availability of habitat types, the thermal conditions of the habitats, and the population densities of several anole populations (Photos 6-7). In the lab, I measured body characteristics, photographed adaptive traits, and quantified body color and patterns (Photo 8). I also obtained tissue samples for genetic analysis, to understand how and when these populations have diverged and evolved in their different environments. I plan to use these multiple lines of evidence to understand how ecology, morphology, and genetics have changed between island and mainland populations, and therefore how ecological and evolutionary processes differ in these environments.
While my main focus that summer was collecting data for my thesis, throughout the entire trip I was also able to experience the incredible beauty and biodiversity of the neotropics. At times, the graduate school experience can be stressful and demanding. But when I find a young boa constrictor during a nighttime survey (Photo 13), see a vine snake along the path to my field site (Photo 14), or come across a charming weevil on a walk near camp (Photo 15), I’m reminded of the sheer magnitude of diversity in the tropics, and I know that I’m lucky just to witness it. The ability to conduct research in Central America is a privilege I do not take for granted, and it is one that I will truly value for the entirety of my Ph.D.
If you liked this article, click here to read related articles on The Environment, Giving and Volunteering, and Flora and Fauna!
More Student Views
Of Salamanders and Spirits
I probably could’ve chosen a better day to visit the CIIDIR-IPN for the first time. It was the last week of September and the city had come to a full stop. Citizens barricaded the streets with tarps and plastic chairs, and protest banners covered the walls of the Edificio de Gobierno del Estado de Oaxaca, all demanding fair wages for the state’s educators. It was my first (but certainly not my last) encounter with the fierce political activism that Oaxaca is known for.
Public Universities in Peru
Visits to two public universities in Peru over the last two summers helped deepen my understanding of the system and explore some ideas for my own research. The first summer, I began visiting the National University of San Marcos (UNMSM) to learn about historical admissions processes and search for lists of applicants and admitted students. I wanted to identify those students and follow their educational, professional and political trajectories at one of the country’s most important universities. In the summer of 2025, I once again visited UNMSM in Lima and traveled to Cusco to visit the National University of San Antonio Abad del Cusco (UNSAAC). This time, I conducted interviews with professors and student representatives to learn about their experiences and perspectives on higher-education policies such as faculty salary reforms and the processes for the hiring and promotion of professors.
Post-Secondary Education Access in Peru
Over the summer, I visited four public schools in Peru located in two regions, about 1,200 miles apart from each other. I interviewed teachers, principals and high school juniors and seniors. I wanted to discover their perspectives on perceived opportunities and barriers for students to plan for and fulfill their higher education goals. I also interviewed the superintendent at each school district to learn about local initiatives aimed at decreasing barriers to higher education transition.
