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In: Israel Journal of Ecology and Evolution

In Israel three rear-fanged snakes (Colubridae: Boiginae) of the genus Telescopus possess a defensive display in which they coil, pose in readiness to strike, and often simultaneously flatten and triangulate the head. Thus they become similar to the venomous Viperidae in general. On indirect evidence, two of them appear to be mimics of sympatric viperid species. The desertic T. dhara somewhat resembles Echis coloratus, and, in Africa, more closely, E. carinatus. The Mediterranean T. fallax vaguely resembles Vipera palaestinae in Israel but it more closely resembles V. ammodytes in Greece, V. xanthina in Anatolia and V. lebetina on Cyprus. The possible evolution of such mimetic systems, Batesian, Müllerian, Mertensian or combined, which presumably begins with the convergence of cryptic coloration, is discussed. The desertic, black-headed T. hoogstraali seems to lack any specific mimetic partner. This might be due to its recent derivation from T. fallax without loss of the behaviour, or more reasonably to some unknown predator that avoids viper-shaped snakes in general.

In: Israel Journal of Ecology and Evolution

Gekkoninae, laying rigid, precisely mensurable eggs in invariable clutches, served to examine the relations between egg shape, egg size and mother size, at intra—and interspecific levels. Ellipticity (ratio width/length) and volume were calculated from linear measurements of 82 eggs obtained in captivity from geckos of eleven Near-Eastern taxa. Clutch volume, apportioned to one or two eggs, was interspecifically correlated to maternal length. Eggs varied in size, intra—and interspecifically, generally retaining near-uniform ellipticity but some exceedingly large eggs were more elongate. In Ptyodactylus hasselquistii guttatus the eggs, flexible when laid, are pushed by the mother into near-spherical shape; hatchling length is correlated to egg diameter. Gecko clutches constitute as much mass, relative to maternal mass, as in many other lizard groups.

In: Israel Journal of Ecology and Evolution

Opinions differ whether tail loss in lizards is mainly caused by predators or by intra-specific fighting. Recently this dilemma was investigated through a comparison of lizard tail loss rates between mainland populations in Greece and those on nearby islands harboring fewer predators. The higher tail loss rate on the islands was interpreted as due to the predation-free denser lizard populations having more intra-specific fighting (, Journal of Animal Ecology 86: 66–74). However, that analysis failed to exclude an alternative hypothesis which I propose and support with well documented circumstantial evidence: The lizards analyzed were Hemidactylus turcicus and Mediodactylus kotschyi (Gekkonidae), both relatively long-lived. On the predator-poor islands they could live longer due to the few predators and thus accumulate the low rate of tail loss. Moreover, both on the mainland and on the islands the tail loss rates are higher in M. kotschyi than in H. turcicus, although life spans are of similar order of magnitude, possibly longer in H. turcicus. But the latter is active at night whereas M. kotschyi is active also in daytime, exposed to more predators during more time. Thus also this inter-specific difference accords with the alternative hypothesis. The two processes are not mutually exclusive and both should be taken into account as potentially responsible for the rate of tail loss in lizards.

In: Israel Journal of Ecology and Evolution
In: Israel Journal of Ecology and Evolution

Vocalizations emitted in a uniform distress situation were recorded from adult, similarly sized, gekkonine lizards Bunopus blanfordii, Cyrtodactylus kotschyi orientalis, Gehyra variegata and Stenodactylus s. sthenodactylus. The 269 calls obtained from the 24 individuals used, analysed sonagraphically, segregated into four distinct call types recurring in each species. Ten independently varying factors combine to make this repertoire extremely variable. This variation is independent of the acoustic environment. Because the vocal response to an attacking predator is so unpredictable, and because the acoustic frequency range transcends the hearing range of the geckos themselves, the calls are believed to have a deimatic, anti-predator, function.

In: Amphibia-Reptilia