Differences in resource storage pattern between Laminaria longissima and Laminaria diabolica (Laminariaceae; Phaeophyta) reflecting their morphological characteristics

The kelps Laminaria longissima and L. diabolica, belonging to the groups of L. angustata and L. japonica, respectively, differ greatly in their morphological characteristics although their geographical distributions overlap widely along the eastern coast of Hokkaido. To clarify the interaction between the morphological and physiological characteristics of the two species, and their link with environmental variables, hatchery-raised young sporophytes of L. longissima and L. diabolica collected from Hokkaido were cultivated simultaneously under similar conditions in Matsushima Bay, Miyagi, from January to July 2004. Seasonal morphological characteristics, gross photosynthetic rate, nutrient uptake rates, and resource contents were examined. The blade lengths of L. longissima and L. diabolica reached a maximum of 329.9 cm and 256.7 cm, respectively, in April to May, and decreased to 284.4 cm and 68.6 cm, respectively, in July. The total elongation length of L. longissima (412.5 cm) was similar to that of L. diabolica (373.8 cm). However, the total erosion length of L. longissima (145.9 cm) was approximately half that of L. diabolica (302.9 cm). The gross photosynthetic rate and uptake rates of NH₄-N, NO₃-N, and PO₄-P of the two species were similar. However, the carbon, nitrogen, and phosphorus contents were transferred and stored in the whole blade tissues in the case of L. longissima, but in the meristem of L. diabolica from May to June. These results suggest that morphological differences are a response to different resource storage patterns. The storage patterns of L. longissima and L. diabolica are likely to be genetically fixed characteristics, which have evolved in adaptation to the specific habitat environments of the groups of L. angustata and L. japonica. The low water temperature and rich nutrients provided by the Oyashio Current are conducive to storage of resources in the whole blade tissues and a large surface area retained for photosynthesis and nutrient uptake in the L. angustata group. Conversely, high temperature and poor nutrients, or large fluctuations in these parameters, provided by the Tsushima Warm Current are more conducive to intensive storage of resources in the meristem for maturation and further growth in the L. japonica group. L. diabolica retains the storage pattern of the L. japonica group but grows in regions affected by the Oyashio Current, allowing it to become the widest distributed Laminaria species.     

Spatial distribution of the basidiocarps of aphyllophoraceous fungi in a tropical rainforest on Borneo Island, Malaysia

The spatial distribution of basidiocarps provides much information on the dispersal abilities, habitat preferences, and inter- and intraspecific interactions of aphyllophoraceous fungi. To reveal the spatial distribution and resource utilization patterns of aphyllophoraceous fungi in Malaysia, we conducted field observations in a primary forest in 2006 and analyzed the relationships between the abundance of eight dominant fungal species and various environmental factors. The topographical characteristics were significantly patchily distributed at the 100-m scale, whereas woody debris and most fungal species were distributed randomly. Although the dominant fungal species differed among the decay classes and diameters of the woody debris, the abundance of a few dominant species was significantly correlated with environmental factors. Although the latter factors might affect the spatial distribution of these fungi, the effects appear to be so small that they would not create an aggregated distribution at a few 100-m scales.     

土壤类型对短葶飞蓬灯盏乙素和咖啡酸酯积累的影响

在相同栽培管理条件下,分别以黑色石灰土、红色石灰土、红壤、黄红壤、紫色土和腐殖土为生长介质对短葶飞蓬（Erigeron breviscapus）进行了人工栽培试验。结果显示,生长在不同土壤类型的短葶飞蓬植株体内总咖啡酸酯和灯盏乙素含量有显著的差异。红色石灰土、紫色土及黄红壤生长的植株总咖啡酸酯和灯盏乙素含量最高,黑色石灰土和腐殖土的最低。相同土类的不同亚类土壤生长植株间2种次生代谢产物含量的差异程度,会超过不同土类间的。植株总咖啡酸酯和灯盏乙素含量与土壤P和K含量没有显著相关关系,但与土壤速效N含量及植株含N量则都有极显著负相关关系。不同土壤生长植株叶片的最大光能转换效率（Fv／Fm）值与灯盏乙素和总咖啡酸酯含量都表现出极显著负相关关系。土壤类型对短葶飞蓬次生代谢影响规律与碳素／营养平衡假说（CNB）及资源获得假说（HA）的预测一致。     

Review of forest landscape models: Types, methods, development and applications

Forest landscape models simulate forest change through time using spatially referenced data across a broad spatial scale (i.e. landscape scale) generally larger than a single forest stand. Spatial interactions between forest stands are a key component of such models. These models can incorporate other spatio-temporal processes such as natural disturbances (e.g. wildfires, hurricanes, outbreaks of native and exotic invasive pests and diseases) and human influences (e.g. harvesting and commercial thinning, planting, fire suppression). The models are increasingly used as tools for studying forest management, ecological assessment, restoration planning, and climate change. In this paper, we define forest landscape models and discuss development, components, and types of the models. We also review commonly used methods and approaches of modeling forest landscapes, their application, and their strengths and weaknesses. New developments in computer sciences, geographic information systems (GIS), remote sensing technologies, decision-support systems, and geo-spatial statistics have provided opportunities for developing a new generation of forest landscape models that are increasingly valuable for ecological research, restoration planning and resource management.     

The impact of <Emphasis Type="Italic">Solanum elaeagnifolium</Emphasis>, an invasive plant in the Mediterranean,on the flower visitation and seed set of the native co-flowering species <Emphasis Type="Italic">Glaucium flavum</Emphasis>

The sprouting response types of 1,151 cork oak (Quercus suber) trees one and half years after a wildfire in southern Portugal were characterised. It was hypothesised that different response types should occur according to the following conceptual model: an increased level of damage (fire severity) on a sprouting tree that suffered a crown fire was expected to be reflected in a sequence of four alternative events, namely (a) resprouting exclusively from crown, (b) simultaneous resprouting from crown and base, (c) resprouting exclusively from base and (d) plant death. To assess whether the level of expected damage was influenced by the level of protection from disturbance, we explored the relationships between response types and tree size, bark thickness and cork stripping, using an information-theoretic approach. The more common response type was crown resprouting (68.8% of the trees), followed by plant death (15.8%), simultaneous resprouting from crown and base (10.1%) and basal resprouting (5.3%). In agreement with the conceptual model, trees which probably suffered a higher level of damage by fire (larger trees with thinner bark; exploited for cork) died or resprouted exclusively from base. On the other hand, trees that were well protected (smaller trees with thicker bark not exploited for cork) were able to rebuild their canopy through crown resprouting. Simultaneous resprouting from the crown and base was determined mainly by tree size, and it was more common in smaller trees.     

Review of forest landscape models: Types, methods, development and applications

Forest landscape models simulate forest change through time using spatially referenced data across a broad spatial scale (i.e. landscape scale) generally larger than a single forest stand. Spatial interactions between forest stands are a key component of such models. These models can incorporate other spatio-temporal processes such as natural disturbances (e.g. wildfires, hurricanes, outbreaks of native and exotic invasive pests and diseases) and human influences (e.g. harvesting and commercial thinning, planting, fire suppression). The models are increasingly used as tools for studying forest management, ecological assessment, restoration planning, and climate change. In this paper, we define forest landscape models and discuss development, components, and types of the models. We also review commonly used methods and approaches of modeling forest landscapes, their application, and their strengths and weaknesses. New developments in computer sciences, geographic information systems (GIS), remote sensing technologies, decision-support systems, and geo-spatial statistics have provided opportunities for developing a new generation of forest landscape models that are increasingly valuable for ecological research, restoration planning and resource management.     

When should signals of submission be given?-A game theory model

During contests, losing animals often show signals communicating submission. From an evolutionary viewpoint, however, it is not so obvious why the losing individual gives such a signal instead of running away and why the winning individual accepts the signal instead of inflicting more severe damage. We investigated factors influencing the evolution of signals of submission using a numerical ESS model. The present analysis reveals that there is much space for the evolution of signals of submission, even when the winner of an escalated contest gets some extra benefit. In most cases, signals of submission are given by animals which are slightly or moderately weaker than the opponent. Signals of submission are expected to occur frequently (1) when the value of contested resource does not differ greatly from the cost of injury, (2) when the extra benefit of winning an escalated contest is small, (3) when the opportunity for safe retreat by the losing animal is small, and (4) when the estimation of the difference in the resource holding potential (RHP) between the combatants is accurate but not perfect.     

Increased brain uptake and brain to blood efflux transport of 14C-GABA in spontaneously hypertensive rats

The brain uptake and brain to blood efflux transport of (14)C-GABA were studied in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats using 20 min bilateral in situ brain perfusion in rats anesthetized using urethane. The volume of distribution (Vd) of (14)C-GABA into cerebrospinal fluid (CSF) and brain regions (cortex, diencephalon, cerebellum, and brain stem) was significantly greater in SHR than in the corresponding regions in WKY rats (p<0.05). The estimated Vd value of (14)C-GABA in CSF of SHR was 3.4 fold greater than that in WKY. Also compared to WKY, the Vd of (14)C-GABA into cerebellum and cortex of SHR was 15.3 fold and 19.4 fold greater, respectively. Although the study of blood-brain barrier (BBB) integrity using (3)H-mannitol revealed increased paracellular permeability at the brain capillaries of SHR when compared to WKY rats, this was found to be only partially responsible for the increased (14)C-GABA uptake. The study of brain to blood efflux transport of (14)C-GABA (after loading of brain with (14)C-GABA by vascular perfusion) revealed that the half-time of elimination was significantly shorter in SHR (5.35+/-0.66 min) than in WKY rats (14.83+/-1.94 min), (p<0.001). HPLC analysis revealed that GABA concentrations in brain extracts and CSF of SHR were similar to those in WKY rats (p>0.05). The faster efflux in SHR might be, at least partially, responsible to compensate for increased uptake of this neurotransmitter and to preserve the protective function of BBB towards GABA. The protective function of the BCSFB towards GABA appears to be also preserved, since systemic infusion of GABA within a wide range of administered doses (0.004-5.00 mg/kg) produced an increase in GABA CSF concentration from around 0.5 microM to only 11 microM, and the obtained pattern of CSF GABA concentrations under these conditions did not differ between SHR and WKY rats, as revealed by HPLC.     

太空诱变对金钗石斛光合特性和生长的影响

为了解太空诱变对金钗石斛(Dendrobium nobile)生长发育的影响,对太空诱变和野生金钗石斛的叶片结构、光合特性和生长指标进行了比较研究。结果表明,太空诱变后的金钗石斛叶片较厚,叶气孔密度大、气孔器长轴和短轴长度均变长。两种金钗石斛的光合速率日变化趋势相似,均为双峰型曲线,但太空诱变的净光合速率低于野生的。太空诱变和野生金钗石斛最大净光合速率分别为4.6和6.8μmol m~(–2)s~(–1),光补偿点分别为18.3和12.6μmol m~(–2)s~(–1),光饱和点分别为1180和720μmol m~(–2)s~(–1)。太空诱变和野生金钗石斛的CO_2补偿点分别为100和102μmol mol(–1),CO_2饱和点分别为2215和2090μmol mol(–1)。太空诱变的金钗石斛单茎鲜重和干重均低于野生种,但由于其分蘖数增加,每盆的总生物量反而增加;太空诱变的金钗石斛生物碱和石斛多糖含量显著高于野生种。因此,太空诱变为金钗石斛育种和品质改良提供了新途径。     

Male contest investment changes with male body size but not female quality in the spider Nephila clavipes

Animals use rules to adjust their level of investment in a contest. We evaluate male strategies during contests over females in the golden orb-web spider Nephila clavipes. We tested whether male behaviour changes with female value, and found that contests were similar in intensity and outcome whether the female was a juvenile or adult, virgin or non-virgin, or whether one male had invested sperm in the female. We found evidence that males use a self-assessment strategy when deciding to withdraw from a contest. Loser body size and contestant size difference were correlated with a higher frequency of contest escalation, and fights involving two large males were more likely to escalate than a fight in which one male was small. A multiple regression showed that loser body size had a stronger effect on contest escalation than contestant body size difference. More importantly, the size of the winning male had no effect on contest escalation, a key prediction of a self-assessment strategy. In N. clavipes, body size is the primary factor that determines the outcome of male contests, and males do not appear to assess their opponent or the quality of the resource when deciding to withdraw from the fight.