Extreme tolerance for nocturnal emergence at low body temperatures in a high-latitude lizard: implications for future climate warming.

High-latitude lizards live in environments where ambient air temperature at night is frequently below retreat temperatures, which likely has implications for nocturnal emergence and activity. However, patterns of lizard activity at night under current temperate climates are poorly understood, a situation that limits our understanding of potential effects of climate change. We investigated patterns of nocturnal emergence and activity in the cold-adapted, viviparous gecko (Woodworthia 'Otago/Southland'). We measured operative environmental temperature (T e) available to geckos that emerged at night and simultaneously assessed nighttime emergence activity using time-lapse trail cameras. Also, we assessed field body temperature (T b) of emerged geckos of various life history groups at night using thermography to understand how current weather conditions affect field T b of emerged geckos. Our results show that Te , nocturnal emergence activity and field-active T b increased with nighttime air temperature. Nocturnal emergence was highest in spring and summer but also occurred in autumn and (unexpectedly) in winter. Geckos were active over a broad range of T b down to 1.4°C (a new record low for lizards) and on rock surfaces typically warmer than air temperature or T b. We conclude that this nocturnal, high-latitude lizard from the temperate zone is capable of activity at low winter temperatures, but that current climate limits emergence and activity at least in autumn and winter. Activity levels for cool-temperate reptiles will probably increase initially as climates warm, but the consequences of increased nocturnal activity under climate change will probably depend on how climate change affects predator populations as well as the focal species' biology.

Thermal heterogeneity of selected retreats in cool-temperate viviparous lizards suggests a potential benefit of future climate warming.

Rocky retreats are limited and geologically constrained resources for rock-dwelling nocturnal lizards. Such lizards should seek retreats that offer thermoregulatory benefits without the risk of overheating during the day, and that protect from predation. For cold-adapted species where air temperature is frequently lower than optimum temperature for performance, factors influencing retreat-site selection and whether future warmer conditions will force superficial rock slabs to be abandoned on hot days remain poorly known. Here, we predicted that retreats selected by a nocturnally foraging, cool-temperate gecko from southern New Zealand would be thermally heterogeneous and that future warmer temperature will force lizards to abandon daytime retreats on hot days. We sampled loose rock slabs (potential retreats) in a tussock-grassland site in all seasons. We measured seasonal rock temperature profiles and field body temperature (Tb) of captured geckos using thermography and quantified the physical characteristics of each potential retreat. We found that both physical characteristics and rock temperatures determine choice of retreats. Field Tb of lizards positively correlated with retreat and air temperatures. Also, retreat temperatures, including those of the substrate below the rock slabs, showed complex heterogeneity enabling lizards to choose microsites within retreats to achieve preferred body temperatures intermittently. Observed seasonal shifts in characteristics of occupied rocks imply that lizards choose retreats to maximise warmth in spring, minimise risk of overheating (remain below voluntary thermal maximum, VTmax) in summer and avoid freezing over winter. Our study demonstrates the importance of microclimatic conditions in influencing retreat-site selection. Climate warming might lead to seasonal changes in use of rock slabs and possibly be beneficial initially, but longer-term implications need to be examined.

Heat and water loss versus shelter: a dilemma in thermoregulatory decision making for a retreat-dwelling nocturnal gecko.

Understanding the interaction between upper voluntary thermal limit (VTmax) and water loss may aid in predicting responses of ectotherms to increasing temperatures within microhabitats. However, the temperature at which climate heating will force cool-climate nocturnal lizards to abandon daytime retreats remains poorly understood. Here, we developed a new laboratory protocol for determining VTmax in the retreat-dwelling, viviparous Woodworthia 'Otago/Southland' gecko, based on escape behaviour (abandonment of heated retreat). We compared the body temperature (Tb) at VTmax, and duration of heating, between two source groups with different thermal histories, and among three reproductive groups. We also examined continuous changes in Tb (via an attached biologger) and total evaporative water loss (EWL) during heating. In the field, we measured Tb and microhabitat thermal profiles to establish whether geckos reach VTmax in nature. We found that VTmax and duration of heating varied between source groups (and thus potentially with prior thermal experience), but not among reproductive groups. Moreover, geckos reached a peak temperature slightly higher than VTmax before abandoning the retreat. Total EWL increased with increasing VTmax and with the duration of heating. In the field, pregnant geckos with attached biologgers reached VTmax temperature, and temperatures of some separately monitored microhabitats exceeded VTmax in hot weather implying that some retreats must be abandoned to avoid overheating. Our results suggest that cool-climate nocturnal lizards that inhabit daytime retreats may abandon retreats more frequently if climate warming persists, implying a trade-off between retention of originally occupied shelter and ongoing water loss due to overheating.

Report of high prevalence of schistosome infection in Biomphalaria snails from a geographic area with no previous prevalence of human schistosomiasis in Nigeria.

Previous study using the traditional method of screening snails for infection reported shedding of Schistosoma cercaria by Biomphalaria snails from a river in Nkalagu, southeastern Nigeria. This is contrary to published reports that Biomphalaria from this part of the country does not shed schistosome cercaria. Here, we employed the use of polymerase chain reaction (PCR) methods to screen and characterize the Biomphalaria snails from Nkalagu. Snails were collected from the River Uzuru in dry season, identified and subjected to molecular assays. Genomic DNA (gDNA) was extracted from whole tissues of the 212 Biomphalaria snails and amplified using conventional PCR to check for the schistosome infection level. Assay for the detection of S. mansoni infection was further done using a nested PCR (nPCR). We amplified the entire internal transcribed spacer 2 (ITS2) regions from gDNA of the 212 snails. The representative samples were sequenced and subjected to BLAST searches to confirm snail species. Of the 212 snails screened, 164 (77.4%) of the snails were infected with schistosomes, but only 16 (9.76%) of the snails were positive for S. mansoni infection. Amplification of the snails' ITS2 region yielded a product of 460 bp, and BLAST searches confirmed the snails to be B. pfeifferi, and BLAST searches confirmed the snails to be B. pfeifferi. This paper reports for the first time the presence of S. mansoni positive B. pfeifferi in Nkalagu, which suggest there may be cases of intestinal schistosomiasis in this part of Nigeria.

Accuracy of an inexpensive, compact infrared thermometer for measuring skin surface temperature of small lizards.

Studies of thermal sensitivity in ectotherms require accurate measurements of body temperature using a reliable device, including in field situations. In this study, we tested the accuracy of a compact and inexpensive mini-infrared thermometer (mini-IRT, 22.3 g) at close distance (within 5 mm) for measuring skin surface temperature of small lizards or their models (painted copper bars). First, we used copper bars to assess the effect of model width on the accuracy of the measurement. We placed the heated models on a cool background, and then surface temperatures were measured with a mini-IRT for comparison with a thermogram from an infrared camera (IRC). We also assessed the accuracy of the mini-IRT for measuring skin temperature for two species of small lizards in the laboratory and in the field, in comparison with the skin surface temperature measured with the IRC and with cloacal temperature measured with a thermocouple thermometer. Our results with inanimate models show that the accuracy of the mini-IRT at a distance within 5 mm is biologically acceptable (within ±1.0 °C of the mean value obtained using a more expensive, calibrated device) when the width is ≥ 7 mm. For live lizards, we observed highly significant relationships between skin surface temperature measured with the mini-IRT and temperatures measured with the two other devices. The mean discrepancies between the mini-IRT and other devices were acceptably small for geckos but larger for the smaller and more slender skinks. Taken together, our results suggest that skin temperature measured with the mini-IRT at a close distance is acceptable for field studies on lizards with an abdominal width ≥7 mm, serving as an inexpensive proxy for core body temperature in situations where portability and affordability of equipment and minimal animal handling are paramount. Nonetheless, calibration of mini-IRTs before use is strongly recommended.

HEXANE EXTRACT OF Dacryodes edulis FRUITS POSSESSES ANTI-DIABETIC AND HYPOLIPIDAEMIC POTENTIALS IN ALLOXAN DIABETES OF RATS.

BACKGROUND: The fruit extract of Dacryodes edulis (D. edulis), the African pear or plum, a tree indigenous to the humid tropics has been used for managing wounds, skin diseases, sickle cell anaemia, dysentery and fever in some African nations. In South Eastern Nigeria, 'herbal doctors' include its marshed fruit in decoctions administered to diabetic patients. However no scientific substantiation of their claim and use exist in literature. Hence, the need to evaluate the antidiabetic and hypolipidaemic activity of hexane extracts of D. edulis fruit in alloxanised animal model. MATERIALS AND METHODS: Sub-toxic doses between 400 and 1600mg/kg were orally administered sub-chronically to alloxan-induced diabetic rats for 15 days and compared to glibenclamide (2.5mg/kg). The glycaemia levels, body weights, lipid profile, blood urea, creatinine and liver enzyme levels were measured. Basic histology of the pancreatic tissue was also performed to examine the effects on the pancreas as possible mechanistic lead. RESULTS: Oral acute dosing of D. edulis hexane extract decreased blood glucose levels, while sub-chronic treatment of the extract down-regulated significantly hyperglycaemia, total cholesterol, triglycerides, LDL-C, ALT and ALP levels. However, the HDL-C levels increased significantly. Histopathological examination of the pancreatic tissues after sub-chronic treatment showed that glibenclamide and the highest dose of the extract 1600mg/kg restored the afore-damaged pancreatic ß-cell architecture. CONCLUSION: Our findings portend that D. edulis hexane fruit extract possesses hypoglycaemic and hypolipidaemic activities as well as restoration of the pancreatic architecture without any obvious untoward hepatic damages, suggesting that its use in the management of the diabetes may be valid. List of Non-standard abbreviations:D. edulis = dacryode edulis, DEnH = Dacryodes edulis n-hexane fruit extract, B.wt. = Body weight, Per os = Oral administration, NC = normal control, DC =Diabetic control, SC = Standard control, LDL-C = low density lipoprotein cholesterol, HDL-C = High density lipoprotein cholesterol, TG = Triglyceride, TC = Total cholesterol.