Additive Partitioning Of Diversity Research Articles

The species richness and community composition of different growth forms and life forms of mosses are dominated by different factors along an elevational gradient of China

Understanding the elevational variation in species richness and community composition as well as their mechanisms is critical for biodiversity conservation. On Mt Jianfengling of China, we examined the elevational patterns of species richness and analyzed the important variables driving the variation of species richness and community composition using boosted regression trees for all mosses and two growth forms and three life forms of mosses, respectively. We assessed the contribution of elevation toward explaining the heterogeneity among sampling sites. Last, we compared the occurrence probability and proportional use of community type along the elevational gradient between two growth forms and three life forms of mosses. Although each taxonomic group displayed a negatively skewed (hump-shaped) diversity pattern and a high turnover rate of community composition along the elevational gradient, the leading drivers for the patterns of each group are different. The habitat complexity and the mid-domain effect (MDE) hypothesis were supported for the diversity patterns of acrocarpous mosses and turfs, whereas the habitat complexity hypothesis was supported for pleurocarpous mosses, mats, and wefts. Habitat composition dominated the community variation of acrocarpous mosses and turfs, whereas solar radiation was the leading factor for pleurocarpous mosses, mats and wefts. According to the additive diversity partitioning, α explained only 4.8–7.3% of the variation in species richness. For many low-lying sampling sites with sunny and dry conditions, extinction and dispersal limitation might be the primary processes producing low species richness pattern, which decreases the overall average diversity for each group. The variations of the occurrence probability and proportional use of community type along the elevational gradient in each group explain the contributions of elevation toward the heterogeneity among sampling sites for all mosses. With higher sensitivity to environmental changes, pleurocarpous mosses and wefts may have greater fluctuations in species richness when environmental conditions turn from unfavorable to optimal, therefore the elevation effect on explaining the heterogeneity among sampling sites was higher (18.9%) for pleurocarpous mosses as compared to 11.1% for acrocarpous mosses; and it ranged from a low of 11.0% in turfs to 19.9% in wefts. Although each group displayed similar biogeographic patterns along the elevational gradient, the underlying drivers are different. Therefore, the total measurements of species will veil the complex mechanisms for each growth form and life form. It is also suggested that conservation efforts should be paid to the top altitude for pleurocarpous mosses, mats and wefts, and the whole elevational range for acrocarpous mosses and turfs.

Effects of Vegetation Structure on Ant Diversity in Different Seasonal Periods in Impacted Fragments of Atlantic Forest

The destruction of forest habitats generates extremely fragmented areas and changes in vegetation structure. That changes the characteristics of microhabitats and the availability of resources and affects the diversity of animal species such as ants, which are a large group with an important ecological role. As ants forage on trees and shrubs, the vegetation structure can affect the presence of these organisms. Abiotic factors such as seasonality can also influence the diversity of the ant community. Based on that, this study aimed to investigate the distribution of the diversity of ant species that forage on plants in different seasonal periods. The study was carried out in eight secondary forest fragments of the Atlantic Forest. We used additive partitioning of diversity, partitioning of β diversity and canonical correspondence analysis to measure the effect of seasonality and vegetation structure on the distribution of ant species diversity. The rainy season positively influences the diversity of ants that forage on plants. Composition was affected by shrub leaf density in the rainy season and by tree circumference in the dry. Each fragment preserved a different pool of ant species, and the vegetation structure positively influenced ant diversity. These results highlight the importance of conserving the majority of forest fragments to better preserve the pool of ant species regionally.

Food web structure of nematode communities in irrigated rice fields

Nematodes are a key component of the soil food web and they play an important role in the provision of ecosystem services. Rice cultivation in Mwea, Kenya involves the intensive use of fertilizers and pesticides which may affect the complexity of the nematode-based soil food web. This study examined the nematode diversity and food web structure in irrigated rice fields in Nyangati and Tebere in Mwea, Kirinyaga County, Kenya. Nematodes were identified up to the genus level and soil physico-chemical properties were also determined. Aphelenchoides and Longidorus occurred in significantly greater proportions in Tebere, while in Nyangati there was a high abundance of Helicotylenchus. Aphelenchoides was positively correlated to soil electrical conductivity. From additive diversity partitioning of genus richness, the α and β components contributed 33.7% and 66.3% of the γ diversity, respectively. For Shannon and Simpson diversity indices, the largest contribution to overall diversity was from α component. Soil food web indices were similar across the two regions. Channel and basal indices were below 30% while Enrichment (EI) and Structure (SI) indices were above 50%. There was no variation in metabolic footprints except for the fungivore footprint which was significantly higher in Tebere. Based on the EI and SI, the soil food web in paddy rice fields in Mwea was structured and enriched with moderate disturbance. Due to the high prevalence of economically damaging parasitic nematodes in the rice fields, appropriate management schemes that enhance specific components of the soil food web and increase the suppressive ability of soil against plant-parasitic nematodes should be implemented.

Diversidade beta de Ephemeroptera, Plecoptera e Trichoptera ao longo de múltiplas escalas espaciais nas corredeiras do rio Xingu

Abstract: Aim Additive diversity partitioning has been used to explain the accumulation of diversity at different spatial scales with relative success. In lotic ecosystems, the spatial extent is extremely relevant in studies of diversity accumulation, because it encompasses environmental variation that causes changes in the observed communities. Despite of previous knowledge on the effect of extent on biological communities and diversity accumulation, little is known about the topic in aquatic insect communities in large rivers. In this context, we studied the effect of spatial extent and environmental variation on diversity components, alpha and beta, in Ephemeroptera, Plecoptera and Trichoptera (EPT) groups in Xingu River rapids. Methods The sampling was carried out in October 2015 in the dry period of the region, in nine rapids in the Xingu, Bacajá and Iriri rivers. At each collection site, five Surber samples were taken. We also recorded pH, dissolved oxygen, electrical conductivity, water temperature, and geographic coordinates. We used additive diversity partitioning to separate the diversity components α and β. For the spatial component, we generated the spatial filters using PCNM (Principal Coordinates of Neighbour Matrices) and partitioned the variance between space and environment using partial Redundancy Analysis (pRDA). Results We collected 12,249 individuals in 27 genera within 11 families in the EPT orders. The greatest accumulation of diversity was observed among rapids of the river, when the β diversity in this spatial extent was greater than the expected. The spatial structure was an indirect effect at this extent, since it is a relevant drive to environmental variables. Conclusions The results indicate that the effect of spatial extent on rapids is a contributing factor in the diversity components of aquatic insect communities in large river rapids. To the conservation and management of this environment is necessary cover as many rapids as possible, since the preservation of only a few rapids can mean a substantial loss of regional diversity.

Sand Flies (Diptera: Psychodidae): Fauna and Ecology in the Northeast of Algeria

Sand flies (Diptera: Psychodidae) transmit several Leishmania (Kinetoplastida: Trypanosomatidae) species, which cause leishmaniasis, a significant public health concern in Algeria. We compared sand fly species abundance and composition among different biotopes (urban, peri-urban, rural areas), bioclimatic zones (humid, sub-humid, semi-arid), and elevation ranges. We also used the additive partitioning of beta diversity to test whether the variation in sand fly composition among biotopes, bioclimatic zones, and elevation ranges is due to species turnover or community subsetting. In total, 7,478 specimens were captured; of which, 7,162 (51.5% males vs. 48.5% females) belong to eight species: Phlebotomus perniciosus Newstead, 1911 (77.4% of the total captured specimens), Phlebotomus perfiliewi Parrot, 1930 (14.6%), Phlebotomus longicuspis Nitzulescu, 1911 (5.9%), Phlebotomus papatasi Scopoli, 1786 (<1%), Phlebotomus sergenti Parrot, 1917 (<1%) and Phlebotomus chadlii Rioux, Juminer et Gibily 1966 (<1%), Sergentomyia minuta Adler et Theodor, 1927 (1%), and Sergentomyia fallax Parrot, 1921 (<1%). Sand fly total abundance showed negative correlations with altitude and was significantly higher in rural areas. Sandfly community composition was significantly different between rural and urban/peri-urban areas. The additive partitioning of beta diversity showed that 71.4% of the compositional dissimilarity among elevation ranges and bioclimates was due to sand fly species turnover, and 28.6% resulted from nestedness. However, the variation in sand fly composition among different biotopes was mainly due to community nestedness. Findings from this study help define the risk of Leishmania transmission and develop methods for vector control in Mila province and Algeria as a whole.

Land use effects on termite assemblages in Kenya

Termites perform key ecological functions and they also cause crop damage. Land use change resulting from agricultural intensification can result in changes in termite species diversity and abundance. Termite species occurring in natural vegetation, maize monocrop and maize-beans intercrop macrohabitats were investigated in Embu and Machakos Counties, Kenya. Influence of soil properties and seasons was also evaluated. Across the two Counties, seven termite species were recorded with Machakos County having the highest number. Additive diversity partitioning of species richness and Simpson diversity showed that, α component contributed to 98.3% and 99.1% of the total diversity, respectively. Population densities of three termite species significantly varied between land use types in Machakos County but there were no differences in termite species abundance in Embu County. In addition, there were no significant differences in species richness between macrohabitats within each County. In Embu, season significantly influenced the abundance of Macrotermes subhyalinus, M. herus, and Coptotermes formosanus which occurred in greater numbers during the wet season. There was a significant influence of land use on Trinervitermes gratiosus and C. formosanus in Machakos with both species occurring in higher numbers in natural vegetation. Trinervitermes gratiosus was negatively associated with Mn and positively correlated to pH and sand. Macrotermes subhyalinus and M. herus showed a positive association with P and silt while C. formosanus was positively correlated to Ca and Mg. These findings provide an insight into the effects of land use change from natural vegetation to maize agro-ecosystems on termite diversity. It also provides a baseline for further studies on termite diversity in Kenya and their ecological significance.

Maputo Special Reserve and dung beetle conservation in the heterogeneous landscape of the Maputaland Centre of Endemism

Background: Maputo Special Reserve (MSR) in Mozambique lays within the Maputaland Centre of Endemism (MCE) and protects the biota of a habitat mosaic dominated by coastal dune forest and inland sand forest patches of different sizes surrounded by natural grassland. Objectives: To determine the importance of woody versus grassland vegetation for supporting endemic east coast versus widespread savanna dung beetles in the MCE in the face of increased accessibility and exploitation of woody vegetation in southern Mozambique, especially by charcoal burners.Method: We used general linear mixed models, additive partitioning of diversity and ordination to analyse species abundance and occurrence across a mosaic of three major habitats in the MSR (grassland, sand and dune forest).Results: High compositional heterogeneity was found between habitat types and study sites so that beta diversity was mostly higher than alpha diversity. Three distinct scarabaeine dung beetle assemblages defined from ordination were largely centred on the three habitat types. Out of a total of 61 species, greater numbers were associated with grassland (38) than sand (17) and dune forest (6) although abundance was greater in both dune forest and grassland than in sand forest. Biogeographical classification indicated that &gt;40% of the species are endemic to the east coast of southern Africa with the remainder centred in adjacent savanna. Endemic east coast species were well represented in both forest (15) and grassland (11). Savanna species were better represented in grassland (27) than forest (8). Proportions of grassland species and their abundance declined across increasing patch sizes of sand forest becoming lowest in dune forest.Conclusions: Conservation of endemic, east coast dung beetle species requires the preservation of both natural grassland and sizeable patches of forest in an undisturbed habitat mosaic. As the east coastal system is relatively small in extent with the MCE widely transformed in South Africa, the MSR is an important contributor to regional conservation of endemic species.

Small Mammals in Forests of Romania: Habitat Type Use and Additive Diversity Partitioning

Small mammals are key components of forest ecosystems, playing vital roles for numerous groups of forest organisms: they exert bottom-up and top-down regulatory effects on vertebrate and invertebrate populations, respectively; they are fungus- and seed-dispersers and bioturbators. Therefore, preserving or restoring the diversity of small mammal communities may help maintain the functions of these ecosystems. In Romania, a country with low-intensity forest management and a high percentage of natural forests compared to other European countries, an overview of forest small mammal diversity and habitat type use is lacking, and our study aimed to fill this gap. We also aimed to partition the total small mammal diversity of Romanian forests into the alpha (plot-level), beta, and delta (among forest types) diversities, as well as further partition beta diversity into its spatial (among plots) and temporal (among years) components. We surveyed small mammals by live trapping in eight types of forest across Romania. We found that small mammal abundance was significantly higher in lowland than in mountain forests, but species richness was similar, being associated with the diversity of tree canopy, with the highest values in mixed forests. In contrast, small mammal heterogeneity was related to overall habitat heterogeneity. As predicted, community composition was most distinct in poplar plantations, where forest specialists coexist with open habitat species. Most of the diversity was represented by alpha diversity. Because of strong fluctuations in population density of dominant rodents, the temporal component of beta heterogeneity was larger than the spatial component, but species richness also presented an important temporal turnover. Our results show the importance of the time dimension in the design of the surveys aiming at estimating the diversity of small mammal communities, both at the local and regional scales.

Value of large Quercus robur fallen logs in enhancing the species diversity of vascular plants in an old-growth mesic broad-leaved forest in the Central Russian Upland

Large old trees and decaying logs are key-retained structures for the retention forestry approach, but quantitative estimations of the role of fallen logs in the overall diversity and composition of forest vascular species are few and controversial. Particularly for mesic deciduous forests only a small number of such estimates are known. Our study aimed to partly fill this gap using data collected in the Reserve Kaluzhskie Zaseki where large Quercus robur individuals of more than 300 years old and fallen logs are frequent. We found 44 fallen oak logs supporting vascular plants within a 200-ha forest tract. The vegetation in plots of 1 m2 located on the fallen logs and on the forest floor adjacent to the logs was surveyed together with vegetation in fifteen 10 × 10 m plots randomly placed in patches without large fallen logs. NMDS and PERMANOVA were applied to examine differences in composition between fallen logs and forest floor. Generalized linear models were used to examine the relationships between environmental variables and species richness. Additive diversity partitioning was performed to examine differences in species richness and to estimate the contribution of the fallen logs to the general diversity in vascular species. In total, 71 vascular plant species in 108 1 m2-plots were identified. Twenty-five and 16 species were detected only on fallen logs and on the forest floor, respectively. More than 60% of the studied logs were in early stages of decomposition; their mean diameter was 75.4 ± 25.6 cm. Fallen logs significantly affected species richness and composition in terms of both woody seedlings and herbaceous species. The diameter of logs significantly and positively affected species diversity and composition. Large logs with cracked bark at the first two stages of decay were places of successful vascular plant establishment and growth. The abundance and frequency of tree seedlings were higher on the logs than on the forest floor and seven out of ten tree species appeared to be significant indicator species for the log-plots. Illumination varied over the observed sites and directly influenced the richness of herbaceous species and the overall species composition, but had no effect on woody species richness. We conclude that retention of large fallen logs can be an effective tool for maintaining and restoring the vascular species richness and composition in mesic broad-leaved forests.

Spatial scale drives diversity patterns of benthic macroinvertebrate communities in tropical estuaries

AbstractIdentifying the hierarchical spatial levels that show the greatest dissimilarities between communities and how these patterns are generated is essential to provide insights into the monitoring and protection of biodiversity. In this study, we additively partitioned diversity of macroinvertebrates into alpha, beta, and gamma diversity across multiple scales in typical and semi‐arid tropical estuaries. We also determined which components of the total beta diversity, in terms of species replacement or richness difference (presence‐absence data) and abundance difference (relative abundance data), had the greatest relative importance in structuring the composition of benthic macrofauna. In typical and semi‐arid tropical estuaries, a non‐random spatial pattern was observed in additive partitioning of diversity, with higher values of beta diversity obtained at the largest scales analyzed. When considering the presence‐absence data, in general there was no clear trend which components of beta diversity had greater relative importance in typical estuaries. In the semi‐arid tropical estuaries, the richness difference component showed greater relative importance in the rainy season, whereas the species replacement presented greater proportions in the dry season. When considering abundance data, in general the abundance difference component showed greater relative importance in typical and semi‐arid tropical estuaries in the two seasonal periods. Therefore, approaches based on the presence/absence and on the relative abundance of species provided complementary answers about the distribution patterns of benthic macroinvertebrate communities. We demonstrated that environmental filtering and dispersal limitation may affect the patterns of distribution of benthic macrofauna in estuaries located in regions with different climatic conditions.

Spatial structure of the diversity of dung beetles (Scarabaeidae: Scarabaeinae) in savanna formations of Central Brazil

Great losses of biodiversity in natural ecosystems are occurring as a result of growing anthropic threats. A better understanding of the contributions of spatial scales to biodiversity organization would allow improved spatial management to conserve biodiversity in those regions that are strongly impacted by anthropic activities, such the Brazilian Cerrado. The aim of this study was to evaluate how dung beetle diversity is spatially organized along the cerrado sensu stricto, a common savanna formation in central Brazil. We tested the following hypotheses: (1) dung beetle diversity shows nonrandom patterns that vary between spatial scales within the same phytophysionomy, and (2) different functional groups and the abundant and rare species display distinct and nonrandom spatial patterns of diversity along spatial scales due to different life histories. We collected dung beetles in eight areas of cerrado sensu stricto distributed in two fragments and analyzed the spatial organization of dung beetle diversity using additive diversity partitioning. A total of 6130 individuals and 54 species were collected. Additive partitioning of diversity showed a prominent importance of the scale of areas in the organization of diversity, demonstrating a stronger influence of local factors on this organization. Assemblages divided into functional groups showed differential contributions of diversity components, indicating distinct habitat influences on these groups. This work provides new insights into the spatial organization of dung beetle diversity, encompassing three spatial levels for the same phytophysionomy in the Brazilian Cerrado. These findings demonstrate the importance of maintaining spatial heterogeneity of habitats. Thus, multiple localities within a region must be preserved because of their unique diversity structuring.

Maximizing the monitoring of diversity for management activities: Additive partitioning of plant species diversity across a frequently burned ecosystem

Monitoring understory plant diversity is important, allowing managers to track current diversity status and trends both spatially and temporally at a landscape-scale. Improving precision in quantifying patterns in understory plant diversity improves efficiency in monitoring design and more accurate measures of success of management intervention over time. Patterns of species diversity are dependent upon the scale in which they are examined – an increase in small-scale diversity across a gradient can convert to a decrease in large-scale diversity across that same gradient. Using two extensive datasets including both mined historical data and supplemental experimental data, we performed an additive partitioning of plant diversity to elucidate the hierarchical spatial patterns of understory plant species richness, and independent measures of alpha and beta diversity in the species-rich longleaf pine ecosystem at Eglin Air Force Base in northwestern FL, USA. This analysis allowed us to identify the spatial scale that most effectively captures plant diversity to inform monitoring efforts by using measures of species turnover, specifically beta diversity. We found that while species richness and alpha diversity increased with spatial scale, beta diversity began to reach an asymptote at smaller (1 m2) scales. Furthermore, we found the sampling effort at this 1 m2 scale required as few as 60 plots to effectively estimate plant diversity within management blocks. While our results are attributable to Eglin AFB specifically, these scaling analyses can help to streamline monitoring efforts in other ecosystems that seek to elucidate the individual contributions of diversity components.

Metacommunity structure, additive partitioning and environmental drivers of woody plants diversity in the Brazilian Atlantic Forest

AbstractAimTo assess the metacommunity structure of woody plants in the Atlantic Forest (AF), compare the structure across its different forest types and evaluate the contribution of multiple scales and environmental drivers for the total biodiversity, providing theoretical basis for efficient conservation of this important hotspot.LocationSouth America, Brazilian Atlantic Forest.MethodsWe compiled the occurrence of 2,071 woody plants in 177 sites across the Brazilian AF. We assessed the elements of metacommunity structure (species coherence, turnover and boundary clumping) to identify which idealized structure (checkerboard, nestedness, Clementsian, Gleasonian, evenly spaced or random) characterizes the AF and its forest types. We used the additive partition of diversity to determine the main spatial scales promoting biodiversity in the AF, that is local (within sites, α‐diversity), regional (among sites in each forest type, β1) or geographical (between forest types, β2), and examined environmental variables driving the metacommunity of the AF and forest types using canonical ordinations.ResultsThe AF and its forest types presented positive coherence, negative turnover and large boundary clumping values which best‐fit the nested subsets metacommunity structure with clumped species loss. The diversity within sites (α‐diversity) and among types (β2) was higher than expected by chance. The climatic gradient driving the species composition differed in the AF. Temperature variation affected the entire AF, particularly Dense and Seasonal forests, whereas precipitation affected mostly the Mixed forest.Main conclusionsDespite the similar structure underlying AF metacommunities, the main environmental gradient in each forest differs, highlighting ecological differences among communities at geographical scale. These differences are determinant for the high levels of biodiversity found in the AF. Conservation efforts should encompass all the AF ecosystems, considering its unique characteristics and prioritizing species‐rich sites given that they adequately represent the regional species pool.

Regional processes drive bryophyte diversity and community composition in a small oceanic island

How are bryophyte alpha and beta diversities distributed across spatial scales along an elevational gradient in an oceanic island? Which mechanisms and drivers operate to shape them? Starting from a multiscale hierarchical sampling approach along an 1000 m elevational transect, we used additive diversity partitioning and null modeling to evaluate the contributions of the alpha and beta diversity components to overall bryophyte diversity in Terceira Island, Azores. Substrate-level diversity patterns were explored by means of the Sørensen Similarity Index and the Lloyd Index of Patchiness. Elevation-level beta diversity was decomposed into its replacement and richness differences components, with several environmental variables being evaluated as diversity predictors. Bryophyte diversity proved to be primarily due to beta diversity between elevation sites, followed by diversity among substrates. Compositional differences between neighboring sites decreased with elevation, being mainly caused by species replacement and correlating with differences in relative humidity and disturbance. At the substrate level, we found a great homogeneity in terms of species composition, coupled with a low substrate specialization rate. We conclude that, in Terceira’s native vegetation patches, regional processes, such as environmental gradients associated with elevation, play a greater role in shaping bryophyte diversity than local processes. Moister and less disturbed areas at mid-high elevation harbor a richer bryoflora, consistently more similar and stable between neighbouring sites. Simultaneously, the different substrates available are somewhat ecologically redundant, supporting few specialized species, pointing to these areas providing optimal habitat conditions for bryophytes. Our findings provide a better understanding of how bryophyte diversity is generated in Terceira Island, indicating that management and conservation measures should focus on island-level approaches, aiming to protect and rehabilitate additional natural vegetation patches at different elevations, especially in the severely disturbed lowlands.

Partitioning the plant diversity of semi-natural grasslands across Japan

AbstractEffective conservation of global species diversity requires a clear understanding of spatial scales that support overall diversity across broad scales. Abandonment of semi-natural grasslands has increased their fragmentation and decreased their areal extent. We quantified diversity patterns of plant communities in Japan across hierarchical scales to facilitate the development of an effective nationwide strategy for conserving species diversity in remnant semi-natural grasslands. We applied additive partitioning of plant species diversity, using a nested hierarchical design at three spatial scales (quadrat, grassland, and western and eastern regions of Japan) for three groups of plant species (all species, grassland species and national Red Listed species). We consistently found lower proportions of among-quadrats diversity, and higher proportions of among-grasslands diversity and between-regions diversity in the overall diversity of the entire species complement than would be expected by chance. The high contribution of among-grasslands diversity to overall diversity suggests that each grassland had a unique species content. The second-ranking contributor to overall diversity differed between grassland species and Red Listed species: the second-ranking contributor for grassland species was diversity at the among-quadrats scale but the second-ranking contributor for all species and for Red Listed species was diversity at the between-regions scale. Thus, effective conservation of diversity of the entire species complement in remnant semi-natural grasslands requires preservation of beta diversity in individual grasslands. Our findings highlight the importance of strengthening local preservation and restoration activities within each grassland, and of nationwide strategies for conserving Red Listed species in remnant semi-natural grassland communities.

Anthropogenic Matrices Favor Homogenization of Tree Reproductive Functions in a Highly Fragmented Landscape.

Species homogenization or floristic differentiation are two possible consequences of the fragmentation process in plant communities. Despite the few studies, it seems clear that fragments with low forest cover inserted in anthropogenic matrices are more likely to experience floristic homogenization. However, the homogenization process has two other components, genetic and functional, which have not been investigated. The purpose of this study was to verify whether there was homogenization of tree reproductive functions in a fragmented landscape and, if found, to determine how the process was influenced by landscape composition. The study was conducted in eight fragments in southwest Brazil. The study was conducted in eight fragments in southwestern Brazil. In each fragment, all individual trees were sampled that had a diameter at breast height ≥3 cm, in ten plots (0.2 ha) and, classified within 26 reproductive functional types (RFTs). The process of functional homogenization was evaluated using additive partitioning of diversity. Additionally, the effect of landscape composition on functional diversity and on the number of individuals within each RFT was evaluated using a generalized linear mixed model. appeared to be in a process of functional homogenization (dominance of RFTs, alpha diversity lower than expected by chance and and low beta diversity). More than 50% of the RFTs and the functional diversity were affected by the landscape parameters. In general, the percentage of forest cover has a positive effect on RFTs while the percentage of coffee matrix has a negative one. The process of functional homogenization has serious consequences for biodiversity conservation because some functions may disappear that, in the long term, would threaten the fragments. This study contributes to a better understanding of how landscape changes affect the functional diversity, abundance of individuals in RFTs and the process of functional homogenization, as well as how to manage fragmented landscapes.

Species-area relationships and additive partitioning of diversity of native and nonnative herpetofauna of the West Indies.

To evaluate the regional biogeographical patterns of West Indian native and nonnative herpetofauna, we derived and updated data on the presence/absence of all herpetofauna in this region from the recently published reviews. We divided the records into 24 taxonomic groups and classified each species as native or nonnative at each locality. For each taxonomic group and in aggregate, we then assessed the following: (1) multiple species–area relationship (SAR) models; (2) C‐ and Z‐values, typically interpreted to represent insularity or dispersal ability; and (3) the average diversity of islands, among‐island heterogeneity, γ‐diversity, and the contribution of area effect toward explaining among‐island heterogeneity using additive diversity partitioning approach. We found the following: (1) SARs were best modeled using the Cumulative Weibull and Lomolino relationships; (2) the Cumulative Weibull and Lomolino regressions displayed both convex and sigmoid curves; and (3) the Cumulative Weibull regressions were more conservative than Lomolino at displaying sigmoid curves within the range of island size studied. The Z‐value of all herpetofauna was overestimated by Darlington (Zoogeography: The geographic distribution of animals, John Wiley, New York, 1957), and Z‐values were ranked: (1) native > nonnative; (2) reptiles > amphibians; (3) snake > lizard > frog > turtle > crocodilian; and (4) increased from lower‐ to higher‐level taxonomic groups. Additive diversity partitioning showed that area had a weaker effect on explaining the among‐island heterogeneity for nonnative species than for native species. Our findings imply that the flexibility of Cumulative Weibull and Lomolino has been underappreciated in the literature. Z‐value is an average of different slopes from different scales and could be artificially overestimated due to oversampling islands of intermediate to large size. Lower extinction rate, higher colonization, and more in situ speciation could contribute to high richness of native species on large islands, enlarging area effect on explaining the between‐island heterogeneity for native species, whereas economic isolation on large islands could decrease the predicted richness, lowering the area effect for nonnative species. For most of the small islands less affected by human activities, extinction and dispersal limitation are the primary processes producing low species richness pattern, which decreases the overall average diversity with a large among‐island heterogeneity corresponding to the high value of this region as a biodiversity hotspot.

Fish larvae diversity in a conservation area of a neotropical floodplain: influence of temporal and spatial scales

The diversity of fish larvae in floodplain environments exhibits spatial and temporal variations since fish have different ontogenetic requirements, and is influenced by their reproductive period. In order to evaluate how the diversity of fish larvae is structured in different temporal and spatial scales in the sub-basin of the Ivinhema River, Upper Parana River floodplain (MS, Brazil), we performed monthly samplings in two reproductive periods (2010/2011 and 2011/2012). Variation in alpha (α) diversity was evaluated through a nested ANOVA, while beta (β) diversity was evaluated with distance-based tests for the homogeneity of multivariate dispersions (PERMDISP). Additive partitioning of diversity was used to verify the relative contribution of each scale to gamma (γ) diversity. The first reproductive period showed higher intensity and duration of flooding, which favored a higher γ diversity. Alpha and beta diversities also varied among the different habitats, each one being occupied by species with distinct reproductive strategies. Components β1 (variation among months) and β3 (variation among habitats) significantly explained γ diversity in both reproductive periods, indicating that more intense floods favor reproduction and increase diversity of fish larvae. This study reinforces the importance of temporal and spatial scales in the maintenance of fish larvae diversity in floodplains.

The importance of taxonomic resolution for additive beta diversity as revealed through DNA barcoding.

Additive diversity partitioning (α, β, and γ) is commonly used to study the distribution of species-level diversity across spatial scales. Here, we first investigate whether published studies of additive diversity partitioning show signs of difficulty attaining species-level resolution due to inherent limitations with morphological identifications. Second, we present a DNA barcoding approach to delineate specimens of stream caddisfly larvae (order Trichoptera) and consider the importance of taxonomic resolution on classical (additive) measures of beta (β) diversity. Caddisfly larvae were sampled using a hierarchical spatial design in two regions (subarctic Churchill, Manitoba, Canada; temperate Pennsylvania, USA) and then additively partitioned according to Barcode Index Numbers (molecular clusters that serve as a proxy for species), genus, and family levels; diversity components were expressed as proportional species turnover. We screened 114 articles of additive diversity partitioning and found that a third reported difficulties with achieving species-level identifications, with a clear taxonomic tendency towards challenges identifying invertebrate taxa. Regarding our own study, caddisfly BINs appeared to show greater subregional turnover (e.g., proportional additive β) compared to genus or family levels. Diversity component studies failing to achieve species resolution due to morphological identifications may therefore be underestimating diversity turnover at larger spatial scales.

Alpha and beta diversity of freshwater meiofauna at different spatial scales in a Neotropical lotic system

Meiofaunal assemblages are important components of benthic communities in freshwater habitats, but studies about their ecology are scarce. In the present study we investigated the spatial and temporal distribution patterns of freshwater meiofaunal taxa, in a lotic system in south-eastern Brazil, assessing α and β diversities through additive partitioning of diversity. At each of six sampling sites, a 50-m transect was divided into five equal sections. Two random samples were collected in each section. Local spatial scales (α and β1) and among areas (β3) made the highest contribution to overall richness, but seasonal variation could be seen. Non-randomness patterns were observed, especially at the lowest and highest spatial scales, showing the effects of local intraspecific aggregation and environmental variability among areas. Temporal scale analysis showed that diversity was highly aggregated at the monthly scale, but sampling location affected these results. Community composition results highlighted the contrasting conditions found at the sampling sites, highlighting β3 as an important component of γ diversity across spatial scales. The effects of different levels of environmental degradation and precipitation on community composition and meiofaunal abundance affected the ability of the community to recover and recolonise the meiobenthos.