Fernando A. O. Silveira

Edge effects on the orchid-bee fauna (Hymenoptera: Apidae) at a large remnant of Atlantic Rain Forest in southeastern Brazil.

Male orchid bees were sampled with chemical baits monthly from July 1999 to April 2000 at six sites situated at different distances from the forest edge (0 to 4,000 m) at Parque Estadual do Rio Doce, the largest remnant of Atlantic Forest in the state of Minas Gerais, southeastern Brazil. The main goal of this study was to assess the abundance, richness, and the community structure of the orchid-bee fauna at different distances from the edge. In all, 1,183 males from 20 species were collected. Only minor and insignificant variation in richness and abundance were observed among the sites. Two dominant species, Euglossa analis Westwood (Hymenoptera: Apidae) and Eulaema cingulata (Fabricius) (Hymenoptera: Apidae), showed strongly opposing habitat associations: while males of the former were most collected in the interior of the forest, the latter was most found at or close to the edge. The responses of individual species, such as these, and not composite measures of richness and abundance, are more informative regarding forest integrity and edge effects.

Orchid bee fauna (Hymenoptera: Apidae: Euglossina) of Atlantic Forest fragments inside an urban area in southeastern Brazil

Male orchid bees were collected by chemical baiting in four forest fragments in parks of the city of Belo Horizonte, Minas Gerais, southeastern Brazil. One thousand three hundred and twenty-five males belonging to 14 species were captured within one year. The capture data were compared through correlation tests. The data suggest that abundance of orchid bees tend to increase with fragment size, although no correlation between species richness and fragment size was obtained. The results presented herein suggest that forest fragments in a large city may be of importance concerning conservation of orchid-bee faunas.

Diversity and distribution of orchid bees (Hymenoptera: Apidae) with a revised checklist of species

The aim of this study was to investigate the diversity and distribution patterns of orchid bees (Euglossina). Cluster and correlation analyses were applied to data extracted from 28 orchid-bee surveys throughout the Neotropical Region. The 28 sampling sites were grouped in three main biogeographic areas that roughly correspond to the Amazonian Basin, the Atlantic Forest and Central America. These three regions, as well as subregions within each of them, correspond approximately to biogeographic components identified through phylogeny-based analyses for other bees and organisms. The Amazonian Forest as a whole has the richest fauna and the highest levels of endemism. The Atlantic Forest, on the other hand, showed the poorest fauna and the lowest levels of endemism. However, a major neotropical biome, in which orchid bees are known to occur, has not been sampled yet, the savanna-like cerrado. At least 30% of the species are endemic to each biome. An updated checklist of the species of Euglossina is provided.

Forest fragments with larger core areas better sustain diverse orchid bee faunas (Hymenoptera: Apidae: Euglossina)

Male orchid bees were attracted to chemical baits and collected in nine Atlantic Forest fragments in southeastern Brazil. Fragments differed in size and shape. Three additional sites were also sampled in a nearby large fragment. Three hypothetical core areas of each fragment were measured as the total area minus an area of 50, 100, and 200-m-wide perimeter. Abundance and richness were not correlated with either fragment size or ratio area/perimeter, but were positively correlated with the size of core areas. These results suggest that orchid bee conservation requires the preservation of the fragments with the largest possible core areas. Neither size nor shape alone (area/perimeter ratio) seemed to be good indicators of the value of a given fragment for sustaining diverse and abundant faunas of orchid bees.

Evolution of physiological dormancy multiple times in Melastomataceae from Neotropical montane vegetation

We investigated seed dormancy among species of Melastomataceae from Neotropical montane vegetation of Brazil. Four out of 50 studied species had dormant seeds: Miconia corallina (Miconieae), Tibouchina cardinalis (Melastomeae), Comolia sertularia (Melastomeae) and Chaetostoma armatum (Microlicieae). For these four species, germinability of seeds collected in different years was always ,10% and the percentages of embryoless seeds and non-viable embryos were both insufficient to explain low or null germinability. This is the first unequivocal report of seed dormancy in tropical Melastomataceae. The production of seeds with permeable seed coats and fully developed, differentiated embryos indicates the occurrence of physiological dormancy. The reconstructed phylogenetic tree of the 50 species suggests that physiological dormancy evolved multiple times during the evolutionary history of Melastomataceae in this vegetation. Physiological dormancy evolved in species and populations associated with xeric microhabitats, where seeds are dispersed in unfavourable conditions for establishment. Therefore, droughtinduced mortality may have been a strong selective pressure favouring the evolution of physiological dormancy in Melastomataceae. We argue that dormancy may have been independently selected in other lineages of Cerrado plants colonizing xeric microhabitats and dispersing seeds at the end of the rainy season. The contributions of our data to the understanding of seed dormancy in tropical montane vegetation are discussed.

Phylogeny strongly drives seed dormancy and quality in a climatically buffered hotspot for plant endemism.

Background and Aims Models of costs and benefits of dormancy (D) predict that the evolutionarily stable strategy in long-term stable environments is for non-dormancy (ND), but this prediction remains to be tested empirically. We reviewed seed traits of species in the climatically buffered, geologically stable and nutrient-impoverished campo rupestre grasslands in Brazil to test the hypothesis that ND is favoured over D. We examined the relative importance of life-history traits and phylogeny in driving the evolution of D and assessed seed viability at the community level. Methods Germination and viability data were retrieved from 67 publications and ND/D was determined for 168 species in 25 angiosperm families. We also obtained the percentage of embryoless, viable and dormant seeds for 74 species. Frequencies of species with dormant and non-dormant seeds were compared with global databases of dormancy distribution. Key Results The majority of campo rupestre taxa (62·5 %) had non-dormant seeds, and the ND/D ratio was the highest for any vegetation type on Earth. Dormancy was unrelated to other species life-history traits, suggesting that contemporary factors are poor predictors of D. We found a significant phylogenetic structure in the dormancy categorical trait. Dormancy diversity was highly skewed towards the root of the phylogenetic tree and there was a strong phylogenetic signal in the data, suggesting a major role of phylogeny in determining the evolution of D versus ND and seed viability. Quantitative analysis of the data revealed that at least half of the seeds produced by 46 % of the surveyed populations were embryoless and/or otherwise non-viable. Conclusions Our results support the view that long-term climatic and geological stability favour ND. Seed viability data show that campo rupestre species have a markedly low investment in regeneration from seeds, highlighting the need for specific in situ and ex situ conservation strategies to avoid loss of biodiversity.

Biogeographic notes on rare species of Euglossina (Hymenoptera: Apidae: Apini) occurring in the Brazilian Atlantic Rain Forest

The significance of specimens of rare species of Euglossina collected recently is discussed in terms of elucidating their biogeography and conservation status. Particularly, two new records are presented for the state of Minas Gerais, which considerably increase the known geographic range of the species they represent. These are a male of Eufriesea aeneiventris (Mocsary), last recorded in 1943, which was attracted to methyl salicylate at the Parque Estadual do Rio Doce, and a male of Eulaema seabrai collected on flowers in the urban area of Sabara. This is also the first record for this species in the state.

Are seed germination and ecological breadth associated? Testing the regeneration niche hypothesis with bromeliads in a heterogeneous neotropical montane vegetation

Abstract The role of seed germination in contributing to species ecological breadth and geographic distribution is still a matter of debate. Here, we attempted to relate seed germination requirements with ecological breadth in 12 bromeliad species from heterogeneous montane vegetation in southeastern Brazil. Seeds were set to germinate under both light and dark conditions at a broad range of temperatures to determine the breadth of the germination niche. We ran a RLQ analysis based on the matrices of species occurrence, environmental parameters and germination traits and found a significant association between germination traits, and the characteristics of sites where adult plants occur. The variation of germination responses to environmental factors was not random with habitat-generalist plants having broader germination niches and habitat-specialist plants having narrower germination niches. The RLQ analysis showed that substrate moisture and light environment were the most important factors correlated with germination traits. Phylogenetic niche conservatism appears to play a role in the patterns found here, especially in the Tillandsioideae. There is an association between the regeneration niche of a species and its ecological range, and this also provides support for the idea that the regeneration niche may help assemble plant species into heterogeneous, species-rich communities.

Relationships between host plant architecture and gall abundance and survival

A hipotese da arquitetura de planta prediz que variacoes na arquitetura da planta hospedeira influenciam a comunidade de insetos herbivoros, sua dinâmica e performance. Neste estudo o efeito da arquitetura de Macairea radula (Melastomataceae) na abundância de galhas induzidas por uma mariposa (Lepidoptera: Gelechiidae) foi avaliado. A arquitetura da planta e a abundância de galhas foram diretamente registradas em 58 individuos de M. radula arbitrariamente selecionados durante a estacao chuvosa de 2006 em uma area de Cerrado no sudeste brasileiro. A altura da planta, biomassa seca, numero de ramos e abundância de galhas foram utilizados como variaveis para prever a abundância de galhas e sobrevivencia das larvas. A abundância das galhas foi positivamente correlacionada com a biomasssa seca e o numero de ramos secundarios. Por outro lado, nenhuma correlacao (p > 0.05) foi encontrada entre a abundância de galhas e ramos terciarios e numero de folhas por planta. De um total de 124 galhas analisadas, 67,7% sobreviveram, 14,5% foram parasitadas e 17,7% morreram por causas indeterminadas. No entanto, o parasitismo e sobrevivencia das larvas nao foram influenciados pela complexidade arquitetonica da planta hospedeira. Os resultados corroboram parcialmente a hipotese de arquitetura da planta, mas como o parasitismo nao foi relacionado com a arquitetura da planta, os efeitos reguladores de niveis inferiores da cadeia alimentar possivelmente sao mais importantes do que os efeitos de niveis superiores da cadeia alimentar na dinâmica populacional do galhador.

Abiotic factors modulate phenotypic plasticity in an apomictic shrub [Miconia albicans (SW.) Triana] along a soil fertility gradient in a Neotropical savanna

Phenotypic plasticity is an important means by which plants cope with environmental heterogeneity; therefore, understanding variation in plant traits in heterogeneous habitats is important to predict responses to changing environments. In this study, we examined the patterns of intraspecific variation in leaf traits of Miconia albicans (Melastomataceae), a widespread, obligatory apomictic shrub, across a soil fertility gradient in the Cerrado (Brazilian savanna). We predicted high plasticity because selection favours high phenotypic plasticity in asexual populations with low genetic variability. Leaves were sampled in campo sujo (grassland), cerrado (savanna) and cerradao (woodland) in south-eastern Brazil during both dry and rainy seasons to calculate leaf area, specific leaf area, leaf tissue thickness, trichome and stomata density. We found significant between-season variation in leaf traits, indicating that the production of season-specific leaves is a strategy to cope with the strong seasonality. Both multivariate analysis and the relative distance plasticity index indicate lower plasticity during the dry season, especially under shade. Our results show that the phenotypic plasticity can be modulated by changes in abiotic factors and the combination of shade and drought can limit the expression of phenotypic plasticity.