Researchers at Pennsylvania State University, commonly referred to as Penn State or PSU, say 24 newly-discovered species of lizards known as skinks in the Caribbean are close to extinction.
In a single new scientific publication, the scientists said the new species have been scientifically named.
According to Blair Hedges, a professor of biology at Penn State University and the leader of the research team, “half of the newly-added skink species already may be extinct or close to extinction and all of the others on Caribbean islands are threatened with extinction.”
The researchers found that the loss of many skink species can be attributed primarily to predation by the mongoose, an invasive predatory mammal that was introduced by farmers to control rats in sugarcane fields during the late 19th century.
The research team reports on the newly- discovered skinks in a 245-page article, published on Apr. 30 in the science journal, Zootaxa.
Primarily through examination of museum specimens, the team identified a total of 39 species of skinks from Caribbean islands, including six species currently recognized, and another nine named long ago but considered invalid until now.
Hedges and his team also used DNA sequences, but most of the taxonomic information, such as counts and shapes of scales, came from examination of the animals themselves.
“Now, one of the smallest groups of lizards in this region of the world has become one of the largest groups,” Hedges said.
“We were completely surprised to find what amounts to a new fauna, with co-occurring species and different ecological types,” he added.
Hedges said some of the new species are six times larger in body size than other species in the new fauna.
“The mongoose is the predator we believe is responsible for many of the species’ close-to-extinction status in the Caribbean,” he said.
“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,” he added.
Hedges said the “smoking gun” is a graph included in the scientific paper showing a sharp decline in skink populations that occurred soon after the introduction of the mongoose.
Hedges said the mongoose originally was brought to the New World to control rats, which had become pests in the sugarcane fields in Cuba, Hispaniola, Puerto Rico, Jamaica, and the Lesser Antilles.
He said while this strategy did help to control infestations of some pests, such as the Norway rat, it also had the “unintended consequence of reducing almost all 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.
“According to our research, all of the skink species found only on Caribbean islands are threatened,” he added. “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,” Hedges continued.
He said there are two reasons why such a large number of species went unnoticed for so many years, in a region frequented by scientists and tourists.
He said since Caribbean skinks already had nearly disappeared by the start of the 20th century, people since that time rarely have encountered them and, therefore, have been less likely to study them.
Hedges also said the key characteristics that distinguish “this great diversity of species have been overlooked until now.”
In addition, he said that many potential new species of animals around the world have been identified in recent years with DNA data.
“However, much more difficult is the task of following up DNA research with the work required to name new species and to formally recognize them as valid, as this team did with Caribbean skinks,” Hedges said.
The research team also stressed that, while the mongoose introduction by humans now has been linked to these reptile declines and extinctions, other types of human activity, especially the removal of forests, are to blame for the loss of other species in the Caribbean.