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February 11, 2014
The summit of Wolf Volcano, the highest volcano of Galapagos located at the northern end of Isabela, is home to the only population of pink land iguanas (Conolophus marthae) in the world — a species we know little about.
The summit of Wolf Volcano is one of the most interesting research sites in Galapagos, according to the field technicians of the Galapagos National Park Directorate (GNPD) after carrying out an ecological survey there. The summit area is completely dry, with cactus forests, shrubs and other vegetation characteristic of arid regions. This arid world is the habitat of the pink iguana, a species first identified in 2009.
Galapagos National Park personnel, in collaboration with scientists from the University of Tor Vergata in Rome, carried out the first comprehensive ecological survey of the higher elevations of Wolf Volcano over a ten-day period. Their primary goal was to find out more about the pink iguanas and their ecology.
Data was collected on the pink iguanas to determine the status of the population and their interactions with the yellow land iguana (Conolophus subscristatus).The field team also collected blood samples from tortoises in search of hybrids carrying genes of Pinta (Chelonoidis abingdonii) and Floreana (Chelonoidis elephantopus) tortoises.
Land Iguana Population, Research, and Monitoring
The field team located six sub-adult pink iguanas (near reproductive age) and a hatchling iguana that was too small to determine the species. This was the first time that evidence of young pink iguanas was found, an encouraging sign for the health of the population. An iguana nesting zone was discovered at the summit of the volcano.
The most important component of the survey was the census of pink iguanas. The population had been estimated at 350 individuals, but according to the preliminary analysis from this recent survey, the total number is more likely between 450 and 500.
Washington Tapia, head of research for the GNPD, stated, “The population is still small. Therefore, we should begin a captive breeding program soon to help increase the numbers and contribute to the overall conservation of the pink iguana.”
The Charles Darwin Foundation collaborated in the analysis of the contents of pink iguana scat. Preliminary results indicate at least 16 species of native and endemic plants in the iguana diet, with Lippia rosmarinifolia, a woody shrub abundant in pink iguana habitat, particularly common.
Pink iguanas live from an elevation of 1,300 meters (4,200 feet) to the summit of the volcano (1,700 meters, or 5,500 feet). They share the habitat with the more common yellow land iguana, also endemic to Galapagos. During the expedition, seven iguanas were found with morphological features that suggested a hybrid between pink and yellow land iguanas. Blood samples were taken from these individuals for genetic analyses to determine whether or not they are hybrids.
Field personnel branded a total of 74 pink iguanas and 67 yellow iguanas and also marked each with a microchip. These are commonly used methodologies for marking reptiles; they allow data collection for the same individuals throughout their life.
Other Species Surveyed
The park rangers also collected blood samples from 35 giant tortoises found within the study area. These samples will undergo DNA analysis to determine if any of them have genes from the extinct tortoises from Pinta or Floreana islands. Those found with Pinta or Floreana genes may then form part of the breeding program for those populations, to provide tortoises similar to the originals for repopulating both Pinta and Floreana islands.
In addition to the reptile and plant work, park rangers recorded a growing population of Galapagos hawks. They also recorded observations of Galapagos and vermilion flycatchers, and various species of Darwin’s finches.
Land Iguana Evolution
Previous genetic studies have revealed that the yellow land iguana diverged from marine iguanas approximately one million years ago. The pink iguana, on the other hand, is estimated to have separated from the other iguana species more than five million years ago, before Isabela Island (where they are currently found) existed. Scientists believe that the evolutionary process resulting in the pink iguana took place on an island that subsequently submerged below sea level.
How the pink iguanas came to live on one of the youngest islands in the archipelago, at the summit of the highest volcano, is a question that technicians of the GNPD of the Ministry of the Environment and scientists from the University of Tor Vergata are attempting to answer. This effort includes the study of a few semi-fossilized iguana bones found on Santiago Island, where land iguanas are now extinct.