Combined effects of climatic gradient and domestic livestock grazing on reptile community structure in a heterogeneous agroecosystem.

Grazing plays an important role in shaping ecological communities in human-related ecosystems. Although myriad studies have explored the joint effect of grazing and climate on plant communities, this interactive effect has rarely been studied in animals. We hypothesized that the effect of grazing on the reptile community varies along a climatic gradient in relation to the effect of grazing on habitat characteristics, and that grazing differentially affects reptiles of different biogeographic regions. We tested our hypotheses by collecting data on environmental characteristics and by trapping reptiles in four heterogeneous landscapes experiencing differing grazing intensities and distributed along a sharp climatic gradient. We found that while reptile diversity increased with grazing intensity at the mesic end of the gradient, it decreased with grazing intensity at the arid end. Moreover, the proportion of reptile species of differing biogeographic origins varied with the interactive effect of climate and grazing. The representation of species originating in arid biogeographic zones was highest at the arid end of the climatic gradient, and representation increased with grazing intensity within this area. Regardless of the climatic context, increased grazing pressure results in a reduction in vegetation cover and thus in changes in habitat characteristics. By reducing vegetation cover, grazing increased habitat heterogeneity in the dense mesic sites and decreased habitat heterogeneity in the arid sites. Thus, our results suggest that the same direction of habitat alteration caused by grazing may have opposite effects on biodiversity and community composition in different climatic contexts.

Show Me Your Teeth And I Will Tell You What You Eat: Differences in Tooth Enamel in Snakes with Different Diets.

Teeth are composed of the hardest tissues in the vertebrate body and have been studied extensively to infer diet in vertebrates. The morphology and structure of enamel is thought to reflect feeding ecology. Snakes have a diversified diet, some species feed on armored lizards, others on soft invertebrates. Yet, little is known about how tooth enamel, and specifically its thickness, is impacted by diet. In this study, we first describe the different patterns of enamel distribution and thickness in snakes. Then, we investigate the link between prey hardness and enamel thickness and morphology by comparing the dentary teeth of 63 species of snakes. We observed that the enamel is deposited asymmetrically at the antero-labial side of the tooth. Both enamel coverage and thickness vary a lot in snakes, from species with thin enamel, only at the tip of the tooth to a full facet covered with enamel. There variations are related with prey hardness: snakes feeding on hard prey have a thicker enamel and a lager enamel coverage while species. Snakes feeding on softer prey have a thin enamel layer confined to the tip of the tooth.

Pathogens in ticks collected in Israel: I. Bacteria and protozoa in Hyalomma aegyptium and Hyalomma dromedarii collected from tortoises and camels.

Ticks were collected from 30 Greek tortoise (Testudo graeca), and 10 Arabian camels (dromedary) (Camelus dromedarius) in Israel. All those collected from Greek tortoises belonged to Hyalomma aegyptium, while all specimens collected from the camels belonged to Hyalomma dromedarii. Out of 84 specimens of H. aegyptium, 31 pools were examined by PCR, while from 75 H. dromedarii specimens nine pools were studied. Out of 31 pools of H. aegyptium 26 were positive for pathogens or endosymbiont; 14 for one, 11 for two and one for three pathogens. Out of nine pools prepared from H. dromedarii, seven were positive for pathogens (two for C. burnetii and five for Leishmania infantum). In H. aegyptium, Rickettsia africae, Rickettsia aeschlimannii, Rickettsia endosymbiont, Coxiella burnetii, Hemolivia mauritanica, Babesia microti, Theileria sp., and Leishmania infantum was detected, while in H. dromedarii C. burnetii and L. infantum were found. None of the ticks were positive for Anaplasma/Ehrlichia, Listeria monocytogenes, Bartonella spp., Hepatozoon spp. and Toxoplasma gondii. H Rickettsia endosymbionts, C. burnetii, B. microti, Theileria sp. and L. infantum are reported for the first time in H. aegyptium, and C. burnetii and L. infantum for the first time in H. dromedarii.

Venous blood gases, plasma biochemistry, and hematology of wild-caught common chameleons (Chamaeleo chamaeleon).

The purpose of this study was to determine a wide range of selected hematologic, venous blood gases, and plasma biochemistry analytes in common chameleons (Chamaeleo chamaeleon). Blood samples were collected from the ventral tail vein of 41 common chameleons to determine reference intervals for 30 different blood analytes. The calcium-to-phosphorus ratio, packed cell volume (PCV), refractometric total solids (TS), blood cell counts, and differentials were also determined. The microscopic evaluation of blood smears revealed inclusion bodies in monocytes in 7 of the samples. Females showed significantly higher values of plasma proteins and calcium and cholesterol concentrations and males showed significantly higher values of aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) plasma concentrations. Significant differences were found between similar analytes determined by different testing methodologies in the PCV/hematocrit, electrolytes (sodium, potassium), and plasma proteins [TS, total protein (TP) and albumin]. Blood analytes determined in this study can provide baseline data that may be useful when evaluating the health status of common chameleons, taking into consideration the potential effects of gender and the type of analyzer used.

Des prélèvements sanguins ont été obtenus de la veine caudale ventrale sur 41 caméléons communs (Chamaeleo chamaeleon) dans l'optique d'établir des intervalles de référence pour 30 analytes sanguins. Le ratio calcium/phosphore, le PCV, les solides totaux par réfractométrie (TS), la numération-formule sanguine ont aussi été déterminés. L'évaluation microscopique des frottis sanguins ont révélé la présence de corps d'inclusions ressemblant aux corps d'inclusions a Chlamydia dans les monocytes sur sept échantillons. Les femelles avaient des valeurs significativement plus élevées pour l'AST et la GGT. Des différences significatives entre les mêmes analytes mais d'après différentes techniques analytiques ont été trouvées pour le PCV/hématocrite, des électrolytes (sodium, potassium) et les protéines plasmatiques (TS, TP et albumine). Les analytes sanguins rapportés dans cette étude pourront fournir des données de base utiles pour l'évaluation de l'état de sante des caméléons communs, tout en considérant les effets potentiels du sexe et de l'analyseur utilisé.(Traduit par les auteurs).

Multidimensional differentiation in foraging resource use during breeding of two sympatric top predators.

Ecologically-similar species were found to develop specific strategies to partition their resources, leading to niche differentiation and divergence, in order to avoid interspecific competition. Our study determines multi-dimensional differentiation of two sympatric top-predators, long-legged buzzards (LLB) and short-toed eagles (STE), which recently became sympatric during their breeding season in the Judean Foothills, Israel. By combining information from comprehensive diet and movement analyses we found four dimensions of differentiation: (1) Geographic foraging area: LLB tended to forage relatively close to their nests (2.35 ± 0.62 km), while STE forage far from their nest (13.03 ± 2.20 km); (2) Foraging-habitat type: LLBs forage at low natural vegetation, avoiding cultivated fields, whereas STEs forage in cultivated fields, avoiding low natural vegetation; (3) Diurnal dynamics of foraging: LLBs are uniformly active during daytime, whereas STEs activity peaks in the early afternoon; and (4) Food-niche: while both species largely rely on reptiles (47.8% and 76.3% for LLB and STE, respectively), LLB had a more diverse diet and consumed significantly higher percentages of lizards, while STE consumed significantly higher percentages of snakes. Our results suggest that this multidimensional differentiation allows the spatial coexistence of these two dense populations in the study area.