Amblyrhynchus cristatus ssp. nanus
|Scientific Name:||Amblyrhynchus cristatus ssp. nanus Garman, 1892|
|Red List Category & Criteria:||Endangered A2b 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. A. c. nanus is found on Genovesa Island. Extent of occurrence is estimated at less than 100 km² and area of occupancy at less than 10 km². The current population is estimated to be around 1,500 individuals and is declining. Census data and informal observations have shown that the population has declined by more than 80% over the last 10 years due to the effects of El Niño.
|Range Description:||A. c. nanus occurs on Genovesa Island. Extent of occurrence is estimated at less than 1,000 km² and area of occupancy at less than 10 km².|
|FAO Marine Fishing Areas:|
Pacific – southeast
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Average generation length is five years for females and 12 years for males. The total current population is estimated at around 1,500 individuals. The population has declined by more than 80% over the last ten years.|
|Current Population Trend:||Decreasing|
|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 has resulted in the population declines seen in this subspecies.|
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 subspecies include: further surveys for the subspecies, taxonomic and limiting factor research. Population Viability Analysis is also recommended along with the setting up of a captive breeding programme (pending recommendations from a PVHA workshop).
Carpenter, C. 1966. The marine iguana of the Galápagos Islands, its behavior and ecology. Proceedings of the California Academy of Sciences 34(6): 329-376.
IUCN. 1994. Iguanidae and Varanidae Conservation Assessment and Management Plan (CAMP) Taxon Reports. IUCN Conservation Breeding Specialist Group.
IUCN. 2004. 2004 IUCN Red List of Threatened Species. Available at: www.iucnredlist.org. (Accessed: 23 November 2004).
Kruuk, H. and Snell, H. 1981. Prey selection by feral dogs from a population of marine iguanas (Amblyrhynchus cristatus). Journal of Applied Ecology 18: 197-204.
Laurie, A. 1981. Marine iguana census. Unpublished document.
Laurie, A. 1983. Marine iguanas in the Galápagos. Oryx 17: 18-25.
Laurie, A. 1987. Marine iguana project to continue. Noticas de Galápagos 45: 19-22.
Laurie, A. and Brown, D. 1990a. Population biology of marine iguanas (Amblyrhynchus cristatus). I. Changes infecundity related to a population crash. Journal of Animal Ecology. 59: 515-528.
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.
Laurie, A. and Brown, D. 1990c. Population biology of marine iguanas (Amblyrhynchus cristatus). III. Factors affecting survival. Journal of Animal Ecology. 59: 545-568.
Merlen, G. 1984. The 1982-83 El Niño: Some of its consequences for Galápagos wildlife. Noticas de Galápagos 41: 8-15.
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.
Trillmich, K. 1983. The mating system of the Marine Iguana (Amblyrhynchus cristatus). Z. Tierpsychology 63: 141-172.
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 ssp. nanus. The IUCN Red List of Threatened Species 2004: e.T44177A10856460.Downloaded on 25 September 2017.|
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