Herbivore intake/habitat productivity correlations can help ascertain re-introduction potential for the Barbary macaque

Re-introductions are increasingly used conservation tools. Often, criteria for re-introducing species are based on policies or politics and little attention paid, albeit theoretical, to understanding what ecological possibilities habitats may have in sustaining introduced animals. Assessing potential carrying capacities is complex but easier for grazers, since biomass of these herbivores is empirically correlated with habitat primary productivity.The case is made here that the Barbary macaque, Macaca sylvanus, a vulnerable North African primate with a large surplus captive stock, can be viewed as a grazer. Because of this attribute, and unlike congenerics, it is possible to estimate potential densities in extant habitats in a fashion similar to predicting stocking levels for domestic herbivores. Thus, from values of consumable primary productivity for domestic stock in Mediterranean countries and the monkey's energy requirements, attainable macaque populations in studied habitats could be much higher than actual. Though these numbers may be unreachable in nature, this study shows that present macaque populations could increase after restorative management of habitats in which re-stocking with captive-born animals may play a part. However, since only 10% of potential monkey habitat in Morocco and Algeria is occupied by the species, finding areas for releasing captive-born macaques is more advisable.     

P53，Rb和c－myc基因在人脑原发性肿瘤中的转录表达

采用RNA斑点杂交分析,对21例人脑原发性胶质瘤和11例人脑膜瘤中p53,Rb和c-myc基因转录水平的表达进行研究.发现48.4%的肿瘤中p53基因表达减弱,21.9%的肿瘤中Rb基因表达减弱;71.9%的肿瘤中c-myc基因表达增强.在p53基因表达减弱的15例病例中有13例(80%)c-myc基因表达增强.结果表明,p53基因表达减弱和c-myc基因表达增强与人脑原发性肿瘤的发生有关.     

Serum-free culture of rat keratinocytes

Summary Procedures for the serum-free culture of rat keratinocytes have been established. Basal cells prepared from epidermis of newborn rat were stored in liquid nitrogen and used for primary culture. Among the available media, MCDB 153, developed originally for human keratinocyte (HK) culture, was the best for the development of serum-free formulation. To grow rat keratinocytes, bovine serum albumin was arbitrarily substituted for the macromolecule supplements needed for HK culture, i.e. fetal bovine serum protein or bovine pituitary extract. Qualitative and quantitative adjustment of supplements was thereafter made to support rapid cell growth. Satisfactory cell growth was achieved in the optimized medium of MCDB 153 supplemented with growth factors and amino acids: insulin (10 μg/ml), hydrocortisone (0.1 μg/ml), epidermal growth factor (25 ng/ml), calcium chloride (0.2 mM), histidine (0.23 mM), isoleucine (0.05 mM), tryptophane (0.015 mM), threonine (1.25 mM), tyrosine (0.031 mM), alanine (4.08 mM), and albumin (2 mg/ml). This optimized culture system was superior to the original HK culture condition for rapid growth of rat keratinocytes. Under our condition, cells grew as a monolayer, becoming confluent, but without stratification, and were passaged 2 to 3 times without any changes in morphology. The serum-free formulation allows us to control more accurately the concentrations of biomolecules in the medium including lipids and hormones, and therefore will be suitable for the study focusing on lipid metabolism or hormonal regulation of rat keratinocytes.     

Effect of meteorological variates on persistence of primary conidia and capilliconidia of Erynia radicans (Zygomycotin: ntomophthorales) under natural conditions

Persistence of conidia of an isolate of Erynia radicans (Syn. Zoophthora radicans) was investigated in relation to the meteorological conditions which occurred during autumn-winter of 1990–91 in the coastal plain in Israel. Capilljconidia shielded from the sun, placed on the abaxial surface of leaves of Plumeria acuminata, persisted for 24 h to at least 120 h. Exposed capilliconidia, placed on the adaxial surface of the same leaves, died within 24 h. Almost all the primary conidia shielded from the sun (placed on the abaxial surface of the same leaves) died within a single day. Conidial viability was expressed in subsequent germination on an agar medium. Capilliconidial persistence was closely related to the daily air temperatures, expressed as cumulative day-degrees. Differences in relative humidity had no substantial effect on capilliconidial mortality. At daytime temperatures of ≤ 20°C, mortality after 24 h incubation was lowest (≤ 34%) and the persistence duration, longest (at least 120 h). Increases in daytime temperature up to 24°C for a few hours increased mortality (37–57% after 24 h incubation) and shortened the persistence duration (72–120 h). Exposure to 24–29°C during daytime greatly increased mortality (65–58% after 24 h) and further shortened the persistence duration (24–48 h). Daytime temperatures of > 29°C were lethal to all capilliconidia within 24 h. Temperature had a profound effect on capilliconidial persistence also under controlled environmental conditions. The significance of capiliiconidial persistence is discussed in relation to activity of the fungus in its natural environment.     

Seasonal succession of phytoplankton in a lake of the Paraná river floodplain,Argentina

Phytoplankton biomass, morphological and taxonomic composition, species diversity and productivity were analyzed in a shallow lake of the Middle Paraná River floodplain (El Tigre, 31 ° 41 S and 60° 42 W), between November 1986 and July 1988. Lake inundation (filling and through-flow phases) constituted an intense long-term perturbation in the physical and chemical environment. As the lake filled with river water, K-selected species (netplanktonic filamentous bluegreens, > 37 µm, with low surface area/volume (SA/V) ratios) that had existed prior to filling (late spring 1986) were replaced in summer-fall by r-selected species (nannoplanktonic chlorophytes and cryptophytes, < 37 µm, mainly stout forms with high SA/V ratios). During the through-flow phase, lentic phytoplankton was replaced by lotic flagellate populations due to the direct flushing by river water. During the period of falling water (drainage and isolation phases), nanoplanktonic algae with similar characteristics to those of the filling phase dominated in late winter-spring. Later in the isolation phase, these were succeeded by K-selected species (netplanktonic algae, mainly motile spherical dinoflagellates and filamentous bluegreens with low SA/V ratios). Simultaneously, primary production per unit biomass decreased and total biomass and specific diversity increased. Seasonal changes of phytoplankton in floodplain lakes can be interpreted as the interaction between true successional development (as observed in the drainage and isolation phases) and intermediate disturbance. Using Reynolds' terminology, short-term disturbance (slight inflow of nutrient-rich river water) caused reversion to an earlier stage in the former succession, and long-term disturbance (lake inundation) truncated the successional progression and a new (or shifted) succession was initiated.     

Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale

Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two–three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries.     

The role of fire in terrestrial vertebrate richness patterns

Productivity is strongly associated with terrestrial species richness patterns, although the mechanisms underpinning such patterns have long been debated. Despite considerable consumption of primary productivity by fire, its influence on global diversity has received relatively little study. Here we examine the sensitivity of terrestrial vertebrate biodiversity (amphibians, birds and mammals) to fire, while accounting for other drivers. We analyse global data on terrestrial vertebrate richness, net primary productivity, fire occurrence (fraction of productivity consumed) and additional influences unrelated to productivity (i.e., historical phylogenetic and area effects) on species richness. For birds, fire is associated with higher diversity, rivalling the effects of productivity on richness, and for mammals, fire's positive association with diversity is even stronger than productivity; for amphibians, in contrast, there are few clear associations. Our findings suggest an underappreciated role for fire in the generation of animal species richness and the conservation of global biodiversity.     

Partitioning the biodiversity effects on productivity into density and size components

Plant density and size — two factors that represent plant survival and growth — are key determinants of yield but have rarely been analysed explicitly in the context of biodiversity–productivity relationships. Here, we derive equations to partition the net, complementarity and selection effects of biodiversity into additive components that reflect diversity-induced changes in plant density and size. Applications of the new method to empirical datasets reveal contrasting ways in which plant density and size regulate yield in species mixtures. In an annual plant diversity experiment, overyielding is largely explained by selection effects associated with increased size of highly productive plant species. In a tree diversity experiment, the cause of overyielding shifts from enhanced growth in tree size to reduced mortality by complementary use of canopy space during stand development. These results highlight the capability of the new method to resolve crucial, yet understudied, demographic links between biodiversity and productivity.     

Human appropriation of net primary production as driver of change in landscape-scale vertebrate richness

Aim

Land use is the most pervasive driver of biodiversity loss. Predicting its impact on species richness (SR) is often based on indicators of habitat loss. However, the degradation of habitats, especially through land-use intensification, also affects species. Here, we evaluate whether an integrative metric of land-use intensity, the human appropriation of net primary production, is correlated with the decline of SR in used landscapes across the globe.

Location

Global.

Time period

Present.

Major taxa studied

Birds, mammals and amphibians.

Methods

Based on species range maps (spatial resolution: 20 km × 20 km) and an area-of-habitat approach, we calibrated a “species–energy model” by correlating the SR of three groups of vertebrates with net primary production and biogeographical covariables in “wilderness” areas (i.e., those where available energy is assumed to be still at pristine levels). We used this model to project the difference between pristine SR and the SR corresponding to the energy remaining in used landscapes (i.e., SR loss expected owing to human energy extraction outside wilderness areas). We validated the projected species loss by comparison with the realized and impending loss reconstructed from habitat conversion and documented by national Red Lists.

Results

Species–energy models largely explained landscape-scale variation of mapped SR in wilderness areas (adjusted R²-values: 0.79–0.93). Model-based projections of SR loss were lower, on average, than reconstructed and documented ones, but the spatial patterns were correlated significantly, with stronger correlation in mammals (Pearson's r = 0.68) than in amphibians (r = 0.60) and birds (r = 0.57).

Main conclusions

Our results suggest that the human appropriation of net primary production is a useful indicator of heterotrophic species loss in used landscapes, hence we recommend its inclusion in models based on species–area relationships to improve predictions of land-use-driven biodiversity loss.     

黄河流域植被格局变化对水分利用效率的影响

黄河流域横跨3个气候带,是全球人类活动最为强烈的地区之一,特殊的地理位置和复杂的下垫面导致其碳-水循环过程较为复杂。研究黄河流域碳水循环不仅是区域水资源利用的基础,也是实现气候变化条件下双碳目标的关键。水分利用效率(WUE)作为表征碳水过程的重要指标,可用于反映生态系统碳水耦合规律及其相互作用关系。基于此,利用全球陆表特征参量数据(GLASS)的净初级生产力(NPP)和蒸散(ET)产品以及中国逐年土地利用与覆盖数据集(CLUD-A),分析了黄河流域植被格局变化背景下WUE在1990—2018年的时空变化特征及其驱动力。结果表明：(1)黄河流域全域WUE在29 a的均值处在0.18—1.53 g C/kg H₂O之间,存在明显的空间异质性,上游地区WUE明显高于中下游地区,分别在0.66—0.92 g C/kg H₂O和0.43—0.62 g C/kg H₂O之间波动,二者均存在波动上升态势。(2)黄河流域全域WUE在以2000年为中间点的10 a的增速达到近29 a的峰值,流域植被格局变化所带来的流域内NPP与ET变化速...