Alpine Botany最新文献

Luzula sect. Luzula is a taxonomically challenging group of angiosperms, whose evolutionary history has been shaped by polyploidy and agmatoploidy (fragmentation of holocentric chromosomes). Several species with different chromosome sizes and numbers, ranging from diploids to hexaploids, occur above the timberline in the Eastern Alps. Species of different ploidies frequently co-occur in the same habitats, but the extent of ecological divergence and niche partitioning among them remains elusive, partly due to their high morphological similarity impeding reliable identification. Here, we focused on three mixed-ploidy sites in the Eastern Alps, where the morphologically similar alpine species L. exspectata (diploid), L. alpina (tetraploid) and L. multiflora (its hexaploid populations) co-occur in close vicinity. We inferred their ploidy via flow cytometry and characterised their small-scale ecological preferences using different ecological indicators like mean Landolt indicator values of accompanying plant species. While diploid L. exspectata is associated with slightly more basic microsite conditions, as it mostly occurs over limestone, no such differentiation was observed between tetraploid L. alpina and hexaploid L. multiflora. We provide evidence for broader niches of tetraploids compared to diploids, whereas tetra- and hexaploids exhibited no differences in niche width. Our results indicate that small-scale co-occurrence of different cytotypes within Luzula sect. Luzula in alpine habitats is accompanied by only a slight niche partitioning, whereas there were significant differences in ecological parameters among the sites. These findings emphasise the influence of geography and geology on ecological microsite conditions and suggest that in this species group, local niche divergence between ploidies is negligible compared to site-specific effects. Different ploidies thus likely have more divergent ecology at a distribution-wide scale than at a local scale.

Studies of floral adaptations in response to divergent pollinators are important for understanding floral evolution and diversification of plants. A plant exposed to a variable pollinator climate is Cypripedium calceolus, a threatened lady's-slipper orchid. Insect pollinators are temporarily trapped in the pouch-like labellum and escape via one of two small posterior exit holes. In escaping, they pass the stigma and an anther, depositing and collecting pollen, respectively. Successful pollination is thought to depend on the morphological fit between pollinators and flowers, with particularly thorax and exit heights being key traits. Too small insects might neither touch the stigma nor collect pollen when exiting, and too large insects do not fit through the exit but leave the flower through the entrance hole or die inside. To discern the likelihood of floral adaptations in C. calceolus to varying pollinator assemblages, we investigated (a) whether floral, vegetative, and insect traits change in a concerted manner along an altitudinal gradient, and whether the morphological fit affects (b) the escape mode of a visiting insect and (c) its probability of exporting pollen. We found that floral and vegetative traits of C. calceolus got smaller with altitude, while insect dimensions were similar across the sites. Hymenoptera, the main visitors, were more likely to escape via the exit and to export pollen when the fit was near-exact. This shows that the morphological fit plays a critical role in the pollination of C. calceolus and that pollinators have the potential to drive size-related floral adaptations.

Due to habitat fragmentation and climate change, many plant populations become smaller and more isolated and thus more prone to local extinction. Whereas it is well established for lowland species that plants of small populations have lower individual fitness, alpine species have not been sufficiently studied in this respect. It is also not clear whether relationships between population size and fitness vary between naturally rare and common species. We assessed how population size and rarity affect seed set, seed mass, seed number, total seed mass per fruit, germination, time to germination, offspring survival and offspring size in four congeneric alpine plant species pairs (Androsace chamaejasme Wulfen, A. puberula Jord. & Fourr., Primulaceae; Gentiana acaulis L., G. alpina Vill., Gentianaceae; Potentilla crantzii (Crantz) Fritsch, P. nivea L., Rosaceae; Viola calcarata L., V. lutea Huds., Violaceae). Across all eight species, plants from smaller populations produced fewer seeds and had lower total seed mass per fruit than plants from larger populations. This demonstrates that population size also affects fitness in alpine species. Rare species did not have lower individual fitness than common species. Therefore, naturally rare species might be well adapted to their environment. Relationships between population size and fitness were equally pronounced in rare and common species. We conclude that plant fitness is reduced in small populations in alpine species, also in common species.

Puya raimondii Harms, an endangered giant bromeliad, has great ecological and cultural significance in the Central Andes. To help studies of population size structure in this species, this study proposes a rapid classification system based on plant developmental stages instead of using absolute size measurements, and applies it to three populations in the Cordillera Blanca, Peru. Plant height, stem height, total and photosynthetically-active rosette diameter and height to the base of the rosette were measured, to illustrate how the developmental stages compare. Five plant developmental stages were identified in the study: juvenile, subadult, adult, reproductive adult, and senescent reproductive adult. The juvenile stage could, in future, be further divided into smaller, vulnerable plants and more established juveniles, but this requires more detailed study to determine appropriate distinguishing developmental criteria. Comparing locations, Puya plants in Queshque were smaller than in the other locations, across all developmental stages. This study provides an efficient and informative classification system for P. raimondii giant rosettes, using well-defined developmental stages, that can reveal important differences between populations and prompt the generation of new hypotheses about the ecology of these important plants. The classification system could be applied in populations across the species’ distributional range in the Central Andes to explore how age, size and environmental factors affect growth and development in this species.

Understanding the relationships between functional traits and changes in the abundance of plant species is essential for estimating future species composition under climate change. Previous studies on the trait-based approach have attempted to explain plant performance using either aboveground or belowground traits at either the organ level or the whole-plant level. To understand the species-specific responses to climate change, however, it is crucial to examine various traits simultaneously and comprehensively, including both organ level and whole-plant-level traits of aboveground and belowground parts, within the same study. Changes in the abundance of plant species have been recorded in an alpine meadow of the Taisetsu Mountains, northern Japan, over a 40-year period. Based on the previous studies, we selected 4 species with decreasing trends and 8 species with increasing trend. Then, we compared 26 functional traits between the decreasing and increasing species to understand the underlying mechanisms that drove the different changes in abundance. Compared to the decreasing species, the increasing species had larger rhizomes and longer and thinner fine roots, suggesting that drought tolerance may be a key factor in understanding the differences in the abundance of alpine meadow plants. Our study demonstrated that belowground traits at the whole-plant level, as well as at the organ level, played essential roles in species-specific abundance changes in alpine meadow plants. This means that belowground traits are a crucial component predicting the changes in species diversity of alpine vegetation under global warming.

Plant-pollinator interactions are crucial for reproduction of both angiosperms and their pollinators, and consequently influence ecological and evolutionary dynamics of diverse ecosystems globally. These interactions range from specialized (involving few species) to generalized (involving many species), with the former being more vulnerable to disturbances because the loss of one member can lead to the disappearance of its mutualist. Thus, understanding the relationships of plant-pollinator interaction networks provide information about ecosystem resilience. It has been hypothesized that the tropics will have specialist pollination systems because of their higher diversity. However, little is known about pollination systems in the tropics, especially at high altitudes. We examined the plant-pollinator network within a Colombian páramo—an alpine tropical ecosystem—through a phytocentric sampling strategy spanning 22 months, including 305 h of direct observation and 3689 h of camera trapping, focusing on 36 common plant species. A total of 90 pollinator morphospecies were documented, including hummingbirds, bats, hymenopterans, dipterans, lepidopterans, coleopterans, and hemipterans. The network was modular (8 modules) and moderately specialized (H2′ = 0.45), yet with many generalist species (pollinator d′ = 0.36; plant d′ = 0.43), but low connectivity (0.10) and low nestedness (9.2). Modularity analysis identified 19 morphospecies pivotal to the network`s integrity including Bombus rubicundus as a network hub. Comparisons with Venezuelan and Costa Rican páramos suggest that the Colombian páramo's higher pollinator diversity may confer greater stability, though the potential loss of any of the hub and connector species could have cascading effects on extinction processes, making their conservation a priority.

Carex nigra is a widespread sedge in the northern hemisphere. Some subspecies have been proposed within C. nigra s.l., reflecting the complex morphological and biogeographical variability within the group. Given this variability and its widespread distribution, we aim to (i) study the phylogeography of C. nigra s.l. by reconstructing the evolutionary relationship of its populations across the entire range, (ii) study its genetic structure and demographic history, and (iii) model the species and main lineages niche and infer their potential distributions. We sequenced RADseq markers for 75 populations representatively covering the entire range of the species and addressed phylogenetic, genetic, and demographic analyses using the software IQTREE, Structure and G-PhoCS, respectively. We modelled species and main lineages potential distributions, including projections to the Pliocene and the Last Glacial Maximum (LGM) using different algorithms (Maximum Entropy algorithm (Maxent), generalized additive models (GAM), Random Forest and generalized linear models (GLM)). The phylogeny was retrieved with high support, confirming the monophyly of the species. We identified three main lineages that could be associated to three monophyletic subspecies: subsp. nigra, subsp. intricata and subsp. transcaucasica. The genetic analyses showed two and four optimal genetic clusters lacking any specific pattern, while the demographic analyses showed genomic migration events among the three subspecies. The species distribution models retrieved the potential distribution of C. nigra complex for the Pliocene and of the three subspecies for the present and the LGM. Additionally, we also recognize climatic refugia during the Quaternary glaciations which could have favored the diversification of the subspecies.