Genetic variation of ecophysiological traits in two gynodioecious species of Schiedea (Caryophyllaceae)

Evolution of dimorphic breeding systems may involve changes in ecophysiological traits as well as floral morphology because of greater resource demands on females. Differences between related species suggest that ecophysiological traits should be heritable, and species with higher female frequencies should show greater sexual differentiation. We used modified partial diallel crossing designs to estimate narrow-sense heritabilities and genetic correlations of sex-specific ecophysiological and morphological traits in closely related gynodioecious Schiedea salicaria (13% females) and Schiedea adamantis (39% females). In S. salicaria, hermaphrodites and females differed in photosynthetic rate and specific leaf area (SLA). Narrow-sense heritabilities were significant for stomatal conductance, SLA and inflorescence number in hermaphrodites, and for SLA and inflorescence number in females. Schiedea adamantis had no sexual dimorphism in measured traits; stomatal conductance, stem number and inflorescence number were heritable in females, and stem number was heritable in hermaphrodites. In both species, significant genetic correlations of traits between sexes were rare, indicating that traits can evolve independently in response to sex-differential selection. Significant genetic correlations were detected between certain traits within sexes of both species. Low heritability of some ecophysiological traits may reflect low additive genetic variability or high phenotypic plasticity in these traits.     

Comparative ecophysiological responses to drought of two shrub and four tree species from karst habitats of southwestern China

Drought stress is one of the most important factors in limiting the survival and growth of plants in the harsh karst habitats of southwestern China, especially at the seedling establishment stage. The ecophysiological response to drought stress of native plants with different growth forms is useful for re-vegetation programs. Two shrub and four tree species were studied, including Pyracantha fortuneana (evergreen shrub), Rosa cymosa (deciduous shrub), Cinnamomum bodinieri (evergreen tree), and other three deciduous trees, Broussonetia papyrifera, Platycarya longipes, and Pteroceltis tatarinowii. The seedlings were randomly assigned to four drought treatments, i.e., well-watered, mild drought stress, moderate drought stress, and severe drought stress. Leaf water relations, gas exchange, chlorophyll fluorescence, and growth of the seedlings were investigated. Under severe drought stress, the two shrubs with low leaf area ratio (LAR) maintained higher water status, higher photosynthetic capacity, and larger percent biomass increase than the most of the trees. The two shrubs also had lower specific leaf area, greater intrinsic water use efficiency, and thermal dissipation than the trees. This suggested that the two shrubs had high tolerance to severe drought and were suitable for re-vegetation in harsh habitats. The evergreen C. bodinieri exhibited higher leaf mass ratio (LMR) and LAR than the deciduous species under mild and moderate stress. However, the low maximum quantum efficiency of PSII photochemistry (F _v/F _m) and net assimilation rate, and the sharp decreases of water potential, LMR, LAR, and biomass under severe stress indicated C. bodinieri’s weak tolerance to severe drought. In response to drought stress, the three deciduous trees revealed sharp reductions of biomass due to the large drought-induced decreases of gas exchange, LAR, and LMR. Under drought conditions, the deciduous trees minimized water loss by stomatal closure and by reducing transpiration leaf area and light harvesting through shedding leaves. This suggested that the three deciduous trees were more sensitive to water availability than the shrubs and used avoidance strategies against drought stress. However, the better growth performance of the deciduous trees than that of the shrubs under favorable conditions suggested that deciduous trees could be suitable for habitats with mild and temporary drought stress.     

岩溶石漠化地区几种生态恢复植物的生理生态学特征

选择石漠化地区树种任豆树、金银花和苦丁茶的植株为对象,测定其光响应曲线和光合、蒸腾、气孔导度的日变化,研究其光合、蒸腾、气孔导度与环境因子间的关系。在岩石裸露率高、地表水缺乏、白天温度极高的石漠化地区,对任豆和苦丁茶进行光响应模拟表明,两者的最大净光合速率分别为15.88μmol.m-2.s-1、4.58μmol.m-2.s-1。从气体交换特征日变化看出,这三种植物均有光合午休现象,任豆午休程度最弱而苦丁茶最强,光合与气孔导度均呈显著的正相关关系;通过对胞间CO2浓度Ci与气孔限制Ls关系分析,任豆和金银花的光合作用上午以气孔限制为主,下午有非气孔因素影响,而苦丁茶则以非气孔限制为主。任豆树具有较高的水分利用效率,金银花次之,而苦丁茶最小。通过综合分析,认为地表缺水并不是石漠化地区简单唯一的限制因子,高温胁迫也造成该区植物同化CO2减少的原因。根系的下扎能力也应是石漠化地区植物长期存活的关键。因此通过人工诱导构建石漠化地区植物群落时一定要考虑植物本身的根系遗传性状。     

Intraspecific variability in functional traits matters: case study of Scots pine

Although intraspecific trait variability is an important component of species ecological plasticity and niche breadth, its implications for community and functional ecology have not been thoroughly explored. We characterized the intraspecific functional trait variability of Scots pine (Pinus sylvestris) in Catalonia (NE Spain) in order to (1) compare it to the interspecific trait variability of trees in the same region, (2) explore the relationships among functional traits and the relationships between them and stand and climatic variables, and (3) study the role of functional trait variability as a determinant of radial growth. We considered five traits: wood density (WD), maximum tree height (H _max), leaf nitrogen content (N_mass), specific leaf area (SLA), and leaf biomass-to-sapwood area ratio (B _L:A _S). A unique dataset was obtained from the Ecological and Forest Inventory of Catalonia (IEFC), including data from 406 plots. Intraspecific trait variation was substantial for all traits, with coefficients of variation ranging between 8 % for WD and 24 % for B _L:A _S. In some cases, correlations among functional traits differed from those reported across species (e.g., H _max and WD were positively related, whereas SLA and N_mass were uncorrelated). Overall, our model accounted for 47 % of the spatial variability in Scots pine radial growth. Our study emphasizes the hierarchy of factors that determine intraspecific variations in functional traits in Scots pine and their strong association with spatial variability in radial growth. We claim that intraspecific trait variation is an important determinant of responses of plants to changes in climate and other environmental factors, and should be included in predictive models of vegetation dynamics.     

Intraspecific phenotypic variability of plant functional traits in contrasting mountain grasslands habitats

Empirical studies that link plants intraspecific variation to environmental conditions are almost lacking, despite their relevance in understanding mechanisms of plant adaptation, in predicting the outcome of environmental change and in conservation. Here, we investigate intraspecific trait variation of four grassland species along with abiotic environmental variation at high spatial resolution (n = 30 samples per species trait and environmental factor per site) in two contrasting grassland habitats in Central Apennines (Italy). We test for phenotypic adaptation between habitats, intraspecific trait-environment relationships within habitats, and the extent of trait and environmental variation. We considered whole plant, clonal, leaf, and seed traits. Differences between habitats were tested using ANOVA and ANCOVA. Trait-environment relationships were assessed using multiple regression models and hierarchical variance partitioning. The extent of variation was calculated using the coefficient of variation. Significant intraspecific differences in trait attributes between the contrasting habitats indicate phenotypic adaptation to in situ environmental conditions. Within habitats, light, soil temperature, and the availability of nitrate, ammonium, magnesium and potassium were the most important factors driving intraspecific trait-environment relationships. Leaf traits and height growth show lower variability than environment being probably more regulated by plants than clonal traits which show much higher variability. We show the adaptive significance of key plant traits leading to intraspecific adaptation of strategies providing insights for conservation of extant grassland communities. We argue that protecting habitats with considerable medium- and small-scale environmental heterogeneity is important to maintain large intraspecific variability within local populations that finally can buffer against uncertainty of future climate and land use scenarios.     

两种木兰科植物叶片光合作用的光驯化

测定了生长在全日、54%和21%日光强下需光植物火力楠(Michelia meachurei)和耐荫植物华东拟单性木兰(Parakmerialotungensis)叶片气体交换参数,用以估测降低光强对光合作用的限制和对低光的光驯化.生长在全日光强下火力楠的光饱和光合速率较华东拟单性木兰高.当日光强降低到54%,火力楠叶片光合速率降低幅度较华东拟单性木兰大.当日光降低至21%,华东拟单性木兰的表观量子产率和光能转换率较火力楠高.在全日光强下,火力楠的Vcmax较华东拟单性木兰高.随着日光强降低,两种木兰植物的Vcmax降低,当日光强降低至54%和21%,火力楠的Vcmax降幅较华东拟单性木兰大,火力楠Vcmax对光强降低较华东拟单性木兰敏感.生长光强降低,两种木兰植物内部CO2传导度(gi)降低.在低光强下火力楠仍保持较华东拟单性木兰高的gi.生长光强降低到全日光强的54%,火力楠gi对光合速率限制(Li)与在全日光强的条件下没有区别(p＞0.05),表现火力楠gi对54%日光强的驯化;在54%的光条件下,华东拟单性木兰的呼吸速率对光合速率的限制(Lr)与全日光照无差别(p＞0.05),显示呼吸速率对低光的驯化.两种木兰植物气孔导度对光合速率的限制(Ls)随光强降低而增大.在遮荫条件下种间叶特性差别明显,这亦反映出两种植物物种光合驯化的差异.火力楠gi对低光驯化,而华东拟单性木兰叶片对较高光强驯化更甚于对低光强.     

Natural selection on ecophysiological traits of a fern species in a temperate rainforest

Unlike other species of the genus Blechnum, the fern Blechnum chilense occurs in a wide range of habitats in Chilean temperate rainforest, from shaded forest understories to abandoned clearings and large gaps. We asked if contrasting light environments can exert differential selection on ecophysiological traits of B. chilense. We measured phenotypic selection on functional traits related to carbon gain: photosynthetic capacity (A _max), dark respiration rate (R _d), water use efficiency (WUE), leaf size and leaf thickness in populations growing in gaps and understorey environments. We assessed survival until reproductive stage and fecundity (sporangia production) as fitness components. In order to determine the potential evolutionary response of traits under selection, we estimated the genetic variation of these traits from clonally propagated individuals in common garden experiments. In gaps, survival of B. chilense was positively correlated with WUE and negatively correlated with leaf size. In contrast, survival in shaded understories was positively correlated with leaf size. We found positive directional fecundity selection on WUE in gaps population. In understories, ferns of lower R _d and greater leaf size showed greater fecundity. Thus, whereas control of water loss was optimized in gaps, light capture and net carbon balance were optimized in shaded understories. We found a significant genetic component of variation in WUE, R _d and leaf size. This study shows the potential for evolutionary responses to heterogeneous light environments in functional traits of B. chilense, a unique fern species able to occupy a broad successional niche in Chilean temperate rainforest.     

Intraspecific variability in leaf traits strongly affects alder leaf decomposition in a stream

This study assessed the intraspecific variability of senescent leaves of alder (Alnus glutinosa Gaertn.) and the effects of this variability on leaf decomposition in streams. Leaves were collected at five geographically distant locations in Europe. We analyzed 10 batches of leaf samples for seven quantitative leaf traits as well as leaf decomposition rate in coarse and fine mesh bags exposed in a single stream. The geographic origin of leaf samples largely explained the observed variation in litter quality and decomposition rate. Phosphorus (0.034–0.187%) and lignin (3.9–18.7%) concentrations in leaves varied widely. Together, these two traits accurately predicted leaf decomposition rate (r²=84.1%). Intraspecific variation in leaf decomposition rate was within a range similar to that reported for interspecific variation among co-occurring riparian plant species in Europe. Our study demonstrates extensive intraspecific variability in leaf traits on a continental scale, which can have enormous effects on major ecosystem processes such as leaf decomposition.     

Contrastive seasonal changes in ecophysiological traits of leaves of two perennial Polygonaceae herb species differing in leaf longevity and altitudinal distribution

To identify the leaf characteristics associated with the difference in altitudinal distribution of Polygonaceae plants, we investigated the seasonal changes in leaf characteristics of co-occurring Aconogonum weyrichii and Reynoutria japonica at 2250 m a.s.l. on Mt. Fuji. Aconogonum weyrichii is distributed in the alpine region and R. japonica from the lowlands to the highlands. At the beginning of the growing period, leaves of A. weyrichii had larger amounts of nitrogen, Rubisco and higher photosynthetic capacity than R. japonica. The relationship between the amounts of nitrogen and Rubisco did not significantly differ between the species, but a higher Rubisco activity per unit Rubisco protein content was found in A. weyrichii, and was thought to be responsible for the high photosynthetic capacity of this species in summer. Activity of ascorbate peroxidase, a key enzyme of the hydrogen peroxide scavenging system against oxidative stress under chilling and light conditions, increased significantly in R. japonica late in the growing period, but did not significantly change in A. weyrichii. In A. weyrichii, rapid maturation of leaves and a high photosynthetic capacity are thought to be adaptive features for the short growing season in alpine regions. On the other hand, the slower accumulation of nitrogen and Rubisco during the early stage of the growing period in R. japonica resulted in insufficient utilization of the growing period for photosynthetic production and is thought to be one of the factors restricting the upper limit of its distribution.     

木兰科四种植物种子油的提取及脂肪酸成分分析

采用超声波辅助提取法和微波辅助提取法同时提取白玉兰、凹叶厚朴、深山含笑和醉香含笑四种木兰科植物的种子油,种子油甲酯化后,运用气相色谱—质谱联用技术测定其脂肪酸成分。结果表明:四种植物种子油的提取率不同,白玉兰平均为27.35%、凹叶厚朴23.34%、深山含笑31.66%,醉香含笑9.27%。不同提取方法所得到的种子油脂肪酸成分和相对含量不同,但四种种子油的主要脂肪酸成分相同,包括油酸、亚油酸、硬脂酸和棕榈酸。     

Geographical variability in ecophysiological traits controlling dormancy in Chrysopa oculata (Neuroptera: Chrysopidae)

Dormancy in Chrysopa oculata, a multivoltine species, is controlled by reponses to photoperiod and temperature. Variation in both the critical photoperiod for diapause induction and the duration of diapause is positively related to the latitudianl origin of the population. The incidence of photoperiodically induced diapause also varies geographically; at 24°C the southern-most population is more variable for diapause induction than the northern populations. By contrast, there is little interpopulation variation in thermally determined rates of post-diapause development. The results suggest that the lower threshold for development and the thermal requirements above the threshold may be functionally correlated.     

中国稻区的生物多样性

中国稻区生物多样性是指该区域各种生命形式的资源总和,包括遗传多样性、物种多样性、生态系统多样性及与此相关的各种生态过程。本文阐述了中国栽培稻、野生稻遗传资源及稻区生境动植物的多样性,初步探讨了稻区生物多样性丧失的原因及其保护措施。     

Intraspecific morphological divergence in two Cichlid species from Benin

Selection on morphological traits can vary across the range of species, inducing a mosaic of phenotypes across populations. Intraspecific morphological divergence had been demonstrated for many fish groups inhabiting environments with varying abiotic or biotic selective pressures. Such intraspecific phenotypic variation can have a strong influence on the ecologies of species. In the current study, we examined patterns of intraspecific morphological divergence between two populations of Sarotherodon melanotheron and Coptodon guineensis in Lake Ahémé and Porto-Novo lagoon, Benin. Using multiple morphological traits, we demonstrated intraspecific morphological divergence between Lake Ahémé and Porto-Novo lagoon for these species. However, evidence for parallel divergence was found for these two species, implying a similar response to selective pressures might have been acting on labile traits. In addition, species specific morphological changes observed in the current study might be because of differing responses to similar selective forces or taxon-specific selective forces acting on labile traits. The intraspecific trait divergence demonstrated in the current study suggests several possible selective pressures acting on these populations, yet the cause of this divergence remains unknown and additional studies are required to test these inferences.     

Selection on leaf ecophysiological traits in a desert hybrid Helianthus species and early-generation hybrids

Leaf ecophysiological traits related to carbon gain and resource use are expected to be under strong selection in desert annuals. We used comparative and phenotypic selection approaches to investigate the importance of leaf ecophysiological traits for Helianthus anomalus, a diploid annual sunflower species of hybrid origin that is endemic to active desert dunes. Comparisons were made within and among five genotypic classes: H. anomalus, its ancestral parent species (H. annuus and H. petiolaris), and two backcrossed populations of the parental species (designated BC2ann and BC2pet) representing putative ancestors of H. anomalus. Seedlings were transplanted into H. anomalus habitat at Little Sahara Dunes, Utah, and followed through a summer growing season for leaf ecophysiological traits, phenology, and fitness estimated as vegetative biomass. Helianthus anomalus had a unique combination of traits when compared to its ancestral parent species, suggesting that lower leaf nitrogen and greater leaf succulence might be adaptive. However, selection on leaf traits in H. anomalus favored larger leaf area and greater nitrogen, which was not consistent with the extreme traits of H. anomalus relative to its ancestral parents. Also contrary to expectation, current selection on the leaf traits in the backcross populations was not consistently similar to, or resulting in evolution toward, the current H. anomalus phenotype. Only the selection for greater leaf succulence in BC2ann and greater water-use efficiency in BC2pet would result in evolution toward the current H. anomalus phenotype. It was surprising that the action of phenotypic selection depended greatly on the genotypic class for these closely related sunflower hybrids grown in a common environment. We speculate that this may be due to either phenotypic correlations between measured and unmeasured but functionally related traits or due to the three genotypic classes experiencing the environment differently as a result of their differing morphology.     

Variation of thermal plasticity for functional traits between populations of an invasive aquatic plant from two climatic regions

Hydrobiologia - Temperature inducible phenotypic plasticity is a major player in plant responses to climate warming. Functional responses and their role in determining thermal plasticity of plants...     

中国木兰科植物爱威胁的状况及其保护措施

木兰科（Magnoliaceae)植物是原始的被子植物,中国是木兰科植物的起源中心,在地史上木兰科植物有过广泛分布,木兰科植物有重要经济作用。近年来,由于各地森林遭受强度破坏和碎化,许多种类的生存受到严重威胁。本文主要探讨中国木兰科植物的地理分布和区系性质,受威胁现状和保护措施,以及木兰科植物的开发利用等。     

Intraspecific functional differences of subalpine plant species growing in low-altitude microrefugia and high-altitude habitats

Plant Ecology - Mountain ice holes are microrefugia at low altitudes characterized by colder temperatures compared to the surrounding areas. Ice holes harbor extra-zonal plant communities composed...