Jaim Sivan

The morphological constraint hypothesis (MCH) states that, in snakes, males typically have relatively longer tails than females to accommodate the hemipenes and retractor muscles. To date, most studies testing the MCH have been interspecific and results have been equivocal. We tested the MCH intraspecifically on Cerastes vipera, a species with a relatively short tail and suitable for testing the MCH. The relative tail length and length of the hemipenes pocket in Cerastes vipera were measured in preserved museum-maintained males (n = 35) and in free-ranging males and females (n = 277). Males exhibited relatively longer tails than females, which was explained fully by the length of the hemipenes pocket. The relatively short tail of C. vipera presents a constraint to the reproductive structures in males, as the length of the hemipenes pocket occupies a greater proportion in shorter- than longer-tailed individuals. This is the first report presenting these intraspecific findings in supp...

At 2330 h, SDB collected a female Lytorhynchus diadema (total length = 333 mm) crossing the road ~21.7 km N on N-1 from the intersection of P-1600 and N-1 just outside of Tan-Tan, Morocco (28.562037°N, 10.907357°W, WGS 84; elev. ~318 m, Ta = 17.8°C). The snake was photographed in life the following morning, and preserved (CM 55251). During the initial encounter, this individual presented a cobra-like display, flattening its neck and raising its head and body about 5 cm off the ground. The entire display lasted 15–20 sec. This behavior has not been reported in this species from northwestern Africa (PG, JMP, L. García- Cardenete, and R. León, pers. comm.; Šmíd 2010. Herpetol. Notes 3:329–332), but it is apparently not rare in Israel where it can be elicited by touching the snake on the base of the tail (Fig. 1).

Venomous viperid snakes possess relatively large and fragile hollow fangs that are an integral part of the envenomation apparatus for predation. We hypothesized that fangs serve like disposable needles and predicted a high loss rate and, hence, high replacement rate in free-ranging snakes. Snakes also possess smaller rear teeth that aid in gripping and swallowing the prey. We reasoned that these teeth are less delicate than fangs and predicted that their loss would be at a slower rate than fangs. To test our predictions, we analyzed fecal samples of free-ranging Saharan sand vipers, Cerastes vipera, in the Northern Negev desert, Israel. Close to 25% of fecal samples contained fangs, averaging more than one fang per sample and, consequently, our first prediction was supported. We estimated that fangs are replaced each fourth predation, and that replacement rate under natural conditions is at a high rate of approximately every twenty days. Fecal samples contained rear teeth at the same proportion as fangs, which indicated that the rapid replacement of teeth was not limited only to fangs and, therefore, our second prediction was not supported. These findings reflect the importance of both front fangs and rear teeth in the hunting of prey in free-ranging C. vipera. This is the first quantitative report of fang and rear teeth loss in a free-ranging viperid which is based on their recovery in feces; and we believe that similar high rates of loss occur in other viperid species.

The Saharan sand viper, Cerastes vipera (Linnaeus, 1758), is distributed in all Saharan countries, being confined to sand and dune systems. This relatively small snake, up to 35 cm, is nocturnal, is active from spring to autumn (April to October) and hibernates during the winter (November to March). We predicted that C. vipera would have peak plasma testosterone concentration at mating and that the vas deferens would contain abundant spermatozoa at that time. To test our predictions, we collected information on the time of mating and measured monthly testosterone concentration, testes size and testicular activity in free-living male C. vipera during its active period from April to October. Mating occurred only during spring. The pattern of plasma testosterone concentration, testes volume, seminiferous tubule diameter and spermatogenesis all followed the general pattern of high values in autumn and spring and low values in early summer. Our predictions were partially supported. There was a high plasma testosterone concentration at mating in spring and the vas deferens contained abundant spermatozoa, as predicted, but there was also a high plasma testosterone concentration in autumn without mating. We concluded that: (1) males are both aestival in that they produce spermatozoa in autumn, which they store over the winter hibernation period, and vernal in that they produce spermatozoa in spring prior to mating; (2) matings are associated with spermatogenesis; and (3) the high plasma testosterone concentration is concomitant with both matings and spermatogenesis in spring and with spermatogenesis in autumn. We propose that C. vipera has a single peak of testicular activity and plasma testosterone concentration which start in autumn and end in spring. We also propose that spermatogenesis is prior to spring mating and, consequently, is prenuptial.

Abstract. The pattern of the testicular cycle and spermatogenic activity of the Neotropical yellow-striped snake Lygophis anomalus in Uruguay was investigated. We gathered data on testicular size, seminiferous tubules, and histological samples of preserved specimens. Testis volume and seminiferous tubule diameter did not differ significantly over the year, and individuals with sperm cells were found all year round. Nevertheless, histological observations show individuals in different stages of spermatogenetic cycle within a single month sample. Our results show that, despite their continuous sperm production, males of L. anomalus populations in Uruguay exhibit a seemingly seasonal cycle, as reflected by changes in testicular volume. Reproductive pattern, even if related to evolutionary lineage, is possibly regulated by environmental factors such as low winter temperatures.

Venomous viperid snakes possess relatively large and fragile hollow fangs that are an integral part of the envenomation apparatus for predation. We hypothesized that fangs serve like disposable needles and predicted a high loss rate and, hence, high replacement rate in free-ranging snakes. Snakes also possess smaller rear teeth that aid in gripping and swallowing the prey. We reasoned that these teeth are less delicate than fangs and predicted that their loss would be at a slower rate than fangs. To test our predictions, we analyzed fecal samples of free-ranging Saharan sand vipers, Cerastes vipera, in the Northern Negev desert, Israel. Close to 25% of fecal samples contained fangs, averaging more than one fang per sample and, consequently, our first prediction was supported. We estimated that fangs are replaced each fourth predation, and that replacement rate under natural conditions is at a high rate of approximately every twenty days. Fecal samples contained rear teeth at the same proportion as fangs, which indicated that the rapid replacement of teeth was not limited only to fangs and, therefore, our second prediction was not supported. These findings reflect the importance of both front fangs and rear teeth in the hunting of prey in free-ranging C. vipera. This is the first quantitative report of fang and rear teeth loss in a free-ranging viperid which is based on their recovery in feces; and we believe that similar high rates of loss occur in other viperid species.

The Saharan sand viper (Cerastes vipera) and the crowned leafnose (Lytorhynchus diadema) are two snake species well adapted to desert sand dunes and, in Israel, coexist in the western Negev Desert. C. vipera is a sit-and-wait ambusher while L. diadema is an active hunter. We studied the seasonal and diel activity patterns and dietary selection of these two species while free-living in the field. Both species were active from early spring until late fall but displayed (i) different seasonal activity patterns -C. vipera was bimodal with peaks in spring and autumn whereas L. diadema was basically unimodal with a peak in summer; (ii) different nocturnal above-ground activity patterns -C. vipera was active mainly during the first three hours of darkness while L. diadema was constantly active during the first seven hours of darkness; and (iii) different patterns of nocturnal behavior -C. vipera moved up to 50 m while L. diadema moved several hundred meters each night. Dietary selection differed between these snake species although lizards, mainly Nidua fringe-fingered lizards (Acanthodactylus scutellatus), were the main dietary item for both. We concluded that temporal partitioning in above-ground activity, different foraging strategies and differences in dietary selection may contribute towards the coexistence of the two snake species.

Sit-and-wait ambushing and active hunting are two strategies used by predators to capture prey. In snakes, hunting strategy is conserved phylogenetically; most species employ only one strategy. Active hunters encounter and capture more prey but invest more energy in hunting and have higher risks of being predated. This trade-off is important to small predators. The small Cerastes vipera employs both modes of hunting, which is unlike most viperids which use only sit-and wait ambushing. This species hibernates in October and emerges in April. Energy intake should be high prior to hibernation to overcome the non-feeding hibernation period and for reproduction on their emergence. We predicted that more individuals would hunt actively towards hibernation and an abiotic factor would trigger this response. Furthermore, since more energy is required for active hunting, we predicted that snakes in good body condition would use active hunting to a greater extent than snakes in poor body condition. To test our predictions, we tracked free-living snakes year round and determined their hunting strategy, estimated their body condition index (BCI), and calculated circannual parameters of day length as environmental cues known to affect animal behaviour. Two novel findings emerged in this study, namely, hunting strategy was affected significantly by 1) the circannual change in day length and 2) by BCI. The proportion of active hunters increased from 5% in April to over 30% in October and BCI of active foragers was higher than that of sit-and-wait foragers and, therefore, our predictions were supported. The entrainment between the proportion of active hunting and the abiotic factor is indicative of an adaptive function for choosing a hunting strategy. A trend was evident among life stages. When all life stages were present (September-October), the proportion of active foragers increased with age: 0.0% among neonates, 18.2% among juveniles and 31.4% among adults. We concluded that vulnerable small neonates used sit-and-wait ambush not only as a hunting strategy but also as a hiding technique.

ABSTRACT The Saharan sand viper, Cerastes vipera, and the crowned leafnose, Lytorhynchus diadema, are small coexisting psammophilic desert snake species, consume primarily lizards and do not engage in male to male combat. They differ in that C. vipera is ovoviparous and L. diadema is oviparous, C. vipera moves by sidewinding while L. diadema uses serpentine movement and C. vipera is a sit-and-wait ambusher while L. diadema is an active hunter. Results showed that C. vipera was heavier than L. diadema per unit snout-vent length (SVL). We concluded that this was related to foraging, as L. diadema had to move quicker than L. diadema, and to reproduction, as C. vipera needed more abdominal space for developing embryos. Sexual size dimorphism was found in adults in both species and it appeared that ecological advantages took precedence over phylogenetic affinity in determining size differences. The relatively small size, ovoviparity, sandy habitat with sidewinding, and lack of male to male combat for C. vipera whereas oviparity and sandy habitat for L. diadema may explain partly sexual size dimorphism in these species. Females showed seasonal fluctuations in BCI in both species but males did not and C. vipera females showed greater fluctuations than L. diadema females. We concluded that the former resulted from higher energy costs of females than males and the latter because ovoviparity is costlier than oviparity.

Scorpio Linnaeus, 1758 (family Scorpionidae Latreille, 1802) was considered monotypic for over a century, and comprised a single species, Scorpio maurus Linnaeus, 1758, with 19 subspecies, distributed from West Africa, throughout the Maghreb and the Middle East, to Iran. Two parapatric subspecies, Scorpio maurus fuscus (Ehrenberg, 1829) and Scorpio maurus palmatus (Ehrenberg, 1828), have long been recognized in Israel. We examined morphological variation, burrow architecture and genetic divergence among 39 populations across the distribution of the two subspecies to assess whether they are conspecific and, if not, how many species might be involved. Cuticle coloration, pedipalp chela digital carina condition, and selected measurements were recorded. Sixty burrows were excavated and examined for burrow structure and depth. A multilocus dataset comprising concatenated fragments of one nuclear (28S rDNA) and three mitochondrial (12S rDNA, 16S rDNA, Cytochrome c Oxidase Subunit I) loci, totaling ca. 2400 base-pairs, was produced for 41 individuals, and a single-locus dataset comprising 658 base-pairs of the COI locus for 156 individuals. Despite overlapping ranges in morphometric characters of pedipalp chela shape, the putative subspecies were easily distinguished by cuticle coloration and condition of the pedipalp chela digital carina, and were also found to differ significantly in burrow architecture and depth. Phylogeographical analyses of the COI and multilocus datasets recovered seven distinct clades. Separate analyses of mitochondrial sequences, and combined analyses of mitochondrial and nuclear sequences support most clades. The two major clades corresponded with the geographical distributions of S. m. fuscus and S. m. palmatus in the region. Specimens from these clades were genetically distinct, and exhibited different burrow structure in geographically-proximate localities, suggesting reproductive isolation. The palmatus clade included two distinct subclades of specimens from localities adjacent to the Dead Sea. Three other clades, comprising specimens from the most northeastern localities, were tentatively assigned to subspecies previously recorded in neighboring Jordan and Syria. The morphological, behavioral and genetic evidence supports previous suggestions that Scorpio maurus is a species complex and justifies the following taxonomic emendations: Scorpio fuscus (Ehrenberg, 1829), stat. nov.; Scorpio kruglovi (Ehrenberg, 1829), stat. nov.; Scorpio palmatus (Ehrenberg, 1828), stat. nov.; Scorpio propinquus (Simon, 1872), stat. nov.