6 resultados para Subtropical grasslands
em Portal do Conhecimento - Ministerio do Ensino Superior Ciencia e Inovacao, Cape Verde
Resumo:
We present a comparative analysis of satellite derived climatologies in the Cape Verde region (CV). In order to establish chlorophyll a variability, in relation to other oceanographic phenomena, a set of, relatively long (from five to eight years), time series of chlorophyll a, sea surface temperature, wind and geostrophic currents, were ensembled for the Eastern Central Atlantic (ECA). We studied seasonal and inter-annual variability of phytoplankton concentration, in relation to the rest of the variables, with a special focus in CV. We compared the situation within the archipelago with those of the surrounding marine environments, such as the North West African Upwelling (NWAU), North Atlantic Subtropical Gyre (NASTG), North Equatorial Counter Current (NECC) and Guinea Dome (GD). At the seasonal scale, CV region behaves partly as the surrounding areas, nevertheless, some autochthonous features were also found. The maximum peak of the pigment having a positive correlation with temperature is found at the end of the year for all the points in the archipelago; a less remarkable rise with negative correlation is also detected in February for points CV2 and CV4. This is behavior that none of the surrounding environments have shown. This enrichment was found to be preceded by a drastic drop in wind intensity (SW Monsoon) during summer months. The inter-annual analysis shows a tendency for decreasing of the chlorophyll a concentration.
Resumo:
We present a comparative analysis of satellite derived climatologies in the Cape Verde region (CV). In order to establish chlorophyll a variability, in relation to other oceanographic phenomena, a set of, relatively long (from five to eight years), time series of chlorophyll a, sea surface temperature, wind and geostrophic currents, were ensembled for the Eastern Central Atlantic (ECA). We studied seasonal and inter-annual variability of phytoplankton concentration, in relation to the rest of the variables, with a special focus in CV. We compared the situation within the archipelago with those of the surrounding marine environments, such as the North West African Upwelling (NWAU), North Atlantic Subtropical Gyre (NASTG), North Equatorial Counter Current (NECC) and Guinea Dome (GD). At the seasonal scale, CV region behaves partly as the surrounding areas, nevertheless, some autochthonous features were also found. The maximum peak of the pigment having a positive correlation with temperature is found at the end of the year for all the points in the archipelago; a less remarkable rise with negative correlation is also detected in February for points CV2 and CV4. This is behavior that none of the surrounding environments have shown. This enrichment was found to be preceded by a drastic drop in wind intensity (SW Monsoon) during summer months. The inter-annual analysis shows a tendency for decreasing of the chlorophyll a concentration.
Resumo:
The Culex pipiens complex includes two widespread mosquito vector species, Cx. pipiens and Cx. quinquefasciatus. The distribution of these species varies in latitude, with the former being present in temperate regions and the latter in tropical and subtropical regions. However, their distribution range overlaps in certain areas and interspecific hybridization has been documented. Genetic introgression between these species may have epidemiological repercussions for West Nile virus (WNV) transmission. Bayesian clustering analysis based on multilocus genotypes of 12 microsatellites was used to determine levels of hybridization between these two species in Macaronesian islands, the only contact zone described in West Africa. The distribution of the two species reflects both the islands’ biogeography and historical aspects of human colonization. Madeira Island displayed a homogenous population of Cx. pipiens, whereas Cape Verde showed a more intriguing scenario with extensive hybridization. In the islands of Brava and Santiago, only Cx. quinquefasciatus was found, while in Fogo and Maio high hybrid rates (~40%) between the two species were detected. Within the admixed populations, second-generation hybrids (~50%) were identified suggesting a lack of isolation mechanisms. The observed levels of hybridization may locally potentiate the transmission to humans of zoonotic arboviruses such as WNV.
Resumo:
Nos estudos sobre a micoflora de muitos ecossistemas os fungos do género Curvularia Boedijn 1933, constituem um dos mais fascinantes grupos, devido à frequência com que são observados especímenes do género e ao elevado número de espécies que são normalmente identificadas. Apesar da maioria dos táxones do género ser conhecida como saprófita em diferentes substratos vegetais e no solo, podendo ainda ser isolada a partir do solo e do ar, muitas espécies são fitopatogénicas, sobretudo em gramíneas e em regiões de clima tropical e subtropical (SIVANESAN 1987). Um pequeno número de espécies pode raramente originar doenças em animais, incluindo humanos, surgindo como agentes de onicomicoses, sinusite alérgica, pneumonia, endocardite e alergia broncopulmonar (CARTER & BOUDREAUX 2004). Descrito com a espécie tipo C. lunata (Wakker) Boedijn, o género Curvularia permitiu acomodar espécies da família Dematiaceae que possuíam conidióforos macronematosos, mononematosos, direitos ou flexuosos, frequentemente geniculados, por vezes nodosos, células conidiogénicas politétricas, integradas, terminais e simpodiais, fragmoconídios solitários, acropleurógenos por proliferação subterminal do conidióforo, oliváceos a castanhos, elipsóides, cilíndricos, obovóides ou piriformes, três ou mais septos transversais, terceira célula ou segunda e terceira distintamente maiores e escuras, muitas vezes desigualmente curvos devido ao alargamento de uma ou duas células centrais, raramente direitos, septos rígidos, hilo truncado ou protuberante (ELLIS 1971). O género actualmente é composto por mais de 40 táxones que se distinguem por diferenças mais ou menos evidentes na morfologia dos conídios, número de septos e aspectos culturais (SIVANESAN 1987, HOSOKAWA et al. 2003, SIVANESAN et al. 2003, ZHANG-MENG & ZHANG 2003, ZHANG-MENG et al. 2004, CHUNG 2005). Algumas espécies possuem teleomorfo conhecido no género Cochliobolus Drechsler 1934, formando ascósporos filiformes paralelos ou frouxamente enrolados em espiral, característica não evidenciada pela espécie tipo do género, C. heterostrophus (Drechsler) Drechsler, teleomorfo de Bipolaris maydis (Nisik. & Miyake) Shoem., na qual os ascósporos se mostram enrolados formando uma espiral fechada. Por isso, teleomorfos dos fungos do género Curvularia são considerados por alguns autores como sendo do género Pseudocochliobolus Tsuda, Ueyama & Nishih. 1978, que é tido como uma sinonímia de Cochliobolus (ALCORN 1983, SIVANESAN 1987). De notar, no entanto, que sendo filogeneticamente próximo do género Bipolaris Shoem. 1959, as suas espécies apresentam semelhanças morfológicas com espécies do género Bipolaris que têm conídios pequenos e direitos e estudos com análise de sequências ITS e com o marcador enzimático gliceraldeído-3-P desidrogenase mostraram que partilham teleomorfo no grupo 2 do género Cochliobolus (BERBEE et al. 1999). A variabilidade morfológica observada nos fungos enquadrados em Curvularia levou a que ao ser criado o género as espécies fossem separadas em três grupos, ‘geniculata’, com a espécie-tipo C. geniculata (Tracy & Earle) Boedijn, ‘lunata’, com a espécie-tipo C. lunata (Tracy & Earle) Boedijn, e ‘maculans’, com a espécie-tipo C. maculans (Bancroft) Boedijn (=C. eragrostidis (Henn.) Mey.), que se diferenciaram pela forma dos conídios e número de septos (CORBETTA 1964). Nos grupos ‘lunata’ e ‘maculans’ ficaram colocadas as espécies com conídios 3-septados e no grupo ‘geniculata’ as espécies que tinham conídios 4- septados ou com maior número de septos. As espécies do grupo ‘lunata’ distinguiram-se das do grupo ‘maculans’ principalmente por apresentarem curvatura mais pronunciada, célula mediana mais volumosa e habitual presença de estroma em cultura. O reconhecimento das características principais do género Curvularia é relativamente fácil, o que permite que seja normalmente possível a identificação ao género de um qualquer espécimen. No entanto, a identificação em espécie é por vezes complicada pelas descrições vagas e ausência de ilustrações em trabalhos mais antigos, inconstância de características morfológicas e biométricas dos esporos, causada por diferentes condições em que ocorre o crescimento, e sobreposição dos valores das medidas apresentadas por diferentes autores (TSUDA & UEYAMA 1982, HOSOKAWA et al. 2003). Contudo, esta situação não impede que a identificação das espécies continue a ser feita numa aproximação fenotípica, com base em características morfológicas e culturais. Recentemente, as espécies C. fallax Boedijn, C. geniculata (Tracy & Earle) Boedijn e C. senegalensis (Speg.) Subram., do grupo ‘geniculata’, que eram aceites como táxones válidos em monografias clássicas do género (ELLIS 1971, SIVANESAN 1987) mostraram-se interférteis (HOSOKAWA et al. 2003), vindo a ser consideradas, com base em características morfológicas e análise de DNA total por RFLP (HOSOKAWA et al. 2003) e na análise da sequência do gene Brn1 (SUN et al. 2003), como espécie única e sinonimizadas com C. geniculata. Sabido que a diversidade dos fungos que ocorrem nos diferentes ecossistemas de Cabo Verde tem sido pouco estudada, iniciou-se um levantamento da micoflora associada a gramíneas, tendo-se obtido uma colecção de Magnaporthe grisea (Hebert) Barr (LIMA & DUCLOS 2001) e de espécies dos géneros Bipolaris, Exserohilum Leonard & Suggs e Curvularia. O presente trabalho tem como objectivo descrever e ilustrar as espécies de Curvularia identificadas na ilha de Santiago e contribuir para o melhor conhecimento do género naquele país. Na bibliografia consultada não foram encontradas referências a fungos do género Curvularia para Cabo Verde.
Resumo:
In the last three decades, the spiralling whitefly (Aleurodicus dispersus) has become an important international pest. The movement of plants and parts of plants (such as fruits) in international trade and tourism, and by natural dispersal, has favoured its introduction to new areas. In common with others whiteflies of economic importance, the immature and adult stages cause direct feeding damage by piercing and sucking of sap from foliage, and indirect damage following the accumulation all over host plants of honeydew and waxy flocculent material produced by the insects. Spiralling whitefly is a pest of tropical and subtropical crops, and highly polyphagous. Up to the 1970s, it had been recorded on 44 genera of plants, belonging to 26 botanical families (Mound & Halsey, 1978). This situation changed with the dispersal of the pest to new areas. Nowadays, the spiralling whitefly is one of the major pest of vegetable, ornamental and fruit crops around the globe (Lambkin, 1999). Important host crops include: banana (Musa sapientum), Citrus spp., coconut (Cocos nocifera), eggplant (Solanum melanogena), guava (Psidium guajava), Hibiscus rosa sinensis, Indian almond (Terminalia catappa), papya (Carica papaya), Rosa sp. and tomato (Lycopersicon esculentum) (Saminathan & Jayaraj, 2001). Spiralling whitefly has its origin in the tropical Americas, including Brazil. Although the pest has been recorded only once in Brasil, in the 1920s in the state of Bahia (Bondar, 1923), it now has official quarantine status because of its economic importance. In the Cape Verte Islands, on the West African coast, the pest was initially introduced in the first half of 2000; it has since become established, reaching urban, natural and agricultural areas of the islands that constitute the archipelago. Since then, the pest has been causing damage to many native plants, ornamentals and cultivated food crops (Anon., 2001; Monteiro, 2004). The present study was done in order to produce an inventory of the most common host plants of spiralling whitefly in this new habitat.
Resumo:
Many species of Apiaceae are found in the Macaronesien Region. Several have been introduccd by human activities, but a number of taxa is endemic to the different archipelagos or even rrstrictcd to a single island. The following enumeration is based mainly on HANSEN & SUNDING ( 1993). In the Arores 28 different taxa of Apiaceae occur; among them four endemic species [AUIMI; hrrrrii WATSON, A. trifoliatum (WATSON) TKEL., Clrtrc~,y~l~~ll~r~~~ cl:oricrm TREL.. SOErich trwrictr GUTIINICK ex SEUB.]. In Madeira the Apiaceae are very diverse and consist ol’ 29 species and subspecies. From the archipelago two monotypic genera, rC/c/trtio. velitru~rr t/ccipicvr.s (SCHRAD. & J. C. WENDL.) Ho~+hl. md kJorli:ia edu[is LOWE and ~hrcc cndcmic species [Oemmrlre diwricore (R. BR.) MABB.. I/nperrr/orio lotvei COSS. and Burrirr~r hre~$~lirrnr LOWE] are described. The Canary Islands have the highest numbcr of plant-species and a high level of endemism. 5-l taxa of Apiaceae are recorded including three endemic genera (Rtrrheopsis A. HANSEX & KUNKEL, Todm-oa PARL. and Tiqyrmm PARL.) and further I5 endemic taxa. The Apiaceae are represented in the Cape Verde Islands by I2 species. Most of the taxa have been introduced by human activities (LOBIN & ZIZKA 1957) like Amvhm grm’eo- 1efr.s L., Apirm grmvolerrs L, Foerricrrhrr urlgore MILL.. Corimrtlru~t~ srrtirvrrrr L. or Petrosilerrm crisprrm (FRILL.) A.W.HILL. These species are cultivated and some of them later became \\esdy. Other species like Ciclosper- UWL /e/~fo/~/l~ll~rrtr (PER%) SPRAGUE (= Apimr leproplr~llrr~rr) are weeds of cultivated grounds or wasted lands. All these species are today widespread in temperate. subtropical or tropical regions all over the world. The only native species are to be found in the endemic genus To~wI~~I~~~ PARL.