Environmental dependence of population dynamics and height growth of a subalpine conifer across its vertical distribution: an approach using high‐resolution aerial photographs

Many studies have reported shifts in the altitudinal ranges of plant species in response to recent global warming. However, most studies of tree species have been conducted on a small scale and have focused on tree line ecotones by examining tree rings and age structure on account of the long life spans of the trees. To examine the impact of climate change on forest dynamics at a regional scale, we investigated differences in the population density and canopy height of a Japanese subalpine coniferous species, Abies mariesii, between 1967 and 2003 by analysis of high‐resolution aerial photographs of the Hakkoda Mountains, Honshu, Japan. In 712 plots within the photographs we analyzed which environmental variables (including elevation, aspect, wetness, and distance from moorlands) account for these changes. The population density of A. mariesii decreased below 1000 m a.s.l. and increased above 1300 m a.s.l. It also increased around moorlands, which may provide refugia at low elevations. The rate of increase in canopy height was lowest on the southeastern slopes and on the periphery of the moorlands. The distinct changes in the population density of A. mariesii at its distribution limits probably reflect the responses of the population to climatic changes during three decades. Areas surrounding the moorlands may offer refugia in spite of the poor growing conditions there.     

Characterization of composted olive mill wastes to predict potential plant disease suppressiveness

Despite its proven agronomic value, the plant disease suppressive effect of composts from olive waste has not been adequately investigated. In the present study, the disease suppressive potential of two olive waste (OW) composts against soil-borne plant pathogens was investigated. Both OW composts showed sizeable, active microbial populations, which were able to grow actively on chitin and cellulose. In plate inhibition trials, OW compost water extracts (CWEs) exerted a significant inhibitory effect on the growth of the pathogens Fusarium oxysporum f.sp. lycopersici (Fol), Pythium ultimum, Phytophtora infestans, Sclerotina sclerotiorum and Verticillium dahliae; and in pot experiments, the OW composts significantly reduced P. ultimum damping-off and Fol wilt diseases on tomato seedlings. The disease suppressive effect of OW composts seems to be due to the combined effects of suppression phenomena caused by the presence of microorganisms competing for both nutrients and space as well as by the activity of specific antagonistic microorganisms.     

Evaluating environmental and geometrical constraints on endemic vertebrates of the semiarid Caatinga (Brazil)

Most hypotheses explaining species diversity are related to the current and/or past environment, but explanations that rely on geometrical constraints, such as the mid-domain effect, have been recently proposed. Under this type of model, more species are expected in the centre of a domain due to the extent of occurrence of the species being constrained by the domain's geometry. Here we evaluated the proportion of the explanatory power of space, the current environment, historical vicariance events and geometric constraints on the richness of the Caatinga's terrestrial endemic vertebrates using a partial regression approach. The current environment had the highest proportion of explanatory power for the variance of the Caatinga's endemic species, in its shared effect, explaining approximately 47%. On the other hand the geometric constraints model (GCM) had the highest proportion in its single explanatory power with 15% of explanatory power. The amount of explanation by GCM changes when analyzing richness of endemics calculated from species with different range sizes. Despite the fact that GCM is the main driver of the Caatinga's endemic species, in its single effect, this does not necessarily indicate that geometric constraints and random dispersal within species ranges drive richness. The GCM model underestimates richness in the centre of the Caatinga, suggesting that other ecological and evolutionary processes may help explain the overall pattern of decreasing richness towards the borders of the biome.     

Performance and fate of tree seedlings on and around nests of the leaf‐cutting ant Atta cephalotes: Ecological filters in a fragmented forest

Habitat fragmentation is currently the most pervasive anthropogenic disturbance in tropical forests and some species of leaf‐cutting ants of the genus Atta (dominant herbivores in the neotropics) have become hyper‐abundant in forest edges where their nests directly impact up to 6% of the forest area. Yet, their impacts on the regeneration dynamics of fragmented forests remain poorly investigated. Here we examine the potential of Atta cephalotes nests to function as ecological filters impacting tree recruitment. Growth, survival and biomass partitioning of experimentally planted seedlings (six tree species) were examined at eight spatially independent A. cephalotes colonies in a large Atlantic Forest fragment. Seedling performance and fate (leaf numbers and damage) were monitored up to 27 months across three habitats (nest centre, nest edge and forest understorey). Plants at illuminated nest centres showed twice the gross leaf gain as understorey individuals. Simultaneously, seedlings of all species lost many more leaves at nests than in the forest understorey, causing a negative net leaf gain. Net leaf gain in the shaded understorey ranged from zero (Licania and Thyrsodium species) to substantial growth for Copaifera and Virola, and intermediate levels little above zero for Protium and Pouteria. Also seedling survival differed across habitats and species, being typically low in the centre and at the edge of nests where seedlings were often completely defoliated by the ants. Lastly, seedling survival increased strongly with seed size at nest edges while there was no such correlation in the forest. Our results suggest that Atta nests operate as ecological filters by creating a specific disturbance regime that differs from other disturbances in tropical forests. Apparently, Atta nests favour large‐seeded tree species with resprouting abilities and the potential to profit from a moderate, nest‐mediated increase in light availability.     

Testing Darwin's naturalization hypothesis in the Azores

Invasive species are a threat for ecosystems worldwide, especially oceanic islands. Predicting the invasive potential of introduced species remains difficult, and only a few studies have found traits correlated to invasiveness. We produced a molecular phylogenetic dataset and an ecological trait database for the entire Azorean flora and find that the phylogenetic nearest neighbour distance (PNND), a measure of evolutionary relatedness, is significantly correlated with invasiveness. We show that introduced plant species are more likely to become invasive in the absence of closely related species in the native flora of the Azores, verifying Darwin's 'naturalization hypothesis'. In addition, we find that some ecological traits (especially life form and seed size) also have predictive power on invasive success in the Azores. Therefore, we suggest a combination of PNND with ecological trait values as a universal predictor of invasiveness that takes into account characteristics of both introduced species and receiving ecosystem.     

Exploiting Allee effects for managing biological invasions

Biological invasions are a global and increasing threat to the function and diversity of ecosystems. Allee effects (positive density dependence) have been shown to play an important role in the establishment and spread of non-native species. Although Allee effects can be considered a bane in conservation efforts, they can be a benefit in attempts to manage non-native species. Many biological invaders are subject to some form of an Allee effect, whether due to a need to locate mates, cooperatively feed or reproduce or avoid becoming a meal, yet attempts to highlight the specific exploitation of Allee effects in biological invasions are surprisingly unprecedented. In this review, we highlight current strategies that effectively exploit an Allee effect, and propose novel means by which Allee effects can be manipulated to the detriment of biological invaders. We also illustrate how the concept of Allee effects can be integral in risk assessments and in the prioritization of resources allocated to manage non-native species, as some species beset by strong Allee effects could be less successful as invaders. We describe how tactics that strengthen an existing Allee effect or create new ones could be used to manage biological invasions more effectively.     

Geographical distribution pattern and interisland movements of Orii’s flying fox in Okinawa Islands, the Ryukyu Archipelago, Japan

The study of mobile animals such as flying foxes in insular habitats involves clarifying the population status on each island and determining the factors affecting movement patterns among the islands in their distributional range. We visited 25 of the Okinawa Islands and documented the number of Orii’s flying foxes Pteropus dasymallus inopinatus from August 2005 to May 2006. We also conducted a monthly road census on the main island (Okinawa-jima Island) and six adjacent islands from June 2006 to January 2007 and counted the number of fruit-bearing trees of the bats’ four main food plants. The results of classification and regression tree analysis suggested that distance from the main island was a primary factor in determining the distribution pattern and population size of this flying fox, whereas island area, number of plant species, and food availability did not directly affect population size. The number of flying foxes on each island tended to decrease with an increase in distance from the main island; no flying foxes existed on islands >30 km away from the main island. On the other hand, the results of the monthly census showed that the population size on each island fluctuated seasonally. Individuals may move between islands in response to seasonal changes in food availability. In conclusion, the distribution and abundance of Orii’s flying foxes in the Okinawa Islands may be determined by the rate of immigration/emigration, depending on each island’s distance from the main island. Seasonal changes in food availability may act as a trigger for interisland movement, but that movement may be restricted by island connectivity.     

西酞普兰联合利培酮治疗难治性抑郁症的近期临床疗效观察

目的：观察西酞普兰联合利培酮治疗难治性抑郁症的近期临床疗效,探讨提高难治性抑郁症近期临床疗效的药物治疗方案方法：选择难治性抑郁症患者86例,随机均分为对照组与观察组,对照组给予常规西酞普兰治疗,观察组给予西酞普兰联合利培酮治疗,比较两组患者治疗第2周、第4周、第6周汉密尔顿抑郁量表（HAMD）、汉密尔顿焦虑量表（HAMA）和副反应量表（TESS）评分,比较两组患者治疗第6周的临床疗效。结果：观察组近期临床疗效好于对照组,HAMD评分、HAMA评分和临床疗效比较,差异具有统计学意义（P〈0.05）;TESS评分比较,差异无统计学意义（P〉0.05）。结论：药物治疗难治性抑郁症时,应选择西酞普兰联合利培酮治疗,可提高近期临床疗效,且不加重用药不良反应。     

早期康复治疗在重度颅脑损伤患者中应用的临床疗效观察

目的：观察早期康复治疗在重度颅脑损伤患者中应用的临床疗效,探讨提高重度颅脑损伤患者临床疗效的治疗方法。方法：选择重度颅脑损伤患者72例,根据康复治疗的时间不同,分为早期组与非早期组,比较两组患者康复治疗3个月后Fugl-Meyer评分、Barthel指数和神经功能恢复情况。结果：早期组患者的,临床疗效好于非早期组患者,两者在上述方面比较,差异均具有统计学意5k（P〈0．05）。结论：对于重度颅脑损伤患者,应积极施行早期康复治疗,可促进患者神经功能恢复,提高l临床疗效。     

Implications of the gene balance hypothesis for dosage compensation

Dosage compensation refers to the equal expression between the sexes despite the fact that the dosage of the X chromosome is different in males and females. In Drosophila there is a twofold upregulation of the single male X. In triple X metafemales, there is also dosage compensation, which occurs by a two-thirds downregulation. There is a concomitant reduction in expression of many autosomal genes in metafemales. The male specific lethal (MSL) complex is present on the male X chromosome. Evidence is discussed showing that the MSL complex sequesters a histone acetyltransferase to the X chromosome to mute an otherwise increased expression by diminishing the histone acetylation on the autosomes. Several lines of evidence indicate that a constraining activity occurs from the MSL complex to prevent overcompensation on the X that might otherwise occur from the high level of acetylation present. Together, the evidence suggests that dosage compensation is a modification of a regulatory inverse dosage effect that is a reflection of intrinsic gene regulatory mechanisms and that the MSL complex has evolved in reaction in order to equalize the expression on both the X and autosomes of males and females.