Notes on the pollination biology of <Emphasis Type="Italic">Notylia nemorosa</Emphasis> (Orchidaceae): do pollinators necessarily promote cross pollination?

The pollination biology of Notylia nemorosa was elucidated from field and ex situ observations. Field observations were carried out in Minas Gerais, southeastern Brazil, where this orchid is pollinated by males of Eulaema nigrita(Euglossini). Plants cultivated in Campinas (S?o Paulo State, southeastern Brazil) were eventually pollinated by males of Eulaema nigrita and Euglossa melanothricha(Euglossini). In both cases, Euglossini males collect aromatic compounds produced on the surface of the lip, fix the pollinaria on the dorsal surface of the labrum and perform pollination. This species is protandrous. Recently opened flowers present their stigmatic surfaces blocked and thus flowers act only as pollen donors. After 2-3 days the viscidium dries out and pollinaria cannot be removed anymore. Then, a narrow slit opens in the stigmatic cavity, allowing pollen deposition. Experiments performed with cultivated plants suggest that this orchid species is strongly, though not completely self-incompatible. Pollination experiments showed that bees tend to stay several minutes in each inflorescence. This behavior may promote some degree of geitonogamous pollination because flowers in male and female phases coexist in the same inflorescence. The combination of self-incompatibility with this specific pollinator behavior may explain the rarity of fruits in several neotropical reward-offering Orchidaceae.     

A decision tool for listing species for protection on different geographic scales and administrative levels

An important task in conservation biology is to assess the spatial scale pertinent for species protection since some species may require protection throughout their distribution, others in only part of their range. Once this is done, species can be correctly identified for listing at different administrative levels (e.g. continental, national, and local). Here, we propose an objective method to list taxa at nested administrative levels based on three criteria (responsibility, rarity and vulnerability). We tested the method using quantitative data on the distribution, abundance and decline of orchids in France. The proposed method enables increased protection status in regions where species’ abundance and diversity are higher, gives priority to species for which an individual administrative unit has high responsibility and allows objective integration of species decline at different administrative levels. The method also enables the integration of locally rare species at their distribution limits and avoids repetition of species listing across second-level administrative units. The use of an objective method such as this could contribute to a standardised system of priority setting that integrates the geographic scale of rarity in relation to different administrative levels for protection.     

Habitat dependent pollination success in a Cape orchid

Summary We examined the pollination success of Disa uniflora (Orchidaceae) in two habitats. Plants occurring in a rocky gorge were far more successful than plants occurring in an adjacent open valley. More than 55% of flowers in the gorge were pollinated and set fruit compared with less than 25% of flowers in the valley. These differences are explained by the preference of Meneris tulbaghia (Satyridae), the exclusive pollinator of the orchid, for rocky, sheltered habitats. Fruit set of hand-pollinated flowers did not differ significantly between the two habitats, indicating that resources did not account for the variation in fruiting success.     

The relationship between biodiversity and population centres: the high Andes region as an example

Several coarse-scale studies have demonstrated a positive correlation between biodiversity and human population density. In this paper this relationship is studied for part of the Andean highland, on a finer spatial scale than in earlier studies, and comparing bird distribution data with pre-Columbian as well as contemporary population centres. A particularly close correspondence was found between ancient population centres and high numbers of species with small distributions. This suggests that the growth of resident human cultures was related, in some way, to local factors which—over a much longer time-scale—stimulated the process of evolution of new species. This correspondence may be a consequence of climate moderation in the mountain areas leading to local persistence, of wild species as well as human communities. However, the result also suggests that we need to study to what extent high biodiversity as such, under certain conditions, yields environmental services which were important for people. It also suggests that traditional efforts to preserve biodiversity in wilderness areas with few people should be supplemented with efforts to promote a more sustainable development in the populated areas, allowing cloud forest and other biologically rich habitats to persist in suitable places near population centres.     

Limitations on reproductive success in endemic <Emphasis Type="Italic">Aquilegia viscosa</Emphasis> (Ranunculaceae) relative to its widespread congener <Emphasis Type="Italic">Aquilegia vulgaris</Emphasis>: the interplay of herbivory and pollination

Plant reproduction can be strongly affected by herbivory and different features of pollination ecology, such as pollinator visitation rates and capacity for self-pollination. The purpose of this study is to compare the relative impact of herbivory and pollination on maternal reproductive success in endemic Aquilegia viscosa and its widespread congener Aquilegia vulgaris. We conducted herbivore exclusion experiments in two populations of each species in 2 different years and showed that the maternal fertility of A. viscosa was significantly more limited by floral predation and pre-dispersal seed predation than its widespread congener. In the absence of herbivory, A. viscosa retained significantly lower maternal fertility than A. vulgaris. Experimental pollinations in an insect-free glasshouse showed that the two species have an equal seed/ovule ratio both in the absence of pollinators and in the presence of non-limiting outcross pollination. Pollinator visitation rates were significantly higher in populations of A. vulgaris than in populations of A. viscosa. In addition, path analyses showed that spur length, an important trait for pollinator attraction in Aquilegia, and, indirectly sepal and petal width, contribute positively to the seed/ovule ratio in A. vulgaris, but not in A. viscosa. These results indicate that maternal fertility of endemic A. viscosa is strongly reduced by flower and seed predation despite low rates of pollinator visitation, and that pollen or resource limitation in the wild may further reduce maternal fertility. Finally, floral trait variation appears to be decoupled from fertility variation in endemic A. viscosa, which possibly constrains the evolution of reproductive traits in this species.     

UV reflectance but no evidence for colour mimicry in a putative brood-deceptive orchid Corybas cheesemanii

Rewardless orchids attract pollinators by food, sexual, and brood-site mimicry, but other forms of sensory deception may also operate. Helmet orchids （Corybas, Nematoceras and related genera） are often assumed to be brood-site deceivers that mimic the colours and scents of mushrooms to fool female fungus gnats （Mycetophilidae） into attempting oviposition and polli- nating flowers. We sampled spectral reflectances and volatile odours of an endemic terrestrial New Zealand orchid Corybas cheesemanii, and co-occurring wild mushrooms. The orchid is scentless to humans and SPME GC-MS analyses did not detect any odours, but more sensitive methods may be required. The orchids reflected strongly across all visible wavelengths （300-700nm） with peaks in the UV （-320nm）, yellow-green （500-600 nm） and red regions （650-700 nm）, whereas mushrooms and surrounding leaf litter reflected predominantly red and no UV. Rather than mimicking mushrooms, these orchids may attract pollinators by exploiting insects＇ strong sensory bias for UV. Modelling spectral reflectances into a categorical fly vision model and a generic tetrachromat vision model provided very different results, but neither suggest any mimicry of mushrooms. However, these models require further assessment and data on fly spectral sensitivity to red wavelengths is lacking - a problem given the predominance of red, fly-pollinated flowers worldwide     

Community studies in pollination ecology in the high temperate Andes of central Chile II. effect of temperature on visitation rates and pollination possibilities

Visitation rates and mean numbers of visits per flower per day are determined at three altitudinal levels (2 200–3 600 m) in the high Andes of central Chile from quantified observations of flowers visitors to a total of 134 species of plants, studied over three flowering seasons. Significant altitudinal decreases in the mean no. visits/flower/minute and per day were recorded, with Level III flowers, on the average, being pollinated only about 1/2 as frequently and to as low as 1/4 as frequently in certain months, as Level I flowers. Visitation rates are generally highest in early and mid-summer at all altitudes. — The lower visitation rates at the higher elevations are due to lower insect abundance relative to plant resources and lower levels of activity for the insects present, stemming from the generally lower ambient temperatures. Seasonal differences in visitation rates may also be related to differences in insect abundance levels. The total probability of ovule pollination cannot be estimated directly from the pollination rates, because stigmas are probably receptive for longer periods at the higher elevations. When differences in the duration of stigma receptivity are estimated from differences in flower lifelength, the probability of pollination in Level III is not very different from that expected in Level I. However, for some months, the deficit in Level III may still be substantial. — These results underline the inherent dangers of predicting pollination possibilities directly from pollination rates. They also suggest that the impoverished pollination conditions assumed in hypotheses predicting higher amounts of self-compatibility at high altitudes might not be justified for all high temperate mountains.First part of this series:Arroyo & al. (1982).     

Pollen and nectar as a reward in the basal epidendroid Psilochilus modestus (Orchidaceae: Triphoreae): A study of floral morphology, reproductive biology and pollination strategy

Psilochilus modestus Barb. Rodr. is a basal epidendroid orchid occurring in both the semi-deciduous and Atlantic rain forests of the state of São Paulo, southeastern Brazil. This species presents a perfect flowering synchrony within populations, since all the mature buds of each plant open simultaneously in the morning hours of the same day. These flowers are available only for 1 day and are pollinated by several species of small solitary and social native bees. These bees exploit both pollen and nectar as a reward. The bees collecting pollen promote a higher fruit set and perform mainly self-pollination while those collecting nectar, which are less numerous, are responsible for an increase in cross-pollinations. P. modestus is self-compatible but pollinator dependent. Natural fruit set (open pollination) is low when compared with the numbers obtained under manual self- and cross-pollination. Low fruit set in natural conditions is related to deficient pollen transfer, and pollinator inefficiency seems to be the main factor. Some factors, such as the small amount of nectar produced, the low number of flowers per inflorescence and their availability for 1 day only added to the perfect flowering synchrony seem to be responsible for the increase of cross-pollinations. The offering of both pollen and nectar as a reward can represent a transitional condition in basal Epidendroideae. Based on floral morphology, reward production and pollinator behavior, the relationship of P. modestus with the basal and most derived groups within Orchidaceae is discussed.     

Large-scale diversity patterns of vascular epiphytes in Neotropical montane rain forests

Aim Epiphytes contribute up to 30% to the number of vascular plant species in certain global biodiversity hotspots, e.g. the Ecuadorian Andes. However, their large scale diversity patterns are still discussed on the base of results from a few, local epiphyte inventories. Consequently, explanatory models on epiphyte diversity concentrate on the impact of local climate on small scale epiphyte species richness. Our aim was to analyse large scale elevational patterns of epiphyte diversity integrating data from different geographic scales. Location Tropical America, with special emphasis on the Ecuadorian Andes. Methods Our study is based on two data sources. First, we analysed the elevational patterns of epiphyte diversity based on the Catalogue of the Vascular Plants of Ecuador and the Libro Rojo de las Plantas Endèmicas del Ecuador. Secondly, the floristic turnover between the epiphyte inventories of seven montane and four lowland study sites in the Neotropics was analysed. Results The floristic turnover between Neotropical montane epiphyte floras is higher than the one between lowland epiphyte floras. Montane study sites located only a few kilometres apart from each other show considerable differences in their epiphyte species inventories. Irrespectively of their similar dispersal mode, the floristic turnover is much higher for orchids than for Pteridophyta. The Orchidaceae are the species richest group in all of the examined 11 Neotropical epiphyte floras. At the larger scale of the Ecuadorian Flora, c. 50% of the species in the elevational zone with maximum epiphyte diversity (between 1000 and 1500 m) are orchids. Elevational patterns of epiphyte diversity strongly reflect patterns of Orchidaceae. Main conclusions Our results support the observation of a ‘mid‐elevation bulge’ of epiphyte diversity by Gentry and Dodson. It has been frequently shown that the high humidity in mid‐elevations is suitable to maintan a high epiphyte species richness. Our findings show that in addition, large scale epiphyte diversity in montane rain forest is increased by the high floristic turnover at local and regional scale. Based on the importance of Orchidaceae for epiphyte diversity, we discuss that speciation processes corresponding to the highly diverse environment are a driving force for endemism, floristic heterogeneity and consequently for large scale epiphyte species richness in montane forests.     

Landscape diversity patterns and endemism of Araceae in Ecuador

Araceae is one of the largest herb families in tropical America, but its patterns of diversity and endemism are poorly known. We used predictive distribution modelling in GIS to study Araceae richness on a landscape scale in Ecuador. Modelling was based on georeferenced herbarium collections with humidity and mean annual temperature as climatic variables. Variation partitioning using multiple regression showed that humidity and altitude were main factors in explaining Araceae diversity patterns. Endemism was less well explained by present climatic factors. Unlike common diversity patterns of herbs or epiphytes, Araceae richness was highest in the eastern (Amazon) lowland rain forest with a secondary centre on the Andean foothills of northwestern Ecuador. The peak in endemism was on the western slopes of the Andes, corresponding to areas that have been severely affected by human activities and deforestation. Eastern lowland (Amazonian) forests were poor in endemic Araceae.     

Johansson revisited: the spatial structure of epiphyte assemblages

Question: Vertical zonation schemes are widely used in biodiversity studies with vascular epiphytes as a tool to capture spatial distribution patterns, the one most commonly used was proposed by Johansson more than 30 years ago. Does a survey of the epiphytes found on larger trees really yield a representative sample of the local community? Location: Lowland rainforest of the San Lorenzo Crane Plot, Republic of Panama. Methods: A complete census of the vascular epiphytes on all trees > 1 cm DBH in 0.4 ha of undisturbed lowland forest was analysed with both cluster and discriminant analysis to detect groupings of epiphyte species. Results: Six different groups of species were detected, five of them preferring different substrates on larger trees (as defined by (1) the height above ground at the attachment site, (2) the diameter of the substrate and (3) the occurrence on stem vs branches/twigs) and resembling to some extent the original Johansson zones. A sixth group of epiphytes, comprising ca. 10% of all taxa, was almost always found on small diameter stems and branches of trees with small DBH at lower and intermediate heights within the forest. Conclusions: Applying pre‐established zonation schemes may lead to misleading results in biodiversity studies with epiphytes. Important aspects of spatial distribution patterns may be missed, and the determination of relative species abundances may carry a strong quantitative and qualitative bias when analyses rely completely on epiphytic plants found on larger trees.     

九龙山濒危植物南方铁杉的生态位研究

采用生态位理论研究了南方铁杉在九龙山群落中的地位。结果表明：乔木层中,南方铁杉（Tsuga tchekiangensis）、猴头杜鹃（Rhododendron simiarum）、木荷（Schima superba）生态位宽度较大,它们之间的生态位相似性比例值较高,生态位重叠值较大;灌木层中,南方铁杉、猴头杜鹃、朱砂根（Ardisia crenata）、木荷、三角枫（Acer buergerignum）的生态位宽度较大,南方铁杉与这几个树种之间的生态位相似性比例值较高,生态位重叠值较大;这些分析结果为珍稀濒危植物南方铁杉种群数量的扩增具有一定的理论价值。     

两种鹪莺的种间生态位关系研究

本文研究了褐头鹪莺（Ｐｒｉｎｉａ ｓｕｂｆｌａｖａ）和黄腹鹪莺（Ｐ．ｆｌａｖｉｖｅｎｔｒｉｓ）在取食高度、取食基层和取食方法３个生态维度上的生态位宽度和生态位重叠以及它们与复合种群密度的关系。结果表明,两种鹪莺的现实生态位有较大的重叠,且种群密度变化时,生态位宽度和生态位重叠发生了显著移动,褐头鹪莺与黄腹鹪莺之 间存在着竞争;它们并没有采取生态位宽度来回避竞争,而是相反地各自扩展生态位宽度来减少重     

Ecological niche modeling as a predictive tool: silver and bighead carps in North America

The silver carp and bighead carp (Cyprinidae), native to eastern Asia, have been introduced into the United States in attempts to improve water quality in aquaculture ponds, reservoirs, and sewage pools. Escaped or released specimens from fish farms have been reported in many states, and both species are already locally established and spreading further. We used the Genetic Algorithm for Rule-set Prediction (GARP) to model the niches of these two carps in their native ranges using hydrologic and general environmental parameters in concert with native distributional data. The results accurately predicted native occurrence data withheld from the modeling process (P < 0.01). We then projected the niche models onto the North American landscape. Native niche range models significantly predicted known occurrence data from North American introductions (P < 0.001). Further, the models suggest that both species have the potential of spreading throughout the eastern U.S. and selected areas of the West Coast.