Patterns of Vertebrate Diversity and Protection in Brazil

Most conservation decisions take place at national or finer spatial scales. Providing useful information at such decision-making scales is essential for guiding the practice of conservation. Brazil is one of the world’s megadiverse countries, and consequently decisions about conservation in the country have a disproportionate impact on the survival of global biodiversity. For three groups of terrestrial vertebrates (birds, mammals, and amphibians), we examined geographic patterns of diversity and protection in Brazil, including that of endemic, small-ranged, and threatened species. To understand potential limitations of the data, we also explored how spatial bias in collection localities may influence the perceived patterns of diversity. The highest overall species richness is in the Amazon and Atlantic Forests, while the Atlantic Forest dominates in terms of country endemics and small-ranged species. Globally threatened species do not present a consistent pattern. Patterns for birds were similar to overall species richness, with higher concentrations of threatened species in the Atlantic Forest, while mammals show a more generalized pattern across the country and a high concentration in the Amazon. Few amphibians are listed as threatened, mostly in the Atlantic Forest. Data deficient mammals occur across the country, concentrating in the Amazon and southeast Atlantic Forest, and there are no data deficient birds in Brazil. In contrast, nearly a third of amphibians are data deficient, widespread across the country, but with a high concentration in the far southeast. Spatial biases in species locality data, however, possibly influence the perceived patterns of biodiversity. Regions with low sampling density need more biological studies, as do the many data deficient species. All biomes except the Amazon have less than 3% of their area under full protection. Reassuringly though, rates of protection do correlate with higher biodiversity, including higher levels of threatened and small-ranged species. Our results indicate a need for expanded formal protection in Brazil, especially in the Atlantic forest, and with an emphasis on fully protected areas.     

Mapping patterns of ferns species richness through the use of herbarium data

This paper aims to analyse the spatial patterns of sampling effort and species richness of pteridophyte in a well-investigated region as Tuscany, Italy, by using data stored from a geodatabase storing information on the specimens preserved in the main herbaria of the region. A total of 6,905 records about pteridophyte specimens were extracted from the geodatabase, and 5,638 of such specimens were studied through the use of spatial statistical techniques. The data about the sampling effort and species richness were analysed in relation to topographical variables to assess any significant relationship. Specimen-based rarefaction techniques were used to compare areas with different number of detected species. The analysis of the sampling effort data showed a nonhomogeneous distribution of herbarium data, with some areas being intensively sampled and others being almost unsampled. Thus, the geographical distribution of specimens was extremely clustered. The comparison across geographical areas through specimen-based rarefaction curves showed great differences in species richness and sampling completeness. The analysis of the residuals of species–area relationships evidenced that the distance to water bodies was the only significant topographical variable in controlling species diversity.     

The positive correlation between avian species richness and human population density in Britain is not attributable to sampling bias

Aim  To assess whether spatial variation in sampling effort drives positive correlations between human population density and species richness.
Location  British 10 × 10 km squares.
Methods  We calculated three measures of species richness from atlas data of breeding birds in Britain: total species richness, species richness standardised for sampling effort, and the number of species only recorded in supplementary casual records in a manner not standardised for survey effort. We then assessed the form of the relationship between these richness estimates and human population density, both with and without taking spatial autocorrelation into account.
Results  Both total and standardised species richness exhibit similar species richness–human population density relationships; species richness generally increases with human population density, but decreases at the very highest densities. Supplementary species richness is very weakly correlated with human population density.
Main conclusions  In this example, sampling effort only slightly influences the form of species richness–human population density relationships. The positive correlation between species richness and human population density and any resultant conservation conflicts are thus not artefactual patterns generated by confounding human density and sampling effort.     

Additive partitioning of butterfly diversity in a fragmented landscape: importance of scale and implications for conservation

Aim Most of the Atlantic Forest in Brazil occurs in fragments of various sizes. Previous studies indicate that forest fragmentation affects fruit‐feeding butterflies. Conservation strategies that seek to preserve organisms that are distributed in high‐fragmented biomes need to understand the spatial distribution of these organisms across the landscape. In view of the importance of understanding the fauna of these forest remnants, the objective of the present work is to investigate the extent to which the diversity of this group varies across spatial scales ranging from within‐forest patches to between landscapes. Location South America, south‐eastern Brazil, São Paulo State. Methods We used bait traps to sample fruit feeding butterflies at 50 points in 10 fragments in two different landscapes during a period of 12 months. Total species richness and Shannon index were partitioned additively in diversity at trap level, and beta diversity was calculated among traps, among forest patches, and between landscapes. We used permutation tests to compare these values to the expected ones under the null hypothesis that beta diversity is only a random sampling effect. Results There was significant beta diversity at the smallest scale examined; however, the significance at higher scales depends on the diversity measurement used. Beta diversity with Shannon index was smaller than expected by chance among fragments, whereas species richness was not. Among landscapes, only beta diversity in richness was higher than expected by chance. Main conclusions The results observed occur because there is great variability in species composition among forest patches in the same landscape, changing this diversity even though the communities are formed from the same pool of species. At the largest scale evaluated (between landscapes), these pattern changes and differences in beta diversity in richness were detectable. This difference is probably caused by the presence of rare species. Thus, a conservation strategy that seeks to preserve as many species as possible per unit of area in high‐fragmented biomes should give priority to protecting fragments in different landscapes, rather than more fragments in the same landscape.     

Temporal Patterns of Species Accumulation in a Survey of Lepidoptera in a Beech-Maple Forest

One of the most significant challenges to insect conservation is lack of information concerning species diversity and distribution. Because a complete inventory of all species in an area is virtually impossible, interest has turned to developing statistical techniques to guide sampling design and to estimate total species richness within a site. We used two such techniques, diversity partitioning and non-parametric richness estimation, to determine how variation in sampling effort over time affected species accumulation for a survey of Lepidoptera in an old-growth beech-maple forest. Temporal scaling of sampling effort had significant effects on two measures of species diversity. Increases in species richness were primarily driven by changes in species occurrences with season, while Shannon diversity was largely determined at the scale of individual sampling units (i.e. by spatial effects). Variation in sampling effort affected the values of the two most widely regarded richness estimators (ICE and Chao 2); neither diversity estimator achieved stable values across a range of sampling efforts. Even after 52 trap-nights and accounting for seasonality, rare species (singletons and uniques) remained a significant component of the moth community. To the extent that moth communities in other forest systems are similarly comprised of many rare species, non-parametric richness estimators should be expected to yield variable estimates with increased effort and should only be used to provide a minimum benchmark for predicting the number of species remaining to be sampled. Our results suggest the best strategy for a short-term survey of forest Lepidoptera should emphasize spreading sampling intervals throughout a given year rather than focusing on intensive sampling during a short time period or prolonged sampling over many years.     

A hot-point within a hot-spot: a high diversity site in Brazil’s Atlantic Forest

The Brazilian Atlantic Forest is considered one of the world’s most important sites for biodiversity conservation, and within this biome there are regions with differing levels of species richness, species composition, and endemism. The present study was undertaken in southern Bahia, Brazil, and employed a standardized sampling method to compare the density of arboreal species in this region with other areas throughout the world known for their high tree species density. A total of 144 tree species with DBH > 4.8 cm were sampled within a 0.1 ha plot of old-growth forest (OGF), and these data were then compared with 22 other world sites that had been sampled using the same methodology and likewise demonstrated high densities of arboreal species. Only one site of ombrophilous forest in Colombia demonstrated a higher tree species density (148 spp. in 0.1 ha) than was encountered in southern Bahia. Other areas of Brazil, including other Atlantic Forest sites, showed significantly inferior tree species densities. These results indicate that this region of southern Bahia has one of the greatest numbers of tree species in Brazil and in the world. These results, associated with the high levels of endemism there, indicate the high biological importance of this region. It is therefore fundamental that efforts aimed at halting the degradation of these forests be linked to programs that will increase our knowledge of the species found there as well as the ecological and evolutionary processes that originated these unique forests.     

Rapid evaluation of ant diversity in land use systems in southern Bahia, Brazil

We aimed to compare the soil ant diversity in different land use systems from Atlantic Forest area, in Southern Bahia state, Brazil. The ants were sampled in 16 sites: two primary forest sites (un-logged forest); three young secondary forests (<8 years old); three intermediate secondary forests (8-20 years old); three old secondary forests (>20 years old); three Eucalyptus grandis plantations (3-7 years old), and two introduced pastures. Each site was sampled in three sampling points 15 m apart, and distant over 50 m from the site edge. In each sampling point we gathered the litter from a 1 m2 and extracted the ants with Winkler extractors during 48h. We found 103 ant species from 29 genera and eight subfamilies. The five richest genera were Pheidole (19 species), Solenopsis (8), Apterostigma (10), Hypoponera (7) e Paratrechina (5). The highest ant richness density was found in the primary forest (7.4 species/sample; S = 37; n = 5); followed by the old secondary forest (5.33 species/sample; S = 48; n = 9); young secondary forest (5.25 species/sample; S = 42, n = 8); eucalyptus plantation (4.22 species/sample; S = 38, n = 9), intermediate secondary forest (3.5 species/sample; S = 35, n = 10, and introduced pasture (2.67 species/sample; S = 16, n = 6). The ecosystems with higher structural complexity showed the highest ant richness density by sample. Therefore, in the Atlantic Forest region, the eucalyptus plantation is a better alternative of land use to conserve the ant biodiversity than pastures, and quite similar to native secondary forests in ant community characteristics.     

Ant diversity decreases during the dry season: A meta-analysis of the effects of seasonality on ant richness and abundance

Tropical studies traditionally describe insect diversity variation throughout the year. The temporally structured responses of insect assemblages to climate seasonality vary across ecosystems due to gradients of resource availability and limiting ecological factors. These idiosyncratic responses might be particularly true across the vast geographical range of the Brazilian territory, including various environments that harbor one of the most diverse ant faunas worldwide. This study addressed the relationship between ant diversity and climatic seasonality, performing a quantitative review of the published data on ant diversity collected in Brazil. We investigated the seasonality effect on ant abundance and richness described in the literature in 47 papers published between 2000 and 2018. These studies were developed mainly in the Atlantic Forest biome and collected ants with pitfall traps on the soil/litter stratum. We initially carried out a vote-counting procedure by comparing the number of significant results describing seasonal differences in the ant assemblage. We found that most papers described a similar pattern of ant abundance, richness, and species composition between seasons. However, when we performed a meta-analysis, we observed a clear pattern of higher ant abundance and richness in the wet/summer season compared with the dry/winter season. Our meta-analysis reveals that the ant diversity decreases in the dry season, strongly in the Cerrado biome. Additionally, we point out differences in the sampling effort across biomes, indicating the need for further investments in studies focused on temporal diversity patterns, including seasonal effects, on the insect assemblage in biomes less investigated so far. Abstract in Portuguese is available with online material.     

Efficiency of sampling methods for accurate estimation of species richness of corticolous microlichens in the Atlantic rainforest of northeastern Brazil

Three different sampling methods were compared with regard to accurate estimation of species richness of crustose and microfoliose lichens in Atlantic rainforest remnants of northeastern Brazil. Quantitative transect sampling yielded three times as many species as non-quantitative opportunistic sampling, even if the number of sampled phorophyte trees was higher on average for the latter method. Repetitive non-quantitative opportunistic sampling of a single site resulted in twice the number of species than one-time sampling, but only two thirds of the number recovered by means of quantitative transect sampling, even of the number of sampled phorophyte trees was highest for this method. The analysis showed that opportunistic sampling fails to detect rare, inconspicuous, sterile, and/or cryptic species, usually neglected or overlooked even by the experienced collector upon visual inspection in the field. On the other hand, quantitative sampling forces even the inexperienced collector to sample lichen thalli or pieces of bark which only after detailed morphological, anatomical, and chemical study in the laboratory reveal themselves as distinct species. Accordingly, of the 456 lichen species collected and identified across the 22 studied localities, no less than 76 were unique to the quantitatively sampled transect, and the lichen species sampled with this method had a significantly higher proportion of rare, inconspicuous, sterile, and/or cryptic species. It is also apparent that it is not the higher number of specimens collected via quantitative sampling that results in a higher number of species, but the method of selection of the specimens, which is subjective and biased towards abundant, conspicuous, fertile and/or distinctive species in opportunistic sampling, but objective and unbiased in quantitative sampling.     

Diversity of mammals in the tropical–temperate Neotropics: hotspots on a regional scale

The tropical–temperate interface of the southern Neotropics harbours an interdigitating array of biomes (Puna, Monte, Chaco, Yungas). This topographic and climatically complex region needs urgent conservation efforts, as it is being transformed by human activities at an accelerating pace. We analyse georeferenced field records of mammal species in northwestern Argentina (provinces: Catamarca, Jujuy, Salta, Tucuman) in order to define biodiversity hotspots on the basis of 0.5°× 0.5° grid cells within northwestern Argentina according to total richness of mammal species, richness of megaspecies (species above 10 kg), and endemic species (species restricted to Argentina or neighbouring countries with shared biomes). The mammal fauna of northwestern Argentina is fairly well known (176 species). The biomes differ considerably in species richness (Puna low, Yungas high) and species composition. We found no significant difference between endemic and non-endemic species regarding cell occupancy or body size. Cell occupancy was not correlated to body size. Across grids, species richness, number of megaspecies as well as richness of endemics are all correlated to sampling effort. More than 50% of the species in the region are restricted to one or two biomes. Overall, the species turn-over between biomes in northwestern Argentina is high. Using a simple algorithm we identified 10 grid cells which covered 90% of the total number of recorded species, and contrast them with the protected areas. While the Puna and Yungas biomes are rather well protected, the arid and semiarid Monte and Chaco are in need of urgent attention in biodiversity conservation.     

Severe Loss of Suitable Climatic Conditions for Marsupial Species in Brazil: Challenges and Opportunities for Conservation

A wide range of evidences indicate climate change as one the greatest threats to biodiversity in the 21st century. The impacts of these changes, which may have already resulted in several recent species extinction, are species-specific and produce shifts in species phenology, ecological interactions, and geographical distributions. Here we used cutting-edge methods of species distribution models combining thousands of model projections to generate a complete and comprehensive ensemble of forecasts that shows the likely impacts of climate change in the distribution of all 55 marsupial species that occur in Brazil. Consensus projections forecasted range shifts that culminate with high species richness in the southeast of Brazil, both for the current time and for 2050. Most species had a significant range contraction and lost climate space. Turnover rates were relatively high, but vary across the country. We also mapped sites retaining climatic suitability. They can be found in all Brazilian biomes, especially in the pampas region, in the southern part of the Brazilian Atlantic Forest, in the north of the Cerrado and Caatinga, and in the northwest of the Amazon. Our results provide a general overview on the likely effects of global climate change on the distribution of marsupials in the country as well as in the patterns of species richness and turnover found in regional marsupial assemblages.     

Endemic birds of the Atlantic Forest: traits,conservation status,and patterns of biodiversity

The bird fauna of the Brazilian Atlantic Forest is exceptionally diverse and threatened, with high levels of endemism. Available lists of the endemic birds of the Atlantic Forest were generated before recent taxonomic revisions lumped or split species and before the recent increase in species occurrence records. Our objective, therefore, was to compile a new list of the endemic birds of the Atlantic Forest, characterize these species in terms of conservation status and natural history traits, and map remaining vegetation and protected areas. We combined GIS analysis with a literature search to compile a list of endemic species and, based on the phylogeny and distribution of these species, characterized areas in terms of species richness, phylogenetic diversity, and endemism. We identified 223 species of birds endemic to the Atlantic Forest, including 12 species not included in previous lists. In addition, 14 species included in previous lists were not considered endemic, either because they occur outside the Atlantic Forest biome or because they are not considered valid species. The typical Atlantic Forest endemic bird is a small forest‐dependent invertivore. Of the species on our list, 31% are considered threatened or extinct. Only ~ 34% of the spatial analysis units had > 10% forest cover, and protected area coverage was consistently low (< 1%). In addition, we found spatial incongruity among the different measures of biodiversity (species richness, relative phylogenetic diversity, restricted‐range species, and irreplaceability). Each of these measures provides information concerning different aspects of biological diversity. However, regardless of which aspect(s) of biodiversity might be considered most important, preservation of the remaining areas of remnant vegetation and further expansion of protected areas are essential if we are to conserve the many endemic species of birds in the Atlantic Forest.     

Rare canopy species in communities within the Atlantic Coastal Forest in Rio de Janeiro State, Brazil

Rare species are one of the principal components of the species richness and diversity encountered in Dense Ombrophilous Tropical Forests. This study sought to analyze the rare canopy species within the Atlantic Coastal Forest in Rio de Janeiro State, Brazil. Six different communities were examined: Dense Ombrophilous alluvial Forest; Dense sub-montane Ombrophilous Forest; Dense Montane Ombrophilous in Serra do Mar and Serra da Mantiqueira. In each area the vegetation was sampled within forty 10 × 25 m plots alternately distributed along a linear transect. All trees with DBH (1.3 m above ground level) ≥5 cm were sampled. The canopy was characterized using the allometric relationship between diameter and height, and included all trees with BDH ≥10 cm and height ≥10 m. A total of 64 families, 206 genera, and 542 species were sampled, of which 297 (54.8%) represented rare species (less than one individual per hectare). The percentage of rare species varied from 34 to 50% in each of the different communities sampled. A majority of these rare trees belonged to the Rosidae, and a smaller proportion to the Dilleniidae. It was concluded that there was no apparent pattern to rarity among families, that rarity was probably derived from a number of processes (such as gap formation), and that a great majority of the rare species sampled were consistently rare. This indicates that the restricted geographic distribution and high degree of endemism of many arboreal taxa justifies the conservation of even small fragments of Atlantic Forest.     

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.     

Decisions on Temporal Sampling Protocol Influence the Detection of Ecological Patterns

Within‐site variability in species detectability is a problem common to many biodiversity assessments and can strongly bias the results. Such variability can be caused by many factors, including simple counting inaccuracies, which can be solved by increasing sample size, or by temporal changes in species behavior, meaning that the way the temporal sampling protocol is designed is also very important. Here we use the example of mist‐netted tropical birds to determine how design decisions in the temporal sampling protocol can alter the data collected and how these changes might affect the detection of ecological patterns, such as the species‐area relationship (SAR). Using data from almost 3400 birds captured from 21,000 net‐hours at 31 sites in the Brazilian Atlantic Forest, we found that the magnitude of ecological trends remained fairly stable, but the probability of detecting statistically significant ecological patterns varied depending on sampling effort, time of day and season in which sampling was conducted. For example, more species were detected in the wet season, but the SAR was strongest in the dry season. We found that the temporal distribution of sampling effort was more important than its total amount, discovering that similar ecological results could have been obtained with one‐third of the total effort, as long as each site had been equally sampled over 2 yr. We discuss that projects with the same sampling effort and spatial design, but with different temporal sampling protocol are likely to report different ecological patterns, which may ultimately lead to inappropriate conservation strategies.     

Sharing of termites (Blattodea: Isoptera) between sugarcane matrices and Atlantic Forest fragments in Northeast Brazil

The Atlantic Forest of South America is one of the most degraded tropical forests and the cultivation of sugarcane is considered one of the main causes. In humid forests termites stand out with regard to their abundance and functional importance. The present study aimed to compare termite assemblages of fragments of the Atlantic Forest with that of the sugarcane matrices that surround them. Collections were performed in two sugarcane plantations in Northeast Brazil. In each plantation a fragment of Atlantic Forest and an adjacent sugarcane field were sampled using a standardized termite sampling protocol. A total of 39 species and 302 encounters were recorded. Species richness, relative abundance and composition differed significantly between forests and the matrices, with the presence of exclusive species in each environment—25 in the forests and seven in the matrices. Soil feeding species of the subfamily Apicotermitinae and species of open areas were found in the matrices. There was a marked difference between the assemblages of the matrices, possibly due to soil characteristics. The majority of the species found in the matrices do not cause damage to the crop, but instead act in the processes of soil decomposition and formation, thereby contributing to increased productivity.     

Forest regeneration affects dung beetle assemblages (Coleoptera: Scarabaeinae) in the southern Brazilian Atlantic Forest

The Brazilian Atlantic Forest is one of the most diverse environments, but it is also one of the most threatened areas in terms of loss of biodiversity and ecosystem services. Assessment of changes in the community structure during the recovery of forests can be performed using indicator organisms. Dung beetles perform several ecological functions and show high sensitivity to natural and anthropogenic environmental changes. This study aimed to investigate the effect of regeneration time of Atlantic Forest sites on structure of Scarabaeinae assemblages. We sampled dung beetles using ten baited pitfall traps per site, in six sites grouped into three classes of forest regeneration time (~30, ~60 and >80 years) in the southern Brazilian Atlantic Forest, during January 2015. A total of 520 individuals belonging to 16 species and nine genera of dung beetles were sampled. Rarefied species richness did not differ between sites with different regeneration times. Average species richness and abundance of Scarabaeinae was smaller in areas of shorter recovery time. True alpha diversity was higher in areas with intermediate recovery whereas Shannon diversity showed higher values in areas of shorter recovery. Approximately 29?% of the variation in abundance data of Scarabaeinae was explained by environmental variables, with one-third of this variation explained also by spatial predictors. External factors such as landscape management and farming practices in the surroundings must be taken into consideration in management plans and the management of natural areas for the recovery of biodiversity in the Atlantic Forest. These external factors can considerably affect the structure of communities and lead to scenarios of greater diversity in intermediate regeneration sites due to the heterogeneity of the landscape.     

Exposing hidden endemism in a Neotropical forest raptor using citizen science

Gaps in our knowledge of the geographical distribution of species represent a fundamental challenge to biogeographers and conservation biologists alike, and are particularly pervasive in the tropics. Here we highlight the case of the Rufous‐thighed Kite Harpagus diodon, a South American raptor commonly mapped as resident across half the continent. Recent observations at migration watch points have indicated it may be partially migratory in the southernmost parts of its range. To investigate this possibility, we collated contemporary and historical specimen records, published sight records and ‘digital vouchers’ – photographs and sound‐recordings archived online (from citizen science initiatives) – and explored the spatiotemporal distribution of records. We were unable to trace any documented records of this species from Amazonia during the austral summer (October–March), or records from the Atlantic Forest biome during the peak of the Austral winter (June–August), and all proven breeding records stem from the Atlantic Forest region. We compared this pattern with that of a ‘control’ species, the congeneric Double‐toothed Kite H. bidentatus, again using specimens and digital vouchers. For this species we found no evidence of seasonality between biomes and can disregard spatiotemporal variation in observer effort as a cause of seasonal biases. We consider that all populations of Rufous‐thighed Kites are fully migratory, wintering in Equatorial forests in the Amazonian basin. We provide evidence that this pattern was previously obscured by erroneous undocumented records and poor or erroneous specimen metadata, and its discovery was primarily facilitated by digital vouchers. This discovery requires a reassessment of the species’ global conservation status as an Atlantic Forest breeding endemic, threatened by habitat loss and degradation, as it was previously considered to be resident across large swathes of undisturbed Amazonian Forest on the Guiana Shield. The bulk of the digital voucher data used to elucidate this pattern were extracted from a Brazilian citizen science initiative WikiAves, which may serve as a model for collating biodiversity data in megadiverse countries and help catalyse environmental awareness.     

Bromeliad architectural complexity and vertical distribution predict spider abundance and richness

Habitat complexity is a main predictor of the distribution of arthropods on vegetation. However, it remains poorly known whether plant architecture and fine‐scale spatial distribution affect the species richness and composition of associated arthropod guilds. In this study, we extensively sampled bromeliad species with a variety of rosette architectures in a megadiversity region. The aims were to investigate whether (i) possible differences in spider species composition among bromeliad species are related to the distinct architectures of the plants, and (ii) bromeliad architectural complexity (an intrinsic feature) and vertical distribution (an extrinsic feature) are good predictors of spider abundance and richness. Contrary to our expectations, spider species composition did not vary significantly among bromeliad species with different architectures. We found a positive effect of the mean number of leaves on spider abundance and species richness, but it occurred indirectly through spider abundance; factoring out the indirect effect revealed a negative effect of leaf number on species richness. Bromeliad species with wider vertical distributions harboured more spider species. Our results suggest that the dominance of a few spider species and reduced space for orb‐web spiders to attach their webs are the main explanations for lower spider richness on bromeliad species with higher architectural complexity. Our findings highlight the importance of both intrinsic and extrinsic plant features as co‐determinants of predator arthropod diversity.     

Biodiversity surrogacy: indicator taxa as predictors of total species richness in Brazilian Atlantic forest and Caatinga

The use of indicator taxa as biodiversity surrogates has received widespread attention in conservation planning, but remains a highly contentious issue. Here we assess biodiversity surrogacy in the two most important biomes of tropical northeastern Brazil, Atlantic forest and Caatinga. We examine the extent to which species richness is correlated among taxonomic groups, and assess relationships between the richness of individual groups, and combinations of groups and total species richness. We introduce a new approach to dealing with autocorrelation between focal taxon richness and total species richness, using standardized data such that each taxon is given equal weight. Our Atlantic forest data covered seven taxa (bryophytes, pteridophytes, trees, ants, euglosine bees, birds, and mammals; total of 768 species) sampled from 12 sites; in Caatinga it was four taxa (trees, spiders, beetles and ants; total of 184 species) from 25 sites. Our results showed that: (1) in nearly all cases the species richnesses of individual taxa were significantly correlated with each other; (2) the species richnesses of most individual taxa were significantly correlated with total species richness in both biomes; (3) only two taxa were required for excellent (R ² > 80%) surrogacy of total species richness in both biomes; and (4) the same two taxa (trees and ants) can provide reasonable (R ² > 60%) surrogacy for total richness in these contrasting biomes. Our findings therefore suggest that the ‘shopping basket of taxa’ required for effective biodiversity surrogacy may not only need to be very small (two taxa), but may also be very limited in composition.