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1.
Developmental preformation is ubiquitous among alpine and arctic tundra plant species and may cause a delay in plant morphological responses to environmental variation. The duration of preformation and seasonal pattern of development were examined in Caltha leptosepala to identify characteristics of architecture and development that may influence the timing of plant responses to environmental cues, both within a single growing season and between years. All structures in C. leptosepala are preformed: leaves are initiated one or two growing seasons before they mature and flowers are initiated one growing season before maturation. Features of development and architecture in C. leptosepala, however, appear to differ from the determinate growth patterns of other exclusively preforming species, and may allow within-season variability in the seasonal development and maturation of structures. Cohorts of leaves initiated are asynchronous with maturation cohorts, and each year the number of leaf primordia per plant at snowmelt exceeds the number to mature aboveground. Therefore, some flexibility in whether leaves complete a 2-yr or 3-yr developmental trajectory might occur. Plasticity in reproductive phenotype might also occur via the process of floral abortion. Despite developmental characteristics that might facilitate the expression of phenotypic plasticity, only slight variability was observed in the duration of preformation or in the seasonal pattern of initiation and emergence of structures. Growth patterns of C. leptosepala thus appear to be fundamentally constrained, and limitations to annual growth may assure that sufficient preformed primordia remain belowground at the end of each growing season for maturation of a full cohort during the subsequent season. 相似文献
2.
Extreme preformation, the initiation of leaves or inflorescences more than 1 yr before maturation and function, is common in arctic and alpine habitats. This extended pattern of development provides a potential means to alleviate an apparent asynchrony between carbon supplied by photosynthesis in the summer and carbon demanded by growth in the spring. Allocation of resources to preforming organs has not been studied in herbs with multi-year patterns of preformation. Acomastylis rossii (Rosaceae) in the southern Rockies initiates leaves and inflorescences 2 yr prior to their maturation and function. Allocation to preforming organs in A. rossii was studied by means of a labeled carbon pulse chase experiment. During the summer, carbon is allocated directly to preforming organs and rhizomes from the mature leaves. Additional allocation of carbohydrate into preforming organs occurs in autumn after photosynthesis by mature leaves has ceased. Organ primordia initiated in the second year do not receive a substantial quantity of the labeled carbon from reserves stored in the rhizome the previous year. We conclude that concurrent photosynthesis is the primary source of carbon for preformation development. 相似文献
3.
Effects of temperature and date of snowmelt on growth, reproduction, and flowering phenology in the arctic/alpine herb, Ranunculus glacialis 总被引:1,自引:0,他引:1
Changes in growing season temperature and duration may have profound effects on the population dynamics of arctic and alpine plant species in snow-bed and fell-field habitats. We examined how a typical herbaceous pioneer species, Ranunculus glacialis, responded to experimental climate change in open-top chambers for three seasons at an alpine site in southern Norway. Warming had no significant effect on any reproductive, growth or phenological variables, except for seed weight, which increased significantly during the first 2 ears. Despite large differences in average date of snowmelt among years, average reproductive output and ramet size differed little among years. Within-year variation in date of snowmelt had no impact on seed number or weight in either control or warmed plots. Leaf width and ramet leaf number decreased significantly with later snowmelt within a year. Experimental warming reduced the negative effect on ramet size of late snowmelt within a year to some extent. In general, R. glacialis reacts contrary to most other arctic/alpine species to experimental warming. Species with such low responsiveness to environmental conditions may be particularly vulnerable to climatic change, especially if their habitat is invaded by other species with higher phenotypic plasticity and a better competitive ability. 相似文献
4.
Preformation of organs involves the initiation of vegetative and generative tissues at least one season before they are actually produced. It is a strategy to deal with environments characterized by predictable seasonality as it enables fast growth of plants at the onset of favorable conditions. However, early preformation also strongly restricts plants in their response to unpredictable environmental changes and disturbance. In this study we investigated the response of the clonal forest understory herb Uvularia perfoliata to disturbance and resource limitation. In U. perfoliata shoot characteristics, as well as vegetative and sexual reproduction are determined at the end of the previous growing season. Plants were grown under two light levels and the rhizome connection between parent and offspring ramets were severed at various times during the growing period. Disturbance did not affect total biomass accumulation but it did affect the relative allocation and survival probability of parents and offspring ramets. Early severing resulted in increased survival chance and future fitness of the parent ramet, while late severing resulted in a higher survival chance and increased fitness of offspring ramets. The response was mediated by plant size and resource availability. These results show that the life history of U. perfoliata includes the possibility to alleviate the effects of disturbance even though the species is characterized by strong developmental canalization through organ preformation.Co-ordinating editor: J. Tuomi 相似文献
5.
The strategy of resource allocation between vegetative and reproductive functions, quantitative relationship between size and reproductive output are central aspects of plant life history. To test the tactics of resource allocation and its altitudinal trend, we examined the reproductive allocation (RA) of Bergenia purpurascens (Saxifragaceae), in six populations along a shady slope in Sejila Mountain of southeast Tibet, at an altitude gradient from 4 200 m to 4 640 m. Our results showed that (1) with increasing altitude, vegetative biomass, reproductive biomass, total aboveground biomass, flower number per plant and length of flower stalk decreased significantly, but the number of leaves did not change greatly. However, the change of RA did not show a monotonic trend when altitude increased, shifting from significantly decreasing below the tree line to slightly increasing above it; (2) vegetative biomass was positively correlated with reproductive biomass, but negatively correlated with RA in all populations, but the level of significance was different among the populations; (3) RA decreased with individual size in all populations, whereas the relationship between absolute resource allocated to reproduction and individual size was allometric; (4) reproductive allometry and a size threshold for reproduction did exist in this alpine perennial, but the obvious altitudinal trend was only found along the populations below the tree line, not above it. We then concluded the altitude could not fully explain the change of resource allocation strategy of this alpine perennial, and different effects of size and habitat on RA may result from various environmental constraints along the altitudinal gradient or genetic background. Therefore, each individual within a population will follow its own developmental trajectory shaped by its genotype and the habitats. The most innovative finding was plant adaptation and resource trade off might be sharply altered at the tree line, which is a sensitive area in alpine mountains. Further investigations are needed to better understand the relationship between the reproductive allocation and changing environmental conditions. 相似文献
6.
岩白菜(虎耳草科)不同海拔居群的繁殖分配 总被引:8,自引:0,他引:8
资源分配策略是植物生活史研究的重要内容之一,植物用于繁殖的相对资源比例(即繁殖分配)与植株的生活史特征、个体大小及植株的生境密切相关。本文研究了藏东南色季拉山一个阴坡上海拔4200m~4640m范围内6个不同居群的虎耳草科多年生草本植物岩白菜(Bergenia purpurascens)的繁殖分配特征,结果发现:(1)繁殖器官生物量、营养器官生物量、地上部分总生物量、花数目、花序轴长度均随海拔的升高而显著降低,而叶数目随海拔变化不大,繁殖分配值则先降低后升高,转折点在林线过渡带(海拔4400m)处;(2)各居群(海拔4300m居群除外)营养器官生物量与繁殖器官生物量均显著正相关,而营养器官生物量与繁殖分配则负相关,但各居群的显著性不同;(3)各居群繁殖器官生物量与植株个体大小(营养器官生物量)呈不同程度的异速增长,而繁殖分配则与植株个体大小负相关;(4)各居群植株都存在一个繁殖所需的个体大小阈值,而且这一阈值在林线以下区域随海拔的升高而显著增大,在林线以上区域变化不显著。研究结果表明,海拔并不是影响岩白菜繁殖分配策略的唯一生态因子,不同居群的生境状况和植株个体大小都与其资源分配策略密切相关,高山地区林线的存在对植物资源的权衡方式会产生巨大影响。 相似文献
7.
8.
Terminal meristems of Pisum sativum (garden pea) transit from vegetative to inflorescence development, and begin producing floral axillary meristems. Determination for inflorescence development was assessed by culturing excised buds and meristems. The first node of floral initiation (NFI) for bud expiants developing in culture and for adventitious shoots forming on cultured meristems was compared with the NFI of intact control buds. When terminal buds having eight leaf primordia were excised from plants of different ages (i.e., number of unfolded leaves) and cultured on 6-benzylaminopurine and kinetin-supplemented medium, the NFI was a function of the age of the source plant. By age 3, all terminal buds were determined for inflorescence development. Determination occurred at least eight nodes before the first axillary flower was initiated. Thus, the axillary meristems contributing to the inflorescence had not formed at the time the bud was explanted. Similar results were obtained for cultured axillary buds. In addition, meristems excised without leaf primordia from axillary buds three nodes above the cotyledons of age-3 plants gave rise to adventitious buds with an NFI of 8.3 ±0.3 nodes. In contrast seed-derived plants had an NFI of 16.5 ±0.2. Thus cells within the meristem were determined for inflorescence development. These findings indicate that determination for inflorescence development in P. sativum is a stable developmental state, separable from determination for flower development, and occurring prior to initiation of the inflorescence at the level of meristems. 相似文献
9.
10.
Heather A. Bechtold Tara A. Forbis William D. Bowman Pamela K. Diggle 《Nordic Journal of Botany》2002,22(3):361-368
Phenotypic plasticity is predicted to be highly advantageous to alpine plants because of the extreme spatial and temporal heterogeneity of the alpine environment. Alpine plants are constrained in their vegetative plasticity by developmental preformation, however, they have the potential for reproductive plasticity via abortion of reproductive structures. Saxifraga rhomboidea Greene (Saxifragaceae) is a perennial of alpine dry meadows. It lacks a mechanism for vegetative reproduction, therefore, seed production is particularly important in maintaining populations of this species. Using long-term fertilized plots at the Niwot Ridge Long-Term Ecological Research Site, we ask if fertilization has changed the abundance of S. rhomboidea , and if S. rhomboidea has shown a plastic reproductive response to nutrient additions. Despite a pronounced increase in community biomass, we found that abundance of S. rhomboidea was not affected by fertilization. Moreover, S. rhomboidea showed no plastic response in seed to ovule ratio or other reproductive measures. Other arctic and alpine species have shown the potential for plasticity of maternal investment; S. rhomboidea appears to lack this reproductive plasticity. We suggest that morphological constraints may limit plasticity in this species. 相似文献
11.
When resource availability changes frequently and unpredictably, natural selection favors flexible resource allocation; however, such versatility may be compromised in perennial plants that differentiate leaves or flowers a year in advance of their development (preformation). We investigated resource allocation by the carnivorous perennial Pinguicula vulgaris to determine whether increased resource availability changes within-season allocation to growth, vegetative propagation, and reproduction. In response to resource supplementation (feeding with fruit flies), plants attained a mass 60% greater than that of unfed plants after a single growing season. Feeding also enhanced vegetative propagation, which is closely associated with growth, without modifying relations between these two vegetative functions. In contrast, feeding did not alter the size of vegetative rosettes or the within-season incidence of either flowering or fruiting. This lack of immediate responses occurred because floral and leaf primordia differentiated up to 10 mo before resource supplementation and flower development. However, enhanced resource status likely affected future reproduction indirectly through resource effects on plant size. Large plants produced more floral primordia and between-year changes in fruiting status corresponded to changes in plant size. These results illustrate that preformation can delay responses to enhanced resources by perennial plants. 相似文献
12.
Regulation of developmental transitions 总被引:4,自引:0,他引:4
Plants undergo a series of profound developmental changes throughout their lifetimes in response to both external environmental factors and internal intrinsic ones. When these changes are abrupt and dramatic, the process is referred to as phase change. Recently, several genes have been discovered that play a role in these developmental transitions. Their sequence and expression patterns shed new light on the mechanisms of phase change, and provide a link between the external and internal factors that control them. Examples of these transitions include changes from juvenile to adult leaf formation, vegetative to inflorescence meristem development, and inflorescence to floral meristem initiation. 相似文献
13.
Morphogenesis of floral structures, dynamics of reproductive development from floral initiation until fruit maturation, and leaf turnover in vegetative short-stem shoots of Saxifraga oppositifolia were studied in three consecutive years at an alpine site (2300 m) and at an early- and late-thawing subnival site (2650 m) in the Austrian Alps. Marked differences in the timing and progression of reproductive and vegetative development occurred: individuals of the alpine population required a four-month growing season to complete reproductive development and initiate new flower buds, whereas later thawing individuals from the subnival sites attained the same structural and functional state within only two and a half months. Reproductive and vegetative development were not strictly correlated because timing of flowering, seed development, and shoot growth depended mainly on the date of snowmelt, whereas the initiation of flower primordia was evidently controlled by photoperiod. Floral induction occurred during June and July, from which a critical day length for primary floral induction of about 15 h could be inferred. Preformed flower buds overwinter in a pre-meiotic state and meiosis starts immediately after snowmelt in spring. Vegetative short-stem shoots performed a full leaf turnover within a growing season: 16 (+/-0.8 SE) new leaves per shoot developed in alpine and early-thawing subnival individuals and 12 (+/-1.2 SE) leaves in late-thawing subnival individuals. New leaf primordia emerged continuously from snowmelt until late autumn, even when plants were temporarily covered with snow. Differences in the developmental dynamics between the alpine and subnival population were independent of site temperatures, and are probably the result of ecotypic adaptation to differences in growing season length. 相似文献
14.
Lorne M. Wolfe 《American journal of botany》1992,79(11):1286-1290
A commonly observed pattern in plants is that the size of some reproductive structures declines through a single flowering season. The experimental design of this study allowed me to determine whether architectural constraints or resource limitation is responsible for the seasonal declines in flower size, inflorescence size, and seed weight in the biennial Hydrophyllum appendiculatum (Hydrophyllaceae). Plant resource status was manipulated by varying the number of inflorescences pollinated (two vs. all). Architectural constraints were inferred by comparing the rates of decline in size of reproductive structures in plants that underwent either high or low pollination intensity. The data demonstrated that the relative importance of resource limitation and developmental constraints is trait-specific. Even when not resource stressed, all traits exhibited a seasonal decline, demonstrating that ontogenetic changes occurred in plant architecture. Yet, for two traits, inflorescence size and seed weight, the temporal decline was significantly more severe for heavily pollinated plants. In contrast, the decline in flower size through time was identical in both pollination treatments. Thus, the size of flowers is buffered from the resource status of the plant. These findings illustrate the importance of considering the physical limitations of plant architecture when investigating patterns of plant reproduction. 相似文献
15.
开花物候及繁殖分配是植物适应环境的重要因素,为了解长期冬季水淹对三峡库区耐淹物种秋华柳(Salix variegata Franch.)繁殖的影响,研究了长期冬季水淹条件下秋华柳的开花物候和繁殖分配情况。实验在2006年11月份设置了如下处理:对照,完全水淹(植株置于水中,顶部距水面2m)30,60,90,120d和150d。结果表明:(1)对照及各水淹处理的秋华柳花期都较长,在7-11月份持续开花,个体开花进程(开花振幅曲线)呈单峰曲线。(2)冬季水淹对秋华柳群体及个体的开花物候有显著影响。水淹时间越长,始花期越晚,花期持续时间越短(P0.05)。(3)长期冬季水淹下,秋华柳显著降低了繁殖分配比例和全株生物量及单株花序数(P0.05)。(4)开花物候指数与繁殖分配的相关分析表明:始花时间越晚的个体,花期持续时间越短。花期持续时间越短的个体花序数越少,致使繁殖分配越小。总的来说,冬季水淹下,秋华柳通过推迟开花日期、缩短花期持续时间使繁殖分配比例降低,将更多的资源分配到生存力上,是秋华柳对长期冬季水淹的一种适应。同时,在长期冬季水淹后,秋华柳仍保持一定的开花繁殖能力,是其在应用于三峡水库消落区植被构建后产生后代延续种群的前提条件。 相似文献
16.
Mean leaf inclination of the arctic and alpine shrub Dryas octopetala is a function of latitude and this functional relationship is consistent with a model that maximizes photosynthesis of the total plant canopy. 相似文献
17.
Developmental preformation can constrain growth responses of shoots to current conditions, but there is potential for flexibility in development preceding formation of the preformed organs. Mayapple (Podophyllum peltatum) is strongly heteroblastic, producing rhizome scales, bud scales, and either a single vegetative foliage leaf or two foliage leaves on a sexual shoot. To understand how and when preformation constrains growth responses, we compare (1) how leaf homologs of the renewal shoot differ in development, (2) whether there are differences in shoot development that occur in advance of morphological determination of shoot type, and (3) whether there are points of developmental flexibility in renewal shoot growth prior to preformation of the foliage and floral organs. We use scanning electron microscopy and histology to show that the three vegetative leaves (both types of scale leaves and the vegetative foliage leaf) are similar in the initial establishment of an encircling and overarching leaf base. Differences among them are found in the timing of differentiation of the leaf base and in the relative timing and degree of growth of the lamina and petiole. In contrast, foliage leaves on sexual shoots show less expression of the leaf base and precocious growth of the lamina and petiole. Prior to shoot type determination, there are no morphological differences in the sequence or position of leaf homologs that predict final shoot type. In this colony, leaves at positions 12 and 13, on average, appear to be identical in development until they are between 700 and 800 μm in length, when it becomes possible to distinguish leaves that will become vegetative foliage leaves from additional bud scale leaves on vegetative or sexual shoots. We suggest that late developmental determination of leaves at positions 12 and 13 reflects ontogenetic sensitivity to a transition to flowering. Thus, in mayapple, heteroblasty appears to facilitate developmental flexibility prior to the point where shoot growth becomes constrained by preformation of determined aerial structures. 相似文献
18.
Environmental changes are likely to alter the chemical composition of plant tissues, including content and concentrations
of secondary compounds, and thereby affect the food sources of herbivores. After 10 years of experimental increase of temperature,
nutrient levels and light attenuation in a sub-arctic, alpine ecosystem, we investigated the effects on carbon based secondary
compounds (CBSC) and nitrogen in one dominant deciduous dwarf shrub, Salix herbacea × polaris and two dominant evergreen dwarf shrubs, Cassiope tetragona and Vaccinium vitis-idaea throughout one growing season. The main aims were to compare the seasonal course and treatment effects on CBSC among the
species, life forms and leaf cohorts and to examine whether the responses in different CBSC were consistent across compounds.
The changes in leaf chemistry both during the season and in response to the treatments were higher in S. herbacea × polaris than in the corresponding current year’s leaf cohort of the evergreen C. tetragona. The changes were also much higher than in the 1-year-old leaves of the two evergreens probably due to differences in dilution
and turnover of CBSC in growing and mature leaves paired with different rates of allocation. Most low molecular weight phenolics
in the current year’s leaves decreased in all treatments. Condensed tannins and the tannin-to-N ratio, however, either increased
or decreased, and the strength and even direction of the responses varied among the species and leaf cohorts, supporting views
of influential factors additional to resource-based or developmental controls, as e.g. species specific or genetic controls
of CBSC. The results indicate that there is no common response to environmental changes across species and substances. However,
the pronounced treatment responses imply that the quality of the herbivore forage is likely to be strongly affected in a changing
arctic environment, although both the direction and strength of the responses will be different among plant species, tissue
types and substances. 相似文献
19.
Niklas J. Wickander Pil U. Rasmussen Bryndís Marteinsdóttir Johan Ehrlén Ayco J. M. Tack 《Oikos》2021,130(2):211-218
The arctic and alpine regions are predicted to experience some of the highest rates of climate change, and the arctic vegetation is expected to be especially sensitive to such changes. Understanding the ecological and evolutionary responses of arctic plant species to changes in climate is therefore a key objective. Geothermal areas, where natural temperature gradients occur over small spatial scales, and without many of the confounding environmental factors present in latitudinal and other gradient studies, provide a natural experimental setting in which to examine the response of arctic–alpine plants to increasing temperatures. To test the ecological and evolutionary response of the circumpolar alpine bistort Persicaria vivipara to temperature, we collected plant material and soil from areas with low, intermediate and high soil temperatures and grew them at three different temperatures in a three-factorial growth chamber experiment. At higher experimental soil temperatures, sprouting was earlier and plants had more leaves. Sprouting was earlier in soil originating from intermediate temperature and plants had more leaves when grown in soil originating from low temperatures. We did not find evidence of local adaptation or genetic variation in reaction norms among plants originating from areas with low, intermediate and high soil temperature. Our findings suggest that the alpine bistort has a strong plastic response to warming, but that differences in soil temperature have not resulted in genetic differentiation. The lack of an observed evolutionary response may, for example, be due to the absence of temperature-mediated selection on P. vivipara, the low rate of sexual recombination, or high levels of gene flow balancing differences in selection. When placed within the context of other studies, we conclude that arctic–alpine plant species often show strong plastic responses to spring warming, while evidence of evolutionary responses varies among species. 相似文献
20.
Distribution and population structure of the anther smut Microbotryum silenes‐acaulis parasitizing an arctic–alpine plant
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Britta Bueker Chris Eberlein Pierre Gladieux Angela Schaefer Alodie Snirc Dominic J. Bennett Dominik Begerow Michael E. Hood Tatiana Giraud 《Molecular ecology》2016,25(3):811-824
Cold‐adapted organisms with current arctic–alpine distributions have persisted during the last glaciation in multiple ice‐free refugia, leaving footprints in their population structure that contrast with temperate plants and animals. However, pathogens that live within hosts having arctic–alpine distributions have been little studied. Here, we therefore investigated the geographical range and population structure of a fungus parasitizing an arctic–alpine plant. A total of 1437 herbarium specimens of the plant Silene acaulis were examined, and the anther smut pathogen Microbotryum silenes‐acaulis was present throughout the host's geographical range. There was significantly greater incidence of anther smut disease in more northern latitudes and where the host locations were less dense, indicating a major influence of environmental factors and/or host demographic structure on the pathogen distribution. Genetic analyses with seven microsatellite markers on recent collections of 195 M. silenes‐acaulis individuals revealed three main genetic clusters, in North America, northern Europe and southern Europe, likely corresponding to differentiation in distinct refugia during the last glaciation. The lower genetic diversity in northern Europe indicates postglacial recolonization northwards from southern refugia. This study combining herbarium surveys and population genetics thus uniquely reveals the effects of climate and environmental factors on a plant pathogen species with an arctic–alpine distribution. 相似文献