ContextMultiscale approaches are essential for understanding ecological processes and detecting the scale of effect. However, nested multiscale approaches retain the effect of the landscape attributes from the smaller spatial scales into the larger ones. Thus, decoupling local vs. regional scales can reveal detailed ecological responses to landscape context, but this multiscale approach is poorly explored. ObjectivesWe evaluated the scale of effect of the forest cover (%) and landscape heterogeneity on Euglossini bees combining coupled and decoupled multiscale approaches. MethodsThe Euglossini males were sampled in forest patches from 15 landscapes within the Atlantic Forest biodiversity hotspot, southeast Brazil. For simplicity, we defined that the coupled approaches represented the local scales and decoupled approaches the regional scales. We 1 decoupled the scales by cutting out the smaller scales inserted into larger ones. We estimated the relationship of the bee community attributes with forest cover (%) and landscape heterogeneity in local and regional scales using Generalized Linear Models. ResultsWe found positive effects of landscape heterogeneity on species richness for regional scales.Forest cover (%) and landscape heterogeneity in local scales showed positive effects on the euglossine abundances. The scale of effect for euglossine richness was higher than species abundances. ConclusionsCombining coupled and decoupled multiscale approaches showed adequate capture of the scale of effect of the landscape composition on bee communities. Therefore, it is of paramount importance to measure the influence of the landscape context on biodiversity. Maintaining landscapes with larger forest cover and spatial heterogeneity is essential to keep euglossine species requirements.
Euglossini bees are important Neotropical pollinators, but there is a lack in the knowledge about this fauna in dry tropical environments. The aims of this study were to evaluate the richness and abundance of euglossine bees in two fragments of seasonally dry tropical forest (Caatinga), as well as to assess the distribution of euglossine species richness in the Caatinga environment. Males were collected along 12 consecutive months, using traps with aromatic baits. The species richness (S=5) was lower than in rainforests and savannas. Euglossa cordata (L.) was the dominant species in the assemblage, representing 70% of the individuals. The highest abundance occurred in the rainy season. Euglossini fauna presents low local species richness in Caatinga areas, however the beta diversity is higher, since assemblages in different habitats have differences in species composition.
Fragmentation and expansion of agricultural activities are sufficient factors for strongly impacting the biodiversity. Thus, sustainable practices of land use, such as agroforestry systems, are adopted with proposal of improving environmental quality and restore ecological processes. In flying insects, fragmentation may cause changes in the wing shape and size. Therefore, we evaluated the wing size and shape of three species of Euglossini (Eulaema atleticana Nemésio, Euglossa cordata (Linnaeus) and Euglossa ignita Smith) at response to landscape structure. The analysed specimens were collected in five areas, four forest areas with strong anthropic influence and an agroforestry system area. The results of the wing shape analysis have showed that the individuals of the three collected species within the agroforestry system diverge significantly (p<0.05) from those collected in the other areas. On the wings of Eg. cordata and Eg. ignita, differences in shape have occurred mainly in the medial region, which actively participates in the individual's flying ability. The wing size has showed meaningful difference only to the population of Eg. ignita (p=0,005). For Eg. cordata and El. atleticana, there was a significant correlation (r<0.05) between the morphometric data and the landscape metrics, which shows a close relationship between these species and the forest cover. The wing shape and size pursue an important function for the individual's ability in the environment, such as dispersion capacity and fertility rate, respectively. We concluded that the morphometric differences can reveal the existence of environmental stress for the biodiversity, therefore, contribute for environmental quality monitoring studies.
Geometric morphometrics is a tool capable of measuring the response of organisms to different environmental pressures. We tested the hypothesis that E. cordata wing morphometry, as an indicator of response to environmental pressure, it would vary depending on habitat changes, in the Atlantic Forest, Savanna and dry forest (Caatinga). For analysis of wing shape and size, 18 landmarks were digitized at the intersections of the wing veins 348 individuals. Except for the two populations sampled in Chapada Diamantina, the wing shape had significant statistical variations among the populations (p < 0.05). The wing size variation was also statistically significant among populations (p < 0.05). Although E. cordata is a species tolerant to different environments, the observed morphometric variability may be related to population adaptations to the conditions of each phytophysiognomy.
Human activities have modified the landscape composition. The changes in the landscape structure can be evaluated by metrics, which are influenced, among other factors, by the number of cover classes used for the landscape classification (thematic resolution). In high thematic resolutions, landscape covers that can influence biological responses are identified and detailed. In low thematic resolutions, this detail level is lower because it aggregates different landscape covers in a few classes. However, how the thematic resolution influences our ability to understand landscape structure on biodiversity is poorly explored, particularly for pollinators. Here we asked how thematic resolution affects the explanatory power of landscape composition on explaining Euglossini bees (richness and abundance) within 15 landscapes composed mainly of coffee and pasture. To address this issue, we quantified the association between five attributes of the euglossine bee community and landscape composition: landscape cover classes (%) and landscape heterogeneity. Moreover, we also evaluated how the thematic resolution influences bee responses to landscape structure. We found a strong and positive influence of landscape heterogeneity in low thematic resolutions (i.e., few cover classes on maps) over the richness and rare species abundance. We also observed that- in addition to the forest cover in the landscape- the pasture cover (%) quantified in high thematic resolution positively influenced the total abundance and abundance of common and intermediate species. Our study highlights the importance of maintaining compositional heterogeneity for the orchid bee community in agroecosystems, and forest cover for the biological requirements and conservation of these pollinators. Moreover, the use of different thematic resolutions showed how specific types of landscape covers influence the euglossine community attributes. This can highlight the species preferences for habitats and landscape covers. Thus, we call the attention of landscape ecologists to the importance of the definition of thematic resolution, as our ability to quantify the association between biological responses and landscape structure may be influenced by the number of classes used when building thematic maps.
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