In a study of morphological directional asymmetry (DA) on the population level, four characters were bilaterally examined in geckos (museum specimens, total n Ptyodactylus puiseuxi, P. guttatus and P. hasselquistii, from Israel and Sinai. Significant DA occurred in adults in five or six out of 12 character‐taxon‐combinations (CTCs): number of supralabilia in P. puiseuxi and guttatus, length of ear aperture in puiseuxi and hasselquistii; number of subdigital lamellae in guttatus; and width of the digital pad in hasselquistii. The average magnitude of DA per CTC ranged from 1.5 to 5% of organ size, without correlation to organ size. Side dominance varied, mostly witin characters between taxa. No sexual differences in DA were significant, although for two CTCs DA was significant only in one sex. Presumably neutral or pleiotropically‐adaptive DA is a potential base for the evolution of functional DA. One practical conclusion is that in comparative biometrical studies, bilateral characters should not be examined consistently on only one side.

With 1 plate and 8 figures in the text)The orthurethran land snail Lauria cylindrucea is ovoviviparous. We examined its life history in Israel, where it lives in litter of the riparian forest floor, in a cool, humid habitat, that has a very stable and predictable temperature. Activity of snails started in winter and continued well into summer with gametogenesis commencing in early winter, after the beginning of the rainy season. In mid winter, all animals showed advanced spermatogenesis, early oogenesis, vitellogenic eggs and a few of the adults contained embryos. By spring and early summer, the gonads were larger, with both mature sperm and up to seven vitellogenic eggs; and up to 100% of the adults contained embryos, usually four per individual. A reproductive adult weighed about 4.5 mg, of which l7-2S% was embryo weight. In later summer and autumn, we observed no feeding or reproductive activity, no gametogenesis, and very few embryos.We distinguished three age groups: juveniles, subadults and adults. Juveniles were born in summer by adults having enough moisture to be active, whereas adults on dry leaves appeared to retain their embryos. The number of juveniles was therefore never as high as could be expected from the number of embryos inside the animals, and never exceeded 26% of the population. The juveniles grew until spring and then, as subadults, stopped growth until the following winter. It took a snail two winters to reach reproductive maturity, and the lifespan was about five years. About 30% of the adult snails died in late summer. All individuals throughout the year were euphallic, which is in contrast to the high frequency of aphally in other pupilloideans.

’Ubeidiya is a 1.4 Myr‐old Lower‐Pleistocene site in the Jordan Valley. Its rich Melanopsis fauna was found to include five species: buccinoidea, costata, turriformis, phanesiana obediensis and multiformis. These species and their conchiometrics are described. M. buccinoidea and costata occur in the Levant also today whereas turriformis, p. obediensis and multiformis are extinct. These findings suggest considerable faunal connections between the Jordan, the Orontes and perhaps also Rodhos during the lower Pleistocene. During the late Miocene, when the Mediterranean Sea level dropped, coastal‐plain freshwater habitats could have expanded and Melanopsis species could then have invaded the Rift Valley via coastal rivers. In addition they could have reached later, via the Rift Valley. Species frequencies of Melanopsis throughout ‘Ubeidiya suggest three’ Melanopsis landscapes’: an early period dominated by buccinoidea, a later one by costata and an upper one by p. obediensis. It is reasonable to speculate that the buccinoidea landscape represents a spring or perhaps a deep lake with a nearby stream; the costata landscape a shallow, nonturbulent, well‐aerated lake with a slow current; and the p. obediensis landscape a turbulent, well‐aerated lake. Intermediates were found between buccinoidea and costata. Their low frequency and their chrono‐distribution suggest they are hybrids, rather than evolutionary transitions between species. The 1.4 Myr old fossils of ‘Ubeidiya may be the earliest direct evidence of hybridization among molluscs in nature, that is still going on today in the same region and aquatic system, among the same species. The Melanopsis hybrid populations may perhaps act as filters that prevent the introgression of most genes, but allow others to disperse into the range of the parent species. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75, 39–57.

In this conchometric study, the systematics and distribution of the freshwater gastropod Melanopsis in the Levant are described. Of the ten species found, three are widespread, two have narrow distributions and five are known only from their type locality. Five smooth-shelled species are recognized ( buccinoidea, ammonis, dircaena, khabourensis and meiostoma ). Within M. buccinoidea , Jordan Valley populations may belong to a separate subspecies. M. ammonis is clearly differentiated from buccinoidea of the nearby Jordan Valley, but less so from buccinoidea of more distant sites; differences between ammonis and meiostoma are significant but not diagnostic. Five species have ribbed shells. Within costata , four subspecies are recognized (in the northern Orontes, upper Jordan, Sea of Galilee, and in southernmost parts of the Levant). Throughout the Levant, M. buccinoidea frequently hybridize s with M. costata and fossil evidence suggests that these species have been hybridizing for the last 1.5 Myr. M. saulcyi differs from M. costata in its narrower shell and shorter, bumpier ribs and frequently hybridize s with M. buccinoidea throughout the Levant. Specimens from Homs differ from those of the Jordan Valley in their higher figurativity index, fewer ribs and lower rib density. M. germaini differs from M. costata in its more numerous ribs, M. pachya in its shorter ribs, and M. infracincta in its bumpy shell in which each rib has huge tubercles, with a pronounced ridge flanking the columella. Our conclusion that there are ten species in the Levant differs from previous studies that suggested only two subspecies of one species (or superspecies). This difference could stem from (1) our use of nonstandard as well as standard conchometrics, (2) a reappraisal of the importance of the shell vs. the radula in intrageneric systematics, and (3) differences of opinion on the subspecies concept.

A correlative radioimmunoassay (RIA) and immunocytochemical (ICC) study was carried out on vasopressin (VP) distribution and content in brains of normal and 3-day water-deprived rats. By RIA there were statistically significant differences in brain VP per pg/mg between normal and osmotically stressed specimens in hypothalamus (338.4 versus 134.4), thalamus (4.8 versus 0.9), septum (18.0 versus 3.4), striatum (1.6 versus 0.7) and amygdala (17.3 versus 1.3), but not in other brain regions measured. Pituitary VP decreased from 71.1 to 8.7 ng/mg, and plasma VP rose from 3.6 to 19.3 pg/ml during water deprivation. Application of the peroxidase-anti-peroxidase ICC method of Sternberger to vibratome sections showed that VP-immunoreactivity in dehydrated specimens decreased in perikarya of paraventricular nucleus and suprachiasmatic nucleus, while intrahypothalamic immunoreactive magnocellular fibers appeared more conspicuous due to proliferation of large Herring bodies. In extrahypothalamic sites VP-immunoreactivity in water-deprived rats was visibly reduced in periventricular thalamus and septum. Thus it is apparent that both intra- and extrahypothalamic VP are affected by osmotic stress, and these results are discussed within the context of current ideas relating to co-activation of neurosecretory cells that project to different sites.