Be'er Sheva fringe-fingered lizard

Be'er Sheva fringe-fingered lizard
Conservation status
Critically Endangered  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Family:	Lacertidae
Genus:	Acanthodactylus
Species:	A. beershebensis
Binomial name
Acanthodactylus beershebensis Moravec, Baha El Din, Seligmann, Sivan & Werner, 1999

The Be'er Sheva fringe-fingered lizard (Acanthodactylus beershebensis) is a species of lizard in the Lacertidae family. It is a member of the subgenus Lacertinae, and the tribe Acanthodactylus (spiny footed lizards). Considered a separate species based on morphological distinction, and isolated location; it shares a large portion of its genetics with Acanthodactylus pardalis in this genus.^[2] Many of the individual species under this genus are similar, but varying coloration explains why each species have been separated. Like all Acanthodactylus, the beershebensis lays eggs, varying from three to seven eggs at a time. Adults vary in size from 17 to 20 centimeters, but can get much larger. It is endemic to the loess scrublands of the Negev desert in Israel and the Palestinian Territories, a biodiversity hotspot.^[3]

It was declared critically endangered after an assessment in 2006 due to a serious population decline. Some estimates claim numbers have declined 80% over the last three generations. The small populations are severely fragmented across the Negev desert. This decline has been caused by habitat destruction and degradation. Conservation efforts also damaged the population, but a small portion of their original range remains untouched and protected.^[1]

Appearance and offspring

The hatchlings of Acanthodactylus beershebensis have a bright blue tail and dark and yellowish stripes on their body. However after a few weeks after birth the tail becomes brownish gray and its body turns to a blotchy brownish, sand-gray^[4] coloration, which remains through adulthood. This pattern gave the name to the Acanthodactylus pardalis group to which Acanthodactylus beershebensis belongs. (In Greek, pardalis, means leopard). On average, the species live less than a year, hatching around the end of May.^[5]

Colorful tails

All Acanthodactylus species(A. longipes, A. scutellatus, A. beershebensis, A. boskianus, A. schreiberi) that change tail colour after a few weeks after birth also go through behavioural changes. However the changes can differ between species, an example would be in foraging movements. Colourful tails and striped patterns on lizards may be used as anti-predator mechanisms. In the early stages of Acanthodactylus beershebensis' life, their colourful tails may be used to "shoo off" predators. After its tail changes colour, the lizards become less vulnerable to predators, thus not needing it anymore.^[4]

Location and habitat

Acanthodactylus beershebensis live only in south-central Israel. Their natural habitat is a topical dry shrubland. They generally live in the loess plains of the northern Negev desert located in Israel and Palestine territory. The Be'er Sheva fringe-fingered lizard is the most common species in this habitat. The area that the species inhibits is less than 10 km^[6] in size and the species lives randomly distributed throughout the area. The Be'er Sheva fringe-fingered lizards live in a structurally simple environment with few perches in which the species can hide from its predators. The species live in an area where trees and other covers are scarce and avoid them because they are often already inhabited by predators. The Be'er Sheva fringe-fingered lizards do not rely much on the perches or covers provided by trees for survival but are known to show the strongest reaction to plantations.

The habitat of the northern Negev desert is one where a more complex or a higher quality habitat would do more harm than improve the lives of its natural inhabitants. A higher quality habitat would only bring in more predatory species into the area, severely affecting the population of the Be'er Sheva fringe-fingered lizards as well as other local species.^[7][8]

Behavior and diet

The diet of Acanthodactylus beershebensis is influenced by the amount and severity of its predation. Because the species face a lot of threat from the many predators inhabiting the area, the Be'er Sheva fringe-fingered lizards have found ways to adapt their dieting style dependent to their predatory situation. When under more than normal pressure from predators, the Be'er Sheva fringe-fingered lizards move around less and catch and consume smaller prey and less plant material. Their diet shifts toward consuming foods that take less time to catch and to eat, all in preparation for possible predators. The reptile also becomes less selective and eats a more diverse range of food when under this predatory pressure.^[9]

Conservation

Acanthodactylus beershebensis is a critically endangered species, partly due to an ecological trap created by the conservation of plant biomass and species richness within their habitat. The conservation plan constructed pits and planted trees in order to reduce resource leakage in the ecosystem. When trees are planted in perch-less habitats it increases the number of avian predators and gives them a hunting advantage. This manipulating of the habitat made it less suitable for the lizards and heightened their chance of predation. The Be'er Sheva fringe-fingered lizard disappeared from their natural and altered habitats 11 years after the construction of the conservation plan. The spatial uncommonness of natural perches and man-made perches hindered the lizard's ability to correlate perches with a low quality habitat. Thus, the rapid increases in the number of available perches lead the lizard to perceive that their natural habitat to be as risky as their altered habitat, creating an equal-preference ecological trap.^[2][8]

Threats

Threats for the Be'er Sheva fringe-fingered lizard include habitat destruction and predation. Intensive agriculture, urbanization, and grazing animals are the factors contributing to the destruction of the lizard's home. It is also easily caught by birds, like falcons and egrets, whose numbers are increasing due to continued tree planting in its niche.^[1]

Conservation efforts

The national legislation in Israel currently protects a small area of its former habitat.^[1]

Taxonomy

While the beershebensis is considered critically endangered, its similar genetic cousin the pardalis is not. Studies have shown many of these species are so genetically similar that they all share similar threats. Since these species are all facing similar threats, all of them should share the same critically endangered label to preserve the diversity. Conservation efforts will be focused on the endemic species, meaning further research is need to sort out this genus to properly focus efforts.^[2]

References