May 1, 2012
Newly Discovered Skink Species Already Close To Extinction
Jason Farmer for RedOrbit.com
In a recent scientific publication, 24 new species of lizards known as skinks, all found on the Caribbean islands, have been discovered and named. Each year, in dozens of scientific publications, approximately 130 new species of reptiles from all over the world are added to the global count. But, since the nineteenth century not more than 20 reptile species have been added at one time in any single publication. The research team responsible for the new discoveries examined museum specimens of the lizards. The team identified a total of 39 species of skinks from the Caribbean islands.
However, Blair Hedges, lead researcher in the study and a professor of biology at Penn State, has concluded that of those newly discovered species, half may already be extinct, and that all of the other skink species on the Caribbean islands are close to or threatened by extinction.
The researchers say predation by the mongoose is the primary cause for the loss of the lizards and the threat of their extinction. The mongoose is an invasive animal to this region that was introduced to the islands in the late nineteenth century by farmers to control rats in sugarcane fields.
Professor Hedges explained that the skinks arrived in the Americas about 18 million years ago from Africa on floating mats of vegetation. Skinks are unique among lizards in that they, like humans, produce a placenta, an organ that provides nutrients to the developing offspring. “While there are other lizards that give live birth, only a fraction of the lizards known as skinks make a placenta and gestate offspring for up to one year,” Hedges said.
Hedges speculates that because pregnant females move slower, the longer gestational period of the skinks may have made them more vulnerable to predators. “Our data show that the mongoose, which was introduced from India in 1872 and spread around the islands over the next three decades, has nearly exterminated this entire reptile fauna, which had gone largely unnoticed by scientists and conservationists until now,” added Hedges.
While the strategy of introducing the mongoose to much of the ℠New World´ to control the infestations of pests may have been effective, it also had the unintended consequence of reducing the vast majority of skink populations. “By 1900, less than 50 percent of those mongoose islands still had their skinks, and the loss has continued to this day,” Hedges said.
This new research will dramatically add many species all at once to the list of reptiles categorized as “critically endangered” by the International Union for Conservation of Nature (IUCN). The IUCN maintains the “Red List of Endangered Plant and Animal Species”, the most comprehensive list of endangered species in the world.
“According to our research, all of the skink species found only on Caribbean islands are threatened,” Hedges said. “That is, they should be classified in the Red List as either vulnerable, endangered, or critically endangered. Finding that all species in a fauna are threatened is unusual, because only 24 percent of the 3,336 reptile species listed in the Red List have been classified as threatened with extinction. Most of the 9,596 named reptile species have yet to be classified in the Red List.”
Caitlin Conn, a researcher at the University of Georgia, added that researchers could potentially use the new information to plan conservation efforts, and to study in more detail the skinks' adaptation to different ecological habitats or niches.
The team of researchers has also emphasized that, while the introduction of the mongoose by humans is the primary cause of the reduction and extinction of the reptiles, other types of human activities, such as deforestation, pose as great a risk and are responsible for the loss of other species in the Caribbean.
The research team published their report on the newly discovered skinks on April 30 in the journal Zootaxa.
Image Caption: An Anguilla Bank skink. Blair Hedges and his team have discovered and scientifically named 24 new species of lizards known as skinks. Credit: Karl Questel