At Fairchild Tropical Botanic Garden in Florida, Puerto Rican crested anoles appeared where researchers were already studying Cuban brown anoles. The two species used different parts of the habitat: crested anoles spent more time higher in trees, while brown anoles used the ground more. Reporting also linked longer legs in brown anoles with higher survival after the crested anoles appeared—a reported association, not proof that the encounter caused individual lizards to grow longer legs.
Which lizards met, and where?
The animals were Cuban brown anoles (Anolis sagrei) and Puerto Rican crested anoles (Anolis cristatellus). The encounter took place at Fairchild Tropical Botanic Garden in Florida, where Georgia Tech researchers led by James Stroud were studying brown anoles when crested anoles appeared. Georgia Tech describes the opportunity as unusual because researchers could observe how ecologically similar species responded while living in the same place. Georgia Tech’s account quotes Stroud, an assistant professor in its School of Biological Sciences and the study’s lead author: “Most of what we know about how animals change in response to this process comes from studying patterns that evolved long ago. This was a rare opportunity where we could watch evolution as it happened.”
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How did the anoles divide the habitat?
Reporting on the study describes a vertical shift in habitat use. Crested anoles spent more time in trees and perched higher on average; brown anoles spent more time on the ground. This kind of difference can reduce overlap in where animals forage or occupy territory, even when they share a site.
| Species | Reported habitat use | Additional reported finding |
|---|---|---|
| Puerto Rican crested anole (Anolis cristatellus) | More time in trees and higher average perches, according to the report. | Not stated in the report. |
| Cuban brown anole (Anolis sagrei) | More time on the ground, according to the report. | Longer-legged individuals had higher survival after crested anoles appeared, according to the report. |
Georgia Tech’s summary describes competition between similar species for resources such as food and territory. Stroud explains that species competing for the same resources can evolve differences that allow them to coexist. The reported habitat separation is consistent with that broad idea, but the available reporting does not establish exactly how much competition occurred or quantify the effect of the habitat shifts.
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Did the brown anoles grow longer legs?
A report dated January 3, 2025, says brown anoles were found to start growing longer legs and that longer-legged individuals had higher survival after crested anoles appeared. The survival relationship is an association as reported; the available account does not provide the sample size, effect size, measurements, or enough methodological detail to establish a causal chain. It therefore does not justify saying that an individual brown anole grew longer legs because the other species arrived.
Was evolution witnessed in real time?
The headline phrase refers to observing an evolutionary response in a living population as conditions changed, rather than inferring all change from species compared over long periods. It does not mean researchers watched one species turn into another. The account describes differences in habitat use and a relationship between leg length and survival, not the formation of a new species during the observation.
The same January 3, 2025 report says the two species are separated by more than 40 million years of evolution. That figure is attributed to the report; Georgia Tech’s institutional summary does not independently give it.
What the reports establish—and what remains unclear
Georgia Tech’s institutional summary supplies the research context and Stroud’s comments. The behavioral and survival details come from a Refractor article republishing New Atlas reporting. Neither account, as available here, gives the primary paper’s sample size, observation dates or duration, survival percentage, effect size, or selection measurements. Those details should not be inferred from the reported pattern.
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- Reported: Crested anoles used higher, more arboreal perches, while brown anoles used the ground more.
- Reported: Longer-legged brown anoles had higher survival after crested anoles appeared.
- Not established by these accounts: How large the survival difference was, whether the arrival caused the leg-length pattern, or whether either species formed a new species.
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