STRUCTURE AND DIVERSITY OF A TROPICAL DRY FOREST ON RESIDUAL RELIEFS IN NORTHEASTERN BRAZIL

We studied the structural characteristics of forests to better understand their current condition and help plan for the sustainable management of their resources. We delimited 14 sampling units, according to physiognomy and geomorphological position (base, medium slope 1, medium slope 2, and inselberg). To characterize vegetation structure, we used the transect method (50 x 2 m) following to Method of Phanerophytes and Chamaephyties Inventory. After this step, we classified the transects into four biotopes: (CAR: Caatinga on rocky substrate, CBA: Caatinga with open woods, CBC: Caatinga with closed woods, and CDA: degraded shrubby “Caatinga”), according to geomorphological position. Our objective was to test the hypothesis that adjacent areas with different topography differ from one another. For those comparisons, we calculated parametric and non-parametric tests in the software R. We recorded a total of 67 species, including trees, shrubs, and herbs, and high values for diversity (3.4 nats/individual) and evenness (0.83). Based on the comparison between rarefaction curves and non-parametric estimates, we observed the highest diversity in the category Caatinga with closed woods (CBC). Considering its species composition and abundance the group degraded shrubby Caatinga      (CDA) is undergoing succession. The Jaccard index did not suggest floristic similarity between biotopes, but rather pointed to a diverse floristic composition in the area, with the presence of species either common or rare to the Caatinga   and a higher heterogeneity than among other Brazilian semiarid areas

Fenologia e biologia floral da urtiga cansanção (Cnidoscolus urens L., Euphorbiaceae)

The phenological patterns and floral biology of Cnidoscolus urens were studied from observations in natural populations in the Bodopitá Mountain, Queimadas, Paraiba, Brazil, between January/2005 and January/2006. We registered data on the floral biology, behavior and frequency of floral visitors and about the intensity and duration of budding, flowering and fruiting. Cnidoscolus urens has phenophases of leaf flushing, flowering and fruiting which are continuous, peaking during the months April and July. The flowers are white and unisexual, with anthesis of 24 hours. The inflorescences have central pistillate flowers, surrounded by staminate flowers. Cnidoscolus urens is self-compatible, without forming fruit apomictic. The flowers are pollinated by hummingbirds, butterflies and hawkmoths. Being a monoecious and protogynous species, the effectiveness of pollinators is very important to allow the flow of pollen between staminate and pistillate flowers.O padrão fenológico e a biologia floral de Cnidoscolus urens foram estudados a partir de observações em populações naturais na Serra do Bodopitá, Queimadas, Paraíba, Brasil, entre janeiro/2005 e janeiro/2006. Foram obtidos dados acerca da biologia floral, comportamento e frequência dos visitantes florais, bem como da intensidade e duração das fenofases de brotamento, floração e frutificação. Cnidoscolus urens possui fenofases de brotamento, floração e frutificação contínuas, com pico de floração durante os meses de abril e julho. As flores são brancas, unissexuais e com antese de duração de 24 horas. As inflorescências possuem flores pistiladas centrais, circundadas por flores estaminadas. Cnidoscolus urens é autocompatível, sem a formação de frutos apomíticos. As flores são polinizadas por beija-flores, borboletas e esfingídeos. Por ser uma espécie monóica e protogínica, a eficiência dos polinizadores tem grande importância para que ocorra o fluxo de pólen entre as flores estaminadas e pistiladas

Bats and hawkmoths form mixed modules with flowering plants in a nocturnal interaction network

Based on the conceptual framework of pollination syndromes, pollination networks should be composed of well-delimited subgroups formed by plants that diverge in floral phenotypes and are visited by taxonomically different pollinators. Nevertheless, floral traits are not always accurate in predicting floral visitors. For instance, flowers adapted to bat-pollination are larger and wider, enabling the exploitation by other nocturnal animals, such as hawkmoths. Thus, should an interaction network comprising bats and hawkmoths, the most important nocturnal pollinators in the tropics, be formed of mixed-taxon modules due to cross-syndrome interactions? Here, we analyzed such a network to test whether resource plants are shared between the two taxa, and how modules differ in terms of species morphologies. We sampled interactions through pollen grains collected from floral visitors in a Caatinga dry forest in northeastern Brazil. The network was modular yet interwoven by cross-syndrome interactions. Hawkmoths showed no restriction to visit the wider chiropterophilous flowers. Furthermore, bats represented a subset of a hawkmoth-dominated network, as they were restricted to chiropterophilous flowers due to constraints in accessing narrower sphingophilous flowers. As such, the bat-dominated module encompassed relatively wider flowers, but hawkmoths, especially long-tongued ones, were unrestricted by floral width or length. Thus, pollination of flowers with open architectures must be investigated with caution, as they are accessible to a wide array of floral visitors, which may result in mixed-pollination systems. Future research should continue to integrate different syndromes and pollinator groups in order to reach a better understanding of how pollination-related functions emerge from community-level interactions. Abstract in Portuguese is available with online material.Fil: Queiroz, Joel A.. Universidade Estadual da Paraiba; BrasilFil: Diniz, Ugo M.. Universidade do Brasília; BrasilFil: Vazquez, Diego P.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Quirino, Zelma M.. Universidade Estadual da Paraiba; BrasilFil: Santos, Francisco A. R.. Universidade Estadual de Feira de Santana; BrasilFil: Mello, Marco A. R.. Universidade de Sao Paulo; BrasilFil: Machado, Isabel. Universidade Federal de Pernambuco; Brasi

Morfoanatomia vegetativa de Opuntia brasiliensis (Willd) HawVegetative morphology and anatomy of Opuntia brasiliensis (Willd) Haw

Opuntia brasiliensis (Willd) Haw. é uma Cactaceae nativa do Brasil utilizada como ornamental, que apresenta caracteres morfológicos semelhantes a outras espécies do gênero, o que dificulta sua identificação. Dessa forma, foi realizado uma descrição morfoanatômica de O. brasiliensis com o objetivo de ampliar o conhecimento sobre a organização estrutural do gênero e fornecer subsídios para a identificação da espécie, bem como observar caracteres importantes na adaptação a ambientes xerófilos. Foram feitas secções transversais e paradérmicas da raiz, caule principal e cladódios com espécimes coletados na zona rural da cidade de Serra Branca (PB), localizada na região do cariri ocidental. O. brasiliensis apresenta raiz ramificada e caule clorofilado formando um eixo principal de onde partem inúmeros cladódios delgados. Observam-se pelos e epiderme unisseriada irregular na raiz, que possui córtex formado por parênquima, seguido de endoderme multisseriada e periciclo. No cilindro central da raiz, ocorrem tecidos vasculares formando cinco pólos seguidos de medula. O caule e o cladódio apresentam epiderme com paredes sinuosas, em que encontram-se estômatos paralelocíticos que apresentam câmara subestomática; e na camada subsequente, hipoderme com grande quantidade de drusas de oxalato de cálcio. O córtex é formado por parênquimas clorofiliano e aquífero, onde observam-se feixes vasculares, com raios de floema voltados para o lado externo, seguido de xilema helicoidal. Porém, nos cladódios, o parênquima clorofiliano é bem mais denso e os feixes vasculares são dispostos irregularmente, enquanto no caule estão distribuídos no sentido radial. O. brasiliensis apresenta várias características importantes na sua identificação, bem como adaptações estruturais a ambientes xerófilos.AbstractOpuntia brasiliensis (Willd.) Haw. (Cactaceae) is a native to Brazil and used as ornamental plant, which presents morphological characters similar to other Opuntia species, what hinders its identification. Thus, a morphoanatomical description of O. brasiliensis was conducted, with the aim of increasing knowledge about the structural organization of genus and provide subsidies for specie identification, well as observe important characters in adaptation to xerophilous environments. Sections of roots, main stem and cladodes were made, with specimens from Serra Branca (PB), located in the western cariri region. O. brasiliensis has ramified root and photosynthetic stem forming a backbone which was followed by numerous slender cladodes. The root has hair and irregular single cell layer epidermis, with cortex composed of parenchyma, followed by multiple cell layers endoderm and pericycle. In central cylinder of root occurs vascular tissue forming five points followed of pith. The stems and cladodes have epidermis with sinuous walls, where occur paralelocytics stomata with substomatal chambers; and in subsequent layer, hypodermis with large amount of druses of calcium oxalate. The cortex consists of aquifer parenchyma and chlorenchyma, where observed vascular bundles, with phloem rays toward the outside, followed of helical xylem. However, in the cladodes, the chlorenchyma is much dense and the vascular bundles are irregularly arranged, while the stems are distributed in radial direction. O. brasiliensis has many important characteristics intheir identification, and structural adaptations to dry.

The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study

Background and Aims Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades