One Lizard Species Turns out to be Four

Ongoing research on species distribution suggests that lowland tropical ecosystems, although commonly associated as places with a widespread abundance of wildlife, do not contain as many species as previously believed. However a new find by a team of biologists reports an exception to the rule made by a little lizard.

In the journal Zookeys, researchers describe four species of the collared treerunner (Pilca pilca) that previously were all considered the same one.

Making their home on vertical surfaces such as tree trunks or rock wall, where they hunt for insects, collared treerunners are native to Central and South America and have a long history of documentation in the taxonomic record, originally described in 1758.

The collared treerunner has been the subject of a number of biological, ecological and behavioral studies in recent years, according to researchers John Murphy of the Field Museum in Chicago and Michael Jowers of the Doñana Biological Station in Seville, Spain.

"The collard treerunner was considered a single species ranging from Trinidad and Tobago and northern Venezuela southward into the Amazon Basin, south of the Amazon River." Murphy said. "The treerunners ancestor diverged about 25-30 million years ago, and throughout this time the South American continent has undergone dramatic remodeling, including the rise of the Andes, rising and falling sea levels, and changing climates that isolated populations for long periods of time, allowing them to become new species."

Murphy and Jowers conducted an extensive study of treerunner populations in northern South America, as well as an overall survey of the lizard's distribution across the Amazon basin. They suspect between five and seven more undescribed treerunner species that are currently classified as the collared treerunner.

The researchers cited genetic differences of up to 5 percent in lizards all previously classified as one species. For comparison, the genetic difference between humans and chimpanzees is less than 2 percent.

Many of the treerunners show obvious morphological differences in appearance that support the genetic data that they are indeed different species. One example the researchers pointed to was a treerunner with as few as 92 scales on the body, while another had more than 200. Distinct and different color patterns also highlight the differences among the newly reclassified species.

The researchers said the takeaway from their study is that there are more species of squamate reptiles (lizards and snakes) than previously believed and also that it is likely that many species have and will become extinct before science is even aware of them.