Uri Shanas

A sheep in wolf's clothing: do carrion and dung odours of flowers not only attract pollinators but also deter herbivores?

Carrion and dung odours of various flowers have traditionally been considered an adaptation for attracting the flies and beetles that pollinate them. While we accept the role of such odours in pollinator attraction, we propose that they may also have another, overlooked, anti‐herbivore defensive function. We suggest that such odours may deter mammalian herbivores, especially during the critical period of flowering. Carrion odour is a good predictor for two potential dangers to mammalian herbivores: (1) pathogenic microbes, (2) proximity of carnivores. Similarly, dung odour predicts faeces‐contaminated habitats that present high risks of parasitism. These are two new types of repulsive olfactory aposematic mimicry by plants: (1) olfactory feigning of carcass (thanatosis), a well‐known behavioural defensive strategy in animals, (2) olfactory mimicry of faeces, which also has a defensive visual parallel in animals.

Seasonality and Seasons Out of Time—The Thermoregulatory Effects of Light Interference

The change in photoperiod is the main environmental cue for seasonal function of the reproductive, thermoregulatory, and immune systems in rodents existing outside of the tropics. In Israel, the social vole Microtus socialis breeds mainly under short photoperiod (SP) conditions. Previous studies showed that exposing voles to light interference (LI) in the field during the winter resulted in death. The aim of the current study was to determine the thermoregulatory response of SP‐acclimated voles to LI. Therefore, heat production (VO2) at different ambient temperatures (Ta) and nonshivering thermogenesis (NST) were measured. Results show that LI of 15 min every 4 h during the dark period significantly (p<0.02) decreased VO2 at Ta=15°C and significantly (p<0.05) decreased NST‐capacity. These results can at least partly explain why LI‐voles died during the winter under field conditions, through eliminating winter acclimatization of the thermoregulatory system, or what is considered as “seasons out of time.”

Diet salinity and vasopressin as reproduction modulators in the desert-dwelling golden spiny mouse (Acomys russatus)

The time for reproduction in mammals largely depends on the availability of water and food in their habitat. Therefore, in regions where rains are limited to definite seasons of the year, mammals presumably will restrict their breeding correspondingly. But while mammals living in predictable ecosystems would benefit by timing their season to an ultimate predictable cue, such as photoperiod, in unpredictable ecosystems (e.g., deserts) they will need to use a more proximate signal. We suggest a mechanism by which water shortage (low water content in plants) could act as a proximate cue for ending the reproductive season. The golden spiny mouse (Acomys russatus), a diurnal rodent living in extreme deserts, may face an increased dietary salt content as the summer progresses and the vegetation becomes dry. Under laboratory conditions, increased diet salinity lead to reproductive hiatus in females, notable in imperforated vagina, and a significant decrease in the ovaries, uteri, and body masses. In females treated with vasopressin (VP), a hormone expressed during water stress, the uteri and body masses have decreased significantly, and the ovaries exhibited an increased number of atretic follicles. VP has also led to a significant decrease in relative medullary thickness (RMT) of the kidney. It is thus suggested that VP could act as a modulator linking the reproductive system with water economy in desert rodents, possibly through its act on the energetic pathways.

Mole-rat harderian gland secretions inhibit aggression

The harderian gland secretions of mole-rats, Spalax ehrenbergiusually released by self-grooming, include odorous substances which are sex dependent. Male secretions were the most attractive to both sexes, while female secretions were attractive to males but not to other females. The rate of attacks by females towards intact males was higher than towards males whose harderian gland had been removed. However, grooming by intact male mole-rats decreased the rate of attacks by their opponents, while grooming by males without harderian glands did not; thus the male harderian secretions appear to have appeasement qualities. Grooming by females with and without harderian glands failed to reduce aggression. Unlike intact males, those without harderian glands had almost no volatiles on their fur, and thus are probably not considered to be a threat to conspecifics. Gas chromatography spectra showed that substances of harderian origin were added to the fur during grooming. Some of these substances remained on the fur long after the animal ceased grooming, and appear to give the animal its specific odour, but some volatile substances peaked briefly after grooming, and were probably responsible for the decline of aggression that occurred after grooming. Although grooming has long been considered to be a displacement activity, we suggest that in the mole-rat its performance is too risky to be merely this, and it has acquired the meaning of appeasement through the release of chemical cues.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Spotted fever group rickettsiae in ticks collected from wild animals in Israel.

We report molecular evidence for the presence of spotted fever group rickettsiae (SFGR) in ticks collected from roe deer, addax, red foxes, and wild boars in Israel. Rickettsia aeschlimannii was detected in Hyalomma marginatum and Hyalomma detritum while Rickettsia massiliae was present in Rhipicephalus turanicus ticks. Furthermore, a novel uncultured SFGR was detected in Haemaphysalis adleri and Haemaphysalis parva ticks from golden jackals. The pathogenicity of the novel SFGR for humans is unknown; however, the presence of multiple SFGR agents should be considered when serological surveillance data from Israel are interpreted because of significant antigenic cross-reactivity among Rickettsia. The epidemiology and ecology of SFGR in Israel appear to be more complicated than was previously believed.

Molecular Evidence for Anaplasma phagocytophilum in Israel

Sequences from the Anaplasma phagocytophilum 16S rRNA gene were detected in 5 ticks representing 3 species (Hyalomma marginatum, Rhipicephalus turanicus, and Boophilus kohlsi) collected from roe deer (Capreolus capreolus) in Mount Carmel, Israel. The sequences were all identical to those of Ap-variant 1 strain.

Grooming expresses harderian gland materials in the blind mole rat

The blind mole rat (Spalax ehrenbergi) is a highly aggressive and solitary rodent that shows the most striking physiological and behavioral adaptations to underground life. The eyes are not detectable externally; they are atrophied and covered by a thick layer of skin. A considerable part of the orbit is occupied by a very large Harderian gland. The current study demonstrates that during autogrooming the mole rat expresses Harderian gland materials from the conjunctival sac to the external nares and spreads them onto the fur. In contrast to other rodents, the mole rats grooming behavior is usually confined to the front part of the body and does not progress after the head wipes to ventrolateral torso licking. Moreover, in highly aggressive encounters grooming sometimes ceases after the second phase ― the nose wipe bouts. The unique first phase of the mole rats grooming consists of highly rapid strokes over the skinny border of the head, which we assume help to squeeze Harderian materials from the gland. Unlike other rodents, in which grooming occupies a considerable part of their waking time, mole rats, cage individually, rarely perform autogrooming behavior. Grooming in mole rats has been found to be highly correlated with aggressive encounters, and submissive animals exhibit significantly more grooming than their dominant opponents. It is speculated that the Harderian gland discharge may serve as an appeasing substance when mole rats meet to reduce the extreme aggressiveness typical of these subterranean rodents

Feeding activity and dietary composition of roe deer at the southern edge of their range

We studied feeding activity and dietary components of hand-reared European roe deer (Capreolus capreolus) in Israel. Our ultimate goal was to assess habitat suitability for future reintroduction of the species, which has been locally extinct for nearly a century. Activity patterns, diet composition, and body mass of four does were monitored in two (fenced) typical east Mediterranean habitats: mature forest and scrubland recovering from fire. Food supplements were provided between trials. Throughout the year, the deer exhibited diurnal and nocturnal activity, mostly at dawn and dusk. Diet composition varied considerably between seasons and habitats, demonstrating the opportunistic flexibility of the deer. In both habitats, the deer fed on over 85% of the plant species but preferred a particular plant species or parts. In summer and early autumn, fruits and seeds became the dominant portion of their diet. In our semi-natural experimental setup, deer maintained body mass through the winter and spring. Weight loss occurred as the dry season advanced, but the animals rapidly regained mass when annuals and grasses became available following the first rains. In the east Mediterranean habitats, water availability seems more problematic for deer survival than food availability.

The effects of season and dietary salt content on body temperature daily rhythms of common spiny mice from different micro-habitats

We compared body temperature (T(b)) daily rhythms in two populations of common spiny mice, Acomys cahirinus, during summer and winter months in relation to increasing dietary salt content. Mice were collected from the North and South facing slopes (NFS and SFS) of the same valley, that are exhibiting mesic and xeric habitats, respectively. During the summer, whilst mice were offered a water source containing 0.9% NaCl, SFS individuals had T(b) peak values at 24:00, whereas NFS individuals had peak values at 18:00. When the salinity of the water source was increased, from 0.9 to 2.5% and then 3.5%, the difference between maximal and minimal T(b) of both populations increased. In addition, with increased salinity, the T(b) daily peak of SFS mice shifted to 18:00. During the winter, the mean daily T(b) values of both populations of mice were lower than during the summer. At 0.9% salinity, the NFS mice exhibited a daily T(b) variation with a peak at the beginning of the night. However, we did not detect any significant variation in daily T(b) in the SFS mice. At 2.5% salinity, the difference between the mean daily T(b) of mice from the two slopes increased. In winter we were unable to increase the salinity to 3.5% as the animals began to lose weight rapidly. We suggest that common spiny mice that inhabit these two micro-habitats are forming two discrete populations that respond differently to the environmental pressures prevailing in each habitat, by evolving different physiological capacities.

Molecular variation and chromosomal stability within Gerbillus nanus (Rodentia, Gerbillinae): taxonomic and biogeographic implications

Abstract The systematics of the rodent genus Gerbillus still needs clarifications. Within this genus, Gerbillus nanus is a species often considered to have a wide geographic distribution ranging from northwest India to the Mauritanian coast. Some authors, however, have suggested that other species, namely Gerbillus amoenus and/or Gerbillus garamantis, may replace G. nanus over a part of, or over the whole of its African area of occurrence. Here, we bring together new karyological data and molecular analyses of cytochrome b mitochondrial gene sequences of G. nanus specimens from various parts of the alleged extended distribution of the species: Pakistan and Israel in Asia, and Libya, Mali, and Mauritania in Africa. The karyotypes of Asian and African specimens appear similar, while a rather important genetic distance was found between samples of specimens from the two continents. This last finding suggests that at least two distinct species exist, G. nanus being the species of Asian distribution, and G. garamantis and/or G. amoenus being the one(s) with African distribution(s). Similar comparative analyses on larger samples are now needed to determine the precise taxonomic situation in this group, as well as the distribution limits of each species.