Thermophilic response post feeding in Pleurodema nebulosum (Anura: Leptodactylidae) from Monte desert,Argentina.

We studied the thermophilic response to feeding of a typical desert adapted anuran from the Monte Desert. Our aim was to evaluate thermal changes in the selected body temperature of adult frogs of Pleurodema nebulosum, and measure the intestinal passage time, and food digestion. Our results show that after feeding, they selected higher micro-environmental temperatures ~ + 2 °C than frogs that remained starved. Pleurodema nebulosum would present a postprandial thermophilic response. The time of retention of food in the digestive tract was thermo-dependent, being lower in those individuals who were incubated at high temperatures (25 °C) compared to those subjected to lower temperatures (20 °C). Although we did not detect effects of temperature on digestive efficiency, the mass of faecal material indicates an increase at temperatures closer to the selected ones, suggesting that the defecation rate is influenced by temperature. Laiuoperinae frogs are characterized by explosive breeding behavior and fast growing rate. The digestive efficiency is essential for acquiring energy necessary for growth, reproduction and refuge-seeking, among others. In this framework, the differential selection of temperatures between moments of fasting and feeding allows the frogs to maintain a high digestive efficiency, maximizing the absorption of nutrients.     

Seasonal changes in the thermoregulatory strategies of Rhinella arenarum in the Monte desert, Argentina

We determined and compared the efficiency of thermoregulation of Rhinella arenarum in the Monte desert (Argentina) in two seasons, dry and wet. In the field, we measured body temperatures, micro-habitat temperatures and operative temperatures; while in the laboratory; we measured the selected body temperatures. Our results show a change in the thermoregulatory strategy of R. arenarum that is related to environmental constraints on their thermal niche. R. arenarum has the ability to be plastic and combine two strategies: (i) a moderate thermoregulator in the wet season, where thermal resources are available such that body temperature is maintained within the set points and physiologicial and behavioral processes are optimized; and (ii) a thermoconformer in the dry season where the thermal environment is more homogeneous and there is greater time invested in searching for food.     

西花蓟马的快速冷驯化及其生态学代价

西花蓟马是我国蔬菜、果树和观赏植物上的一种重要入侵害虫.该害虫通过取食寄主汁液和传播多种植物病毒造成危害,而后者危害造成的经济损失更大.温度是影响西花蓟马生长发育和繁殖的一个重要非生物因子,而该虫对温度的耐受性决定了它的越冬存活率和地理分布.为探明低温对西花蓟马的不利影响,研究了西花蓟马若虫和成虫的快速冷驯化对其存活、发育和繁殖的影响.结果表明,随着温度降低,西花蓟马若虫和成虫存活率逐渐下降,但若虫对低温更为敏感.当成虫和若虫暴露于-13℃和-13.5℃下2h后,其存活率分别为25％和27％.根据识别温度定义,这两个温度分别被定义为若虫和成虫的识别温度.将西花蓟马成、若虫在0℃或5℃驯化2h后,再置于各自识别温度下,其存活率都得到了明显提高,但雌雄成虫间的存活率并无差异;然而,在0℃下驯化2h后,若虫和雌雄成虫的存活率得到了最大幅度的地提高,分别达46％、54％、49％.西花蓟马若虫经不同低温处理后,其发育历期、羽化后的成虫寿命、产卵时间与对照相比无显著差异,但产卵量显著降低;成虫经过低温处理后,其寿命,产卵量和产卵时间明显降低.研究结果支持昆虫快速冷驯化与其适合度之间存在平衡的假说;同时,也可为该虫的分布和治理研究提供相应的基础信息.     

西花蓟马在6种蔬菜寄主上的实验种群生命表

自西花蓟马Frankliniella occidentalis传入我国后,该虫对蔬菜寄主的危害趋于严重,组建了25℃条件下,西花蓟马在黄瓜、甘蓝、莴苣、茄子、芹菜和大蒜叶片的实验种群生命表,以研究西花蓟马的危害差异性,为西花蓟马的防治提供基础数据。结果表明西花蓟马的生长发育、繁殖和生命表参数等在不同寄主之间有明显差异。西花蓟马在黄瓜上发育最快,其未成熟期为11.43 d,同时在黄瓜上最先开始产卵,产卵前期为1.22 d,在芹菜上发育最慢,为16.11 d。其每雌每天在甘蓝上和莴苣上产卵量最大,分别为2.88粒和2.48粒,在大蒜上最小,为0.77粒;每雌每天产雌率、子代雌性比在甘蓝和莴苣上都大于其他寄主。雌虫寿命在甘蓝上最长(29.06 d)、雄虫寿命在莴苣上最长(13.22 d)。西花蓟马在黄瓜、莴苣、茄子、甘蓝、芹菜和大蒜上的内禀增长力rm值分别为0.1318、0.1228、0.1154、0.1197、0.0860和0.0791;净增殖率R0分别为19.1248、30.8523、17.9322、34.5322、8.9491和8.3536。种群趋势预测指数(I)在甘蓝(34.17)、莴苣(30.09)上明显高于其它寄主,在芹菜(8.00)和大蒜(8.22)上最低。     

Evolutionarily conserved thermal biology across continents: The North American lizard Plestiodon gilberti (Scincidae) compared to Asian Plestiodon

1.

The lizard genus Plestiodon (Scincidae; formerly Eumeces) is widespread in North America and Asia, but the thermal biology of only a few species has been studied.     

石榴园西花蓟马种群动态及其与气象因素的关系

2007-2008年,对云南省建水石榴园西花蓟马种群动态进行了系统调查,并采用回归分析(逐步回归分析、通径分析)、主成分分析及灰色系统分析就气象因子对该虫种群动态的影响进行了系统分析。结果表明,西花蓟马在建水石榴园常年发生,冬季较低,夏季最高,成虫全年种群消长呈单峰型,高峰期为5月份。相关性分析结果表明,西花蓟马种群数量与月相对湿度间呈极显著正相关性(P<0.01),与月均气温和月最低气温间呈显著正相关性(P<0.05),与月最高气温、月均降雨量和月均蒸发量间无相关性(P>0.05)。回归分析结果表明,石榴园西花蓟马种群动态的决定因子中影响最大的气象因素是月最低气温,而月均气温和月相对湿度是影响种群数量变动的主要因素。主成分分析表明,月最低气温是主要成分,其累积方差贡献率达73.03%。灰色系统分析结果表明,影响石榴园6种蓟马种群动态最关键的因子是月相对湿度;年度间影响最大的是年总降雨量;石榴花期各蓟马的种群数量与气象因素间关联度最大的是月最低温;果期各种蓟马的种群数量与气象因素间关联度最大的是月均降雨量。     

Re-evaluation of morphological and chloroplast DNA variation in Juniperus osteosperma Hook and Juniperus occidentalis Torr. Little (Cupressaceae) and their putative hybrids

Relationships between variation in cpDNA and morphology were examined to test the hypothesis of hybridization between Juniperus osteosperma and Juniperus occidentalis. Principal components analysis of 11 taxonomically-important characters distinguished individuals collected from eastern Nevada and Utah from those of southern Oregon. In contrast, many individuals collected from sympatric populations in western Nevada were morphologically intermediate to these two groups. Comparative sequencing of the trnS-trnG intergenic spacer and restriction site analysis of a trnL-trnF PCR product revealed nine haplotypes, and examination of haplotype-morphology associations allowed identification of species-specific genetic markers as well as those that transcend species limits. The confinement of morphological intermediacy and transcendent haplotypes to zones of sympatry, the discovery of haplotypes characteristic of one species in the morphological background of the other, and determination that the character intermediacy encountered is of the type expected under interspecific gene flow are marshaled in support of introgressive hybridization between J. osteosperma and J. occidentalis.     

Response of two species of Indo-Pacific corals, Porites cylindrica and Stylophora pistillata, to short-term thermal stress: The host does matter in determining the tolerance of corals to bleaching

The role of both host and dinoflagellate symbionts was investigated in the response of reef-building corals to thermal stress in the light. Replicate coral nubbins of Stylophora pistillata and Porites cylindrica from the GBR were exposed to either 28 °C (control) or 32 °C for 5 days before being returned to an ambient reef temperature (28 °C). S. pistillata was found to contain either Symbiodinium genotype C1 or C8a, while P. cylindrica had type C15 based on ITS genotyping. Analysis of the quantum yield of photosystem (PS) II fluorescence of the symbionts in P. cylindrica showed that light-induced excitation pressure on the C15 Symbiodinium was significantly less, and the steady state quantum yield of PSII fluorescence at noon (ΔF/Fm′) greater, than that measured in C1/C8a Symbiodinium sp. from S. pistillata. Immunoblots of the PS II D1 protein were significantly lower in Symbiodinium from S. pistillata compared to those in P. cylindrica after exposure to thermal stress. The biochemical markers, heat-stress protein (HSP) 70 and superoxide dismutase (SOD), were significantly greater in P. cylindrica before the experiment, and both species of coral increased their biosynthesis of HSP 70 and SOD when exposed to thermal stress. Concentrations of MAAs, glycerol, and lipids were not significantly affected by thermal stress in these experiments, but DNA damage was greater in heat-stressed S. pistillata compared to P. cylindrica. There was minimal coral mucus, which accounts for up to half of the total energy budget of a coral and provides the first layer of defense for invading microbes, produced by S. pistillata after heat stress compared to P. cylindrica. It is concluded that P. cylindrica contains a heat resistant C15 Symbiodinium and critical host proteins are present at higher concentrations than observed for S. pistillata, the combination of which provides greater protection from bleaching conditions of high temperature in the light.     

Gender differences and a new adult eukaryotic record for upper thermal tolerance in the desert moss Syntrichia caninervis

1.

Two competing hypotheses relating to thermostress were proposed to understand skewed sex ratios in Syntrichia caninervis, a reproductive investment hypothesis and a wildfire selection hypothesis.     

Effects of summer- and winter-like acclimation on the thermoregulatory behavior of fed and fasted desert hamsters, Phodopus roborovskii

1.

Thermoregulatory behavior of fed and fasted desert hamsters (Phodopus roborovskii) acclimated to summer- [16 light (L):8 dark (D), ambient temperature (T_a)=26.5 °C] and winter-like (8L:16D, T_a=10 °C) conditions was studied. Body temperature (T_b), selected temperature and activity were measured in hamsters placed in a thermal gradient system for 48 h.     

Reactive oxygen species and anti-oxidant defenses in tail of tadpoles, Xenopus laevis

Tail regression in tadpoles is one of the most spectacular events in anuran metamorphosis. Reactive oxygen species and oxidative stress play an important role during this process. Presently, the cell- and tissue-specific localization of antioxidant enzymes such as superoxide dismutase (SOD) and catalase as well as neuronal and inducible nitric oxide synthase isoforms (nNOS and iNOS) responsible for production of nitric oxide (NO) were carried out during different stages of metamorphosis in tail of tadpole Xenopus laevis. NO also has profound effect on the mitochondrial function having its own nitric oxide NOS enzyme. Hence, in situ staining for NO and mitochondria also was investigated. The distribution of nNOS and iNOS was found to be stage specific, and the gene expression of nNOS was up-regulated by thyroxin treatment. In situ staining for NO and mitochondria shows co-localization, suggesting mitochondria being one of the sources of NO. SOD and catalase showed significant co-localization during earlier stages of metamorphosis, but before the tail regression begins, there was a significant decrease in activity as well as co-localization suggesting increased ROS accumulation. These findings are discussed in terms of putative functional importance of ROS and cytoplasmic as well as mitochondrial derived NO in programmed cell death in tail tissue.     

荒漠沙蒿根围AM真菌和DSE的空间分布

2009年7月在内蒙古黑城子北、多伦县城东和正蓝旗元上都遗址3个样地分别从0-10 cm、10-20 cm、20-30cm、30-40 cm和40-50 cm 5个土层采集沙蒿(Artemisia sphaerocephala)根围土壤和根样,系统研究了沙蒿根围AM真菌和DSE(Dark septate endophytes)的空间分布及与土壤因子的相关性。结果表明,沙蒿根系能被AM真菌高度侵染形成典型的I-型(Intermediate type)丛枝菌根,并发育形成泡囊和丛枝结构, 并与DSE形成良好的共生关系,样地生态条件和采样深度对AM真菌分布和活动有显著影响。黑城子样地孢子密度最高,元上都样地泡囊定殖率最高,不同样地间丛枝、菌丝、总定殖率和DSE定殖率无显著差异。孢子密度峰值出现在0-10cm表层土,并随土壤剖面深度增加而降低;泡囊定殖率峰值出现在10-20cm土层;AM真菌其他结构定殖率及DSE定殖率在各土层间差异不显著或变化无规律。孢子密度与AM真菌不同结构定殖率无显著相关性,与各土壤因子极显著正相关。泡囊定殖率与脲酶和碱性磷酸酶极显著负相关,与酸性磷酸酶显著负相关。菌丝定殖率、总定殖率及DSE定殖率与各土壤因子均无显著相关性。土壤碱解N和有机C与脲酶、酸性磷酸酶和碱性磷酸酶极显著正相关;土壤速效P与碱性磷酸酶极显著正相关,与脲酶显著正相关。对沙蒿根系AM真菌和DSE真菌分布和定殖规律的研究,可进一步明确AM真菌和DSE的生态功能,为利用菌根生物技术促进荒漠植被恢复和生态重建提供依据。     

Hydrothermal and thermal time models for the invasive grass, Arundo donax

Controlled laboratory and field experiments were performed to determine the developmental response to temperature and moisture of Arundo donax, a riparian invasive grass and potential bioenergy crop. A logistic function was parameterized and used to predict thermal times to sprouting and the nine-leaf stage. Consistent estimates of the base temperature (T_b) and base water potential (ψ_b) below which development ceases were obtained from various statistical and mathematical analyses. Estimates of T_b and ψ_b were 12.7 ± 1.7 °C and −1.56 ± 0.43 MPa, respectively, for the median fraction of sprouting rhizomes. Median hydrothermal time to sprouting was 124.1 MPa °Cd under laboratory conditions and median thermal times, or degree-day (°Cd), to sprouting and nine-leaf stage was estimated to be 94 and 129 °Cd under field conditions, respectively. A degree-day is defined as one day (24 h) spent one degree above T_b. Results demonstrated that thermal time alone is sufficient to accurately predict time to sprouting under field conditions. Further, there may be a fixed moisture threshold of about 6% volumetric water content above which sprouting rate was constant. This threshold corresponded very closely to the −1.5 MPa for ψ_b that was estimated under laboratory conditions for the soil typically infested by A. donax. This information is crucial for assessing risk of invasive spread for A. donax.     

Metabolic thermogenesis and evaporative water loss in the Hwamei Garrulax canorus

Basal metabolic rate (BMR) is thought to be a major hub in the network of physiological mechanisms connecting life history traits. Evaporative water loss (EWL) is a physiological indicator that is widely used to measure water relations in inter- or intraspecific studies of birds in different environments. In this study, we examined the physiological responses of summer-acclimatized Hwamei Garrulax canorus to temperature by measuring their body temperature (T_b), metabolic rate (MR) and EWL at ambient temperatures (T_a) between 5 and 40 °C. Overall, we found that mean body temperature was 42.4 °C and average minimum thermal conductance (C) was 0.15 ml O₂ g⁻¹ h⁻¹ °C⁻¹ measured between 5 and 20 °C. The thermal neutral zone (TNZ) was 31.8–35.3 °C and BMR was 181.83 ml O₂ h⁻¹. Below the lower critical temperature, MR increased linearly with decreasing T_a according to the relationship: MR (ml O₂ h⁻¹)=266.59–2.66 T_a. At T_as above the upper critical temperature, MR increased with T_a according to the relationship: MR (ml O₂ h⁻¹)=−271.26+12.85 T_a. EWL increased with T_a according to the relationship: EWL (mg H₂O h⁻¹)=−19.16+12.64 T_a and exceeded metabolic water production at T_a>14.0 °C. The high T_b and thermal conductance, low BMR, narrow TNZ, and high evaporative water production/metabolic water production (EWP/MWP) ratio in the Hwamei are consistent with the idea that this species is adapted to warm, mesic climates, where metabolic thermogenesis and water conservation are not strong selective pressures.     

Mycobiota associated with the ambrosia beetle Scolytodes unipunctatus (Coleoptera: Curculionidae, Scolytinae)

Ambrosia beetles (Coleoptera: Scolytinae) are associated with strictly entomochoric and mutualistic fungi. We studied the mycobiota associated with Scolytodes unipunctatus, ambrosia beetles that infest Cecropia trees in Central America. Isolates were characterized using morphology and rDNA sequences (ITS region, LSU, and SSU rDNA). Four species are described here: Raffaelea scolytodis sp. nov. (Ophiostomatales), Gondwanamyces scolytodis sp. nov., Custingophora cecropiae sp. nov., and Graphium sp. (Microascales). The genus Custingophora is emended to include Knoxdaviesia anamorphs of Gondwanamyces based on uniformity of DNA sequences and phenotype.     

Seasonal changes in the thermal tolerances of the toad Rhinella arenarum (Bufonidae) in the Monte Desert of Argentina

We studied the thermal tolerances of Rhinella arenarum during the dry and wet seasons of the Monte Desert in San Juan Province, Argentina. This toad had differences in CT_max between dry and wet seasons, and the CT_max values were higher in the wet season (Austral summer). Operative temperature, body temperature, environmental maximal temperature, and relative humidity were related to CT_max, suggesting seasonal acclimatization of R. arenarum. Additionally, the CT_max recorded for R. arenarum was 36.2 °C, and the maximum ambient temperature recorded during the toads' activity time was 37 °C. Also, the CT_min recorded for R. arenarum was 5.3 °C and the minimum environmental temperature recorded was 7.2 °C. The wide thermal tolerance range recorded and the relationship between tolerance limits and the environmental extremes indicate that seasonal acclimatization is an effective mechanism by which toads can raise their thermal tolerance, allowing them to survive in the challenging conditions of the Monte Desert. Additional studies are needed to understand the relationship between the thermal tolerance of this desert amphibian and the environmental parameters that influence its thermal physiology.     

Evaporative water loss and energy metabolic in two small mammals,voles (Eothenomys miletus) and mice (Apodemus chevrieri), in Hengduan mountains region

Evaporative water loss (EWL) and energy metabolism were measured at different temperatures in Eothenomys miletus and Apodemus chevrieri in dry air. The thermal neutral zone (TNZ) of E. miletus was 22.5–30 °C and that of A. chevrieri was 20–27.5 °C. Mean body temperatures of the two species were 35.75±0.5 and 36.54±0.61 °C. Basal metabolic rates (BMR) were 1.92±0.17 and 2.7±0.5 ml O₂/g h, respectively. Average minimum thermal conductance (C_m) were 0.23±0.08 and 0.25±0.06 ml O₂/g h °C. EWL in E. miletus and A. chevrieri increased with the increase in temperature; the maximal EWL at 35 °C was 4.78±0.6 mg H₂O/g h in E. miletus, and 5.92±0.43 mg H₂O/g h in A. chevrieri. Percentage of evaporative heat loss to total heat production (EHL/HP) increased with the increase in temperature; the maximal EHL/HP was 22.45% at 30 °C in E. miletus, and in A. chevrieri it was 19.96% at 27.5 °C. The results may reflect features of small rodents in the Hengduan mountains region: both E. miletus and A. chevrieri have high levels of BMR and high levels of total thermal conductance, compared with the predicted values based on their body masses, while their body temperatures are relatively low. EWL plays an important role in temperature regulation.     

Phylogeny of Phaeomollisia piceae gen. sp. nov.: a dark, septate, conifer-needle endophyte and its relationships to Phialocephala and Acephala

Dark, septate endophytes (DSE) were isolated from roots and needles of dwarf Picea abies and from roots of Vaccinium spp. growing on a permafrost site in the Jura Mountains in Switzerland. Two of the isolates sporulated after incubation for more than one year at 4 °C. One of them was a hitherto undescribed helotialean ascomycete Phaeomollisia piceae gen. sp. nov., the other was a new species of Phialocephala, P. glacialis sp. nov. Both species are closely related to DSE of the Phialocephala fortinii s. lat.-Acephala applanata species complex (PAC) as revealed by phylogenetic analyses of the ITS and 18S rDNA regions. Morphologically dissimilar fungi, such as Vibrissea and Loramyces species, are phylogenetically also closely linked to the new species and the PAC. Cadophora lagerbergii and C. (Phialophora) botulispora are moved to Phialocephala because Phialocephala dimorphospora and P. repens are the closest relatives. Several Mollisia species were closely related to the new species and the PAC according to ITS sequence comparisons. One DSE from needles of Abies alba and one from shoots of Castanea sativa formed Cystodendron anamorphs in culture. Their identical 18S sequences and almost identical ITS sequences indicated Mollisia species as closest relatives, suggesting that Mollisia species are highly euryoecious.