The Gulf sand gecko is one of the few animals that can survive the harsh Empty Quarter

A team of scientists have found that the gecko lives in areas of the vast desert between Saudi Arabia, the UAE, Yemen and Oman where it had previously never been spotted.

The gecko gets water by drinking dew on plants and from eating insects. Courtesy Dr Salvador Carranza

ABU DHABI // The vast Empty Quarter that covers hundreds of thousands of square kilometres of the UAE, Saudi Arabia, Oman and Yemen must be one of the most inhospitable places in the world.

With searingly high temperatures and little rainfall, it is no wonder that large swathes of this desert, also known as Rub Al Khali, appear devoid of vegetation.

Despite its extreme conditions, the area does play host to some especially hardy forms of animal life, including a small lizard unearthed in a new location by a team of researchers.

The Gulf sand gecko, Pseudoceramodactylus khobarensis, was already known from salt flats, or sabkha, in coastal and inland areas of the UAE, coastal parts of Oman, plus areas in Qatar, Saudi Arabia, Kuwait and the Iranian island of Qeshm, in the Arabian Gulf.

Yet these sites left a vast area between far eastern Saudi Arabia and coastal Oman where the nocturnal creature had never been found by scientists.

At least that was the case until Dr Salvador Carranza, a senior researcher at Barcelona’s Institute of Evolutionary Biology, Dr Margarita Metallinou, at the time a PhD student, and a number of other scientists set out to find them in inland salt flats in Oman, not far from the Saudi border.

The team, who were in the area carrying out a survey for the government of Oman, spent two nights searching for the creatures. According to Dr Metallinou, now a postdoctoral researcher at Villanova University in Pennsylvania, United States, finding them was “very difficult”.

“But it gets better when you train the eye. You have to imagine a vast desert area, with hardly any vegetation, that could attract animal species, no light beside the beam of your headlamp, no sound at all and looking for an eight to 10 centimetre-long gecko that is roughly the same colour as the ground,” she said.

Despite the difficulty of spotting the creatures, the keen-eyed team turned up a specimen of the gecko in each of two areas of salt flats they surveyed, and they have recently described their late 2013 find in Biodiversity Data Journal.

The areas where they were searching, which were accessible by small roads, are about 250km from the inland UAE salt flats where the species has been recorded previously, and a similar distance from the eastern coastal Omani sites where it has also been found. The authors believe there are probably many other locations in Oman where this type of gecko lives that have not been discovered yet.

The gecko, which gets its water by drinking dew on plants and from eating insects, is among the “very few organisms” able to cope with the “extremely high salt concentrations” found in the desert salt flats, said Dr Metallinou, the lead author of the paper, which was co-authored by scientists based in the Czech Republic, Italy and Portugal.

The gecko has spiny scales under its toes that make walking on the salty and sticky ground easier, in contrast to the many other types of geckos with toes that have evolved to stick to surfaces. It also has huge, beady eyes for foraging at night and is well adapted physiologically.

“These animals can not eat for days or even weeks and not drink for a long time. They’re not like mammals that need to eat and drink constantly,” said Dr Carranza.

However, even this species is not able to cope with the daytime sun. In these conditions, Dr Carranza said “they would fry”. Instead, during daylight hours they hide away in burrows near the base of the few plants found in the harsh environment.

To look at the relationship between the geckos found in inland Oman and those collected in other areas by scientists, a comparison was made of the genetic material from the mitochondria of the creatures’ cells. Mitochondria are tiny “organelles” that release energy, and which have their own DNA separate from that found in the chromosomes in cell nuclei.

It was found that the inland Omani creatures have very similar mitochondrial genes to those of Gulf sand geckos from Kuwait and eastern Oman, with the overall variability for a genetic marker called 12S being just 0.4 per cent.

Because DNA accumulates mutations over time, the small number of differences suggest the inland populations are still in genetic contact with — meaning there is some interbreeding with — Gulf sand geckos far away, perhaps through populations of the lizard in between. Alternatively, if the groups have become cut-off genetically, this separation did not happen a long time ago.

“There might be a continuum or the connection was stopped very recently,” said Dr Carranza.

“You cannot differentiate between 20,000 years and 100,000 years with DNA, [but] if the isolation had been two million years, we could say that.”

Further research could identify additional populations of the lizard in parts of Oman and other Gulf countries where so far none have been found by scientists.

“Maybe it’s patchy but there are other areas, for sure. We just came across this one. We’re limited by the available roads but there are other salt flats and good environments for this species in between, but maybe not so accessible [to people],” said Dr Carranza.

Interesting though it is for scientists to learn about the distribution of the Gulf sand gecko, the recent study has significance beyond academic curiosity.

The scientists note in their paper that the species is classified by the International Union for the Conservation of Nature as being of “least concern”, meaning it is widespread and is at no risk of becoming extinct at present.

However, there are factors that may affect numbers, including the large-scale development of areas of coastal sabkha in the UAE and, increasingly, in Oman, which has meant that some areas where the gecko lived are no longer suitable as habitats.

Knowing more about where the creature is found could, the scientists say, help to prevent additional areas it inhabits from being threatened by development.

“If it’s more widespread, it’s better,” said Dr Carranza.