Land iguanas under continuing threat on Galapagos a...( The Galpagos Islands which provided ...)

The Galpagos Islands, which provided impetus and inspiration for Charles Darwin's seminal work, "On the Origin of Species", are home to unique populations of reptiles. Since the time of man's first visit in the 16th century to this crucial incubator for evolutionary theory, 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. In the 20th century, conservation efforts began, but according to new research published this week in the scientific journal Molecular Ecology considerably more must be done to insure the long-term survival of land-dwelling iguanas on the archipelago.

In their new article, "Galapagos Land Iguanas Remnant Populations," an international coalition of scientists, led by Michel Milinkovitch, from the University of Geneva, Switzerland, detail their near-decade-long effort to assess the population genetics of land iguanas on the six islands where the reptiles occur today.

Population genetics is a cornerstone of modern evolutionary synthesis. It employs principles of molecular genetics and sophisticated data analysis to identify populations and characterize the genetic diversity within and the levels of genetic differentiation among these evolutionarily significant groups. Changes are influenced by the evolutionary forces of natural selection, genetic drift, mutation and gene flow. Scientists obtain blood or tissue samples from subjects and examine multiple loci across their genome. In so doing, researchers are able to draw conclusions regarding relationships, genetic diversity and genetic drift among various populations.

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