Land-dwelling iguanas under continuing threat on Galapagos archipelago

Washington, Nov 27 : New research has indicated that land-dwelling iguanas are under continuing threat on the Galapagos archipelago, and more must be done to insure their long-term survival.

Since man first visited the archipelago in the 16th century, the islands' native plants and animals have faced grave challenges, including severe pressures from introduced species, habitat destruction and predation by man himself.

In some instances, this has led to reduced populations and even extinction.

Though conservation efforts began in the 20th century, but according to new research, published in the scientific journal Molecular Ecology, more must be done to insure the long-term survival of land-dwelling iguanas on the archipelago.

Led by Michel Milinkovitch, from the University of Geneva, Switzerland, the international coalition of scientists, have detailed their near-decade-long effort to assess the population genetics of land iguanas on the six islands where the reptiles occur today.

Galapagos land iguanas diverged from the famous Galapagos marine iguanas 10 to 20 million years ago, and there are currently two recognized species of terrestrial iguanas: Conolophus subcristatus and C. pallidus.

Beginning in the 1930s, and continuing through the 1980s, various threatened populations of land iguanas were relocated from one island habitat to another, or were subject to captive breeding and reintroduction programs.

Combined with the eradication of invasive species at some locations, this patchwork of dedicated conservation efforts by the Charles Darwin Foundation and the Galapagos National Park Service did preserve some native species from extinction, but unfortunately the records of these activities were not always detailed.

As a result, the genetic diversity of captive and reintroduced populations is uncertain. Given that genetic diversity within - and relationships among - populations are crucial for long-term species survival, the authors investigated genetic variation at nine nuclear micro satellite loci among more than 700 land iguanas from six island habitats.

For comparison, the information obtained was compared with similar information gathered from 20 marine iguanas.

This represents the first time that extensive and modern molecular genetic analyses have been applied to the study of these unique terrestrial reptiles.

Results revealed four distinct "clusters" of iguanas, including two potential new species.

Results also revealed that, while some populations enjoy robust genetic diversity, others do not. As such, they are at increased risk from any future changes in environmental pressures.

According to the researchers, "Molecular data could prove of paramount interest for improving management of (off-site) captive populations and for guiding the development of proper (natural habitat) population survival and habitat management plans for this spectacular reptile."

ANI