|Scientific Name:||Amblyrhynchus cristatus|
|Species Authority:||Bell, 1825|
|Infra-specific Taxa Assessed:|
|Red List Category & Criteria:||Vulnerable B2ac(iv) ver 3.1|
|Assessor(s):||Nelson, K., Snell, H. & Wikelski, M.|
|Reviewer(s):||Hudson, R. & Alberts, A. (Iguana Red List Authority)|
The marine iguana Amblyrhynchus cristatus is endemic to the Galápagos Islands, Ecuador. The population occurs as ten subpopulations on separate islands in the range. Total extent of occurrence is less than 5,000 km² and area of occupancy is estimated to be less than 500 km². Total population size is unknown, however, El Niño effects are known to cause periodic declines in population (at least 85% mortality). In addition to this, the population is threatened by pollution (e.g., oil spills) and predation by exotic species on the islands.
|Range Description:||The marine iguana occurs on the Galápagos Islands of Baltra, Daphne, Darwin, Marchena, Pinzon, Rabida, Santa Fe, Seymor, Sin Nombre and Wolf. Extent of occurrence is estimated at less than 5,000 km² and area of occupancy at less than 500 km². Average generation length is 5 years for females and 12 years for males.|
|FAO Marine Fishing Areas:||
Pacific – southeast
|Range Map:||Click here to open the map viewer and explore range.|
The global population size is currently unknown. Although the island subpopulations listed below are currently classified as A. cristatus, there has been no attempt to evaluate these subpopulations for subspecific status (i.e., they may not all be A. cristatus). Seven of these islands with supposed A. cristatus subpopulations have never been surveyed or studied. Numbers of iguanas in each of the subpopulations are estimated at:
Marchena = 4,000–10,000; Rabida = 1,000–2,000; Santa Fe = 15,000–30,000; Baltra = unknown; Daphne = unknown; Darwin = unknown; Pinzon = unknown; Seymor = 300? Sin Nombre = unknown; Wolf = unknown.
|Habitat and Ecology:||The world's only marine lizard species. Adults and juveniles occur on rocky coast and intertidal zones. Adult females can be found nesting up to 2 km inland and adult males can be found in marine waters, up to depths of 20 m.|
|Major Threat(s):||El Niño causes periodic dramatic (> 85%) mortality. The 2001 "Jessica" oil spill had a particularly severe immediate effect on the Santa Fe subpopulation, comparable to the 85% mortality caused by el Niño events. Introduced predators may be having a negative effect on the Baltra subpopulation,|
A. cristatus is included on CITES Appendix II. It is under "Special Law" in the Galápagos and occurs in three protected areas: Galápagos National Park and National Marine Reserve; Galápagos Islands Man and Biosphere Reserve (UNESCO); and Galápagos Islands World Heritage Site.
Conservation actions recommended for the species include: further surveys of the islands, taxonomic and genetic research, and monitoring of the population.
The seven marine iguana subspecies described to date have been based on morphology. The taxonomic status of the ten subpopulations of A. cristatus is unclear. Taxonomic/genetic research is recommended for the different island subpopulations to establish whether any of them should be reclassified. Additionally, the status of seven of the ten subpopulations is unknown. Populations on different islands face different threats and should be included in future surveys.
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Laurie, A. and Brown, D. 1990b. Changes in annual survival rates and the effects of size, sex, age and fecundity in a population crash. Journal of Animal Ecology 59: 529-544.
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Rassmann, K., Tautz, D., Trillmich, F. and Gliddon, C. 1997. The microevolution of the Galápagos marine iguana Amblyrhynchus cristatus assessed by nuclear and mitochondrial genetic analyses. Molecular Ecology 6: 437-452.
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Wikelski, M. and Trillmich, F. 1997. Body size and sexual size dimorphism in marine iguanas fluctuate as a result of opposing natural and sexual selection: an island comparison. Evolution 51(3): 922-936.
Wikelski, M., Carborne, C. and Trillmich, F. 1996. Lekking in marine iguanas: female grouping and male reproductive strategies. Animal Behaviour 52: 581-596.
|Citation:||Nelson, K., Snell, H. & Wikelski, M. 2004. Amblyrhynchus cristatus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 31 March 2015.|
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