The concept of areas of endemism (AoEs) has rarely been discussed in the literature, even though the use of methods to ascertain them has recently increased. We introduce a grid-based protocol for delimiting AoEs using alternative criteria for the recognition of AoEs that are empirically tested with harvestmen species distributions in the Atlantic Rain Forest. Our data, comprising 778 records of 123 species, were analysed using parsimony analysis of endemicity and endemicity analysis on four different grids (two cell sizes and two cell placements). Additionally, we employed six qualitative combined criteria for the delimitation of AoEs and applied them to the results of the numerical analyses in a new protocol to objectively delimit AoEs. Twelve AoEs (the most detailed delimitation of the Atlantic Rain Forest so far) were delimited, partially corroborating the main divisions previously established in the literature. The results obtained with the grid-based methods were contradictory and were plagued by artefacts, probably due to the existence of different endemism patterns in one cell or to a biogeographical barrier set obliquely to latitudinal and longitudinal axes, for example. Consequently, the congruence patterns found by them should not be considered alone; qualitative characteristics of species and clade distributions and abiotic factors should be evaluated together. Mountain slopes are the main regions of endemism, and large river valleys are the main divisions. Refuges, marine transgressions and tectonic activity seem to have played an important role in the evolution of the Atlantic Rain Forest.

Habitat selection and seasonal changes are key drivers of the population dynamics of many species. We analyzed how the environmental structure influences species establishment in an area by comparing microhabitat preference and functional richness of scorpions (Arachnida: Scorpiones) in wet (Atlantic forest) and semiarid (Caatinga) areas. Variations in superficial foraging activity and microhabitat colonization during dry and rainy seasons were evaluated as an indication of the climatic impact on population dynamics. We collected 12 scorpion species using ultraviolet light lamps. We found that differential patterns in spatial distribution were independent of forest type, and we provide evidence for partial niche partitioning among scorpion species based on age class and climatic conditions. Foraging activity was also seasonally influenced. Functional richness was higher in wet forests than in dry forests, whereas taxonomical richness exhibited an opposite pattern. We conclude that spatiotemporal resource partitioning and refuge sharing are important drivers of the population dynamics and spatial distribution of scorpion species in Neotropical forests.

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The montane forests of northeastern Brazil are patches of rainforests, surrounded by xeric vegetation, that originated during the expansion of rainforests in the Pleistocene epoch. Their historical processes make these areas ideal for biogeographical investigations of organisms, particularly in groups with low dispersion and habitat specificity, such as scorpions. We perform a macroecological investigation of the community assembly process of scorpions, disentangling the pattern of β-diversity to test the hypothesis that the similarity in the composition of scorpion fauna in areas of montane forests and coastal rainforests is greater when these localities are geographically close. We also investigated if larger patches of montane forests exhibit a positive species–area relationship. Our results state that species replacement accounts for 71% of the total scorpion β-diversity in montane forest remnants. Additionally, scorpion assemblages were influenced by the spatial arrangement, with a higher similarity between the fauna of montane forests and coastal forests when these areas were geographically close. We did not find a species–area relationship in montane forest patches. The expressive contribution of species replacement to the overall β-diversity may reflect both the high environmental heterogeneity and the historical and independent colonization events that took place in these areas.

Brazilian Atlantic rainforest is one of the largest hotspots of biodiversity in the world, with the highest number of harvestmen (Arachnida: Opiliones) species per given area. Currently, however, information on the species richness or spatial distribution of these arachnids in this northeastern Brazilian biome is extremely scarce. We conducted a field study to examine the microhabitat use of harvestmen in a fragment of the highland Atlantic rainforest. Harvestmen fauna and the microhabitat preference were assessed by nocturnal active search across 3 months (September to November 2011). Three hundred and eighteen individuals of eight harvestmen species from seven microhabitats were sampled. Four species were categorized as generalists, colonizing five or six microhabitats, whereas three species showed microhabitat specificity, being found in only one or two microhabitats. The forest ground microhabitat revealed higher harvestmen species richness, indicating that the majority of the harvestmen assemblage is composed of ground-dwelling species.