The lizard that Darwin missed: A new land iguana lineage in the Galápagos.

In 1835 Darwin visited the Galápagos and missed a rare pink, black-striped phenotype of land iguanas (hereafter: “rosada”; i.e. pink in Spanish) from Isabela island, recorded for the first time in 1986. Here we use mtDNA sequence data to investigate patterns of genetic diversification and times of divergence between all extant populations, including the “rosada” form. We show that the base of the evolution and diversification of the Galápagos land iguanas led to two lineages. The first lineage led to the diversification of extant taxonomically recognized land iguanas. The second led only to the “rosada” form. The estimated time of divergence appears to predate the age of the oldest extant island. An alternative scenario that implied a recent diversification of the “rosada” from populations that already had colonized Isabela is not supported by the analysis. The deep time of divergence of the “rosada” lineage, if confirmed by genealogies based on multiple independent DNA sequences, would fall in a temporal band of classification rank equivalent to genus level. Microsatellite data indicate substantial genetic isolation between the “rosada” and the syntopic yellow form, with possible minor occasional introgression. Conservation efforts are needed to prevent this newly recognized taxon from extinction.