Galapagos pink land iguana (Conolophus marthae)
Mohamed bin Zayed Species project number 12254183
In 2009, the Galápagos Pink Land Iguana (Conolophus marthae) was reported to science. The species, endemic of a single location of a single island (Isabela), was found on Volcan Wolf. There are several issues that threaten the existence of this species. These include small population size, extremely limited distribution, possible competition with a syntopic population of C. subcristatus, and introduced predators. In 2012, the species was included in the IUCN Red List, under the category "Critically Endangered". Persistent evidence of lack of recruitment for C. marthae and genetic introgression due to rare hybridation between C. marthae and C. subcristatus urged for immediate conservation actions. Clarifying the frequency of hybridization and level of genetic introgression between C. marthae and C. subcristatus was urgently needed, for the purposes of a coming head-start/captive breeding program, conducted in Galapagos, in the facilities of the Galapagos National Park.
Hybridization can act as a powerful natural evolutionary factor. However, it may also cause genetic introgression and contamination of pure populations, endangering natural populations and species, as already documented for other species of iguanas. From a conservation perspective, interspecific hybridization deserves attention even when it may occur without being direct or indirect consequence of human activities. In fact, hybridization can have several detrimental effects which may result in loss of rare and important species, especially when one of the species involved is more abundant than the other. This is the case of the Galápagos pink land iguana.
In fact, prior to the present project, some evidence of hybridization and introgression had already been found between the two species, although hybridization was considered to be rare and insufficiently strong to prevent genetic differentiation between the two species. However, it must be considered that number of individuals used in the previous study by Gentile and collaborators in 2009, as well as the number of markers used, were small and did not allow strong conclusions. During her PhD work, Livia Di Giambattista investigated possible genetic introgression between C. marthae and C. subcristatus in Volcan Wolf. For this project 108 C. marthae and 163 C. subcristatus from Volcan Wolf were sampled during different sampling seasons from 2005 to 2009, for a total of 271 individuals. All individuals were genotyped for 20 microsatellite markers.
Livia found interesting results. The higher number of markers used in her study allowed a more refined analysis than the previous study. The hybrid status of the individual, morphologically assignable to C. subcristatus, that Gentile and collaborators found as possible second generation hybrid, could not be confirmed. Interestingly, despite the analyses concluded that there is not hybridization currently ongoing between C. marthae and C. subcristatus, they also offered some support to the hypothesis that hybridization might have occurred in the past. If this scenario is correct, it opens up to the question of the existence and effectiveness of reproductive isolation mechanisms between C. marthae and C. subcristatus.
These findings have great importance for the design of management actions and conservation plans as hybridization between C. marthae and C. subcristatus no longer represents a concern for C. marthae. Consequently, hybridization can be cancelled from the IUCN list of threats for the species. Additionally, the project reached the original goal: by genotyping of a large sample of C. marthae population, it will now be possible to effectively ensure the representation of original genetic variation in the reintroduced pool, by properly selecting juveniles to be reintroduced or possible breeders, in the frame of a head-start/captive breeding program.
Dr. Gabriele Gentile, University of Rome Tor Vergata and member of the ISG, has been leading a specific project on conservation genetics of Galápagos Land Iguanas since 2003. He has extensive experience in the conservation genetics field. He is responsible for the individual genetic characterization of C. marthae and C. subcristatus on Volcan Wolf. Such genetic work will ensure proper representation of original genetic variation in the reintroduced pool, by properly selecting the juveniles to be reintroduced (in case of a head-start program) or the possible breeders (in case of a captive breeding program). The Galápagos National Park has a long term experience in the field of head-start and captive breeding of Galapagos iguanas (C. subcristatus). GNP qualified personnel is involved in the project.
- In this paper, hybridization and other factors, are discussed as a risk for the species. Results from the project specifically supported by the MBZ Fund are described
Project 12254183 location - Ecuador, South America