The morphology and exine ornamentation of fresh pollen from four dipterocarp species in Sabah

Peer reviewedPublisher PD

Food for pollinators: quantifying the nectar and pollen resources of urban flower meadows

Planted meadows are increasingly used to improve the biodiversity and aesthetic amenity value of urban areas. Although many ‘pollinator-friendly’ seed mixes are available, the floral resources these provide to flower-visiting insects, and how these change through time, are largely unknown. Such data are necessary to compare the resources provided by alternative meadow seed mixes to each other and to other flowering habitats. We used quantitative surveys of over 2 million flowers to estimate the nectar and pollen resources offered by two exemplar commercial seed mixes (one annual, one perennial) and associated weeds grown as 300m2 meadows across four UK cities, sampled at six time points between May and September 2013. Nectar sugar and pollen rewards per flower varied widely across 65 species surveyed, with native British weed species (including dandelion, Taraxacum agg.) contributing the top five nectar producers and two of the top ten pollen producers. Seed mix species yielding the highest rewards per flower included Leontodon hispidus, Centaurea cyanus and C. nigra for nectar, and Papaver rhoeas, Eschscholzia californica and Malva moschata for pollen. Perennial meadows produced up to 20x more nectar and up to 6x more pollen than annual meadows, which in turn produced far more than amenity grassland controls. Perennial meadows produced resources earlier in the year than annual meadows, but both seed mixes delivered very low resource levels early in the year and these were provided almost entirely by native weeds. Pollen volume per flower is well predicted statistically by floral morphology, and nectar sugar mass and pollen volume per unit area are correlated with flower counts, raising the possibility that resource levels can be estimated for species or habitats where they cannot be measured directly. Our approach does not incorporate resource quality information (for example, pollen protein or essential amino acid content), but can easily do so when suitable data exist. Our approach should inform the design of new seed mixes to ensure continuity in floral resource availability throughout the year, and to identify suitable species to fill resource gaps in established mixes

The Evolution of Sexual Reproduction in \u3cem\u3eCuscuta\u3c/em\u3e (Convolvulaceae)

Cuscuta (Convolvulaceae), the dodders, is a genus of ca. 200 species of obligate stem parasites distributed across a great diversity of habitats worldwide. The existence of a handful of species that are dangerous crop weeds has led researchers to historically focus on their growth and control. Consequently, there is a dearth of information about their biodiversity, ecology, and in particular their reproductive biology. This thesis surveys aspects of sex allocation, floral evolution, floral rewards for pollinators, and mechanisms of reproductive assurance across the genus. I demonstrate that Cuscuta has evolved a broad spectrum of breeding systems, from obligate selfing to obligate outcrossing. Predictions made by sex allocation theory of negative correlations between pollen number and pollen grain size, and between male investment and female investment are shown to be false in Cuscuta. Histological examination of the floral nectary demonstrates that it is typical in structure, and I predict that it is functional in most facultatively and obligately xenogamous species. Cuscuta pollen is variable in the proportions of lipid and starch reserves, and has a sticky external pollenkitt. The role of the infrastaminal scales is narrowed to 1) defense against seed predators, and 2) a shield against early self-pollination in some strongly protandrous species. Lastlly, I demonstrate that the evolution of two styles, followed by unequal styles in Cuscuta, were critical for the radiation of the genus. The more flexible floral design enabled Cuscuta to evolve different mechanisms of reproductive assurance in coordination with their exploitation of novel host species and new pollination environments

Native and ornamental exotic resources in pollen loads and garbage pellets of four stingless bees (Apidae, Meliponini) in an urban environment with riparian native forest

An entomopalynological study to assess pollen use by wild bees was performed in an urban environment with riparian native forest in the Chaco region of Argentina. A combined method for sampling pollen loads and garbage pellets at nest entrances in four stingless bees with different entrance size and forager traffic was here successfully used. Sampling was carried out in a short period of time (late winter) and located within a distance of 50 m. Pollen analysis using acetolysis showed that most identified pollen types (31) were from native species, 12 from ornamental exotic species, 5 included native and ornamental exotic species and 18 of uncertain status. A much broader pollen spectrum was present in garbage pellets (62 types) than loads (14 types). A few resources from previous blooming (late spring-summer) were identified in garbage pellets, which were mainly composed of current flowerings. From the 66 pollen types found in all samples, many (18) remained unidentified due to the complex nature of the vegetation surrounding the nests and the generalist behaviour of these bees. The versatile foraging behaviour on spontaneous (mostly native) and cultivated (mostly ornamental exotic) pollen resources is an important issue for the conservation and rearing of stingless bee colonies in urban habitats where native flora is preserved, particularly the riparians, where a high richness of blooming plants is available.Fil: Vossler, Favio Gerardo. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentin

Comparação entre o volume e número de grãos de pólen na determinação floral do mel coletado de Scaptotrigona bipunctata (Hymenoptera, Apidae, Meliponini) em diferentes períodos do ano em Fortaleza, Ceará.

A abelha sem ferrão Scaptotrigona bipunctata é uma abelha pouco conhecida tanto em seu comportamento alimentar quanto na sua biologia gera l. O objetivo desse trabalho foi comparar o número e o volume de grãos de pólen encontrados em amostras de mel coletadas por essa abelha, para investigar a importância de cada espécie de planta visitada como recurso alimentar. Amostras de mel foram coletadas de duas colméias padrão de S. bipunctata do meliponário da Universidade Federal do Ceará entre novembro de 2006 e outubro de 2007. O preparo das lâminas das amostras de mel foi realizado no laboratório de Abelhas do Setor de Apicultura, de acordo com o método de MAURIZIO & LO UVEAUX, descrito por BARTH (1989). Calculou-se o volume do grão de pólen em função das medidas e formatos de cada grão. Foram identificados 9 tipos polínicos, sendo os mais representativos: sabiá (Mimosa caesalpiniefolia), mamona (R. communis), juazeiro,vassourinha de botão (Spermacoce verticillata ), mutre (Aloysia virgata ) e cássia (Cássia fistula ). Quanto ao volume dos grãos, as plantas com maiores valores foram: mamona (R. communis ), guaxuma (W . brachypetala), vassourinha de botão (S. verticillata ), cássia (C. fistula ), mutre (A. virgata ) e sabiá (M. caesalpiniefolia). Nem sempre um tipo polínico que foi bastante representa do em termos de número de grãos necessariamente apresentou grande volume. Assim, na determinação da origem floral do mel de S. bipunctata deve-se levar em consideração também o volume dos grãos de pólen

Evolution of mating system and inbreeding depression in the Mimulus moschatus (Scrophulariaceae) alliance

Thesis (Ph.D.) University of Alaska Fairbanks, 2002The transition from cross- to self-fertilization is considered a major pattern in the evolution of angiosperms. Yet, evolutionists continue to struggle to explain the evolutionary processes involved in maintaining both self- and cross-fertilization, which often occur within the same species. The diversity of mating systems suggests that selective pressures are also diverse, sometimes promoting selfing and other times promoting outcrossing. Inbreeding depression is commonly invoked as the primary selective force balancing the advantages of selfing or promoting outcrossing. The interaction between levels of inbreeding depression and mating system evolution has been fertile ground for both theoretical and empirical studies; however, a long-term patterns and processes remain ambiguous. I examined the relationship of inbreeding depression and outbreeding depression to mating system in a group of closely related Mimulus taxa, specifically incorporating information on their evolutionary relationships. I posed the following questions: Do selfing populations have low inbreeding depression and outcrossing populations have high outbreeding depression? Is selfing an evolutionary 'dead-end'? Are morphological traits correlated with molecular estimates of mating system? How evolutionary labile is mating system and inbreeding depression? Is inbreeding depression negatively correlated with outbreeding depression? Results from this study largely supported theoretical expectations. Inbreeding depression was lowest in the most selfing species and highest in the most outcrossing species. Outbreeding depression was not observed. Many populations actually experienced positive fitness consequences of between-population crosses. The question of selfing species being evolutionary dead-ends remained equivocal. Flower morphology was strongly related to molecular estimates of mating system as expected. Contrary to expectations, inbreeding depression appears to evolve much more quickly than does mating system. I conclude that in the Mimulus moschatus alliance, inbreeding depression is not as strong a selective force as often implied in the evolution of mating system. Although generally low, inbreeding depression can be high in some populations of rare taxa. Outbreeding depression was minimal. Last, inbreeding depression was positively correlated with outbreeding depression, suggesting that mediating the negative effects of inbreeding depression cannot occur by the introduction of foreign genes for many populations

How much flower-rich habitat is enough for wild pollinators? Answering a key policy question with incomplete knowledge.

In 2013, an opportunity arose in England to develop an agri-environment package for wild pollinators, as part of the new Countryside Stewardship scheme launched in 2015. It can be understood as a 'policy window', a rare and time-limited opportunity to change policy, supported by a narrative about pollinator decline and widely supported mitigating actions. An agri-environment package is a bundle of management options that together supply sufficient resources to support a target group of species. This paper documents information that was available at the time to develop such a package for wild pollinators. Four questions needed answering: (1) Which pollinator species should be targeted? (2) Which resources limit these species in farmland? (3) Which management options provide these resources? (4) What area of each option is needed to support populations of the target species? Focussing on wild bees, we provide tentative answers that were used to inform development of the package. There is strong evidence that floral resources can limit wild bee populations, and several sources of evidence identify a set of agri-environment options that provide flowers and other resources for pollinators. The final question could only be answered for floral resources, with a wide range of uncertainty. We show that the areas of some floral resource options in the basic Wild Pollinator and Farmland Wildlife Package (2% flower-rich habitat and 1 km flowering hedgerow), are sufficient to supply a set of six common pollinator species with enough pollen to feed their larvae at lowest estimates, using minimum values for estimated parameters where a range was available. We identify key sources of uncertainty, and stress the importance of keeping the Package flexible, so it can be revised as new evidence emerges about how to achieve the policy aim of supporting pollinators on farmland.LVD was funded by NERC (NE/K015419/1), CC by Defra and Natural England (flower density data); MB and CC by BBSRC Defra, NERC, the Scottish Government and the Wellcome Trust under the Insect Pollinators Initiative (BB/I000925/1 and Agriland - BB/H014934/1).This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1111/een.1222

Temporal variation in production and nutritional value of pollen used in the diet of Apis mellifera L. in a seasonal semideciduous forest

The flora of mountain formations in the Caatinga biome is composed predominantly by semi-deciduous species with representatives of both Atlantic and Amazon forest. Information on the potential for bee pollen production of these species is limited. In this study we evaluated the potential of production, the temporal variation, the botanical origin and the nutritional value of bee pollen produced in a seasonal semideciduous forest in northeastern Brazil. We identified a total of 252 flowering plant species throughout the year. The diet of Apis mellifera consisted of 74 pollen types distributed in 58 genera and 27 families. We identified two production peaks of bee pollen, the highest occurring in the rainy season. Nutritional value considering crude protein, carbohydrates, lipids and mineral matter changed over the study period, with influence of rainfall on the dry matter level. Some taxonomic groups of plants showed a strong relationship with nutrients, suggesting that although the diet of A. mellifera is broadly diversified, this species devoted most of its pollen foraging effort on the genus Mimosa and the palm tree species of Attalea speciosa. The results show that the seasonal semideciduous forest of the mountain range in the Northeast Brazil presents plant species: Mimosa caesalpiniifolia, Baccharis trinervis, Mimosa tenuiflora Myracrodruom urundeuva, Cecropia pachystachya, Attalea speciosa, with high nutritional level and potential for the pollen production

Interspecific reproductive barriers in the tomato clade

2011 Fall.Includes bibliographical references.Interspecific Reproductive Barriers (IRBs) preserve species identity by preventing interspecific hybridization, an essential facet of the biological species concept. Wild tomato species (Solanum sect. lycopersicum) are useful for studying interspecific reproductive barriers. Within the tomato clade there are 13 closely related species possessing diverse mating systems and complex IRBs. IRBs can be divided into two types: those occurring before mating (premating barriers) and those operating after mating (postmating barriers). Premating barriers include a variety of floral morphological characters correlated with a diversity of mating systems. Postmating barriers can be subdivided into prezygotic, those acting after mating but before fertilization, and postzygotic, those acting after fertilization. In the tomato clade, regulation of pollen tube growth in pistils constitutes postmating prezygotic barriers that are known to be important for preventing hybridization. Unilateral incongruity/incompatibility (UI), which prevents hybridization in one direction of an interspecific cross by inhibiting pollen tube growth in the pistil, is common in the tomato clade. Postzygotic barriers are also important as genetic isolating mechanisms resulting in failure of fruit or viable seed production in cases where prezygotic barriers are absent. In this study, I first examined the hypothesis of positive correlation between pollen grain size and style length among nine species in the tomato clade, because differences between species in pollen size and style length have been proposed to be a potentially important isolating mechanism between species, since larger pollen grains (containing more stored nutrients) may be needed to traverse longer styles. However, I found no correlation between pollen grain size and style length in the tomato clade, and therefore did not find this to be a likely isolating mechanism among the species in this study. Second, I examined UI barriers between species of domesticated tomato (self-compatible, SC) and three wild red-fruited SC species as pollen donors onto pistils of eight green-fruited species. Pistils of (self-incompatible) SI green-fruited species rejected pollen from all SC red-fruited species. However, pollen rejection and/or pollen tube growth of the three wild SC red-fruited species varied in pistils of green fruited SC species and SC populations of SI species. Finally, three types of IRBs including stigma exsertion, UI, and postzygotic barriers were investigated in 10 sympatric pairs of wild species. In these sympatric pairs, prezygotic and postzygotic barriers were found to prevent interspecific hybridization. This research will help elucidate the nature of reproductive barriers in wild populations. Studies of IRBs in tomato, a major food crop, also have potential for understanding reproductive barriers as they pertain to agronomic improvement