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1.
P. Convey 《Polar Biology》1994,14(1):65-69
Rates of dark respiration (DR), gross photosynthesis (GPS) and net photosynthesis (NPS) were investigated for 14 species of moss from a maritime Antarctic locality. The rates found were similar to those reported in studies of temperate, alpine and Arctic species, indicating no physiological specialisation to the Antarctic environment. There was no relationship between the habitat occupied by a species (hydric, mesic, xeric) and physiological measures. There was, however, a loose correlation between NPS and a species' ecology or reproductive behaviour in the maritime Antarctic — species with high NPS being either colonists or those that show high and regular investment in sporophyte production. 相似文献
2.
Anouchka Guyon-Debast Alain Lécureuil Sandrine Bonhomme Philippe Guerche Jean-Luc Gallois 《BMC plant biology》2010,10(1):158
Background
The proteasome subunit RPT5, which is essential for gametophyte development, is encoded by two genes in Arabidopsis thaliana; RPT5a and RPT5b. We showed previously that RPT5a and RPT5b are fully redundant in the Columbia (Col-0) accession, whereas in the Wassilewskia accession (Ws-4), RPT5b does not complement the effect of a strong rpt5a mutation in the male gametophyte, and only partially complements rpt5a mutation in the sporophyte. RPT5b Col-0 and RPT5b Ws-4 differ by only two SNPs, one located in the promoter and the other in the seventh intron of the gene. 相似文献3.
植物性状是植物对环境变化响应和适应的综合反映。目前对苔藓植物个体水平功能性状的研究较为匮乏。以安徽大龙山国家森林公园分布的东亚小金发藓(Pogonatum inflexum)雌株为例,在其孢子体成熟期测定地上部分孢子体和配子体的形态特征及生物量,系统分析了植株性状变异特征、异速生长关系及协变(整合)格局。结果表明,东亚小金发藓配子体形态性状变异性高于孢子体,且二者生物量变异系数最大。孢子体高度是配子体的2倍,但其生物量仅占地上部分的23%。孢子体和配子体功能性状之间有一定相关性;形态性状(Y)与生物量(X)之间多为指数<1.0异速生长关系,而孢子体和配子体生物量之间为等速生长关系(指数为1.135±0.158)。孢子体生物量分配比例随个体增大而显著减小,体现出显著的负的个体大小依赖。主成分分析表明,东亚小金发藓孢子体和配子体主要个体性状具有不同的协变方向(即两个不同的性状群),其中孢子体生物量是两类性状群的关键结点。综合来看,东亚小金发藓个体性状间具有与维管植物相似的协变关系。 相似文献
4.
《Journal of bryology》2013,35(2):107-117
AbstractContrary to the generally accepted hypothesis that bryophyte fertility decreases with increasing latitude and therefore climatic severity, a detailed study of bryophyte reproductive strategies at sites in the southern maritime Antarctic (68–72°S) has revealed that an unexpectedly high proportion of species is capable of producing sporophytes. Of the regional bryoflora, 43% (19 species; 17 mosses, 2 liverworts) in Marguerite Bay and 47% (17 species; 16 mosses, 1 liverwort) in Alexander Island are known to produce sporophytes, although the number fruiting at comparable latitudes on the colder and more arid Antarctic continent is less (33%). These numbers and proportions are much greater than were previously known at such relatively high southern polar latitudes. Sporophytes of several species are recorded for the first time within the Antarctic biome, while those of two liverworts (Lophozia excisa and Cephaloziella varians) are reported for the first time south of 62°S. High incidence of sporophyte production is attributed to locally favourable microclimatic conditions producing small-scale 'oases'. The large majority of fertile mosses are monoecious short acrocarps growing on rather calcareous soils. Spore production and size data for a number of species are compared with previously published studies of the same or closely related species from the northern maritime Antarctic and sub-Antarctic, but no consistent trends are revealed between species over the latitudinal gradient. 相似文献
5.
The terrestrial arthropod fauna of the Byers Peninsula,Livingston Island,South Shetland Islands 总被引:3,自引:2,他引:1
We report the first detailed study of the terrestrial invertebrate fauna of the Byers Peninsula SSSI, Livingston Island, South Shetland Islands. Fourteen micro-arthropod taxa (10 Acari, four Collembola) and two Diptera are recorded, including the first record of the mite Edwardzetes dentifer from the maritime Antarctic. The first record of the midge Belgica antarctica from neighbouring Snow Island is also given. Population composition and density were described in samples from a wide range of terrestrial and freshwater habitats. There was no strong relationship between habitat and microarthropod species occurrence, although comparison of completely vegetated and more stony sites revealed greater population densities at the vegetated sites, and different species proportions at each. Some individual samples contained a wide range of species with none achieving numerical dominance, whilst others from superficially similar sites were dominated by one species. Dipterans were limited to a small number of lakes, streams and seepage areas, where they were sometimes abundant. Population density data and species occurrence are compared with previously published studies from the maritime Antarctic and elsewhere. 相似文献
6.
Hiroshi Kawai 《Journal of phycology》1986,22(3):286-291
The life history in culture of Akkesiphycus lubricus Yamada et Tanaka, an alga which has been placed in the Coilodesmaceae or the Punclariaceae, Dictysiphonales, was studied. In culture the species alternates between a microscopic filamentous gametophyte and a macroscopic polystichous sporophyte, a pattern common to the Dictyasiphonales and Laminariales. However, it has a unique anisogamous dioecious gametophyte. Fusions between mac-ro-gametes and micro-gametes were not observed, Macro-gametes or zygotes germinated, mostly developing into sporophytes that formed unilocular sporangia and the rest developed into reduced gametophytic flaments again. The gametophyte matures in 50C short-day conditions, corresponding to winter in Hokkaido. The sporophyte develops normally and matures only in low-temperature conditions irrespective of daylength. In regard to iits systematic position, Akkesiphycus lubricus is considered to have a closer relationship with the Laminariales than with the Dietyosiphonales in the following characters; lack of pyrenoids; early stages of parenchyma formation in the sporophyte; direct development of sporophytes from gametes or zygotes without forming a besal system zoospore becomes almost empty after germination by the migration of cell contents into a germ lube; formation of macro-gametangia by direct conversions of mother cells of mother cells of fertile branches; and micro-gametangia formed in clusters showing closeresemblance to the antheridia of Pseudochorda nagii (Tokida) Inagaki. 相似文献
7.
当年生小枝具有较少的次生组织,同时是植物分支系统中最具活力的部分,木本植物当年生小枝性状与生物量分配的海拔变化是理解物种对不同生境适应策略的重要内容。通过分析青藏高原东缘岷江源区两种优势亚高山针叶乔木(紫果云杉和岷江冷杉)当年生小枝性状(茎长、茎粗、比茎长)与不同部位器官(茎、叶)的生物量随天然生境的海拔(3500-3550 m、3650-3700 m和3800-3850 m)变化,尝试揭示两物种当年生小枝在不同海拔下的生物量权衡及其生长策略。结果表明:(1)不同海拔下茎生物量种间差异大于种内差异,3650-3700 m处的茎生物量变异最大(128.4%)。(2)云杉的茎生物量、总叶生物量与海拔间存在显著的负相关关系(P<0.05),比茎长与海拔呈显著正相关(P<0.05);冷杉的总叶生物量与海拔间为显著负相关关系(P<0.05)。(3)随着海拔的升高,云杉茎生物量分配比逐渐从33.0%降低到27.0%;而冷杉的茎生物量分配比则从23.0%渐增至28.0%。(4)3500-3550 m和3650-3700 m两处的云杉茎生物量与总叶生物量、茎长与茎粗呈异速生长关系;3500-3550 m、3650-3700 m和3800-3850 m三处的冷杉茎生物量与总叶生物量、茎长与茎粗一直呈现异速生长关系。两种针叶树的茎生物量分配比及相关性状随海拔的变化差异表明冷杉更适应高海拔的胁迫环境。 相似文献
8.
以新疆准噶尔盆地藜科猪毛菜属植物紫翅猪毛菜(Salsola affinis C.A.Mey)、钠猪毛菜(Salsola nitraria Pall)为研究对象,用繁殖分配比例的方法对比分析了两种猪毛菜不同海拔同一种群内不同个体大小繁殖分配的特点,并用异速生长模型分析了不同海拔繁殖生物量与营养生物量之间分配与个体大小的依赖关系。结果发现:1)不同海拔繁殖生物量(R)与营养生物量(V)呈不同程度的异速生长。紫翅猪毛菜随海拔的升高R-V的异速生长斜率显著升高,截距随海拔的升高没有显著增加;而钠猪毛菜的斜率随海拔升高显著降低,截距则显著升高。2)紫翅猪毛菜在较低海拔个体大小与繁殖分配呈负相关,在较高海拔呈正相关;钠猪毛菜在较低海拔个体大小与繁殖分配呈正相关,在较高海拔呈负相关;两种猪毛菜繁殖分配的适应对策相反。3)将同一种群个体大小分成大、中、小3种类型,多重比较发现紫翅猪毛菜在较低海拔,中小个体的繁殖分配显著高于大个体的繁殖分配;在较高海拔,大个体的繁殖分配显著高于中小个体的繁殖分配。钠猪毛菜在较低海拔,大个体的繁殖分配显著高于中、小个体的繁殖分配;在较高海拔,小个体的繁殖分配显著高于大、中个体的繁殖分配。综合分析认为:两个物种随海拔变化产生不同的繁殖分配策略,除遗传效应外,环境和个体大小对钠猪毛菜繁殖分配的变化均产生重要影响,而紫翅猪毛菜繁殖分配的变化主要由海拔差异导致。由于微生境对同一种群的个体大小产生影响,进而产生不同的繁殖分配模式,所以在干旱区更应重视个体大小对繁殖分配的影响。 相似文献
9.
R. Froese 《Zeitschrift fur angewandte Ichthyologie》2006,22(4):241-253
This study presents a historical review, a meta‐analysis, and recommendations for users about weight–length relationships, condition factors and relative weight equations. The historical review traces the developments of the respective concepts. The meta‐analysis explores 3929 weight–length relationships of the type W = aLb for 1773 species of fishes. It shows that 82% of the variance in a plot of log a over b can be explained by allometric versus isometric growth patterns and by different body shapes of the respective species. Across species median b = 3.03 is significantly larger than 3.0, thus indicating a tendency towards slightly positive‐allometric growth (increase in relative body thickness or plumpness) in most fishes. The expected range of 2.5 < b < 3.5 is confirmed. Mean estimates of b outside this range are often based on only one or two weight–length relationships per species. However, true cases of strong allometric growth do exist and three examples are given. Within species, a plot of log a vs b can be used to detect outliers in weight–length relationships. An equation to calculate mean condition factors from weight–length relationships is given as Kmean = 100aLb?3. Relative weight Wrm = 100W/(amLbm) can be used for comparing the condition of individuals across populations, where am is the geometric mean of a and bm is the mean of b across all available weight–length relationships for a given species. Twelve recommendations for proper use and presentation of weight–length relationships, condition factors and relative weight are given. 相似文献
10.
At an early stage of growth gametophytes support the sporophytes of ferns. Young sporophytes become independent of gametophytes
when the first leaves develop. Although large fern gametophytes produce multiple archegonia simultaneously, only one sporophyte
is typically established on one gametophyte. The number of sporophytes is believed to be controlled in two possible directions,
from gametophyte to sporophyte or from preceding sporophyte to another sporophyte. To investigate the effects of gametophytes
on their sporophytes, we studied the relationship between organic matter production by gametophytes and the growth of young
sporophytes of Thelypteris palustris. We cut gametophytes in half (CGs) to reduce the gametophytes’ production of matter. There was no significant difference
between the growth of sporophytes on intact gametophytes (IGs) and that on CGs. According to our estimates, based on the rate
of organic matter production, the large gametophyte was able to produce two or more sporophytes. The resources required for
CGs to make similar-sized sporophytes was twice that for IGs. In polyembryony each of the multiple sporophytes was similar
in size to the single sporophytes. Resource limitation does not seem to explain why fern gametophytes establish single sporophytes. 相似文献
11.
David W. Bierhorst 《American journal of botany》1971,58(7):634-648
The gametophyte, old embryo, and sporophyte of Schizaea pseudodichotoma sp. nov., sporophyte and female parental gametophyte of S. diversispora hybr. nov. (S. pseudodicholoma X probably S. dichotoma), sporophyte of S. rhacoindusiata sp. nov., and gametophyte, old embryo, and sporophyte of Actinostachys macrofunda sp. nov. are described. The taxonomy of Schizaea is discussed and the system of Diels is strongly supported. The two sectional names used by Diels, Euschizaea Hook, and Lophidium Rich, are replaced by Pectinatae Prantl and Schizaea respectively. The prime morphological significance of Schizaea pseudodicholoma lies in its leafless embryo and its simple leaf differing from other species in its section, and that of Actinostachys macrofunda lies in its reduction to nearly complete heterotrophic existence and its frequent multiple annulus. Fungal hyphae have been traced from Schizaea and Actinostachys through the substratum and into root nodules of Casuarina and into roots of two other angiosperms. 相似文献
12.
Laboratory studies were used to examine how variation in the density of spore settlement influences gametophyte growth, reproduction, and subsequent sporophyte production in the kelps Pterygophora californica Ruprecht and Macrocystis pyrifera (L.) C. Ag. In still (non-aerated) cultures, egg maturation in both species was delayed when spores were seeded at densities 300 · mm?2. Although the density at which this inhibition was first observed was similar for both species, the age at which their eggs matured was not. P. californica females reached sexual maturity an average of 4 days (or ~ 30%) sooner than did M, pyrifera. As observed previously in field experiments, per capita sporophyte production was negatively density dependent for both species when seeded at spore densities of 10 · mm?2. Total sporophyte production (i.e. number · cm?2) for both species, however, was greatest at intermediate densities of spore settlement (~ 50 spores · mm?2). In contrast, total sporophyte production by P. californica steadily increased with increasing spore density in aerated cultures; highest sporophyte density was observed on slides seeded at a density of 1000 spores · mm?2. Preliminary experiments with P. californica involving manipulation of aeration and nutrients indicate that inhibition of gametophyte growth and reproduction at higher densities of spore settlement in non-aerated cultures was probably caused by nutrient limitation. 相似文献
13.
Bryopsidella ostreobiformis sp. nov. is presented as the second species of the genus. The latter is amended to accomodate this new species. The derbesioid sporophyte is capable of producing three- to eight-rayed stellate propagules. The dioecious gametophyte is a heterotrichous thallus with branched, prostrate filaments and unbranched, erect ones, and does not resemble Bryopsis. The life cycle is distinctly diplohaplontic, with a diploid sporophyte and a haploid gametophyte. B. ostreobiformis is postulated as the starting point of a hypothetical evolutionary sequence of life histories in the Derbesia/Bryopsis complex. 相似文献
14.
Zhe‐Xuan Fan Bao‐Ming Chen Hui‐Xuan Liao Guo‐Hao Zhou Shao‐Lin Peng 《Ecology and evolution》2019,9(20):11647-11656
Herbivory tolerance can offset the negative effects of herbivory on plants and plays an important role in both immigration and population establishment. Biomass reallocation is an important potential mechanism of herbivory tolerance. To understand how biomass allocation affects plant herbivory tolerance, it is necessary to distinguish the biomass allocations resulting from environmental gradients or plant growth. There is generally a tight balance between the amounts of biomass invested in different organs, which must be analyzed by means of an allometric model. The allometric exponent is not affected by individual growth and can reflect the changes in biomass allocation patterns of different parts. Therefore, the allometric exponent was chosen to study the relationship between biomass allocation pattern and herbivory tolerance. We selected four species (Wedelia chinensis, Wedelia trilobata, Merremia hederacea, and Mikania micrantha), two of which are invasive species and two of which are accompanying native species, and established three herbivory levels (0%, 25% and 50%) to compare differences in allometry. The biomass allocation in stems was negatively correlated with herbivory tolerance, while that in leaves was positively correlated with herbivory tolerance. Furthermore, the stability of the allometric exponent was related to tolerance, indicating that plants with the ability to maintain their biomass allocation patterns are more tolerant than those without this ability, and the tendency to allocate biomass to leaves rather than to stems or roots helps increase this tolerance. The allometric exponent was used to remove the effects of individual development on allocation pattern, allowing the relationship between biomass allocation and herbivory tolerance to be more accurately explored. This research used an allometric model to fit the nonlinear process of biomass partitioning during the growth and development of plants and provides a new understanding of the relationship between biomass allocation and herbivory tolerance. 相似文献
15.
Leaf meristems: an easily ignored component of the response to human disturbance in alpine grasslands 总被引:1,自引:0,他引:1
Grazing and fencing are two important factors that influence productivity and biomass allocation in alpine grasslands. The relationship between root (R) and shoot (S) biomass and the root:shoot ratio (R/S) are critical parameters for estimating the terrestrial carbon stocks and biomass allocation mechanism responses to human activities. Previous studies have often used the belowground:aboveground biomass ratio (Mb/Ma) to replace the R/S in alpine ecosystems. However, these studies may have neglected the leaf meristem biomass, which belongs to the shoot but occurs below the soil surface, leading to a significant overestimation of the R/S ratio. We conducted a comparative study to explore the differences between the R/S and Mb/Ma at both the species (Stipa purpurea, Carex moorcroftii, and Artemisia nanschanica) and community levels on a Tibetan alpine grassland with grazing and fencing management blocks. The results revealed that the use of the Mb/Ma to express the R/S appeared to overestimate the actual value of the R/S, both at species and community levels. For S. purpurea, the Mb/Ma was three times higher than the R/S. The Mb/Ma was approximately two times higher than the R/S for the species of C. moorcroftii and A. nanschanica and at the community level. The relationships between the R‐S and Mb‐Ma exhibited different slopes for the alpine plants across all the management practices. Compared to the fenced grasslands, the plants in the grazing blocks not only allocated more biomass to the roots but also to the leaf meristems. The present study highlights the contribution of leaf meristems to the accurate assessment of shoot and belowground biomasses. The R/S and Mb/Ma should be cautiously used in combination in the future research. The understanding of the distinction between the R‐S and Mb‐Ma may help to improve the biomass allocation mechanism response to human disturbances in an alpine area. 相似文献
16.
《Journal of bryology》2013,35(3):375-379
Abstract(1) The ratio of 14CO2 uptake of fully expanded capsules to that of corresponding gametophytes in the species studied was about 1 : 15 in Mnium hornum, 1 : 35 in Pleurldium acuminatum and around 1 : 1 in Funaria hygrometriea. (2) Translocation of photosynthate from gametophyte to sporophyte took place within 1 to 4 days of exposure to 14CO2; in expanded capsules the final activity was at least equal to that remaining in the gametophyte.(3) In M hornum there was no evidence of reverse translocation from sporophyte to gametophyte.(4) Translocation from gametophyte continued at a high level throughout the expansion and differentiation of the capsule in M. hornum. The activity reaching the sporophyte was approximately proportional to its fresh weight.(5) Both in situ photosynthesis and translocation to the capsule of F. hygrometrica rose to a maximum during the latter part of capsule expansion and ensuing differentiation, subsequently declining as the green tissues of the capsule senesced.(6) Fully expanded (but premeiotic) capsules of M. hornum contributed approximately 20% of the assiinilate necessary for their growth. The corresponding figure for P. acuminatum was about 10%, and for F. hygrometrica about 50%. 相似文献
17.
香根草(Vetiveria zizanioides)是一种良好的矿业废弃地生态修复物种,研究其生物量分配和异速生长关系,有助于深入了解香根草在矿区的生存策略与生态功能。该研究以贵州省六盘水市大河煤矿煤矸石山种植年限为4、5、8和15 a的香根草为对象,采用挖掘法和称重法对不同种植年限香根草的器官生物量、分配比例及异速生长关系进行了对比分析。结果表明:(1)随种植年限的增加,根、茎、叶生物量均呈现先增加后减少的趋势,且均在种植年限为5 a时最大,15 a时最小。(2)茎生物量分配比在种植年限15 a时最大(37.3%),叶生物量分配比在种植年限5 a时最大(36.1%),根生物量分配比不随种植年限的增加而发生变化,基本保持在30%左右。(3)种植年限为4、5、8 a时,地上部总生物量与根生物量、叶生物量呈异速生长关系;种植年限为5 a时,叶面积与根、叶生物量呈异速生长关系,与茎生物量呈等速生长关系。不同种植年限间的生物量分配及异速生长关系虽然没有一致规律,但体现了香根草在煤矸石基质中生物量分配的特点,且显示了其特别的生长方式和资源分配策略,为今后香根草在煤矸石山生态治理方面提供了参考依据。 相似文献
18.
Scinaia latifrons Howe is one of the main species in rhodolith beds between 30 and 90 feet; however, little known about the morphological changes of this species. Consequently, we investigated the phenological changes of the species at San Lorenzo channel from December 1998 to December 1999 (based on bi‐weekly sampling during the first 6 months and monthly sampling during the last part of the study). The gametophyte phase of the species is present from December to late May and the sporophyte potentially is present the rest of the year. The peak of the development occurs in April and reproduction occurs in small size plants with two cohorts in the period. This species presents an allometric growth pattern due to the lack of correlation between size and width of the plant or branching patterns. Our data suggest that temperature and light control the development of the plant. Furthermore, we found the spermatagonial structure in the same thallus as the female/carposporophyte plant indicating that this species is monoeious (contrary to what was considered previously). This suggests that some taxonomic problems are present in this species in relation with S. cottoni. 相似文献
19.
To test our hypothesis of hybrid formation involving the ‘independent gametophyte’ phenomenon in ferns, we identified the genomic formulae and ploidy level of gametophytes of the Vandenboschia radicans complex at the periphery of a sporophyte population. We identified haploid gametophytes of V. kalamocarpa (one of the two putative parents of V.×stenosiphon) in a hybrid sporophyte population in Japan that lacks fertile non‐hybrid individuals. Furthermore, diploid sporophytes of the species were not found within a 50‐km radius. This finding supports a hypothesis of hybridization involving the ‘independent gametophyte’ phenomenon and provides a new perspective on the geographical distribution of fern hybrids. 相似文献
20.
《Journal of bryology》2013,35(2):279-284
AbstractPhotosynthetic activity of attached sporophytes is very low (a few per cent or less) compared with that of associated gametophyte structures (perianth, bracts and uppermost leaves) in Cephalozia bicuspidata and Lophocolea heterophylla, or with even small areas of thallus in Pellia epiphylla. Photosynthetic uptake of 14CO2 by developing sporophytes of P. epiphylla, C. bicuspidata and L. heterophylla is at most a few per cent of the 14C translocated subsequently from the gametophyte, and could be negligible. In L. heterophylla, the perianth, bracts and uppermost leaves appear to play only a limited role in nutrition of the sporophyte, the leafy shoots making a major contribution. In C. bicuspidata the perianth and leaves of the short archegonial shoot may provide a substantial part of the nutrition of the sporophyte. There is some indication in all three species that translocation from the gametophyte is most active when the sporophyte reaches full size but is still green, declining in the final stages of maturation of the capsule. 相似文献