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.
YEHUDAH L. WERNER
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.
YEHUDAH L. WERNER
WERED WERNER and YEHUDAH L. WERNER
Yehudah L. Werner
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 (Itescu et al. 2017, 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.
RAN NATHAN and YEHUDAH L. WERNER
We review and analyze the altitudinal distribution of reptiles (from museum collections) and breeding birds (from literature records and a recent field sampling project) on Mt. Hermon (latitude ca. 33°30′N), over the range 300–2814 m. Species richness was greater in breeding birds (n = 86–90) than in reptiles (n = 34), declining with increasing altitude in both groups, but more steeply so in birds. We suggest that the simplification of vegetation structure with increasing altitude may explain this difference, because birds probably better use the three-dimensionality of densely-vegetated habitats that dominate low elevations. But in both taxa the overall decline was nonlinear; species richness actually increased from low to mid-elevations, forming a hump-shaped pattern. Standardization of species richness for surface area, across altitudinal belts of 100 m up to 1,900 m, revealed the area effect as both significant and unpredictable. It did not affect the overall decline, but contrary to a general expectation of a linear trend turning hump-shaped, the hump—shaped curve became concave, i.e., from low to mid-elevations the number of species per unit area declined sharply, and at higher elevations it remained fairly stable. In a comparison with other mountains in the Mediterranean Basin (between latitudes 35°00′ and 42°30′N), the very same reptile species reached higher maximum elevations on Mt. Hermon, while the same bird species reached similar elevations in both areas. This difference may reflect lesser ability of reptiles, compared to birds, to inhabit high elevations at higher latitudes, but their altitudinal distribution on Mt. Hermon showed no evidence for such a physiological difference. In general, in contrast with other reports, we found no positive correlation between the extent of altitudinal range of the species and their position on the altitudinal gradient, as would have been implied by Rapoport's altitudinal rule. Future mapping of local distributions of the Mt. Hermon biota, required for efficient conservation, should derive from planned, extensive field sampling, augmented with museum records for clarification of taxonomie uncertainties.
YEHUDAH L. WERNER and NAOMI SIVAN
Contact zones between Israeli Ptyodactylus species were evaluated from museum material and hybridization experiments, the first controlled hybridization between gekkonid species. In southern Israel and Sinai P. guttatus and hasselquistii are partly sympatric, occasionally syntopic. Intermediate specimens were absent and experimental hybridization failed. Probably prezygotic isolation operates. In northern Israel, P. guttatus and P. puiseuxi are parapatric; in and near their boundary, occasional putative hybrids occur. These resemble the few laboratory hybrids obtained. No F2 were obtained. Probably the two species are separated by a combination of partial isolating mechanisms.