Disentangling the correlates of species and site contributions to beta diversity in dung beetle assemblages

Prioritizing the multifaceted community and species uniqueness for the conservation of lacustrine fishes in the largest subtropical floodplain, China

Hydrological variations affect habitat characteristics and fish distribution in floodplain lakes. Assessing the contributions of the local community (i.e., LCBD, community uniqueness) and species to overall β diversity (i.e., SCBD, species uniqueness) of fish assemblages is valuable for habitat and species conservation planning, particularly from functional and phylogenetic perspectives. We examined the changes in multifaceted LCBD and SCBD of fish across different hydrological periods in the Poyang Lake, China, and analyzed their responsive mechanisms using regression models, based on which the conservation priorities of habitats and species were evaluated. The findings revealed that taxonomic, functional, and phylogenetic LCBD and SCBD were lowest during the wet season compared to the normal and dry seasons, emphasizing the regulatory effects of hydrological regimes on fish assemblages. Taxonomic and functional LCBD were significantly impacted by the mean abundance of migratory fish, highlighting the importance of specific species combinations on community uniqueness. Taxonomic and functional SCBD exhibited positive correlations primarily with mean abundance, suggesting the potential uniqueness of certain common species. Additionally, we identified the river-lake junction (Hukou station) and natural reserve (Xingzi and Nanjishan stations) with high overall community uniqueness as critical habitats. We also emphasized the necessity for increased conservation efforts for species having high overall species uniqueness during different hydrological periods, including Coilia brachygnathus, Ctenopharyngodon idella, Coilia nasus, Saurogobio dabryi, Hypophthalmichthys molitrix, Megalobrama amblycephala, and Parabramis pekinensis. This research underscores the significance of integrating multiple ecological perspectives to manage biodiversity changes and maintain ecological conservation values effectively.

Searching for common patterns in parasite ecology: species and host contributions to beta-diversity in helminths of South African ungulates and fleas of South American rodents

We searched for common patterns in parasite ecology by investigating species and host contributions to the beta-diversity of infracommunities (=assemblages of parasites harboured by a host individual) in helminths of three species of South African ungulates and fleas of 11 species of South American rodents, assuming that a comparison of patterns in distinctly different parasites and hosts would allow us to judge the generality or, at least, commonness of these patterns. We used data on species' composition and numbers of parasites and asked whether (i) parasite species' attributes (life cycle, transmission mode, and host specificity in helminths; possession of sclerotized combs, microhabitat preference, and host specificity in fleas) or their population structure (mean abundance and/or prevalence) and (ii) host characteristics (sex and age) affect parasite and host species' contributions to parasite beta-diversity (SCBD and HCBD, respectively). We found that parasite species' morphological and ecological attributes were mostly not associated with their SCBD. In contrast, parasite SCBD, in both ungulates and rodents, significantly increased with either parasite mean abundance or prevalence or both. The effect of host characteristics on HCBD was detected in a few hosts only. In general, parasite infracommunities' beta-diversity appeared to be driven by variation in parasite species rather than the uniqueness of the assemblages harboured by individual hosts. We conclude that some ecological patterns (such as the relationships between SCBD and parasite abundance/prevalence) appear to be common and do not differ between different host-parasite associations in different geographic regions, whereas other patterns (the relationships between SCBD and parasite species' attributes) are contingent and depend on parasite and host identities.

Local environment and fragmentation by drought and damming shape different components of native and non-native fish beta diversity across pool refuges

Pool refuges are critical for maintaining stream fish diversity in increasingly intermittent streams. Yet, the patterns and drivers of beta diversity of native and non-native fish in pool refuges remain poorly known. Focusing on Mediterranean streams, we decomposed beta diversity of native and non-native fish into richness difference (RichDiff) and species replacement (Repl), and local (LCBD, LCBDRichDiff and LCBDRepl) and species (SCBD) contributions. We assessed the influence of environmental and spatial factors associated with drought and damming fragmentations on beta diversity components and LCBDs, and of local species richness and occupancy on LCBDs and SCBD, respectively. Overall, non-native species showed a more limited occupancy of pool refuges than native fish. RichDiff dominated beta diversity, though it was influenced by drought and damming fragmentations for native fish and local environment for non-native fish. Repl for native fish was slightly influenced by local environment, but for non-native fish was largely driven by drought and damming, albeit with a contribution of local environment as well. LCBD and LCBDRichDiff increased in pools in low order streams for native fish and at low elevations for non-native fish, and with high or low species richness. SCBD was higher for native species with intermediated pool occupancy, but for non-native species with low occupancy. Our results suggest that stream fragmentation may drive native species loss and non-native species replacement in pool refuges, and that environmental filtering may shape non-native species loss. Pools in lower order streams harbouring unique species-rich or species-poor assemblages should be prioritize for conservation and restoration, respectively, and pools at low elevation with unique non-native assemblages should deserve control efforts. We encourage the partitioning of beta diversity and individual analysis of native and non-native fish in intermittent streams, which may be key in stressing the importance of pool refuges in safeguarding native fish diversity.

Long-term subtropical grassland plots take a long time to change: Replacement is more important than richness differences for beta diversity

We studied β diversity of grasses in a subtropical grassland over 60 years in South Africa. We examined the effects of burning and mowing on 132 large plots. We sought to determine the effects of burning and mowing, and mowing frequency, on the replacement of species and the species richness. We conducted the study at Ukulinga, research farm of the University of KwaZulu-Natal, Pietermaritzburg, South Africa (29°24'E, 30°24'S) from 1950-2010. Plots were burned annually, biennially, triennially, and a control (unburned). Plots were mowed in spring, late summer, spring plus late summer, and a control (unmowed). We calculated β diversity, with a focus on replacement and richness differences. We also used distance-based redundancy analyses to examine the relative effects of replacement and richness differences on mowing and burning. We used beta regressions to test for the effect of soil depth and its interactions with mowing and burning. There was no significant change in grass beta diversity until 1995. Thereafter, there were changes in β diversity that demonstrated the primary effects of summer mowing frequency. There was no significant effect of richness differences but a strong effect of replacement post-1995. There was a significant interaction between mowing frequency and soil depth in one of the analyses. Changes in grassland composition took a long time to manifest themselves and were unapparent prior to 1988. However, there was a change in sampling strategy prior to 1988, from point hits to nearest plants, that may also have influenced the rates of changes in replacement and richness differences. Using β-diversity indices, we found that mowing was more important than burning that burning frequency was unimportant, and there was a significant interaction effect between mowing and soil depth in one of the analyses.

A Taxonomic Revision of the Dichotomius reclinatus (Felsche, 1901) Species Group (Coleoptera: Scarabaeidae: Scarabaeinae)

The taxonomic revision of the Dichotomius reclinatus species group (Coleoptera: Scarabaeidae: Scarabaeinae: Dichotomius Hope, 1838) sensu Arias-Buriticá and Vaz-de-Mello (2019) is presented. The group comprises four species previously included in the Dichotomius buqueti species group: Dichotomius horridus (Felsche, 1911) from Brazil, French Guiana, and Suriname; Dichotomius nimuendaju (Luederwaldt, 1925) from Bolivia, Brazil, and Peru; Dichotomius quadrinodosus (Felsche, 1901) from Brazil; and Dichotomius reclinatus (Felsche, 1901) from Colombia and Ecuador. A definition of the D. reclinatus species group and an identification key are presented. In the key we included to Dichotomius camposeabrai Martínez, 1974, this species due the external morphology can be confused with the D. reclinatus species group and for the first time photographs of males and female of this species are presented. For each species of the D. reclinatus species group, the following information is provided: taxonomic history, citation of the species in published literature, redescription, list of material examined, photographs of the external morphology, illustrations of male genital organs and the endophallites, and distribution map.

Disproportionate loss of threatened terrestrial mammals along anthropogenic disturbance gradients

Tens of thousands of species are increasingly confronted with habitat degradation and threatened with local extirpation and global extinction as a result of human activities. Understanding the local processes that shape the regional distribution patterns of at-risk species is useful in safeguarding species against threats. However, there is only limited understanding of the processes that shape the regional distribution patterns of threatened species. We explored the drivers and patterns of species richness of threatened, non-threatened and total terrestrial mammals by employing multi-region multi-species occupancy models based on data from a broad camera trapping survey at 1096 stations stratified across different levels of human activities in 54 mountain forests in southwest China. We compared correlates between total and threatened species richness and examined relationships of human impact variables with the proportion of threatened species and the site's local contribution to β diversity (LCBD). We found that threatened species richness was negatively related to human modification and human presence. However, both non-threatened and total species richness increased as human modification increased. Predicted proportions of threatened species were strongly and positively related to LCBD but negatively related to human modification and human presence. Our results indicate that human impacts can lead to disproportionate loss of threatened terrestrial mammals and highlight the importance of considering threatened species diversity independently from total species richness for directing conservation resources. Our approach represents one of the highest-resolution analyses of different types of human impacts on regional diversity patterns of threatened terrestrial mammals available to inform conservation policy.

Taxonomic dependency of beta diversity for bacteria, archaea, and fungi in a semi-arid lake

Microbial beta diversity has been recently studied along the water depth in aquatic ecosystems, however its turnover and nestedness components remain elusive especially for multiple taxonomic groups. Based on the beta diversity partitioning developed by Baselga and Local Contributions to Beta Diversity (LCBD) partitioning by Legendre, we examined the water-depth variations in beta diversity components of bacteria, archaea and fungi in surface sediments of Hulun Lake, a semi-arid lake in northern China, and further explored the relative importance of environmental drivers underlying their patterns. We found that the relative abundances of Proteobacteria, Chloroflexi, Euryarchaeota, and Rozellomycota increased toward deep water, while Acidobacteria, Parvarchaeota, and Chytridiomycota decreased. For bacteria and archaea, there were significant (p < 0.05) decreasing water-depth patterns for LCBD and LCBDRepl (i.e., species replacement), while increasing patterns for total beta diversity and turnover, implying that total beta diversity and LCBD were dominated by species turnover or LCBDRepl. Further, bacteria showed a strong correlation with archaea regarding LCBD, total beta diversity and turnover. Such parallel patterns among bacteria and archaea were underpinned by similar ecological processes like environmental selection. Total beta diversity and turnover were largely affected by sediment total nitrogen, while LCBD and LCBDRepl were mainly constrained by water NO2 --N and NO3 --N. For fungal community variation, no significant patterns were observed, which may be due to different drivers like water nitrogen or phosphorus. Taken together, our findings provide compelling evidences for disentangling the underlying mechanisms of community variation in multiple aquatic microbial taxonomic groups.

Protected areas and compositional diversity of fish from Serranias Costeiras of the Ribeira de Iguape River basin, Southeast Brazil

Abstract The Serranias Costeiras of the Ribeira de Iguape River basin comprise landscapes with steep slopes, where many streams are contained in protected areas. We evaluated the importance of these protected areas for stream fish diversity. We sampled the ichthyofauna during the dry season of 2010, 2018 and 2019 in 36 stream stretches. We used beta diversity measures and estimated species richness and dark diversity in streams from two types of protected areas (full protection, FP and sustainable use, SU) and outside (Out). The altitude-width and velocity gradient of the streams explained the species turnover. The PA type promoted the richness difference, with FP streams having less species richness than SU and outside. Streams from FP presented lower species richness and dark diversity. These results indicate that the few species in FPs are well protected. The FP streams contain a relevant proportion of the regional species pool and, therefore, are essential for conserving fish stream diversity in the study region. On the other hand, streams from SU or Out have higher species richness, but their fish fauna is more vulnerable. Due to longitudinal stream connectivity, we highlight the importance of rethinking the limits of protected areas.

Plant Sedimentary Ancient DNA From Far East Russia Covering the Last 28,000 Years Reveals Different Assembly Rules in Cold and Warm Climates

Woody plants are expanding into the Arctic in response to the warming climate. The impact on arctic plant communities is not well understood due to the limited knowledge about plant assembly rules. Records of past plant diversity over long time series are rare. Here, we applied sedimentary ancient DNA metabarcoding targeting the P6 loop of the chloroplast trnL gene to a sediment record from Lake Ilirney (central Chukotka, Far Eastern Russia) covering the last 28 thousand years. Our results show that forb-rich steppe-tundra and dwarf-shrub tundra dominated during the cold climate before 14 ka, while deciduous erect-shrub tundra was abundant during the warm period since 14 ka. Larix invasion during the late Holocene substantially lagged behind the likely warmest period between 10 and 6 ka, where the vegetation biomass could be highest. We reveal highest richness during 28–23 ka and a second richness peak during 13–9 ka, with both periods being accompanied by low relative abundance of shrubs. During the cold period before 14 ka, rich plant assemblages were phylogenetically clustered, suggesting low genetic divergence in the assemblages despite the great number of species. This probably originates from environmental filtering along with niche differentiation due to limited resources under harsh environmental conditions. In contrast, during the warmer period after 14 ka, rich plant assemblages were phylogenetically overdispersed. This results from a high number of species which were found to harbor high genetic divergence, likely originating from an erratic recruitment process in the course of warming. Some of our evidence may be of relevance for inferring future arctic plant assembly rules and diversity changes. By analogy to the past, we expect a lagged response of tree invasion. Plant richness might overshoot in the short term; in the long-term, however, the ongoing expansion of deciduous shrubs will eventually result in a phylogenetically more diverse community.

Site and species contribution to β-diversity in terrestrial mammal communities: Evidence from multiple Neotropical forest sites

In a scenario where escalating human activities lead to several environmental changes and, consequently, affect mammal abundance and distribution, β-diversity may increase due to differences among sites. Using the ecological uniqueness approach, we analyzed β-diversity patterns of ground-dwelling mammal communities recorded through comprehensive camera trap monitoring within eight tropical forests protected areas in Mesoamerica and South America under variable landscape contexts. We aimed to investigate whether the contribution of single sites (LCBD) and single species (SCBD) to overall β-diversity could be explained by community metrics and environmental variables, and by species metrics and biological traits, respectively. Total β-diversity was also partitioned into species replacement and richness difference. We related LCBD to species richness, total relative abundance, functional indices, and environmental variables (tree basal area, protected area size, NDVI, and precipitation seasonality), and SCBD to species naïve occupancy, relative abundance, and morphoecological traits via beta regression. Our findings showed that LCBD was primarily explained by variation in species richness, rather than relative abundance and functional metrics. Protected area size and tree basal area were also important in explaining variation in LCBD. SCBD was strongly related to naïve occupancy and relative abundance, but not to biological traits, such as body mass, trophic energy level, activity cycle, and taxonomic category. Local β-diversity was a result of species replacements and to a lesser extent differences in species richness. Our approach was useful in examining and comparing the ecological uniqueness among different sites, revealing the regional scale current status of mammal diversity. High LCBD values comprised sites embedded within smaller habitat extents, hosting lower tree basal areas, and harboring low species richness. SCBD showed that relatively ubiquitous species that occur at variable abundances across sites contributed most to β-diversity.

Variation Patterns of Functional Trait Moments Along Geographical Gradients and Their Environmental Determinants in the Subtropical Evergreen Broadleaved Forests

Understanding how environmental change alters the composition of plant assemblages is a major challenge in the face of global climate change. Researches accounting for site-specific trait values within forest communities help bridge plant economics theory and functional biogeography to better evaluate and predict relationships between environment and ecosystem functioning. Here, by measuring six functional traits (specific leaf area, leaf dry matter content, leaf nitrogen, and phosphorus concentration, leaf nitrogen/phosphorus, wood density) for 292 woody plant species (48,680 individuals) from 250 established permanent forest dynamics plots in five locations across the subtropical evergreen broadleaved forests (SEBLF) in China, we quantified functional compositions of communities by calculating four trait moments, i.e., community-weighted mean, variance, skewness, and kurtosis. The geographical (latitudinal, longitudinal, and elevational) patterns of functional trait moments and their environmental drivers were examined. Results showed that functional trait moments shifted significantly along the geographical gradients, and trait moments varied in different ways across different gradients. Plants generally showed coordinated trait shifts toward more conservative growth strategies (lower specific leaf area, leaf N and P concentration while higher leaf nitrogen/phosphorus and wood density) along increasing latitude and longitude. However, trends opposite to the latitudinal and longitudinal patterns appeared in trait mean values along elevation. The three sets of environmental variables (climate, soil and topography) explained 35.0-69.0%, 21.0-56.0%, 14.0-31.0%, and 16.0-30.0% of the variations in mean, variance, skewness, and kurtosis across the six functional traits, respectively. Patterns of shifts in functional trait moments along geographical gradients in the subtropical region were mainly determined by the joint effects of climatic and edaphic conditions. Climate regimes, especially climate variability, were the strongest driving force, followed by soil nutrients, while topography played the least role. Moreover, the relationship of variance, skewness and kurtosis with climate and their geographical patterns suggested that rare phenotypes at edges of trait space were selected in harsher environments. Our study suggested that environmental filtering (especially climate variability) was the dominant process of functional assembly for forest communities in the subtropical region along geographical gradients.

How mountains and elevations shape the spatial distribution of beetles in Peninsular Malaysia

This study was conducted to assess the spatial distribution of beetles in mountain ecosystems and their elevational diversity. Malaise, pitfall and light traps were used to collect beetles from nine different mountains in Malaysia from September 2014 to September 2016, where from Gunung Angsi, Gunung Belumut, Gunung Basor and Gunung Tebu samples were collected at 500 m and 1000 m (above sea level) elevations, while beetles were sampled at 500 m, 1000 m and 1500 masl from Gunung Benom, Gunung Inas, Cameron Highland, Gunung Besar Hantu and Gunung Basor. In this study, 9628 beetles belonging to 879 different species were collected with highest representation from family Staphylinidae and Carabidae. Chamah Highland had the highest beetle diversity followed by Gunung Benom, Gunung Inas, Cameron Highland, Gunung Belumut, and Gunung Basor. Chamah Highland was different to all mountains on abundance and species richness. The highest species richness was observed at 1000 m, followed by 500 m and 1500 m. We identified characteristic species associated with habitat conditions at Gunung Benoum and Gunung Inas mountains, according to INDVAL values. The beetle diversity of the sampled mountains showed multiple alpha and beta patterns according to type of mountain ecosystem and elevation, providing guidelines for the scientific community to underpin conservation efforts in Malaysia.

Taxonomic dependency of beta diversity components in benthic communities of bacteria, diatoms and chironomids along a water-depth gradient

Community variation (i.e., beta diversity) along geographical gradients is a well-known ecological pattern, but the corresponding variation in beta diversity components (e.g., species turnover and nestedness) and underlying drivers remain poorly understood. Based on two alternative approaches (that is, the beta diversity partitioning proposed by Baselga and the Local Contributions to Beta Diversity (LCBD) partitioning proposed by Legendre), we examined the patterns of beta diversity components of lacustrine benthos, from bacteria to diatoms and chironomids, in the surface sediments along a 100-m water-depth gradient in Lugu Lake. We further quantified the relative importance of spatial, environmental and biotic variables in explaining water-depth patterns in beta diversity. Based on the Baselga's framework, there was a taxonomic dependency for the patterns of beta diversity components with water-depth, showing a significant species turnover pattern for bacteria, while diatoms and chironomids showed significant nestedness. This dependency was also evident in the patterns of community uniqueness with water-depth because based on Legendre's framework, the LCBD decreased with water depth for bacteria whereas increased with depth for diatoms. The total beta diversity and species turnover of bacteria could be explained by the pure effects of spatial, environmental and biotic variables. A total of 26.8% and 23.6% of the nestedness component of diatoms and chironomids was explained by environmental variables, respectively, while species turnover was mostly related to spatial variables. Bacteria total LCBD and species replacement were driven only by environmental variables. For diatoms and chironomids, however, most of the total LCBD and its two components were explained by spatial variables, and biotic variables were most important for the diatom replacement component. Our findings provide insights into the mechanisms responsible for community organizations along water-depth gradients from the perspective of beta diversity components.

Seasonal patterns of ecological uniqueness of anuran metacommunities along different ecoregions in Western Brazil

Beta diversity can be portioned into local contributions to beta diversity (LCBD), which represents the degree of community composition uniqueness of a site compared to regionally sampled sites. LCBD can fluctuate among seasons and ecoregions according to site characteristics, species dispersal abilities, and biotic interactions. In this context, we examined anuran seasonal patterns of LCBD in different ecoregions of Western Brazil, and assessed their correlation with species richness and if environmental (climatic variables, pond area and ecoregions) and/or spatial predictors (spatial configuration of sampling sites captured by distance-based Moran's Eigenvector Maps) would drive patterns of LCBD. We sampled anurans in 19 ponds in different ecoregions in the Mato Grosso do Sul state, Western Brazil, during one dry and one rainy season. We found that LCBD patterns were similar between seasons with sites tending to contribute in the same way for community composition uniqueness during the dry and rainy season. Among studied ecoregions, Cerrado showed higher LCBD values in both seasons. In addition, LCBD was negatively correlated with species richness in the dry season. We also found that LCBD variation was explained by ecoregion in the dry season, but in the rainy season both environmental and spatial global models were non-significant. Our results reinforce the compositional uniqueness of the Cerrado ecoregion when compared to the other ecoregions in both seasons, which may be caused by the presence of species with different requirements that tolerate different conditions caused by seasonality.

Patterns of plant communities along vertical gradient in Dhauladhar Mountains in Lesser Himalayas in North-Western India

Mountains are definitely the most rugged, yet frail resources and biodiversity-rich regions of the world. Environmental variables directly affect species composition, growth patterns, and the ecosystem resulting in a drastic change in the vegetation composition along ascending elevations. The present study investigated vegetation composition, nestedness, and turnover in plant communities along a vertical gradient (2000 to 4000 m) in Dhauladhar Mountains, Lesser Himalayas, India. We determined how α-diversity pattern and nestedness-related processes or turnover (β-diversity) causes dissimilarity in plant communities' composition along the vertical gradient. Overall, 21 permanent plots (20 × 20 m²) at every 100 m interval from 2000 to 4000 m were established. A sampling of shrubs and herbaceous species was done by marking sub-plots of 5 × 5 m² and 1 × 1 m², respectively, within permanent plots. We observed an inverted hump-shaped pattern for evenness index (E), a unimodal hump-shaped pattern for Shannon index (H'), Margalef's richness index, and β-Whittaker (β_w) diversity, and mild-hump-shaped pattern for Simpson index (λ) across the elevational gradient. Turnover (β_sim) and the nestedness-resultant component of β-diversity (β_sne) significantly differed across the elevational gradient. The observed β-diversity patterns revealed that the species replacement rate was less in the mid-altitude communities as compared to lower and higher altitude communities. It was largely attributed to the ecotonic nature of mid-altitudes, which benefited mid-elevational communities rather than low or high altitude communities. Besides lower altitudes, the increased human interference has led to disturbance and subsequent homogenization of flora across the mid-altitudes. With respect to this, the present study signifies the need for preserving the mid-altitudinal communities, without undermining the importance of conserving the low and high altitude communities.

Can taxonomic and functional metrics explain variation in the ecological uniqueness of ecologically-associated animal groups in a modified rainforest?

The conservation of biodiversity requires adequate information about species and ecosystem attributes. The local contribution to β-diversity (LCBD) is a community composition-based metric of ecological uniqueness of sites. Here, we tested the capability of taxonomic and functional attributes of biological communities to explain variation in LCBD at a large spatial extent. We approached this idea using data on dung beetles and mammals (medium-to-large, small and volant) recorded across the Atlantic Forest of South America due to their millennial-scale evolutionary relationship (food providers and consumers). We related LCBD values to both taxonomic and functional metrics via beta regression. Our results revealed that taxonomic and functional features of assemblages can be used to predict variation in ecological uniqueness (LCBD). High LCBD values were associated with low species and functional richness for all animal groups. For dung beetles, high LCBD values were associated with low values of all functional metrics. For mammalian groups high ecological uniqueness was associated with low abundance, low Rao's quadratic entropy, as well as high functional divergence, functional evenness, functional originality, and either low or high functional specialization. This implies that variation in ecological uniqueness can be explained by functional features at large spatial extents, although the type of functional metrics' response of assemblages may be animal group specific. The potential of the LCBD metric to inform about both taxonomic and functional changes at large scales makes its use in conservation planning a highly promising approach.

Beta diversity of gastrointestinal helminths in two closely related South African rodents: species and site contributions

A fundamental aim of parasite ecology is to understand the mechanisms behind spatial variation in diversity and structure of parasite assemblages. To understand the contribution of individual parasite species and their assemblages to spatial variation in parasite communities, we examined species contributions to beta diversity (SCBD) and local contributions to beta diversity (LCBD) of parasitic gastrointestinal helminths (nematodes and cestodes) in two closely related rodents, Rhabdomys dilectus and Rhabdomys pumilio, from 20 localities across South Africa. Although the two Rhabdomys spp. are morphologically similar, they differ substantially in body size, habitat preference, and sociality. We asked whether the variation in life history traits and infection parameters are associated with SCBD of helminths and whether variation in environmental factors, host population density, and species richness of host communities are associated with LCBD of component assemblages of helminths. We also considered spatial factors to test whether LCBD of helminth assemblages demonstrate geographic structure. We found that the contribution of helminth species parasitic in both hosts to beta diversity significantly increased with characteristic prevalence of these species, whereas mean abundance, type of life cycle, and location in the host's gut had no effect on SCBD. The LCBD of helminth assemblages showed a significant positive correlation with environmental factors in both host species. Our results suggest that predictors of variation in SCBD and LCBD may substantially differ between parasites with different infection parameters and/or parasite communities at different hierarchical scales.

Species and site contributions toβ-diversity in fleas parasitic on the Palearctic small mammals: ecology, geography and host species composition matter the most

Theβ-diversity of fleas parasitic on small mammals in 45 regions of the Palearctic was partitioned into species [species contributions toβ-diversity (SCBD)] and site ( = assemblage) contributions [local contributions toβ-diversity (LCBD)]. We asked what are the factors affecting SCBD and LCBD and tested whether (a) variation in ecological, morphological, life history and geographic traits of fleas can predict SCBD and (b) variation in flea and host community metrics, off-host environmental factors, host species composition of flea assemblages can predict LCBD. We used spatial variables to describe geographic distribution of flea assemblages with various LCBD values. SCBD significantly increased with an increase in abundance and a decrease in phylogenetic host specificity of a flea as well as with size and latitude of its geographic range, but was not associated with any morphological/life history trait. LCBD of flea assemblages did not depend on either flea or host species richness or environmental predictors, but was significantly affected by compositional uniqueness ( = LCBD) of regional host assemblages and variables describing their species composition. In addition, variation in LCBD was also explained by broad-to-moderate-scale spatial variables. We conclude that SCBD of fleas could be predictedviatheir ecological and geographic traits, whereas LCBD of their assemblages could be predictedviahost composition.