Hybridization between invasive Green Iguanas and native Little Cayman Island rock iguana takes scientists by surprise and indicates a heightened risk for rare island iguanas.

By: Sara Kaiser

What happens when a native iguana and an invasive iguana meet, and kind of like each other? According to new research published in the scientific journal Biological Invasions, invasive-native hybrid iguanas have been found on Little Cayman Island.

Hybridization is when two different species mate and have offspring that are unable to reproduce. This is a normal occurrence in the natural world where two similar species’ ranges overlap. But when hybridization occurs between a native species and an invasive species, it could spell trouble.

If the invasive species is very common and the native species is rare, there is a risk that through hybridization the native iguana’s genes can be overwhelmed by the invasive species’ genes. That would lead to a decline of the unique genetic makeup that defines the rare native iguana population. For rare species that are already threatened with extinction, hybridization with an invasive heightens their vulnerability.

On Little Cayman Island, researchers have found that invasive Green Iguanas are interbreeding with native Cyclura rock iguanas. The research suggests that six other iguana species could also be at risk of hybridization with invasive Green Iguanas. To safeguard against native species population decline, the researchers recommend enhanced biosecurity measures to keep Green Iguanas away from islands with rare and at-risk iguana species.

While the Little Cayman iguana species and Green Iguanas are drawn to each other, it may not be in biodiversity’s best interest for them to get together. It may take human intervention to save Little Cayman’s native iguanas from their own evolutionarily risky mating preferences.

Source: Biological Invasions
Featured photo: Little Cayman Rock Iguana. Credit: Jay Colbath