DNA Evidence Prevents the Extermination of a Species of Iguanas

    In this NY Times article, a Mexican island has been invaded by these spiny-tailed iguanas, or so they thought. Clarion Island houses these iguanas, who were assumed to arrive on the island through humans around the late 20th century. This has never been tested, but because they were considered invasive, the government planned on exterminating them to help the ecosystem. Dr. Mulcahy had seen the iguanas and collected DNA to find that they don't match the sequence of the spiny-tailed iguanas on the mainland. Once he heard about the plan to exterminate, he went to publish the analysis he found to prevent the elimination.

    To analyze the DNA, Dr. Mulcahy and his colleagues compared the mitochondrial DNA of the Clarion iguanas to the mainland iguanas to find a 1.5% difference in the DNA. This meant that the iguanas on the island were distinct enough that they couldn't have recently been introduced to the island. They used data and fossils to find when the split between the two species had happened and found it may have been around 425,600 years ago. This was well before humans arrived in the Americas and implies that the iguanas came to the island on the second-longest known aquatic journey iguanas have gone through.

    These findings came in time to prevent the eradication of these animals and, ironically, the disruption of the ecosystem. The question of how these iguanas went unnoticed has been asked. This could possibly be because of the change in landscape on the island, as settlers brought livestock onto the island that ate away at much of the vegetation. Iguanas are naturally scared and wary of humans and hide when close by, which would leave people unaware of their presence until these hiding spots started running out. 

    This kind of situation happens when the assumption of an animal's role in the ecosystem isn't tested. Research on these iguanas was necessary to prevent a mistake from coming out of extermination, and if it had never been done, there would have been many problems coming about on the island. Assumptions without proof can hurt, and I am glad that someone was able to piece the puzzle together on why they looked and were genetically different from the mainland species.