Silvana Buzato

The Saw-billed HermitRamphodon naevius and its flowers in southeastern Brazil

The large Saw-billed HermitRamphodon naevius and its foraging behaviour on a variety of ornithophilous flowers were studied at one site in the Atlantic rainforest in southeastern Brazil. The flower assemblage visited by this endemic hermit throughout the year is composed mainly by epiphytes and herbs, Bromeliaceae and Heliconiaceae being the staple foodplants. Most of the plant species present steady-state, long-tubed and high-reward flowers, and bloom sequentially. The Saw-billed Hermit is a year-round resident and traplining forager, behaves aggressively over its feeding routes, and excludes conspecifics and other hummingbird species from its main flower sources. This large hermit regularly visited and pollinated about 45 % of the native ornithophilous plants at the study site, thus acting as the major pollinator on this flower assemblage. Der große in Südbrasilien endemische Sägeschnabel-Schattenkolibri (Ramphodon naevius) und dessen Nahrungsverhalten an ornithophilen Blüten einer Pflanzengesellschaft des atlantischen Regenwaldes wurde untersucht. Die von ihm besuchten Blüten gehören hauptsächlich zu Kräutern und Epiphyten, wobei Bromeliaceen und Heliconiaceen die Hauptnahrungspflanzen bilden. Diese Arten haben eine lange Blühperiode und blühen konsekutiv. Die Blüten besitzen lange Kronröhren und sondern reichlich Nektar ab. Der standortstreue Kolibri hält eine bestimmte Route und einen Zeitplan bei der Nahrungsaufnahme ein; er verhält sich aggressiv sowohl gegenüber Individuen seiner eigenen Art als auch solchen anderer Kolibriarten, die er von den wichtigsten Nahrungsquellen vertreibt. Der Sägeschnabel-Schattenkolibri besuchte regelmäßig ca. 45 % der ornithophilen einheimischen Pflanzen einer bestimmten Gesellschaft. Damit ist er der wichtigste Bestäuber dieser Pflanzen.

Nectar by day and night:Siphocampylus sulfureus (Lobeliaceae) pollinated by hummingbirds and bats

Most species of the neotropical genusSiphocampylus are believed to be bird-pollinated. The pollination biology ofSiphocampylus sulfureus was studied in a montane region in SE Brazil. This species has features intermediate between ornithophilous and chiropterophilous syndromes: it presents a striking combination of yellowish flowers with strong odour (chiropterophilous features), and diurnal anthesis and sucrose-dominated nectar (ornithophilous features). Major pollinators were hummingbirds by day, and a phyllostomid bat by night.Siphocampylus sulfureus may be viewed as a recent derivate from the presumed ornithophilous stock within sect.Macrosiphon, and thus benefits from the activity of both diurnal and nocturnal vertebrate pollinators.

Pollination of three species of Abutilon (Malvaceae) intermediate between bat and hummingbird flower syndromes

Summary Some species of Abutilon in southeastern Brazil overlap their flower features between hummingbird and bat pollination syndromes. We studied three such species in the montane rainforest in southeastern Brazil. Abutilon rufinerve , A. regnellii and A. aff. regnellii present the following combination of ornithophilous and chiropterophilous features: bell to bowl-shaped flowers lasting about 30 h, coloured pinkish to purplish, or yellowish, crepuscular (dusk or dawn) anthesis, and very faint cabbage odour. The flowers are visited and pollinated by a species of phyllostomid bat at night, and by several species of hummingbirds during the day. Although somewhat intermediate between ornithophily and chiropterophily, the floral features of the three species of Abutilon tend towards the bat-pollination syndrome.

Variation in pollinator assemblages in a fragmented landscape and its effects on reproductive stages of a self-incompatible treelet, Psychotria suterella (Rubiaceae)

Few studies of plant–pollinator interactions in fragmented landscapes evaluate the consequences of floral visitor variation on multiple stages of plant reproduction. Given that fragmentation potentially has positive or negative effects on different organisms, and that self-incompatible plant species depend on pollinators for sexual reproduction, differences in floral visitor assemblages may affect certain plant reproductive stages. We evaluated how pollinator assemblage, availability of floral resources, pollination, reproductive output, and seed and seedling performance of Psychotria suterella Muell. Arg. varied among three fragmentation categories: non-fragmented habitats, fragments connected by corridors, and isolated fragments. Richness and frequency of floral visitors were greater in fragments than in non-fragmented sites, resulting mainly from the addition of species typically found in disturbed areas. Although 24 species visited Psychotria suterella flowers, bumblebees were considered the most important pollinators, because they showed the highest frequency of visits and were present in eight out of ten sites. Additionally, the number of pollen tubes per flower per visit was lower in areas without bumblebees. The increased visitation in fragments seemed to enhance pollination slightly. However, fruit and seed output, germination, and seed and seedling mass were similar in non-fragmented sites, connected sites, and isolated fragments. Our results suggested that, even for a self-incompatible species, responses to habitat fragmentation at different stages of plant reproduction might be decoupled from the responses observed in floral visitors, if fruit set is not pollen limited. If all reproductive stages were considered, variation on the small scale was more important than the variation explained by fragmentation category. In spite of its self-incompatible breeding system, this plant–pollinator system showed resilience to habitat fragmentation, mainly as a result of high availability of potential mates to P. suterella individuals, absence of pollen limitation, and the presence of bumblebees (Bombus spp.) throughout this highly connected landscape.

Tetrastylis ovalis : a second case of bat-pollinated passionflower (Passifloraceae)

The floral biology ofTetrastylis ovalis and its pollination by bats was studied in southeastern Brazil. The flowers ofT. ovalis seem more fitted to bat-pollination than those ofPassiflora mucronata, the other known chiropterophilous passionflower. Two species of bats were observed visiting flowers ofT. ovalis: the phyllostomidsGlossophaga soricina andRhinophylla pumilio. Due to the attributes ofTetrastylis, its presumed primitiveness and a better defined bat-pollination syndrome we suggest that chiropterophily evolved independently in the former genus and inPassiflora.

Biologia reprodutiva de Psychotria suterella Muell. Arg. (Rubiaceae) e a abordagem de escalas ecológicas para a fenologia de floração e frutificação

Foraging behavior of pollinators and seed dispersers is related to resource heterogeneity in the environment, making it important to know the spatio-temporal variation of resources in order to understand the mutualistic relationships established between plants and animals. Psychotria suterella flowered from January to April, months with highest annual rainfall, and exhibited high synchronism among the populations in the landscape studied. The flowering pattern found on the category of individuals corresponds to that one found in populations and landscape categories. Fructification occurred all year long, with greater availability of mature fruits in May and December; and synchronism was lower in this phenophase than in flowering. Only intermorph pollinations produced fruits and seeds, indicating that this plant species relies on pollen vectors for sexual reproduction. Since there is no evidence of pollen limitation, we consider that differences in fructification among populations could be related to abiotic factors. The overlap between flowering pattern of Psychotria suterella and Bombus brasiliensis foraging activicty, the fact that B. brasiliensis is the most important pollinator of this plant species, as well as the importance of P. suterella for this bee diet, suggest that selective pressures could be acting between these species, underlying this mutualistic interaction.