福建武平米槠林恢复生态学研究

从优势种,分布格局,种丰富度和群落间种相似系数角度,探讨不同人为干扰尺度对福建武平米槠林恢复的影响。结果表明,随着人为干扰尺度（A级择伐更新,B级天然更新,C级人工促进天然更新和D级杉木林）的加大,顶极种米槠重要,不同人为干扰群落与天然来桩群落种相似系数随之降低,降至D级分别为0和40％;而米槠分布格局（聚集强度）和种丰富随之上升,升至B级或C级后显著下降,据此可见,A级属于轻度干扰,现已恢复;B级属于中度干扰,将很快恢复;C级虽然顶级种米槠处于第二优势种,阳性树种裂斗锥处于第一优势种,但种丰富度达到最大值,属中度干扰,但恢复时间要较B级略长;D级属于强度干扰,产难恢复到米桩顶极群落。     

A scale-eating triacanthodid, Macrorhamphosodes uradoi: prey fishes and mouth "handedness" (Tetraodontiformes, Triacanthoidei)

Gut content analyses of deep-sea triacanthodid (Macrorhamphosodes uradoi) specimens from Tosa Bay and the Kyushu-Palau Ridge, southern Japan, revealed that the species primarily feeds on fish scales. A total of 55 042 scales from 48 specimens were grouped into 19 types, 14 being identifiable between family and species levels. Scale composition differed significantly between the two localities, with only 6 types occurring at both. Glossanodon semifasciatus (Argentinidae) and Emmelichthys struhsakeri (Emmelichthyidae) were the dominant prey in Tosa Bay and on the Kyushu-Palau Ridge, respectively. The scale morphology indicated that M. uradoi steals scales from the caudal fin and base of prey. The long tubular snout of M. uradoi was recognized as an adaptation for obtaining scales while keeping the body in a relatively posterior position, thereby minimizing the likelihood of being noticed by the prey. Furthermore, the mouth was twisted to various degrees, either to the left or the right, the angle of twisting not being correlated with specimen size. The variable nature of twist angles was hypothesized as providing a variety of strike tactics, each angle defining an optimum, resulting in lessened opportunities for learned responses by prey fishes. Received: April 17, 2001 / Revised: August 16, 2001 / Accepted: September 15, 2001     

内蒙古草原植被近地面反射波谱特征与地上生物量相关关系的研究

在1994～2001年7～8月期间,对内蒙古草原的15个草地群落类型进行了反射波谱与生物学参数的测量,在1996、2001年分别对其中的7个群落开展了反射波谱与生物学参数季节变化研究,利用Duncan方差分析、主分量分析方法在3个空间尺度上讨论了不同群落类型波谱特征的差异性与可区分性。在大尺度上,草甸草原、典型草原和荒漠草原的植被反射波谱特征之间存在显著的差异,它们之间的平均鉴别错误概率小于20%,在中小尺度上,典型草原中不同群落之间波谱特征差异程度较高,平均鉴别错误概率在15%左右,而在草甸草原和荒漠草原中,不同群落之间波谱特征的差异性较小。相关分析结果指出,空间尺度和群落类型决定了地上生物量与植被指数之间相关性的大小、相关形式以及植被指数的类型,随着尺度的增大,生物量与植被指数的相关性趋于下降,在盖度较高的草原群落中,直线型的估产模型相关性最高,估测精度大于90%,而在覆盖度低于30%～40%的荒漠草原群落中, 非线性估产模型相关性最高,估测精度只有85%。对典型草原和荒漠草原估产模型的季节动态分析表明, 在6月中旬至9月中旬期间的估产模型之间没有显著差异,可以利用一个共同的估产模型来监测草地生物量季节动态。     

Linking small desert mammal distribution to habitat structure in a protected and grazed landscape of the Monte, Argentina

Interpretation of landscape patterns from the perspective of different species allows knowing the way in which they perceive landscape, and how their perception varies with scale. We examined distribution of four small mammal species at different scales over a landscape including protected and grazed areas, and associated species distribution with landscape structure. The study was conducted in the central Monte Desert (Reserve of Ñacuñán). Trap grids were set in both areas at two scales, varying their grain and extent. To determine whether spatial patterns are random, clumped or regular, we used a point pattern analysis. Logistic regressions were performed to relate the presence-absence of small mammals to environmental variables. Intensity of the point pattern was not constant, either in the Reserve or the grazed area. Small mammal abundance exhibited a heterogeneous distribution, and the existence of a first-order effect was detected for all species. No second-order effects were detected, the point pattern was random for all species in both areas. Both areas were differently perceived by rodent species. Habitat structure in both conditions and its variations with scale appear to be important factors affecting distribution patterns.     

Characterization of beta-keratins in lizard epidermis: electrophoresis, immunocytochemical and in situ-hybridization study

Lizard scales are composed of alpha-(cyto-) keratins and beta-keratins. The characterization of the molecular weight and isoelectric point (pI) of alpha- and beta-keratins of lizard epidermis (Podarcis sicula) has been done by using two-dimensional electrophoresis, immunoblotting, and immunocytochemistry. Antibodies against cytokeratins, against a chicken scale beta-keratin or against lizard beta-keratin bands of 15-16 kDa, have been used to recognize alpha- and beta-keratins. Acid and basic cytokeratins of 42-67 kDa show a pI from 5.0 to 8.9. This indicates the presence of specific keratins for the formation of the stratum corneum. Main protein spots of beta-keratin at 15-17 kDa, and pI at 8.5, 8.2, and 6.7, and one spot at 10 kDa and pI at 7.3 were recognized. Therefore, beta-keratins are mainly basic proteins, and are used for the formation of the hard corneous layer of the epidermis. Ultrastructural immunocytochemistry confirms that beta-keratin is packed into large and dense bundles of beta-keratin cells of lizard epidermis. The use of a probe against a lizard beta-keratin in situ-hybridization studies confirms that the mRNA for beta-keratins is present in beta-cells and is localized around or even associated with beta-keratin filaments.     

Periplast structure of the cryptomonad flagellateHemiselmis brunnescens

Summary The periplast ofHemiselmis brunnescens Butcher is a complex cell covering comprised of the plasma membrane (PM) sandwiched between a surface periplast component (SPC) and an inner periplast component (IPC). The SPC is revealed by deep-etching, and consists of hexagonal plates composed of tripartite subunits that appear to self-assemble into a crystalline layer with a hexagonal symmetry. Small scales (termed fibrillar scales) accumulate on the crystalline plates during cell growth, eventually forming a carpet that itself may appear crystalline when fully formed. Heptagonal rosette scales are occasionally observed on the surface as well. The position of the crystalline plates is precisely mirrored by both the E and P fracture faces of the PM. The plate proper is underlain by membrane with a high concentration of intramembrane particles (IMPs) while the bands of membrane underlying the plate borders lack IMPs. Access of subunits and fibrillar scales to the cell surface following initial plate formation appears to be at the plate boundaries. This study suggests that cryptomonad flagellates may provide model systems for studying the self-assembly of cell surface components, and for relating membrane structure to function, as evidence suggests a major role for the PM in mediating periplast assembly and development.     

Fine structure of the developing frontal bones and scales of the cranial vault in the cichlid fish Hemichromis bimaculatus (Teleostei,Perciformes)

The development of the frontal bone and the formation of the first head scales are described during post-embryonic ontogeny of Hemichromis bimaculatus, using light and transmission electron microscopy. The frontal bone originates close to the cartilaginous taenia marginalis in a loose mesenchymal cell condensation (=primordium) lying 1 m from the epidermis with which it establishes no cell contacts. The anlage appears at 4.2 mm standard length (SL) in the form of the membranodermal component of the bone, and extends first over the brain and then over the eye; the neurodermal component forms later to surround the supraorbital canal. The first head scales appear at 10.0 mm SL in a dense cell condensation (papilla) adjoining the epidermal-dermal junction and, once formed, remain in this position. In both organs, the initial matrix is similarly composed of woven-fibred bone that soon mineralizes in a similar manner to other dermal elements. In some areas of the frontal bone, parallel-fibred bone is deposited unequally on both surfaces, whereas isopedine is deposited in scales on the deep surface only. Osteoblastic features confirm this eccentric growth. Differences in the shape, organization and localization of the mesenchymal condensations giving rise to the frontal bone and to the scale reflect the existence of two types of dermal cell condensations. Our data are compared with those available for the post-cranial dermal skeleton of fishes both from a developmental and structural viewpoint. Structural differences in the matrices of the frontal bone and scales are discussed in a phylogenetic perspective.     

2010年春季干旱对石林喀斯特植物群落的影响

研究干旱对退化喀斯特植被影响是治理退化喀斯特生态系统或石漠化的基础.为了解2010年春中国西南特大干旱对喀斯特植被的影响,于2010年5月采用记名计数交叉样线法调查了云南石林3种自然恢复植物群落(滇青冈林、栓皮栎林、灌丛)和5种人工恢复植物群落(云南松林、原土旱冬瓜林、客土旱冬瓜林、圣诞树林、墨西哥柏林).选用气象要素距平指数分析此次干旱的特征;用受旱率、死亡率分析植物群落和物种的受旱程度;用受旱(死亡+萎蔫)物种数及其植株数、耐旱(存活)物种数及其植株数、群落(受旱+存活)物种数及其植株数计算生物多样性指数来评估极端干旱对生物多样性的影响.结果表明:此次特大干旱具有持续时间长、程度深的特点.8种群落的平均死亡率、受旱率分别是25.1%和30.6%,不同群落的受旱率和死亡率差异较大.极端干旱后,自然恢复群落的更新层仍维持了物种结构;人工恢复群落差异较大,原土旱冬瓜林、云南松林基本未受影响,墨西哥柏林受到一定影响,客土旱冬瓜林、圣诞树林物种结构基本被破坏.极端干旱一定程度上改变了喀斯特植物群落的径级结构和生物多样性,人工恢复群落结构变化大且耐旱性总体上弱于自然恢复植物群落.因此,退化喀斯特生态系统的植被恢复必须选择合理的物种和恢复方式.     

Phylogenetic position and morphology of Raphidiophrys elongata sp. nov. (Haptista: Centroplasthelida) with notes on cyst wall structure and evolution

The majority of centrohelids bear external coverings consisting of organic spicules or siliceous scales. Cyst coverings are usually reinforced with additional layers of modified scales. The cyst wall of Raphidiophrys heterophryoidea has an unusual and complex structure. It consists of three different types of scales and includes the mosaic scale layer not known in other centrohelids. During excystment, the cyst wall fragments along the sutures of the mosaic layer. For other Raphidiophrys species, cyst coverings are not studied. The present paper describes a new Raphidiophrys species, R. elongata, belonging to the NC7 environmental clade. Trophozoites bore thin plate scales with reduced upper plate. Under starvation, cysts emerged in clonal cultures. Cyst coverings of R. elongata and R. heterophryoidea were studied in comparison with the use of FIB-SEM. Cyst wall of R. elongata was significantly thinner than in R. heterophryoidea and was formed with 3–5 layers of uniform overlapping scales. No mosaic scale layer was present. During excystment, trophozoite exited cyst shell through random fissure. Possible evolutionary events and driving forces behind the complication of cyst wall within Raphidiophrys were discussed.     

Genera as surrogates of bryophyte species richness and composition

Surrogates offer quick and cost-efficient solutions to assess and monitor biodiversity. In this study we have tested higher taxa surrogates, particularly genera richness and composition as surrogates for bryophyte species richness and composition, in two different habitats (exposed rock outcrops and watercourses), across two spatial scales (local and micro scale), in central and northern Portugal. Furthermore, we have also tested the influence of environmental variables on the richness and composition of species and genera. Our results showed significant and positive relationships between species and genera richness and composition for the habitats and scales studied. Also, concerning the analyzed scales analyzed, correlations between species and genera richness, as well as species and genera composition, were found to be positive and significant. Moreover, the environmental variables tested influenced species and genera richness and composition in the same way. In conclusion, the higher taxa approach could be an effective method for a rapid assessment and monitoring of bryophytes in the studied area, for the habitats and scales considered.