Group: FAB-lab - with tag pdfi [164 articles]

Abstract

Species co-occurrence at fine spatial scales is expected to be nonrandom with respect to phylogeny because of the joint effects of evolutionary (trait convergence and conservatism) and ecological (competitive exclusion and habitat filtering) processes. We use data from 11 existing vegetation surveys to test whether co-occurrence in schoenoid sedge assemblages in the Cape Floristic Region shows significant phylogenetic structuring and to examine whether this changes with the phylogenetic scale of the analysis. We provide evidence for phylogenetic overdispersion in an alliance ...

Abstract

Pollination of a total of 155 plant species was evaluated monthly in relation to flowering phenology, habitats, and life forms in the Venezuelan Central Plain. The relationships between flowering phenology and pollinating agent classes and their abundance were evaluated. The total number of pollinating agent classes was significantly correlated with the number of plant species for habitats and life forms, and at the community level. The number of pollinating agent classes did not change statistically with respect to flowering phenology for ...

Abstract

We surveyed rarity in the vascular plants of the continental U.S.A. and Canada and the vascular plants of Hawaii to test the hypothesis that rates of rarity are independent of taxonomic group size. We demonstrated that taxonomic groups of plants with few species consistently contained fewer than the expected numbers of rare species. This pattern was apparent at the levels of genus, family, order and class. We also found that the pattern remained when we examined rates of rarity by comparing ...

Abstract

Interactions with animals are potentially important in shaping the life histories of plants. However, we still largely lack the quantitative information that is necessary to compare plant-animal interactions and plant life histories. This is because most studies have focused on only a single interaction and a single component of fitness. This review suggests a protocol for how plant-animal interactions, as well as other, interactions can be quantitatively investigated. I review results from the forest herb Lathyrus vernus to examine how plant performance ...

Abstract

Growing evidence of morphological diversity in angiosperm flowers, seeds and pollen from the mid Cretaceous and the presence of derived lineages from increasingly older geological deposits both imply that the timing of early angiosperm cladogenesis is older than fossil-based estimates have indicated. An alternative to fossils for calibrating the phylogeny comes from divergence in DNA sequence data. Here, angiosperm divergence times are estimated using non-parametric rate smoothing and a three-gene dataset covering ca. 75% of all angiosperm families recognized in recent ...

Abstract

We studied the pollination ecology and assemblage structure of 31 species of Stylidium (Stylidiaceae) at 25 sites in Western Australia. The number of species per study site varied between two and size. Stylidium species are pollinated by a variety of nectar-seeking solitary bees and bombyliid flies. Within and among species there is significant variation in nectar-tube length (and therefore in the insects that visit the flowers) and in pollen placement on pollinators. Pollen is placed "explosively" on the insect by a ...

Abstract

The frequency distribution of numbers of species in taxonomic groups, where many species belong to a few very diverse higher taxa, is mirrored by that of species in most communities, where many individuals belong to a few very abundant species. Various hypotheses mechanistically link a species' community abundance with the diversity of the higher level taxon (genus, family, order) to which it belongs, but empirical data are equivocal about general trends in the relation between rank-taxon diversity and mean abundance. One ...

Abstract

The specialist bee, Hoplitis anthocopoides, foraged for pollen from Echium vulgare, its preferred plant, more efficiently than did four generalist species. Efficiency was measured as the weight of pollen (the larval food) harvested from Echium flowers per unit handling time, divided by the weight of the discrete pollen mass required to rear one offspring. This measure of efficiency corresponds more closely to reproductive output than does the usual measure, net energy gained per unit time. The specialists produced more potential offspring ...

Abstract

Organisms experience a complex suite of species interactions. Although the ecological consequences of direct versus indirect species interactions have received attention, their evolutionary implications are not well understood. I examined selection on floral traits through direct versus indirect pathways of species interactions using the plant Ipomopsis aggregata and its pollinators and nectar robber. Using path analysis and structural equation modeling, I tested competing hypotheses comparing the relative importance of direct (pollinator-mediated) versus indirect (robber-mediated) interactions to trait selection through female plant ...

Abstract

Pollination biology at the community level was investigated using quantitative techniques, comparative methodology, measurements of the physical habitat, and consideration of floral characteristics. The frequency of insect visits to flowers was investigated in three contrasting communities: a deciduous woodland-meadow site in eastern Massachusetts, alpine tundra in New Hampshire, and Mediterranean scrub (fynbos) in South Africa. Visits to flowers were most common in woodland-meadow, followed by alpine tundra, and least frequent in fynbos. Bees were the most common visitor in the woodland-meadow ...

Abstract

A 50-month continuous observation of the pollinator fauna of a 30 ha phrygana plot near Athens revealed an alpha diversity of 666 species which is the highest polinator diversity recorded so far. Of these, 262 species were Apoidea, of which only three (Apidae) species were eusocial. In comparison with the pollinator fauna of comparable ecosystems in Chile and California, phrygana has a relatively high number of Bombyliidae and especially Syrphidae. Only approximately 20% of the pollinator species occurred in all years ...

Abstract

Abstract Aims Several bird-pollinated or ornithophilous flowers are present on the Macaronesian archipelagos, the Canary Islands and Madeira, but absent from nearby NW Africa and Europe. In Macaronesia, no specialist nectar-feeding birds are found, but several generalist passerine bird species visit flowers for nectar. Two hypotheses attempt to explain the origin and evolution of ornithophily in the Macaronesian flora. According to 'the island de novo hypothesis', bird-flowers evolved from mainland insect-pollinated ancestors after island colonization. Alternatively, ancestors of the ornithophilous Macaronesian ...

Abstract

We conducted field studies on the Juan Fernandez Islands flora on the breeding system of 25 endemic species from 17 families. We recorded data on flower features, pollen and ovule number, pollen/ovule ratio, pollen size, self-compatibility, floral visitors, and pollination. Flowers are mostly hermaphrodite, inconspicuous, small, and green. Six species are dioecious. Over 80% of the cosexual species are self compatible. However, many species are dichogamous (mostly protandrous); thus, even the self-compatible species may require pollen transfer. Selfing through geitonogamy seems ...

Abstract

Animal pollination in a warm temperate evergreen broad-leaved forest was observed on Yaku-shima Island, south of Kyushu, Japan. Three groups of plants were categorized: canopy-flowering tree species, understory-flowering tree species, and climber and epiphyte species. Each of these formed different pollination systems. The canopy-flowering tree species had shallow, dish-shaped flowers and utilized various types of opportunistic pollinators. Most of the climber and epiphyte species had deep, tube-shaped flowers and specialized pollinators, although some climber species which bloomed in the canopy especially ...

Abstract

The insect pollination of an alpine plant community consisting of herbs and shrubs, was observed on Mt. Kisokoma-ga-take, central Honshu, Japan. There were two main groups of pollinators, syrphid flies and bumble bees. Although some shrubs were visited by both types of insects, other shrubs and the herbs were visited by either syrphid flies or bumble bees. Two types of herbs categorized by the difference of flower-visiting insects, the Syrphid-type and the Bombus-type, exhibited some clearly contrasting ecological characteristics such as ...

Abstract

A wide variety of lepidopterans, bees, flies, and beetles visit the flowers of most species of New Zealand montane plants. Of the 82 plant species which were well-collected, 4 species exhibited specialised pollination relationships with an insect order; 3 species are not apparently visited by insects; and the remaining 75 species are visited by a variety of insects in 2 or more orders. Introduced plant species in the Composite family are visited predominantly by introduced bumblebees. The most common lepidopteran flower ...

Abstract

Levels of specialization of the pollination systems were evaluated in 155 plant species from the Venezuelan Central Plain. In all, 29 pollination systems were found, resulting from various combinations of nine pollen-vector types or pollinating agent classes. The number of pollen-vector types composing a pollination system ranged from one to five. Ninety-one species were pollinated by only a single pollen-vector type; the frequency of pollination systems fell monotonically with increasing number of constituent pollen-vector types. Some 30–40 per cent of bee-, ...

Abstract

Confined within a volcanic caldera at 2000 m a.s.l., the sub-alpine desert of Tenerife, Canary Islands, harbors a distinct biota. At this altitude the climate is harsh and the growing season short. Hence, plant and animal communities, constituting the sub-alpine plant-flower-visitor network, are clearly delimited, both spatially and temporally. We investigated species composition and interaction structure of this system. A total of 11 plant species (91% endemics) and 37 flower-visiting animal species (62% endemics) formed 108 interactions. Numbers of interactions among ...

Abstract

The pollination ecology of tropical shrubland was studied in the Venezuelan Guayana Highlands. Most flowers are white or pink. Flower length is less than 0.5 cm for 45.4 percent of plant species (N = 55). The diameter has a similar distribution. Of the 62 visiting agents recorded on 55 plant species, 80.6 percent are pollinators and 19 4 percent are visitors only. Four families of bees are represented. Pollen is normally carried on only one location, frequently ventral, although it can ...

Abstract

Species flowering during the dry season (late December to early April) form three main pollinator groups, namely, butterfly, solitary bee, and hummingbird flowers. The animal vectors present match these three flower syndromes. The daily and seasonal rhythms of flower opening and pollination activity are synchronized. Butterflies and solitary bees, active chiefly in the morning, visit flowers blooming only half a day. The number of seeds per fruit and the pollen-carrying capacity of the pollen vector are correlated. Butterflies, carrying few pollen ...

Abstract

A significant proportion of the global diversity of flowering plants has evolved in recent geological time, probably through adaptive radiation into new niches. However, rapid evolution is at odds with recent research which has suggested that plant ecological traits, including the β- (or habitat) niche, evolve only slowly. We have quantified traits that determine within-habitat α diversity (α niches) in two communities in which species segregate on hydrological gradients. Molecular phylogenetic analysis of these data shows practically no evidence of a ...

Abstract

Niche breadth of species has been hypothesized to be associated with species' responses to disturbance. Disturbance is usually believed to affect specialists negatively, while generalists are believed to benefit from disturbance; we call this the "specialization-disturbance" hypothesis. We also propose an associated hypothesis (the "specialization-asymmetry-disturbance" hypothesis) under which both specialization and asymmetry of interactions would explain species' responses to disturbance. We test these hypotheses using data from a plant-pollinator system that has been grazed by cattle (i.e., a biological disturbance) in ...

Abstract

Identifying ecological factors that affect seed number and seed size is key to understanding the persistence of large seed mass variation in some plant species. Pathogens may increase seed mass variation by increasing resource demand over the growing season such that late fruits experience higher resource competition than early fruits. We tested whether Fusarium sp. and Rhizoctonia sp., soil fungi that cause wilt, contributed to seasonal decline in flower size, seed number, or seed mass in Hydrophyllum appendiculatum and H. canadense. ...

Abstract

<div>Just as flowering plants depend on their pollinators, many birds, insects, and bats rely on plants for energy and nutrients. This plant-pollinator relationship is essential to the survival of natural and agricultural ecosystems. <i>Plant-Pollinator Interactions</i> portrays the intimate relationships of pollination over time and space and reveals patterns of interactions from individual to community levels, showing how these patterns change at different spatial and temporal scales. <br><br>Nickolas M. Waser and Jeff Ollerton bring together experts from around the world to offer ...

Abstract

A key to conserving organisms is identification of the habitat bounds and essential resources within them. In population studies (metapopulations) of phytophagous arthropods it is tacitly assumed that habitat bounds portray short-term stability and that habitat is largely synonymous with hostplant areas or with a single vegetation unit comprising hostplants; structural components are usually ignored. We test these assumptions by monitoring the behaviour and relative abundance of Plebejus argus (L.) (Lepidoptera: Lycaenidae) in relation to changing weather conditions in two patches ...

Abstract

Cryptically colored prey species are often polymorphic, occurring in multiple distinctive pattern variants. Visual predators promote such phenotypic variation through apostatic selection, in which they attack more abundant prey types disproportionately often. In heterogeneous environments, disruptive selection to match the coloration of disparate habitat patches could also produce polymorphism, but how apostatic and disruptive selection interact in these circumstances is unknown. Here we report the first controlled selection experiment on the evolution of prey coloration on heterogeneous backgrounds, in which blue ...

Abstract

It was hypothesized that the local geographic distributions of bumblebees near Crested Butte, Colorado and the community patterns exhibited by these bumblebees are the products of competition for plants. To evaluate this hypothesis several transects were established and at regular intervals throughout a summer growing season, data were collected along each transect on how many bumblebees of each species and caste were visiting the various plant species. The distributions and abundances of the plant species involved were recorded qualitatively. Seven species ...

Abstract

I present a model predicting the distribution and abundance of two species of competing nectarivore exploiting nectar in two types of flower. The model uses a submodel of resource renewal and depletion, and the principle that individuals attempt to maximize individual fitness, to construct habitat isolines. The habitat isoline for a population of nectarivores is a line in an abundance phase-plane along which all individuals of the population, regardless of the habitat they are currently exploiting, have equal expected fitness. At ...

Abstract

Patterns of connectance and strength of mutual dependence in mutualisms have been examined by comparing the fraction of possible pairwise interactions established in a series of plant-pollinator and plant-seed disperser systems. As the number of species in the mutualistic system increases, the absolute number of interactions established increases, but connectance decreases exponentially. A given increase in diversity adds twice the number of interactions to dispersal systems as to pollination systems, suggesting a higher global specificity of the latter. Connectance patterns in ...

Abstract

Plants are under siege from a diversity of enemies that consume both leaf and floral parts. Plants resist damage to leaves in a variety of ways, and we now have a rich literature documenting how plants defend themselves against herbivore attack. In contrast, the mechanisms by which plants resist enemies that consume floral parts or resources are much less known, even though damage to floral tissue usually has tighter links to plant fitness than damage to leaf tissue. Many plants experience ...

Abstract

A system comprising 2 species of bumblebess (Bombus appositus and Bombus flavifrons) and 2 species of flowers (Delphinium barbeyi and Aconitum columbianum) in Gothic, Colorado, USA, was manipulated to determine whether resource utilization by each bumblebee species was influenced by the presence of the other species of bumblebee. Each bumblebee species concentrated its foraging efforts on a different flower species, apparently choosing the species whose corolla tube length matched its proboscis length most closely. When each bumblebee species was temporarily removed ...

Abstract

Four common species of bumblebees in central Maine each utilized the nectar from a great variety of both native and exotic flowers. The number of individuals that utilized a nectar resource was directly related to supplies available. Seasonally, @? 92% of the "Standing crop" of food energy available per day was utilized in 1972. No interference competition was observed, and competition was primarily exploitative. Small wild bees generally foraged at high temperatures from the small food rewards left after Bombus exploitation. ...

Abstract

Although rarely tested, it is often assumed that interspecific competition results in the divergence of traits related to resource use. Using a plant-pollinator system as a model, I tested the prediction the presence of a competitor for pollination influences the strength and/or direction of pollinator-mediated selection on floral traits. I measured phenotypic selection via female fitness on five floral traits of Ipomopsis aggregata in seven populations. Four contained only conspecifics (I only) and three also contained the competitor Castilleja linariaefolia (C ...