RESUMO

The last decade was marked by efforts to define and identify the main cyanobacterial players in biological crusts around the world. However, not much is known about biocrusts in Brazil's tropical savanna (cerrado), despite the existence of environments favorable to their development and ecological relevance. We examined the community composition of cyanobacteria in biocrusts from six sites distributed in the Southeast of the country using high throughput sequencing of 16S rRNA and phylogenetic placement in the wider context of biocrusts from deserts. Sequences ascribable to 22 genera of cyanobacteria were identified. Although a significant proportion of sequences did not match those of known cyanobacteria, several clades of Leptolyngbya and Porphyrosiphon were found to be the most abundant. We identified significant differences in dominance and overall composition among the cerrado sites, much larger than within-site variability. The composition of cerrado cyanobacterial communities was distinct from those known in biocrusts from North American deserts. Among several environmental drivers considered, the opposing trend of annual precipitation and mean annual temperature best explained the variability in community composition within Brazilian biocrusts. Their compositional uniqueness speaks of the need for dedicated efforts to study the ecophysiology of tropical savanna biocrust and their roles in ecosystem function for management and preservation.

RESUMO

Animal-pollinated plants can be susceptible to changes in pollinator availability. Honeydew-producing treehoppers frequently occur on inflorescences, potentially enhancing ant-mediated negative effects on pollination services. However, the effect of ant-attended, honeydew-producing insects on plant reproduction remains uncertain. We recorded the abundance of treehoppers and ants on Byrsonima intermedia (Malpighiaceae), and monitored floral visitors in a Brazilian cerrado savanna. We manipulated the presence of ants and ant-treehopper associations on inflorescences to assess their effect on pollination and fruit formation. We used dried ants pinned to inflorescences to evaluate the effect of ant presence and ant identity on potential pollinators. Results show that the presence of treehoppers increases ant abundance on flowers and disrupts pollination by oil-collecting bees, decreasing the frequency and duration of floral visits and reducing fruit and seed set. Treehopper herbivory has no direct effect on fruit or seed production, which are independent of treehopper density. Pinned ants promote avoidance by floral visitors, reducing the number of visits. Ant identity mediates visitation decisions, with Ectatomma brunneum causing greater avoidance by floral visitors than Camponotus rufipes. Field videos show that pollinating bees are harassed by ants near flowers, prompting avoidance behavior by the bees. This is the first demonstration of indirect effects by honeydew-gathering ants, via disrupted pollination, on plant reproduction in tropical cerrado savanna. Our results highlight the importance of studying other interactions near flowers, in addition to just observing pollinators, for a proper understanding of plant reproduction.

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RESUMO

Landscape structure is an important determinant of biological fluxes and species composition, but species do not respond equally to landscape features or spatial extents. Evaluating "multi-scale" responses of species to landscape structure is an important framework to be considered, allowing insights about habitat requirements for different groups. We evaluated the response of Brazilian Cerrado's bees (eusocial vs. solitary ones) to both the amount and isolation of remnant vegetation in eight nested multiple-local scales. Response variables included abundance, observed, and estimated species richness, and beta diversity (split into nestedness and turnover resultant dissimilarities). Eusocial species' abundance responded to landscape structure at narrow scales of fragment isolation (250 m of radius from sampling sites), while solitary species' abundance responded to broader scales to fragment area (2000 m). Eusocial species nestedness also responded to landscape features in broader scales (1500 m), especially to increasing fragment isolation. However, all the remaining response variables did not respond to any other landscape variables in any spatial scale considered. Such contrasting responses of the abundances of eusocial vs. solitary species are related to the inherent life-history traits of each group. Important attributes in this context are different requirements on food resources, population features, and flight abilities. Species-specific dispersal abilities may be the main determinants of the nested patterns found for eusocial species at 1500 m. Considering these results, we suggest that different bee groups are considered separately in further landscape analyses, especially in other Brazilian biomes, for a better understanding of landscape effects on these organisms.

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RESUMO

Given the substantial lacunas in the understanding of the occurrence and distribution of bat species in the eastern portion of the Brazilian state of Mato Grosso (Araguaia basin), this study presents an inventory of the species known to occur in the region, highlighting the areas sampled adequately and the species known to occur in conservation units. Georeferenced records of the occurrence of bat species in the region were obtained from published studies, scientific collections, through either the SpeciesLink network or directly from the curator, as well as the capture of specimens by our research group between 2008 and 2013. A 0.5° x 0.5° (latitude/longitude) grid was added to the map of the region for the quantification of the bat species richness of each grid cell. A total of 63 chiropteran species were recorded for the study area. Only 10 of the 30 grid cells had records of bats, and just three contained more than 20 species, and were considered to be sampled adequately on a minimal level. Bat species have been recorded in three conservation units, two state and one municipal. The number of species recorded represents 82.7% of the total of chiropterans known to occur in Mato Grosso, although 12 species were recorded in the state for the first time, reinforcing the paucity of data available on the distribution of bats in the region. The high bat species richness recorded in the present study reinforces the importance of eastern Mato Grosso, a transition zone between the Amazon forest and the Cerrado savanna of central Brazil, for the conservation of Neotropical chiropterans.

Frente è lacuna existente sobre a real ocorrência e distribuição das espécies de morcegos objetivamos listar as espécies registradas na região leste do estado de Mato Grosso, Brasil, apontando os locais minimamente amostrados e as espécies catalogadas dentro das Unidades de Conservação. Foram consideradas espécies com registros georrefenciados para a região disponibilizados por periódicos científicos, coleções científicas, por meio do sistema SpeciesLink ou disponibilizados diretamente pela curadoria, além de capturas realizadas entre 2008 e 2013 pelo nosso grupo de pesquisa. Ao mapa da região leste do estado foi incorporado células de 0,5° latitudinais X 0,5° longitudinais e quantificadas sobre a riqueza de espécies de morcegos em cada célula. Foram registradas 63 espécies para a região. Das 30 células geradas 10 tiveram pelo menos uma espécie registrada e três tiveram mais de 20 espécies sendo consideradas minimamente amostradas. Três Unidades de Conservação tiveram espécies catalogadas, sendo duas estaduais e uma municipal. A região leste teve o registro de 82,7% do total de espécies conhecidas para o estado de Mato Grosso, sendo que 12 ainda não haviam sido assinaladas para o estado demonstrando que ainda pouco se conhece sobre a real distribuição dos morcegos na região. Considerando a alta riqueza encontrada enfatizamos a importância da região leste de Mato Grosso, zona de transição entre Cerrado e Amazônia, e também o potencial do estado na conservação dos morcegos neotropicais.

RESUMO

The Brazilian cerrado has undergone an intense process of fragmentation, which leads to an increase in the number of remnants exposed to edge effects and associated changes on environmental conditions that may affect the phenology of plants. This study aimed to verify whether the reproductive phenology of Xylopia aromatica (Lam.) Mart. (Annonaceae) differs under different light conditions in a cerrado sensu stricto (a woody savanna) of southeastern Brazil. We compared the reproductive phenology of X. aromatica trees distributed on east and south cardinal faces of the cerrado during monthly observations, from January 2005 to December 2008. The east face had a higher light incidence, higher temperatures and canopy openness in relation to south face. X. aromatica showed seasonal reproduction at both faces of the cerrado, but the percentage of individuals, the synchrony and duration of phenophases were higher at the east face. The study demonstrated the influence of the environmental conditions associated to the cardinal orientation of the cerrado faces on the phenological pattern of X. aromatica. Similar responses may be observed for other species, ultimately affecting patterns of floral visitation and fruit production, which reinforces the importance of considering the cardinal direction in studies of edge effects and fragmentation.

O cerrado brasileiro vem sofrendo um processo intenso de fragmentação, que levou ao aumento de remanescentes sujeitos aos efeitos de borda e a alterações nas condições ambientais que podem afetar a fenologia das plantas. O objetivo deste trabalho foi verificar se a fenologia reprodutiva de Xylopia aromatica (Lam.) Mart. (Annonaceae) difere sob diferentes condições de luz em um cerrado sensu stricto no sudeste do Brasil. Comparamos a fenologia reprodutiva de árvores de X. aromatica distribuídas nas faces leste e sul do cerrado, observadas mensalmente de janeiro de 2005 a dezembro de 2008. A face leste apresentou maior incidência de luz, temperaturas e aberturas do dossel em relação à face sul. X. aromatica apresentou reprodução sazonal em ambas as faces do cerrado, mas a porcentagem de indivíduos, sincronia e duração das fenofases foram maiores na face leste. O estudo demonstrou a influência das condições ambientais associadas à orientação cardeal das faces do cerrado no padrão fenológico de X. aromatica. Respostas similares poderão ser observadas em outras espécies de cerrado, afetando os padrões de visitação floral e produção de frutos, o que reforça a importância de considerarmos a orientação cardeal nos estudos de efeitos de borda e fragmentação.

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