Β-diversity Components Research Articles

Primates as Predictors of Mammal Community Diversity in the Forest Ecosystems of Madagascar.

The geographic distribution of species is the typical metric for identifying priority areas for conservation. Since most biodiversity remains poorly studied, a subset of charismatic species, such as primates, often stand as surrogates for total biodiversity. A central question is therefore, how effectively do primates predict the pooled species richness of other mammalian taxa? We used lemurs as indicator species to predict total non-primate mammal community richness in the forest ecosystems of Madagascar. We combine environmental and species occurrence data to ascertain the extent to which primate diversity can predict (1) non-primate mammal α-diversity (species richness), (2) non-primate complementarity, and (3) non-primate β-diversity (species turnover). Our results indicate that primates are effective predictors of non-primate mammal community diversity in the forest ecosystems of Madagascar after controlling for habitat. When individual orders of mammals are considered, lemurs effectively predict the species richness of carnivorans and rodents (but not afrosoricids), complementarity of rodents (but not carnivorans or afrosoricids), and all individual components of β-diversity. We conclude that lemurs effectively predict total non-primate community richness. However, surrogate species alone cannot achieve complete representation of biodiversity.

β-diversity of deep-sea holothurians and asteroids along a bathymetric gradient (NE Atlantic)

ABSTRACT: Measuring and understanding patterns of β-diversity remain major challenges in community ecology. Recently, β-diversity has been shown to consist of 2 distinct components: (1) spatial turnover and (2) species loss leading to nestedness. Both components structure deep-sea macrofaunal assemblages but vary in importance among taxa and ocean basins and with energy availability. Here, we present the first evidence for turnover and nestedness along a bathymetric gradient in 2 major megafaunal taxa, holothurians and asteroids. Turnover is the dominant component of β-diversity throughout bathyal and abyssal zones in both taxa, despite major differences in β-diversity and trophic composition. High spatial turnover suggests a role for evolutionary adaptation to environmental circumstances within depth bands. This pattern differs fundamentally from those in some macrofaunal groups in low-energy environments where abyssal nestedness is high and diversity low, with diversity maintained partly by source-sink dynamics.

Spatial and Temporal Patterns in Macrofaunal Diversity Components Relative to Sea Floor Landscape Structure

We examined temporal changes in macrofaunal α- and β-diversity over several spatial scales (within patches, among patches, across landscapes and across regions) in Long Island Sound on the northeast USA coast. Regional ε-diversity was estimated at 144 taxa, however γ-diversity fluctuated over time as did α- and β-diversity components. Based on additive partitioning, patch- and region-scale β-diversity components generally had the highest contributions to γ-diversity; lower percentages were found at within-patch and landscape scales. Multiplicative diversity partitioning indicated highest species turnover at within- and among patch scales. For all partition results, within-patch and patch-scale β-diversity increased sharply when hypoxia impacted benthic communities. Spatial variation in diversity components can be attributed to the collection of different patch types at varying spatial scales and their associated habitats across the benthic landscapes, as well as gradients in depth and other estuarine-scale characteristics. Temporal variation in diversity components across spatial scales may be related to seasonal changes in habitat heterogeneity, species population dynamics, and seasonal disturbances. Rare species were significant and temporally consistent components of macrofaunal diversity patterns over different spatial scales. Our findings agree with other marine and terrestrial studies that show diversity components vary significantly over different spatial scales and the importance of habitat/landscape heterogeneity in supporting diversity. However, our results indicate that the relative contributions of scale-specific β-diversity components can also change significantly over time. Thus, studies of diversity patterns across patches and landscapes based on data collected at one time, or assembled into a single data set from different times, may not capture the full suite of diversity patterns that occur over varying spatial scales and any time-specific determinants of those patterns. Many factors that shape and maintain sedimentary communities vary temporally, and appear to play an important role in determining and maintaining macrofaunal diversity over different spatial scales.

Contrasting patterns of α- and β-diversity in deep-sea bivalves of the eastern and western North Atlantic

We analyzed patterns of α- and β-diversity in deep-sea bivalves collected by epibenthic sleds from the western North Atlantic south of New England, and from the eastern North Atlantic in the Rockall Trough, Porcupine Seabight and Porcupine Abyssal Plain. In the western North Atlantic, species diversity, measured as the normalized expected number of species, shows a unimodal bathymetric trend peaking at mid-bathyal depths. In the eastern North Atlantic, diversity increases monotonically with depth reaching a maximum at abyssal depths. We used Baselga's (2010) metrics to distinguish two separate components of β-diversity along depth gradients, species dissimilarity among sites due to spatial replacement (turnover) and species loss leading to nestedness. We also examined the rank order of nestedness with depth using Rodríguez-Gironés and Santamaría's (2006) BINMATNEST. The primary difference in β-diversity between west and east centers on the composition of abyssal communities. In the western North Atlantic, abyssal assemblages are nested subsets of bathyal assemblages. In the eastern North Atlantic, turnover dominates at all depths. These very fundamental differences in community structure between the basins may be attributable to differences in food supply, which is greater in the eastern North Atlantic region sampled. POC-flux to abyssal depths in the east may not reach levels low enough to depress species diversity as it does in the west. In the west, the abyssal fauna is largely an impoverished nested subset of the bathyal fauna that shows less endemism and may be maintained partly by source–sink dynamics.

Geographical patterns and partition of turnover and richness components of beta-diversity in faunas from Tocantins river valley

There has been a resurging interest in patterns of β-diversity, especially by the mechanisms driving broad-scale, continental and global patterns, and how partitioning β-diversity into richness (or nestedness) and turnover components can be linked with such mechanisms. Here we compared two recent methodologies to find richness and turnover components of β-diversity, using a large regional scale dataset of mammal, bird, reptiles and amphibian species found in seven regions of Central, North and Northeastern Brazil. As well as a simple comparison of the metrics available, we analyzed spatial patterns (i.e., distance-decay similarity) and the effects of biome type in these components using raw and partial Mantel tests. Our analyses revealed that turnover estimated using Baselga's (2010) approach is slightly higher than the estimate using Carvalho's et al. (2012) approach, but all analyses show consistent spatial patterns in species turnover using both methods. Spatial patterns in β-diversity revealed by Mantel tests are also consistent with expectations based on differential dispersal abilities. Our results also reinforce that spatial patterns in β-diversity, mainly in the turnover components expressing faunal differentiation, are determined by a mix or broad scale environmental effects and short distance spatially-structured dispersal.

The influence of species traits and q-metrics on scale-specific β-diversity components of arthropod communities of temperate forests

Protection of biodiversity and ecosystem functions requires a better understanding of spatial diversity. Here we studied diversity patterns of true bugs and saproxylic beetles, sampled in 28 forest stands of southern Germany, using a hierarchical nested design of five increasingly broader spatial levels: trap location, stratum, forest stand, forest site, and ecoregion. We predicted that: (1) for large body-sized species (as a surrogate for highly mobile species) and host generalist species (low host specificity), the proportion of β-diversity decreases from small to large spatial scales; and (2) the differences between trait-based functional guilds in the proportion of β-diversity increase with increasing weighting of more-abundant species. Our results indicated that the ecoregion level is the most important diversity scale for both taxa and among functional guilds sampled, followed by the forest stand level. Specialized species were more strongly affected on the ecoregion level than generalist species. Differences in the proportion of β-diversity between functional guilds increased with increasing weighting of abundant species. The β-diversity patterns based on body size and host specificity were similar for true bugs, but partly contrasting for saproxylic beetles. Our results suggest that (1) future conservation schemes should focus on establishing new conservation sites in new ecoregions, rather than on enlarging existing protected areas; (2) host specificity might be a more meaningful trait than body size to be considered in biodiversity studies; and (3) common conservation approaches restricted to only large, conspicuous, but rare species might result in a mismatch of important biodiversity scales.

Structure and conservation of lepidopteran communities in managed forests of northeastern North America: a review

AbstractWe review the existing literature on patterns of moth (Lepidoptera) species richness and community composition in northeastern Nearctic forest ecosystems across hierarchical scales ranging from individual trees to entire managed ecoregions. Moths are species-rich in northeastern forests of North America, with the most diverse families being Noctuidae and Geometridae. Individual trees and forest stands, however, are often dominated by few species. Climate, stand age, disturbance regime, and landscape heterogeneity are significant predictors of abundance of dominant species. Most other moth species in the regional pool are patchily distributed and appear to occur regularly at very low abundance. Moth communities respond predictably to forest-management practices, and the outcomes of postmanagement response are largely driven by changes in the plant community. Significant reductions in moth species richness and changes in community composition are correlated with clear-cut harvesting, whereas selective logging appears to cause more moderate changes in moth community structure. Broad-scale effects of forest fragmentation on moth communities in unglaciated regions are best described by species replacement rather than species loss; moth species richness decreases slightly across a gradient of fragment sizes, but shifts in moth community composition are more important, especially in the relative importance of herbaceous-plant-feeding species in large and small fragments. Species that appear to be most sensitive to timber management or habitat loss are dietary specialists as larvae, dispersal-limited as adults, or dependent on commercially valuable tree species such as oaks,QuercusL. (Fagaceae). Restored forest stands tend to converge in terms of lepidopteran species dominance and diversity among stands, suggesting that the long-term consequences of timber management or habitat loss include a significant reduction of regional β-diversity. Finally, future research on forest Lepidoptera should include an emphasis on understanding the role of urban woodland habitat in retaining viable and diverse moth communities and how the spatial pattern of timber harvest affects the relative magnitude of α- and β-diversity components within a given ecoregion.

P4.013 Effects of donepezil on behavioral andpsychological symptoms in Korean patients with Alzheimer's disease

We analyzed patterns of α- and β-diversity in deep-sea bivalves collected by epibenthic sleds from the western North Atlantic south of New England, and from the eastern North Atlantic in the Rockall Trough, Porcupine Seabight and Porcupine Abyssal Plain. In the western North Atlantic, species diversity, measured as the normalized expected number of species, shows a unimodal bathymetric trend peaking at mid-bathyal depths. In the eastern North Atlantic, diversity increases monotonically with depth reaching a maximum at abyssal depths. We used Baselga's (2010) metrics to distinguish two separate components of β-diversity along depth gradients, species dissimilarity among sites due to spatial replacement (turnover) and species loss leading to nestedness. We also examined the rank order of nestedness with depth using Rodríguez-Gironés and Santamaría's (2006) BINMATNEST. The primary difference in β-diversity between west and east centers on the composition of abyssal communities. In the western North Atlantic, abyssal assemblages are nested subsets of bathyal assemblages. In the eastern North Atlantic, turnover dominates at all depths. These very fundamental differences in community structure between the basins may be attributable to differences in food supply, which is greater in the eastern North Atlantic region sampled. POC-flux to abyssal depths in the east may not reach levels low enough to depress species diversity as it does in the west. In the west, the abyssal fauna is largely an impoverished nested subset of the bathyal fauna that shows less endemism and may be maintained partly by source–sink dynamics.