Aim
Ancient tropical mountains are megadiverse, yet little is known about the distribution of their species. We aimed to disentangle the effects of latitudinal and elevational gradients on the ...distribution of species of Aculeata and to understand the effects of climatic variables across different spatial scales of diversity (α‐, γ‐, and β‐diversity).
Location
Campo rupestre in the Espinhaço Mountain Range, Southeast Brazil.
Taxon
Bees, wasps, and ants (Aculeata: Hymenoptera).
Methods
We used a unique dataset built from sampling species of Aculeata at 24 study sites across 12 mountains, covering 1200 km from south to north and an elevational range of 1000 to 2000 m. We explored the elevational and latitudinal patterns of α‐ (site), γ‐ (mountain), and β‐diversity among samples at each location (βLocal). We also tested the effect of elevational range on β‐diversity in each mountain (βMountain) and, on a larger scale (βRegional), if β‐diversity is influenced by geographical and environmental distances. Finally, we tested whether climatic variables underpin the observed patterns.
Results
Latitude had no effect on diversity. We found a decrease in both site and mountain diversity and, only for bees, βLocal increased with elevation. Climatic variables (temperature, wind, and precipitation) and their interactions were important drivers of diversity, with temperature being the most important. Finally, βMountain increased with mountain elevation range, and βRegional increased with the geographical and environmental distances.
Main conclusions
Our results showed that variation in species richness and composition across mountains is strongly associated with elevational gradient, which showed stronger climatic variation than latitudinal gradient. Therefore, despite having narrow elevational ranges, the biogeographical effects of tropical mountains drive high diversity. Facing global climate changes, this limited elevational gradient may limit species range shifts, leading to severe biodiversity losses.
Climate conditions tend to differ along an altitudinal gradient, resulting in some species groups' patterns of lower species richness with increasing altitude. While this pattern is well understood ...for tropical mountains, studies investigating possible determinants of variation in beta-diversity at its different altitudes are scarce. We sampled bee and wasp communities (Hymenoptera: Aculeata) along an altitudinal gradient (1,000-2,000 m.a.s.l.) in a tropical mountainous region of Brazil. Trap nests and Moericke traps were established at six sampling points, with 200 m difference in altitude between each point. We obtained average climate data (1970-2000) from Worldclim v2 for altitudes at each sampling site. Nest traps captured 17 bee and wasp species from six families, and Moericke traps captured 124 morphospecies from 13 families. We found a negative correlation between altitude and species richness and abundance. Temperature, precipitation, water vapor pressure, and wind speed influenced species richness and abundance, and were correlated with altitude. β-diversity was primarily determined by species turnover as opposed to nestedness, and Aculeate community similarity was higher for more similar altitudinal ranges. Moericke traps seem to be more efficient for altitudinal surveys compared to nest traps. We found high occurrence of singleton and doubleton species at all altitudes, highlighting the need for long-term studies to efficiently assess hymenopteran diversity in these environments.
Abstract
Aim
We evaluated the effects of forest island size, isolation and area in the landscape driving temporal changes of insect biodiversity in a mountaintop forest archipelago. We expected that ...(i) in smaller, less isolated forest islands, changes in insect composition are more prominent, primarily driven by gains over time; (ii) more forest in the landscape leads to increased gains of vagile species over time, regardless of forest island size and isolation; (iii) less vagile groups undergo heterogenisation, while highly vagile groups experience homogenisation due to differing dispersal capabilities.
Location
Espinhaço Range Biosphere Reserve, Brazil.
Taxon
Insects.
Methods
We used ants, dung beetles, bees, wasps and butterflies as study models to represent a gradient of low‐to‐high dispersal capability. We evaluated the colonisation‐ and extirpation‐resultant components of temporal β‐diversity using area‐ and isolation‐related variables as predictors.
Results
Distinct colonisation‐ and extirpation‐resultant homogenisation and heterogenisation processes are acting according to each insect group, likely due to different dispersal capabilities. Species losses dominated in ants, with widespread and rare species being lost. Butterflies gained species, represented mainly by widespread species, leading to an increased colonisation‐resultant homogenisation. Distance to neighbouring forest islands was the underlying predictor affecting the temporal β‐diversity of insect groups, and also species gains and losses but differently according to the survey period. Effects of the forest amount in the landscape increased the temporal β‐diversity of bees and butterflies but decreased that of ants, dung beetles and wasps.
Main Conclusions
These findings provide valuable biogeographic insights into the complex interactions between forest island characteristics, landscape attributes, and dispersal capabilities that shape the temporal dynamics of insect biodiversity on mountaintops. Conserving the forest amount in the landscape and keeping forest connectivity among forest islands are necessary because the temporal dynamics of local colonisation and extirpation can depend on the organisms' dispersal capability.
Resumo
Objetivo
Avaliamos os efeitos do tamanho da ilha florestal, do isolamento e da área de floresta na paisagem que direcionam mudanças temporais na biodiversidade de insetos em um arquipélago florestal no topo de montanhas. Esperávamos que (i) em ilhas florestais menores e menos isoladas as mudanças na composição de insetos fossem mais proeminentes, impulsionadas principalmente por ganhos ao longo do tempo; (ii) maior quantidade de floresta na paisagem leva a maiores ganhos de espécies vágeis ao longo do tempo, independentemente do tamanho e isolamento das ilhas de floresta; (iii) grupos menos vágeis sofrem heterogeneização, enquanto grupos altamente vágeis sofrem homogeneização devido a diferentes capacidades de dispersão.
Localização
Reserva da Biosfera da Serra do Espinhaço, Brasil.
Táxon
Insetos.
Métodos
Usamos formigas, besouros rola‐bosta, abelhas, vespas e borboletas como modelos de estudo para representar um gradiente de capacidade de dispersão. Avaliamos os componentes de colonização e extirpação resultantes da diversidade β temporal usando variáveis relacionadas à área e ao isolamento como preditores.
Resultados
Processos distintos de homogeneização e heterogeneização resultantes de colonização e extirpação estão agindo nos distintos grupos de insetos, provavelmente devido a diferentes capacidades de dispersão. As perdas de espécies predominaram nas formigas, com espécies raras e generalizadas sendo perdidas. As borboletas ganharam espécies, representadas principalmente por espécies amplamente distribuídas, levando a um aumento da homogeneização resultante da colonização. A distância às ilhas florestais vizinhas foi o principal preditor que afetou a diversidade β temporal dos grupos de insetos, e também os ganhos e perdas de espécies, mas de forma diferente de acordo com o período da pesquisa. Os efeitos da quantidade de floresta na paisagem aumentaram a diversidade β temporal de abelhas e borboletas, mas diminuíram a de formigas, besouros rola‐bosta e vespas.
Principais conclusões
Estas descobertas fornecem percepções biogeográficas valiosas sobre as complexas interações entre as características das ilhas florestais, os atributos da paisagem e a capacidade de dispersão que moldam a dinâmica temporal da biodiversidade de insetos nos topos das montanhas. Conservar a quantidade de floresta na paisagem e manter a conectividade entre ilhas florestais é necessário pois a dinâmica temporal da colonização e extirpação local pode depender da capacidade de dispersão dos organismos.
Abstract
Understanding community assembly in habitat patches requires an integrative approach, considering the potential role of local and regional factors and organisms' dispersal abilities among ...patches. For this, assessing the degree of species overlap between patches (nestedness) can be particularly informative, especially regarding different taxa and distinct patch properties.
We assessed the potential role of landscape‐patch structure in shaping the nestedness patterns of five taxonomic groups with distinct dispersal abilities (ants, bees, dung beetles, fruit‐feeding butterflies and aculeate wasps).
We collected insects from 11 forest patches in the Espinhaço mountain range in southeast Brazil. We assessed the potential contribution of three forest island attributes (size, distance and shape) to the nestedness of insect communities and then tested if metacommunities were significantly nested with respect to habitat (forest islands). Finally, we evaluated how species of each taxonomic group contribute to metacommunity nestedness.
While there was a substantial variation in the contribution to the nested pattern within each taxon, all taxa studied exhibited a significantly nested pattern of species distribution. The landscape‐patch structure and the vagility of the different taxa did not influence the contribution of sites to the metacommunity nested pattern.
Our integrative approach provides critical data on the role of different factors in shaping species distribution in natural patches. Species with different dispersal abilities and patches with distinct landscape properties contributed similarly to nestedness, indicating the potential role of the vegetation matrix permeability in shaping the distribution of organisms in the studied forest archipelago.
The Earth's most diverse group of organisms is facing an imminent crisis, as recent investigations suggest a remarkable decline in insect diversity. Within this context, altimontane forest islands ...might emerge as important refuges holding an invaluable diversity of species that would be doomed to disappear. Here, we aimed to examine the impact of fire on the temporal variation of ant, bee, butterfly, dung beetle, and wasp communities in natural and highly threatened altimontane forest islands. We predicted that fire incidence would increase the natural variation in the structure of these insects' communities over time. Furthermore, we predicted that each taxon would respond accordingly to their ability to move between forest islands (i.e., vagility). We sampled these five bioindicator taxa in the rainy seasons of 2014, 2015, 2018, and 2020 within 14 forest islands in southeast Brazil. We assessed the incidence (presence/absence) of fire occurrence on each forest island toward the end of the dry season in each sampling year. We found an influence of fire incidence on the species composition changes over time (temporal β‐diversity) in the less vagile insect groups: ants, and dung beetles. Nevertheless, we found no influence of fire incidence on shifts in species composition of highly vagile insects: bees, butterflies, and wasps. Importantly, species turnover was the primary component of temporal β‐diversity driving the interannual variation of all insect taxa examined in this study. Our results highlight the distinct responses of more‐or‐less vagile insect groups to fire in forested ecosystems and shed light on the drivers of vulnerability and resilience of these groups to this critical anthropogenic pressure. By understanding and elucidating the intricate responses of distinct insect communities to global stressors, we can strengthen our capacity to predict future trends in biodiversity decline and provide valuable insights for conservation efforts and environmental management strategies.
Fire incidence influences changes in species composition over time (temporal β‐diversity) in less vagile insect groups (ants and dung beetles). Species turnover is the primary component of temporal β‐diversity driving the interannual variation of all insect taxa examined in this study.
From 2013 to 2016, a study using malaise was carried out throughout the Espinhaço Mountain range in the Brazilian states of Minas Gerais and Bahia. A total of 1,000 butterflies belonging to six ...families, namely Pieridae (n=353), Nymphalidae (n=274), Hesperiidae (n=205), Lycaenidae (n=139), Riodinidae (n=17), and Papilionidae (n=12), were captured during this period. Because of the collecting method, most butterflies became mangled and resulted in faded colours, making them difficult to be identified. Nevertheless, three interesting species were identified in the collected material as they were either threatened, endemic, or undescribed. These new records highlight the importance of storing and making available all collected material, including bycatches, since this can provide important information for studies on ecology, taxonomy, and conservation.
Naturally fragmented landscapes provide suitable scenarios through which to investigate patch and landscape effects on biodiversity patterns in areas that are isolated from the disturbances usually ...associated with human-made fragments. We aimed to investigate the patch and landscape effects on the diversity of forest-dependent and matrix-tolerant dung beetles in a naturally fragmented landscape. We also assessed the influence that seasonal and vegetation variations had on these dung beetles. We sampled dung beetles during two summers and two winters in 14 forest islands of various sizes and shapes within a natural mountainous forest archipelago in southeast Brazil. We measured the patch and landscape variables based on high-resolution multispectral images of circular sectors with radii of 100, 250, and 500 m. We used generalized linear mixed models to relate dung beetle metrics to patch and landscape attributes. The interaction between canopy cover and season influenced both species' richness and abundance of the dung beetle metacommunity. The forest-dependent species' richness increased with greater canopy cover, regardless of the season. Patch attributes (e.g., size, canopy cover, distance to the closest patch, and distance to continuous forest) and landscape attributes (e.g., percentage of forest in the landscape, total edge, number of patches, distance to the nearest neighbor, and shape complexity) had small general effects on dung beetle species as a whole and on matrix-tolerant species in particular. However, these values strongly influenced forest-dependent species' richness, abundance, and temporal beta diversity. The matrix-tolerant species, therefore, mask the effects of patch and landscape effects on forest-dependent species within the mountainous forest archipelago. In other words, the changes in these patch and landscape attributes influenced forest-dependent and matrix-tolerant species differently. Therefore, the evaluation of entire metacommunities may not be helpful when evaluating species-specific responses in mixed landscapes—a fact that impairs the conservation of forest-dependent species.
Display omitted
•Canopy cover drives the overall dung beetle metacommunity only in winter season.•Forest-dependent species richness increased with canopy cover regardless the season.•Patch and landscape metrics drive habitat specialists and generalists differently.•Matrix-tolerant species hide patch and landscape effects on forest-dependent species.
•Ecological dynamics were explored highlighting the challenges for conservation.•Natural islands of forests are fire-sensitive.•Fire stands out as one of the most serious conservation threats.•We ...propose management strategies based on ecological dynamics.•Society must avoid the costs related to the degradation of forests islands.
Naturally fragmented landscapes are adequate systems for evaluating patterns and mechanisms that determine species distribution without confounding effects of anthropogenic fragmentation and habitat ...loss. We aimed to evaluate an ant metacommunity’s spatiotemporal patterns in montane forest islands amid a grassland-dominated matrix. We assessed these patterns by deconstructing the ant metacommunity into forest-dependent and habitat generalist species. We sampled twice a year (summer and winter) over 2 years (2014 and 2015), using soil and arboreal pitfall traps, in fourteen forest islands (varying in size, shape, and connectivity) in the Espinhaço Range Biosphere Reserve, Brazil. We evaluated the relationship between ant species richness, composition (β-diversity), and predictor variables of forest island structure (canopy cover and understory density) and landscape structure (forest amount, number of forest islands, and shape). We sampled 99 ant species, 66.7% of which were classified as forest-dependent and 33.3% as habitat generalist species. We found that ant β-diversity was higher in space than in time, and that species composition variation in time (temporal β-diversity) differed between ant species groups. Both ant groups responded differently to forest island and landscape structure characteristics. Landscape structure seems to act as a spatial filter and the forest islands’ local characteristics as an environmental filter, which jointly determine the local and regional diversity. We demonstrate the importance that forest archipelagos pose to ant metacommunity’s structure and dynamics in montane tropical regions. Mountaintop conservation and management strategies must consider the forest island archipelago to maintain the biodiversity and the functioning of these systems.
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