Evolutionary Biology

"It looks like they've moved up the Metro-North line into Connecticut. There's also a population in Hastings-on-Hudson."
"It's a body plan [10 centimetres in length, split-second fast, evolutionarily flexible] that has been around for hundreds of millions of years. That's the cool part of this story. We have this historical perspective that evolution is one of these processes that takes a really, really long time. But we're also finding that evolutionary changes can take place over a few generations."
"Across the board, this is just an interesting ecological oddity."
"I think it's possible they are jumping on a train [facilitating their geographic spread]. But it's more likely that they are just running up the train tracks They're really fast, and it's a straight runway."
Colin Donihue, post-doctoral biologist, Harvard University

Yale Peabody Museum of Natural History

They do get around, for tiny animals not native to New York, let alone Connecticut and elsewhere in the United States where they're showing up. Their native habitat is far from the United States, though. They're not called Italian wall lizards as a cute reference to sleazy bar-hangers-on of Italian origin. These tiny reptiles are originally from the Tuscany region of Italy where it is hot and sunny and dry. And just as many exotic species of living things find their way into pet stores, so too did Italian wall lizards.

It has been theorized that the creatures somehow escaped their shipment boxes either en route to the pet stores where they were meant to be sold, or in the shops themselves. In the late 1960s evidently, a Bronx pet dealer was said to have sold 210 of the lizards to the township of Mount Laurel, New Jersey, touting them as a natural pest control solution to a local problem. Releasing them to the environment in the interests of ridding it of undesirable insects would have the natural consequence of their adaptation and subsequent natural increase.

When this lizard species was brought to an island off Croatia their usual diet of insects underwent a change in the absence of insects, with the lizards swiftly turning to the local flowers, berries and foliage for sustenance. After life on the island for 36 years, a researcher discovered they had managed to develop a solution to their changed diet; a new pocket in their gut for processing the plant material, and that, in evolutionary terms is a swift blink of the eye in terms of time.

The fascinating topic of species' adaptation on introduction to new environments -- when nature has established their presence elsewhere, providing the required food that is species-specific, discovering that some species are capable of accepting alternate foods that are available in a new environment -- keeps biologists busy scrutinizing all examples that come to their attention. Dr. Donihue is being aided by colleagues at Yale University.

Yale Peabody Museum of Natural History

In Vienna, Austria, it was discovered that spiders began to build webs close to street lights to take advantage of moths drawn to those lights during the dark night hours. While in Amsterdam, Madrid, Berlin and Prague as well as other geographic name-places, European blackbirds which had abandoned their native forests for urban life, sing as a result, at a higher pitch, to be heard over traffic sounds. In the process, something which might have been a source of aggravation, led them instead to develop temperaments that were calmer.

Ecosystems have been altered in lock-step with the globalization of travel, where long-distance air, and ship travel introduced the potential for not only human beings but other natural creatures to travel unnoticed, as extra cargo. That's what happened when bird-eating snakes, securing themselves in the landing gear of airliners introduced themselves to Hawaii. As for the lizards, they were somehow released in Ohio, Kansas and British Columbia, as well.

At least four of the five boroughs around New York City have discovered these tiny lizards in their midst. And since there are no existing native lizards in New York, the Italian lizards pose no threat to local biological peers. Dr. Donihue is interested in tracking the lizards to discover how far north they will be able to move, surviving cold in winters far surpassing that of their native habitat. To survive they must also hide from predators like cats, snakes and birds and the rocky beds of train tracks could be their salvation, Dr. Donihue feels.

Yale Peabody Museum of Natural History