Coupling effects of altitude and human disturbance on landscape and plant diversity in the vicinity of mountain villages of Beijing, China

Villages represent the source of human disturbance in mountain regions, but how they alter surrounding landscapes and further affect plant diversity distribution along altitudinal gradient is still not well documented. Although the unimodal pattern along latitudinal gradient and the hypothesis of immediate disturbance (IDH) have been supported in many studies, their coupling effects on plant diversity distribution have been given less attention. In this paper, the coupling effects surrounding mountain villages were detected: (1) altitude determined the mountain landscape at regional scale, while human disturbance altered landscape fragmentation and diversity at local scale surrounding villages. (2) With the reducing human disturbance away from villages, plant diversity decreased, then increased, and finally decreased in different land uses. The plant diversity of shrubs reached the lowest. With the increasing altitude, plant diversity of the forest represented the unimodal trend, but other land use types had different properties. (3) The mechanism of the coupling effects is that the combination of topographic and soil factors determines plant diversity distribution at both landscape and plant community levels surrounding villages.     

Pileated Gibbon Density in Relation to Habitat Characteristics and Post‐logging Forest Recovery

ABSTRACT Although it is known that forest loss and degradation negatively impact most forest‐dwelling primates, such relationships are difficult to quantify because many primates are difficult to survey over large areas. Furthermore, recovery times are also difficult to assess due to a lack of long‐term data. Here, we determined how forest characteristics and habitat disturbance correlate with the abundance of pileated gibbons, Hylobates pileatus. We studied a population in Khao Ang Rue Nai Wildlife Sanctuary in southeastern Thailand, assessed its density using an auditory method combined with distance sampling at 24 randomly placed sample sites. In addition, we determined how simple forest structural characteristics and habitat disturbance correlate with the gibbon abundance. Average gibbon density per site was 1.02 ± 0.16 (SE) groups/km² (range 0–2.74). Bivariate analyses indicated that densities depended on food tree biomass, level of disturbance, evergreen forest cover, time since protection, and distance to the sanctuary boundary. Multiple regression analysis suggested evergreen forest cover and distance to boundary were the most influential factors. Because evergreen forest cover, time since protection, and habitat disturbance are correlated, these results suggest a direct dependence of gibbon densities on mature, undisturbed evergreen forest. While gibbons can persist in disturbed areas if the forest is protected, it appears that recovery to previous densities may take decades. We suggest that this is due to the slow pace of forest regeneration and/or poor recovery potential of gibbons.     

WHBE兔血液蛋白的特性

目的比较大耳白黑眼兔（WHBE兔）与日本大耳白兔（JW兔）和新西澜兔（NZW兔）血液蛋白的多态性,从分子水平了解WHBE兔特殊性状的遗传背景。方法采用聚丙烯酰胺凝胶电泳对WHBE兔、JW兔和NZW兔血液中的前白蛋白（Pr）,后白蛋白（Po）,前转铁蛋白1（Prt1）,前转铁蛋白2（Prt2）,转铁蛋白1（Tf1）,转铁蛋白2（Tf2）,后转铁蛋白（Ptf）,慢α球蛋白（Sag）、血红蛋白（Hbα、Hbβ）和白蛋白（Alb）共11个蛋白位点进行检测。结果Pr、Ptf、Hbα、Hbβ、Alb、Po、Sag和Prt2在所有实验兔个体中的表型一致,而Tf1、Tf2和Prt1的表型在各实验兔品系间存在显著差异。在Tf1位点,NZW兔以BC表型为主,无AA型;JW兔只有AA型,而WHBE兔以AB型为主。在Tf2位点,NZW兔有AA型,而JW兔和WHBE兔无AA型。在Prt1位点,NZW兔无AB、BB和BC表型而有AC表型。NZW兔蛋白位点的平均杂合度大于JW兔和WHBE兔。JW兔与WHBE兔的遗传距离最近。结论Tf1、Tf2和Prt1可作为区分NZW兔、JW兔和WHBE兔的特征标记,并且与WHBE兔特殊性状形成有关。JW兔与WHBE兔的亲缘关系最近。     

植物群落物种共存机制:负密度制约假说

负密度制约假说主要描述由于资源竞争、有害生物侵害(比如病原微生物、食草动物捕食)等, 同种个体之间发生的相互损害行为; 它主要强调同种个体之间的相互作用, 解释自然群落物种共存的机理; 负密度制约机制主要在小尺度上降低群落内同种个体生长率, 同时提高个体死亡率, 从而为其他物种的生存提供空间和资源, 促进物种共存。目前负密度制约假说的检验研究主要侧重密度制约、距离制约、群落补偿效应等三个方面。最近, 研究者又探讨了近缘物种之间由于对相似资源的竞争所产生的负效应, 扩展了负密度制约假说, 进而提出异群保护假说和谱系多样性制约假说。负密度制约假说引起生态学家长久的探讨和关注, 世界范围内大尺度森林动态样地的建立, 又为探索不同尺度上密度制约效应的研究提供了条件。然而目前的研究仍然存在不足, 比如负密度制约假说的检验受到其他因素的干扰、区域研究不平衡等。因此, 生态学家们仍然怀疑负密度制约效应调节群落物种共存的重要性, 但是目前的研究还没有发现否定负密度制约假说的充分证据。     

用EST-SSR标记检测我国甘蓝型油菜品种的遗传多样性

杂交育种依然是我国油菜育种的主要方法,杂种优势的利用仍然是提高产量的重要途径.为了解我国甘蓝型油菜的遗传变异,采用16个EST-SSR标记对近年来推广的91个品种的遗传多样性进行了分析.共扩增到100个条带,其中84个多态性带,多态性比率为84%.平均每对引物扩增的带数和多态性带数分别为6.25个和5.25个.多态性信息含量(PIC)变化在0.022-0.926之间,平均为0.677,所揭示的基因型数变化于2-24之间,平均为12.44个.供试材料间遗传距离变幅较大(0.0530-0.7223之间),说明它们具有广泛的遗传变异.其中,杂交种和2000年以后育成品种的遗传基础较宽,遗传多样性分别明显高于常规品种和2000年以前育成的品种.按非加权成对平均数法(UPGMA)进行的聚类分析显示,在遗传距离为0.313处,参试材料可以分为三大类,其中,包含87份材料的第一大类在遗传距离为0.233处又可进一步分为10个亚类.聚类结果与系谱来源基本一致,比较真实反映了所用材料的遗传变异情况.     

Microspatial population genetic structure of the Mediterranean shrub Fumana thymifolia

Fumana thymifolia (Cistaceae) is an insect-pollinated, gravity-dispersed evergreen shrub, which is a common component of fire-prone Mediterranean shrubland ecosystems. Despite the availability of basic knowledge on its ecology, little is known of its breeding system and no information is available on its population genetic structure. We explored the within-population genetic structure of this species using amplified fragment length polymorphism (AFLP) molecular markers and related this to predictions based on its breeding system, pollen and seed dispersal. Existing information on the reproductive ecology of F. thymifolia was supplemented by artificial pollination experiments. We determined that self-fertilisation can occur in F. thymifolia but results in reduced fruit set. Significant genetic structuring was detected within the population, a likely consequence of localised seed dispersal in combination with a mixed mating system. In a study site covering approximately 0.5 ha, amova revealed that approximately 9% of genetic variability was distributed among population subsamples. Significant spatial genetic structure was detected, with kinship coefficients being significantly elevated above the null expectation in the first six distance classes (maximum 5 m), and a value of Sp of up to 0.0342, comparable with species having similar ecological characteristics. Weak isolation by distance at the plot scale was detected, suggesting that insect-mediated pollen flow is non-random, despite being more extensive than seed dispersal. Fumana thymifolia provides a promising model for the investigation of both short- and long-term population dynamics in relation to fire frequency within this plant community.     

A new cost‐distance model for human accessibility and an evaluation of accessibility bias in permanent vegetation plots in Great Smoky Mountains National Park,USA

Question: Can a new cost‐distance model help us to evaluate the potential for accessibility bias in ecological observations? How much accessibility bias is present in the vegetation monitoring plots accumulated over the last three decades in Great Smoky Mountains National Park? Location: Great Smoky Mountains National Park, North Carolina and Tennessee, USA. Methods: Distance, slope, stream crossings, and vegetation density were incorporated into a least‐cost model of energetic expenditure for human access to locations. Results: Estimated round‐trip energy costs for the park ranged from 0 to 1.62 × 10⁵ J kg^?1. The estimated round‐trip energetic expenditure for the surveys ranged from 53 to 1.51 × 10⁵ J kg^?1. Their distribution was more accessible than the random expectation. Ten (17%) of the vegetation types in the park are significantly under‐sampled relative to their area, and 16 (29%) are over‐sampled. Plots in 18 of the 40 vegetation types exhibited a significant positive correlation with accessibility. Conclusions: The least‐cost model is an improvement over previous attempts to quantify accessibility. The bias in plot locations suggests using a least‐cost model to test for bias in cases in which human accessibility is confounded with other sources of ecosystem variation.     

Ontogenetic changes in foraging tactics of the piscivorous cornetfish <Emphasis Type="Italic">Fistularia commersonii</Emphasis>

Foraging behaviors of the piscivorous cornetfish Fistularia commersonii were observed at shallow reefs in Kuchierabu-jima Island, southern Japan. This fish foraged on two types of prey fishes: one was reef fish that typically dwell on or near substrata (e.g., Tripterygiidae and Labridae), and the other was pelagic fish that shoal in the water column (e.g., Clupeidae and Carangidae). The prey sizes, prey types and foraging behaviors changed as the predator size increased. Prey sizes were largely limited by gape size of the cornetfish, and small predators consumed small prey. The small cornetfish (10–30 cm in total length) fed only on reef fish captured after stalking (where the fish slowly approaches the prey and then suddenly attacks). The stalking was done either solitarily or in foraging association with conspecifics. Large fish (30–120 cm) fed on both types of fishes by stalking and/or chasing (where the fish chases the prey using its high mobility and attacks), either solitarily or in foraging association with con- or heterospecifics. Thus, chasing was only performed by the large cornetfish against pelagic prey fish in associative foraging with other con- and heterospecific predators. As their body sizes increased, F. commersonii began to show a diversification of foraging behaviors, which was strongly related not only to the habitat types and anti-predatory behaviors of the prey fishes but also to associative foraging with con- or heterospecifics, which improves their foraging success.     

Regional analysis of the impacts of climate change on cheatgrass invasion shows potential risk and opportunity

Interactions between climate change and non-native invasive species may combine to increase invasion risk to native ecosystems. Changing climate creates risk as new terrain becomes climatically suitable for invasion. However, climate change may also create opportunities for ecosystem restoration on invaded lands that become climatically unsuitable for invasive species. Here, I develop a bioclimatic envelope model for cheatgrass ( Bromus tectorum ), a non-native invasive grass in the western US, based on its invaded distribution. The bioclimatic envelope model is based on the Mahalanobis distance using the climate variables that best constrain the species' distribution. Of the precipitation and temperature variables measured, the best predictors of cheatgrass are summer, annual, and spring precipitation, followed by winter temperature. I perform a sensitivity analysis on potential cheatgrass distributions using the projections of 10 commonly used atmosphere–ocean general circulation models (AOGCMs) for 2100. The AOGCM projections for precipitation vary considerably, increasing uncertainty in the assessment of invasion risk. Decreased precipitation, particularly in the summer, causes an expansion of suitable land area by up to 45%, elevating invasion risk in parts of Montana, Wyoming, Utah, and Colorado. Conversely, increased precipitation reduces habitat by as much as 70%, decreasing invasion risk. The strong influence of precipitation conditions on this species' distribution suggests that relying on temperature change alone to project future change in plant distributions may be inadequate. A sensitivity analysis provides a framework for identifying key climate variables that may limit invasion, and for assessing invasion risk and restoration opportunities with climate change.     

Movement of sturgeons (Acipenser oxyrinchus oxyrinchus and A. fulvescens) in the St. Lawrence Estuary: A 35-year tagging study

Movement of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) and lake sturgeon (A. fulvescens) in the St. Lawrence Estuary (Québec, Canada) are not fully understood. To assess the movement extent of both species, a mark–recapture study was conducted in collaboration with commercial fishermen operating in the St. Lawrence Estuary. Between 1981 and 2015, 3,367 Atlantic sturgeon (fork length 21.8–199.5 cm) and 3,180 lake sturgeon (fork length 17.8–190.8 cm) were tagged and released. Of these, 673 Atlantic sturgeon and 42 lake sturgeon were recaptured. The maximum distances traveled between capture and recapture locations were 1,307 km for Atlantic sturgeon (8 years after initial capture) and 252 km for lake sturgeon (less than 1 year after initial capture). Statistical analyses identified differences in the dispersal distance of both species as revealed by a first component characterized by individuals with short dispersal distances (98% and <35 km for Atlantic sturgeon; 58% and <1 km for lake sturgeon) and a second component characterized by individuals with longer dispersal distances (2% and >600 km for Atlantic sturgeon; 42% and >190 km for lake sturgeon). We suggest that the short dispersal distances detected in the vast majority of Atlantic sturgeon recaptures likely reflect strong site fidelity, highlighting the importance of the St. Lawrence Estuary as a preferred habitat for juveniles and subadults. Although recaptures were low for lake sturgeon because this species is only marginally targeted by commercial fishermen in the St. Lawrence Estuary, our results also showed that this species uses estuarine habitats and that half of the population seems to exhibit strong site fidelity (67% of individuals were recaptured within 2 km).