Triage for conserving populations of threatened species: The case of woodland caribou in Alberta

Prioritization of conservation efforts for threatened and endangered species has tended to focus on factors measuring the risk of extirpation rather than the probability of success and cost. Approaches such as triage are advisable when three main conditions are present: insufficient capacity exists to adequately treat all patients, patients are in a critical state and cannot wait until additional capacity becomes available, and patients differ in their likely outcome and/or the amount of treatment they require. The objective of our study was to document the status of woodland caribou (Rangifer tarandus) herds in Alberta, Canada, with respect to these three conditions and to determine whether a triage approach might be warranted. To do this we modeled three types of recovery effort - protection, habitat restoration, and wolf control - and estimated the opportunity cost of recovery for each herd. We also assessed herds with respect to a suite of factors linked to long-term viability. We found that all but three herds will decline to critical levels (<10 animals) within approximately 30 years if current population trends continue. The opportunity cost of protecting all ranges by excluding new development, in terms of the net present value of petroleum and forestry resources, was estimated to be in excess of 100 billion dollars (assuming no substitution of activity outside of the ranges). A habitat restoration program applied to all ranges would cost several hundred million dollars, and a provincial-scale wolf control program would cost tens of millions of dollars. Recovery costs among herds varied by an order of magnitude. Herds also varied substantially in terms of their potential viability. These findings suggest that woodland caribou in Alberta meet the conditions whereby triage should be considered as an appropriate conservation strategy.     

Predicting survival, reproduction and abundance of polar bears under climate change

Polar bear (Ursus maritimus) populations are predicted to be negatively affected by climate warming, but the timeframe and manner in which change to polar bear populations will occur remains unclear. Predictions incorporating climate change effects are necessary for proactive population management, the setting of optimal harvest quotas, and conservation status decisions. Such predictions are difficult to obtain from historic data directly because past and predicted environmental conditions differ substantially. Here, we explore how models can be used to predict polar bear population responses under climate change. We suggest the development of mechanistic models aimed at predicting reproduction and survival as a function of the environment. Such models can often be developed, parameterized, and tested under current environmental conditions. Model predictions for reproduction and survival under future conditions could then be input into demographic projection models to improve abundance predictions under climate change. We illustrate the approach using two examples. First, using an individual-based dynamic energy budget model, we estimate that 3-6% of adult males in Western Hudson Bay would die of starvation before the end of a 120 day summer fasting period but 28-48% would die if climate warming increases the fasting period to 180 days. Expected changes in survival are non-linear (sigmoid) as a function of fasting period length. Second, we use an encounter rate model to predict changes in female mating probability under sea ice area declines and declines in mate-searching efficiency due to habitat fragmentation. The model predicts that mating success will decline non-linearly if searching efficiency declines faster than habitat area, and increase non-linearly otherwise. Specifically for the Lancaster Sound population, we predict that female mating success would decline from 99% to 91% if searching efficiency declined twice as fast as sea ice area, and to 72% if searching efficiency declined four times as fast as area. Sea ice is a complex and dynamic habitat that is rapidly changing. Failure to incorporate climate change effects into population projections can result in flawed conservation assessments and management decisions.     

桃雄性不育的表现形式及其败育途径

研究了桃［Ｐｒｕｎｕｓ ｐｅｒｃｉｃａ Ｂａｔｓｃｈ（Ｌ．）］２３个品种花粉发生发育和花粉败育过程中细胞形态学上的变化特征。结果表明：桃雄性不育的主要表现形式为空粒花粉和花药空囊及花粉形似发育正常，但生活力极低。导致空粒花粉产生的主要途径：①花粉母细胞减数分裂不正常；②花粉处于单核晚期至二核早、中期绒毡层细胞发生液化、增生现象。空囊产生的主要途径：①四分体至单核早期绒毡层细胞体积发生明显的增大、液化；②绒毡层细胞在四分体至单核早期发生增生；③造胞细胞或花粉母细胞生长发育不良。     

Genetic Variation for Heat Tolerance During the Reproductive Phase in Brassica rapa

We investigated heat tolerance at the reproductive stage in six spring‐type B. rapa accessions and one B. juncea accession as a control. Plants were subjected to two temperature treatments for seven days in controlled environmental rooms, beginning one day before the first open flower on the main stem inflorescence. The high‐temperature treatment ranged from 25 °C to 35 °C during 16 h light and 25 °C during 8 h dark. The control temperature treatment was set at 23 °C during 16 h light and 15 °C during 8 h dark. Soil moisture was maintained at close to field capacity to avoid drought stress. Main stem buds that emerged during the treatment period were tagged, and pod and seed production was recorded at each reproductive node. Leaf temperature depression and leaf conductance increased in the high‐temperature treatment which indicated that plants were not drought stressed. A leafy vegetable type of B. rapa from Indonesia was the most tolerant to high temperature, as defined by its ability to set seed equally well in the control and high‐temperature treatments, followed by an oilseed type from Pakistan. Pollen viability remained above 87 % in all accessions and treatments. We conclude that bud number and length, and pod number produced under high temperatures, might provide a useful preliminary screen for high‐temperature tolerance and that B. rapa may be a valuable source of heat tolerance in canola (B. napus).     

利用花粉管通道技术将抗虫基因导入大豆的研究

利用花粉管通道技术，将Bt基因导入大豆品种。对132株D1代植株进行PCR检测，得到5株阳性转化植株。再将获得的5株D1代阳性转化植株的种子放在温箱中发芽，提取DNA进行检测，结果得到2株D2代稳定遗传的阳性转化植株。用X－Glue溶液对转Bt基因132株D1代植株进行检测，结果没有发现阳性反应。另外，本实验还采用荧光制片方法从植物组织结构的角度证明利用花粉管通道方法导入外源基因的可行性，并提出花粉管通道方法操作的最佳时间为授粉后6－20h。     

毛白杨花粉败育机制的研究

从细胞遗传学角度较为系统地揭示了毛白杨花粉败育的机制，即主要是毛白杨异质性遗传基础与环境相互作用的结果。（1）在减数分裂中有数目不等的联合程度较差的单价体以及落后染色体出现，这种与异质性相关的染色体行为异常，导致同源染色体向子细胞的不均衡，造成且功能染色体的缺失，从而引起毛白杨一定比率的败育花粉的产生；（2）遗传上的不平衡与温度等环境因子相互作用，进一步引发毛白杨生理乃至结构上的不平衡，花粉母细胞（或孢原细胞）和绒毡层细胞发育异常，从而造成不产粉或产粉较少；环境与基因型互作的差异性导致了花粉败育的年度不稳定性。（3）易位、倒位等染色体结构变异和天然三倍体株系的存在也是造成毛白杨花粉败育的原因。     

Viability of maternally heat-stressed mouse zygotes in vivo and in vitro

Mammalian preimplantation embryos are susceptible to heat stress. This present study examined how maternal heat stress affects the development of mouse zygotes in vivo and in vitro. In Experiment 1, zygotes collected from female mice that were heat‐stressed for 12 h on day 1 of pregnancy were cultured in vitro. Maternally heat‐stressed zygotes developed normally to the two‐cell stage, but the majority of embryos failed to develop into morulae or blastocysts. In Experiment 2, pregnant mice were heat‐stressed on day 1 or from day 1 to day 3 of pregnancy. The number of living fetuses on day 14 of pregnancy was lower in heat‐stressed mice than in non‐stressed mice, but the difference was significant only in successively heat‐stressed mice. These results demonstrate that maternally heat‐stressed zygotes have reduced in vitro viability, but this phenomenon does not necessarily lead to embryo loss in the maternal environment.     

Hermetically Sealed Storage of Cereal Seeds and its Influence on Vigour and Germination

Investigations of the influence of hermetic cereal seed storage on germination were carried out in the laboratory of the Faculty of Agriculture in Osijek (Croatia) over 5 years (1992–96). Seeds of four species (winter wheat, winter barley, spring oat, and maize) were stored in hermetic glass containers at an air temperature of 20 °C and a relative humidity of 65 %. The moisture level in stored seeds was 13 %. After 5 years, statistically highly significant associations (P < 0.01) were found between storage longevity (five researched years) and seed germination of the four cereals. Germination of all investigated cereals was high (between 97.25 % for maize and 93 % for winter wheat) after harvest. The germination level decreased for all cereals, on average by 38 %, over the 5 years of storage. The highest germination values were found for wheat seeds (84.75 %) and the lowest germination values for maize seeds (36.0 %). The results showed that germination of all investigated cereals seeds was negatively correlated with storage longevity. The differences in germination found amongst the cereals were statistically highly significant (P < 0.01).     

内蒙古草原针茅属六种植物的花粉形态研究

作者对内蒙古天然草原六种针茅属植物的花粉粒进行扫描电子显微镜观察，发现在花粉粒大小，萌发孔直径，颗粒状纹饰的粗细及孔环特征等性状方面均有显著差异。     

蜂花粉系列研究

系统研究了蜂花粉营养成分及生物学功能，说明花粉属于完全营养食品并具有多种生物学作用。