This study describes the fruiting phenology of woody plants and their dispersal syndromes in caatinga (semi-arid region in the northeast of Brazil). The fruiting phenology of 42 species with different dispersal modes and life-forms was followed over a period of 1 y. Animal dispersal was the most commonly observed dispersal mode (36%), followed by anemochory (33%), ballistic dispersal (19%) and barochory (12%). Overall, a greater number of species fruited during the rainy season. Zoochorous species were the most representative in the rainy season, whereas anemochorous species predominated during the dry season. Five different life-forms were observed, and the occurrence of dispersal modes was discussed for each of them. In the caatinga plant community studied the patterns of life-forms, fruiting phenology and seed dispersal syndromes were similar to other tropical seasonal ecosystems.Este trabalho teve como objetivo principal descrever como se comportam as espécies de caatinga (região semi-árida do Nordeste brasileiro) com relação ao modo de dispersão durante as estações seca e chuvosa. Foram observados também os modos de dispersão apresentados em cada forma de vida. A fenofase de frutificação foi acompanhada em 10 indivíduos de 42 espécies durante um intervalo de um ano. A zoocoria representou o modo de dispersão mais observado (36%), seguido da anemocoria (33%), balística (19%) e barocoria (12%). Um maior número de espécies frutificou durante a estação de chuvas, sendo a zoocoria mais representativa nesta estação, enquanto que a anemocoria foi mais representativa na época de estiagem. Foram observadas várias formas de vida, discutindo-se o modo de dispersão em cada uma delas. Constatou-se que as espécies de caatinga estudadas encontram-se dentro dos padrões gerais de época de dispersão dos diásporos e representatividade das síndromes de dispersão observados em outros ecossistemas com sazonalidade.

The phenology of 19 species of plants was followed for two years at Serra Talhada, Pernambuco State, Northeastern Brazil. Ten plants of each species were monitored biweekly. All plants had a complete canopy cover from February (well established rainy season) until May-June (just after rains ceased), and all but a few individuals, belonging to six species, were leafless in October-November (peak of the dry season). Leaf fall and flush, flowering, and fruiting were almost continuous in the community throughout both the years, but they peaked at different periods. The peak of leaf flush preceded the rainy season, spurred by occasional rains, followed by flowering early in the rainy season, and then fruiting. Leaf fall became more pronounced after the rainy season. The species covered a whole range of deciduousness, from those which retained their leaves throughout both years to those which were leafless during 6-7 months each year. This was mostly due to the capacity of leaf retention after the onset of the dry season. Autochoric and mchoric species produced fruits mostly during the rainy season and anemochoric species during the dry period. The patterns of flowering and fruiting were complex. One species did not produce flowers or fruits in either year; five produced flowers and fruits in one year only and two others produced flowers in both years but fruits in only one. Most of the other species had high intraspecific synchrony and produced flowers for a shorter period than fruits. RESUMOA fenologia de 19 espkcies de plantas foi acompanhada por dois anos, em Serra Talhada, PE. D a plantas de cada e s w i e foram observadas a intervalos de duas semanas. Todas as plantas tinham a copa completa de fevereiro (estago chuvosa bem estabelecida) a maio-junho (logo apds o tbrmino das chuvas) e todas, com excego de poucos individuos pertencentes a seis especies, estavam sem foihas em outubro-novembro (auge da estago seca). Queda e formago de folhas novas, florago e frutificago foram quase continuas na comunidade, durante 0 s dois anos, mas corn picos em perlodos diferentes. 0 pic0 de formago de folhas precedeu a estago chuvosa, impulsionado por chuvas esporhdicas, seguido do de florago, no inicio da estago de chuvas, e depois pel0 de frutificago. Queda de folhas foi mais pronunciada depois do perlodo chuvoso. As espkcies cobriram toda m a gama de caducifolia, desde as que mantiveram as folhas durante 0 s dois anos As que ficaram defoliadas durante 6-7 meses cada ano. Isto deveuse, principalmente, As suas capacidades de reter folhas ao longo da estago sea. Espkcies autodricas e zoocdricas produziram frutos principalmente no periodo chuvoso e as espkcies anemocdricas no perlodo seco. 0 s padr6es de florago e frutificago foram complexos. Uma e s e i e nio produziu flores ou frutos nos dois anos, cinco produziram flores e frutos apenas em um dos anos e duas outras, em urn dos anos, produziram flores que nPo se desenvolveram em frutos. A maioria das outras espkcies teve alta sincronia intra-especlfica e produziu flores por urn p...

The results indicated that the pollination systems in Caatinga, despite climatic restrictions, are diversified, with a low percentage of generalist flowers, and similar to other tropical dry and wet forest communities, including those with high rainfall levels.

Recebido em 17/03/00. Aceito em 04/07/2000 RESUMO -(Sistema de polinização e reprodução de Byrsonima sericea DC (Malpighiaceae)). A polinização, o sistema reprodutivo e a fenologia de floração de Byrsonima sericea, foram estudados no período de outubro/1997 a fevereiro/1998 na Reserva Ecológica de Dois Irmãos, Recife (PE). Byrsonima sericea possui porte arbóreo (3 a 20m), com período de floração de outubro a fevereiro. As flores são hermafroditas, zigomorfas, agrupadas em inflorescências do tipo racemo terminal. A corola é amarela e possui cinco pétalas unguiculadas, sendo a superior modificada em forma de estandarte. O cálice é formado por cinco sépalas com dez glândulas epiteliais produtoras de óleo, os elaióforos. Em alguns indivíduos essas glândulas são ausentes. O androceu é formado por dez estames, com anteras rimosas e deiscência ocorrendo em fase de pré-antese floral. A viabilidade dos grãos de pólen foi de 93,3% e 98,3%, em indivíduos com e sem elaióforos, respectivamente, sendo o número de grãos de pólen por antera de 1.216,66 e 923,33 e a razão pólen/óvulo (P/O) de 308.000 e 405.500. Como visitantes das flores, observaram-se abelhas pertencentes às famílias Anthophoridae (coletoras de óleo e pólen), Apidae e Halictidae (somente pólen). Baseandose nas estratégias e recompensas florais (óleo e pólen), elevada razão P/O e, principalmente, na ausência de formação de frutos nos experimentos de autopolinização, conclui-se que esta espécie é xenógama.Palavras-chave -Malpighiaceae, Byrsonima, melitofilia, flores de óleo, Anthophoridae ABSTRACT -(Pollination and reproductive system of Byrsonima sericea DC (Malpighiaceae)). The pollination, the reproductive system and the flowering phenology of Byrsonima sericea DC. were studied from October/1997 to February/1998 in the Ecological Reserve of "Dois Irmãos", in Recife (PE). Byrsonima sericea is a woody species (3-20 m tall), flowering from October to February. The flowers are hermaphrodites, zygomorphic, arranged in terminal inflorescence, of the raceme type. The corolla is yellow and has five clawed and fringed petals. The superior one is modified as a flag. The calyx has five sepals with 10 elliptic epithelial oil glands, the elaiophores. In some individuals these elaiophores are absent. The androecium has 10 stamens, the anthers are rimoses and the dehiscence occurs at the pre-anthesis phase. Pollen viability was 93,3% and 98,3%, respectively to individuals with and without elaiophores, the number of pollen grains per anther was 1.216,66 and 923,33, and the pollen/ovule (P/O) ratio was 308.000 and 405.500. Floral visitors were only female bees of the families Anthophoridae (that collected oil and pollen), Apidae and Halictidae (that collected only pollen). Based on the strategies and rewards (oil and pollen), the high P/O ratio, and mainly because of the absence of fruits from self-pollination tests, it is concluded that this species is xenogamic.

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.

Aim: Among the world's three major nectar-feeding bird taxa, hummingbirds are the most phenotypically specialized for nectarivory, followed by sunbirds, while the honeyeaters are the least phenotypically specialized taxa. We tested whether this phenotypic specialization gradient is also found in the interaction patterns with their floral resources.Location: Americas, Africa, Asia and Oceania/Australia. Methods:We compiled interaction networks between birds and floral resources for 79 hummingbird, nine sunbird and 33 honeyeater communities. Interaction specialization was quantified through connectance (C), complementary specialization (H 2 0 ), binary (Q B ) and weighted modularity (Q), with both observed and null-model corrected values. We compared interaction specialization among the three types of bird-flower communities, both independently and while controlling for potential confounding variables, such as plant species richness, asymmetry, latitude, insularity, topography, sampling methods and intensity.Results: Hummingbird-flower networks were more specialized than honeyeaterflower networks. Specifically, hummingbird-flower networks had a lower proportion of realized interactions (lower C), decreased niche overlap (greater H 2 0 ) and greater modularity (greater Q B ). However, we found no significant differences between hummingbird-and sunbird-flower networks, nor between sunbird-and honeyeaterflower networks.

ReSUMoExistem cerca de 330 espécies de abelhas que usam óleo coletado em flores para alimentar as larvas e revestir as células de cria, e pertencem aos grupos Melittinae (Melittidae), Centridini, tapinostapidini e tetrapediini (Apidae). As últimas três tribos são exclusivamente do hemisfério oeste e especialmente diversas na região Neotropical. Abelhas coletoras de óleo possuem modificações nas pernas ou esterno (Tapinotaspoides) para coletar, manipular e transportar o óleo. essas estruturas normalmente são relacionadas aos diferentes tipos de elaióforos (as glândulas secretoras de óleo): epitelial ou em tricomas. estima-se que mais de 1800 espécies de plantas de nove famílias ofereçam óleo floral como recurso, sendo Malpighiaceae a mais importante. Neste trabalho organizamos uma revisão sobre o processo de nidificação de algumas abelhas coletoras de óleo, bem como sobre associação com as plantas produtoras de óleo. As abelhas coletoras de óleo são de vida solitária, mas algumas espécies nidificam em agregação. As espécies que fazem ninho no solo usam superfícies planas ou barrancos (como Epicharis, Monoeca, Lanthanomelissa). existem espécies que utilizam ninhos de cupins e formigas (como Ptilotopus) ou cavidades pré-existentes (como Tetrapedia). os parasitas geralmente são abelhas cleptoparasitas como Coelioxys, Coelioxoides, Mesoplia, Mesocheira, Protosiris, Paraepeolus, que ovipositam dentro da célula de cria e suas larvas (com mandíbulas afiadas) matam o ovo ou larva da hospedeira. Apesar de todo avanço no conhecimento sobre as abelhas coletoras de óleo ainda restam questões a serem desvendadas sobre a utilização deste produto pelas abelhas Palavras-chave: Flores produtoras de óleo, Centridini, tapinotaspidini, tetrapediini, Apoidea.

Recent studies show that the mutualistic role of lizards as pollinators and seed dispersers has been underestimated, with several ecological factors promoting such plant-animal interactions, especially on oceanic islands. Our aim is to provide a quantitative assessment of pollination and seed dispersal mutualisms with lizards in continental xeric habitats. We carried out focal observations of natural populations of Melocactus ernestii (Cactaceae) in the Caatinga, a Brazilian semiarid ecosystem, in order to record the frequency of visits, kind of resource searched and behaviour of visiting animals towards flowers and/or fruits. We made a new record of the lizard Tropidurus semitaeniatus foraging on flowers and fruits of M. ernestii. During the search for nectar, T. semitaeniatus contacted the reproductive structures of the flowers and transported pollen attached to its snout. Nectar production started at 14:00 h, with an average volume of 24.4 μl and an average concentration of solutes of 33%. Approximately 80% of the seeds of M. ernestii found in the faeces of T. semitaeniatus germinated under natural conditions. The roles of T. semitaeniatus as pollinator and seed disperser for M. ernestii show a clear relationship of double mutualism between two endemic species, which may result from the environmental conditions to which both species are subject. Seasonality, low water availability and arthropod supply in the environment, high local lizard densities, continuous nectar production by the flower and fruits with juicy pulp may be influencing the visits and, consequently, pollination and seed dispersal by lizards in this cactus.