Preserving Wildlife

Micro Markers Highlight Caribbean Iguana Relatedness

Reptiles and Amphibians

The San Diego Zoo Institute for Conservation Research has long understood the need to protect these endangered iguanas and their habitats and this focus was underscored with the 2000 appointment of Conservation Research Postdoctoral Fellow Dr. Glenn Gerber. He has focused on the rock iguana species of Anegada Island Cyclura pinguis and the Turks and Caicos Islands Cyclura carinata, enlisting the help of several Institute for Conservation Research divisions in addressing conservation research needs such as recovery of wild populations and captive breeding.

Because genetic studies have become major components in characterizing biological diversity in the wild and for management of captive populations, the Genetics Division was asked to share in this collaborative effort. A key objective of the Anegada project was to evaluate kinship in the Zoo’s small captive population of iguanas by comparing their genetic variation to that found in the wild iguanas.

Because the molecular markers known as microsatellites have been useful in assessment of genetic diversity and kinship evaluation, microsatellite genotyping and analysis were used to evaluate the suitability of the captive individuals to serve as the basis for a genetically healthy captive breeding program. Screening of the Cyclura pinguis microsatellite library found over 20 informative loci, and these were used on DNA from the six captive potential founders as well as two groups of wild iguanas: randomly captured animals (assumed to be unrelated) and hatchlings from marked nests (assumed to be siblings).

Using a statistical approach, three separate pairs of related individuals were identified within the captive cohort, and this information is now being used to design a management plan that will maximize genetic diversity in the captive collection.

The genetic diversity found in the wild population on Anegada was surprisingly high and, despite their critically low number of about 200 individuals, they do not appear to be inbred when compared to other species. While these are preliminary data, they are encouraging results for the conservation of this species. An exploratory screening using the Cyclura pinguis microsatellite library was done on the Turks and Caicos iguanas, and early results were promising.

Another project will examine changes in the genetic makeup of four new island populations (established via translocation) as compared to their respective island source populations. The approach to these studies will be to continue the microsatellite screening of Cyclura carinata to try and identify at least 20 informative loci. The Cyclura pinguis library will also be used to screen other Caribbean iguana species of interest; positive results would allow for relatedness and other genetics studies that can aid in conservation management decisions across the entire group.