This aim of this study was to distinguish grasslands from forests in southern Brazil by analyzing Poaceae pollen grains. Through light microscopy analysis, we measured the size of the pollen grain, pore, and annulus from 68 species of Rio Grande do Sul. Measurements were recorded of 10 forest species and 58 grassland species, representing all tribes of the Poaceae in Rio Grande do Sul. We measured the polar, equatorial, pore, and annulus diameter. Results of statistical tests showed that arboreous forest species have larger pollen grain sizes than grassland and herbaceous forest species, and in particular there are strongly significant differences between arboreous and grassland species. Discriminant analysis identified three distinct groups representing each vegetation type. Through the pollen measurements we established three pollen types: larger grains (>46 μm), from the Bambuseae pollen type, medium-sized grains (46–22 μm), from herbaceous pollen type, and small grains (<22 μm), from grassland pollen type. The results of our compiled Poaceae pollen dataset may be applied to the fossil pollen of Quaternary sediments.
Bee populations are declining globally due to different environmental stressors, such as pathogens, malnutrition, and agrochemicals. Brazil is the home of hundreds of stingless bee species, some of them now considered endangered, though very little is known about the impact of disease on native bees. In Southern Brazil the endangered stingless bee Melipona quadrifasciata is affected by an annual syndrome that causes sudden death of workers, eventually leading colonies to collapse.Although novel viruses were found in foragers from diseased colonies, none has been consistently implicated in the outbreak. Here we used transcriptomics in combination with an integrative longitudinal survey on managed colonies to identify predictors for preventing M. quadrifasciata colony failures. We found that key genes related to xenobiotic metabolization, nutrition and immune responses are downregulated in foragers from colonies that became diseased three months later. The period that preceded the outbreak was marked by pronounced forager weight loss as well as behavioural changes. Our findings support the proposition that worldwide bee mortality is influenced by a combination of diverse sublethal factors, and increase awareness of the long-term effects of genetic diversity erosion in stingless bee species, which enhances their vulnerability to environmental stressors.
Several South American species of Iridaceae, especially those of Tigridieae, produce floral oils as rewards to oil-bee pollinators. The present study aimed to contribute to a deeper understanding of the reproductive biology, pollination ecology and level of specialization of the interactions of species encompassed in Tigridieae. Data on breeding and pollination systems were acquired from six species native to Southern Brazil. The visitation frequency and pollen load of pollen- and oil-collecting bees were also investigated. The results strongly suggest that the studied species are distributed along a specialization–generalization continuum. Three oil-producing taxa, Cypella herbertii, Cypella pusilla and Cypella amplimaculata, were pollinated effectively by oil-bees, whereas in the other two studied species, Kelissa brasiliensis and Herbertia pulchella, the oil-bees appeared to function as oil thieves, owing to failure to contact the plant reproductive parts during oil-foraging behaviour. New insights into aspects of the specialization–generalization continuum of pollination systems, differences in pollinator behaviour during oil and pollen foraging, and reproductive outputs of the studied species are provided. Taken together, our results provide a significant contribution towards a better understanding of reproductive biology and plant–pollinator interactions between Iridaceae and oil-collecting bees.
The Poaceae species have their use for food known in Brazil and in the world. Maize, which today accounts for 21% of human nutrition, was changed 9,000 years ago from Teosinte. Many indigenous people grow maize in South America to feed the tribe. In Brazil, several Poaceae species of African origin were introduced accidentally purposely in the colonial period, to be used as fodder, as was the case of annoni grass (Eragrostis plana Nees). Palynological studies may reconstitute a vegetation of the past, but due to the similarity of Poaceae pollen grains, so far maize (Zea mays L.) can be identified with the safety of the palynological studies. The aim of the study here is to identify and describe the pollen grains of Poaceae exotic cultivated species. The pollen grains were collected from herborized plants and processed by usual techniques of palynology (acetolysis). The results allow identification of three pollen groups (pollen of ornamental, cereal and corn plants). Pollen morphology of 14 species of exotic Poaceae in Rio Grande do Sul state showed differences in sizes of pollen grains. The results of this research showed that cultivars of grasses can be identified in sedimentary profiles. However, some pollen grains have the size of pollen similar to Poaceae pollen of native species. Thus, it is necessary knowledge about the vegetation of study area and surrounds distributed cultivars of grasses. Nevertheless, this pollen database is important to mapping with more precision the cultivation of these cereals in the Late Holocene.
Citation: Radaeski JN, Evaldt ACP, Bauermann SG. Anthropic pollen indicators: poaceae pollen of non-native species in Southern Brazil. Open Access J Sci. 2018;2(2):134-141. Citation: Radaeski JN, Evaldt ACP, Bauermann SG. Anthropic pollen indicators: poaceae pollen of non-native species in Southern Brazil. Open Access J Sci. 2018;2(2):134-141.
ResumoNeste trabalho é apresentada a produção polínica por antera, por lor e por espigueta das espécies Bromus catharicus (campestre) e Guadua trinii (lorestal), ambas da família Poaceae, que apresentam a síndrome da polinização divergente. Com o objetivo de averiguar diferenças de produção polínica dependente do sistema de polinização, foram coletadas dez anteras de cada táxon que após maceradas foram contabilizados os grãos de pólen em câmara de Neubauer. As morfologias polínicas também foram observadas sob microscopia óptica para estabelecer relação entre produção-morfologia dos grãos de pólen. A espécie anemóila Bromus catharticus (2.556.000 grãos de pólen por espigueta) apresenta o dobro de produção polínica por antera e por espigueta em relação à espécie com assistência biótica para polinização Guadua trinii (1.716.000 grãos de pólen por espigueta). O tamanho do grão de pólen é inversamente proporcional à produção polínica. A ornamentação microequinada não esperada para espécies anemóilas foi observada nos dois táxons. Os resultados indicam que a frequência de espécies lorestais de Poaceae em registros quaternários pode ser subestimada, enquanto táxons campestres de gramíneas são superestimados, interferindo na representação de suas respectivas loras no passado.
Palavras-chave: Dinâmica de transporte polínico; Gramíneas; Tafonomia polínica
AbstractEvaluation of pollen production in Bromus catharticus Vahl and Guadua trinii (Nees) Nees ex Rupr. (Poaceae) for interpretation of fossil data. We evaluated pollen production per anther, per lower, and per spikelet of the grassland species Bromus catharticus and the forest taxon Guadua trinii (Poaceae), which have divergent pollination syndrome. We collected ten anthers of each taxon to determine differences in pollen production based on pollination system. Anthers were macerated and pollen grains were counted in a Neubauer chamber. Pollen morphology was observed using optical and scanning electron microscopy to establish relationships between pollen grain production and morphology. The anemophilous species Bromus catharticus (2,556,000 pollen grains/spikelet) has twice the pollen production per anther and per spikelet compared to Guadua trinii (1,716,000 pollen grains/spikelet), a species that requires biotic assistance for pollination. Pollen grain size is inversely proportional to production. Microechinate ornamentation, which is not expected to
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