Higher Gamma Diversity Research Articles

Environmental Heterogeneity and Salinity Gradient Impacted the Alpha and Beta Diversities of Diatom Assemblages in a Coastal Delta Wetland

The coastal deltas are ecologically diverse and complex ecosystems that can contain different habitat types. The effect of environmental heterogeneity on diatom beta diversity is a poorly understood research topic. Freshwater (floodplain forest, river) and brackish (three lagoons) water bodies in the study area construct distinct environmental heterogeneity at a small spatial scale. The connection of the lagoons with an inland sea caused a high salinity gradient. All water bodies in the wetland were determined as hypereutrophic. CCA, Cluster, ANOSIM, and SIMPER analysis clearly explained the distribution of diatom assemblages according to salinity gradient and environmental heterogeneity. The environmental heterogeneity resulted in the presence of freshwater, brackish, and marine diatom species in the studied wetland. Diatom assemblages generally consist of freshwater species with euryhaline character adapted to wide salinity gradients. We determined the rapid replacement and richness difference in diatom assemblages due to environmental heterogeneity and salinity gradient causes high overall alpha, beta, and gamma diversity. Unlike many other studies, the high beta diversity mainly consists of the richness difference rather than species replacement. The high overall beta diversity showed low similarity between the habitats, while high overall alpha diversity exposed high species diversity at the local scale in the study area.

Host biology, ecology and the environment influence microbial biomass and diversity in 101 marine fish species

Fish are the most diverse and widely distributed vertebrates, yet little is known about the microbial ecology of fishes nor the biological and environmental factors that influence fish microbiota. To identify factors that explain microbial diversity patterns in a geographical subset of marine fish, we analyzed the microbiota (gill tissue, skin mucus, midgut digesta and hindgut digesta) from 101 species of Southern California marine fishes, spanning 22 orders, 55 families and 83 genera, representing ~25% of local marine fish diversity. We compare alpha, beta and gamma diversity while establishing a method to estimate microbial biomass associated with these host surfaces. We show that body site is the strongest driver of microbial diversity while microbial biomass and diversity is lowest in the gill of larger, pelagic fishes. Patterns of phylosymbiosis are observed across the gill, skin and hindgut. In a quantitative synthesis of vertebrate hindguts (569 species), we also show that mammals have the highest gamma diversity when controlling for host species number while fishes have the highest percent of unique microbial taxa. The composite dataset will be useful to vertebrate microbiota researchers and fish biologists interested in microbial ecology, with applications in aquaculture and fisheries management.

Floristic composition and turnover analysis in Dahomey Gap and the surrounding sub-humid Togolese mountain minor forest refuges: Importance for biogeography and biodiversity conservation in sub-Saharan Africa.

The origin of Dahomey Gap (DG) flora is one of the central biogeographical questions in sub‐Saharan, which has been addressed in several studies. However, floristic evidence based on representative samples from the DG seems to be lacking in the scientific debate. The present study was conducted to fill this gap. Specifically, we assessed Togolese mountain riparian forests as minor forest refugia, examined their contribution to larger sub‐Saharan forest refugia, and discussed the significance of these findings for biogeography and biodiversity conservation. Southwest Togo, West Africa, and sub‐Saharan Upper Guinea Region Floristic data were collected in riparian forests through an intensive botanical inventory (n = 198; 50 × 10 m2). A comparative analysis was performed based on the floristic evidence related to forest refuges. The results showed significantly high species richness (868 species) and a high gamma and beta diversity associated with spatial turnover patterns. They also showed a high affinity between the study forests and large sub‐Saharan forest refugia. Riparian forests share about 60% of their current species richness with large sub‐Saharan forest refugia and contained refuge bio‐indicator species. The floristic evidence, consistent with those of other studies, suggests that Togolese mountains would have very ancient origins and have experienced paleoclimatic events. The studied riparian would have served as refuges during recurrent climatic episodes. Our results support the minimal forest fragmentation hypothesis (network of refugia along rivers). However, they seem to be incompatible with the idea that the DG flora may be essentially a relic of the early Holocene. In sub‐Saharan Africa, where maintaining a vast area of natural forest is difficult due to human pressure, efforts to preserve maximum species diversity should include a focus on the conservation of minor forest refuges, particularly in sub‐humid mountain riparian zone.

Urban park layers: Spatial variation in plant community structure

Horizontal structure of natural plant communities attracted the attention of researchers for a long time, while the problem of horizontal structure of urban park plantations was not studied sufficiently. Species richness of different tiers of park plantation in the large industrial city of Dnipro (Ukraine) was revealed in this study. Also features of variation in the structure of plant communities at different spatial levels were revealed, the influence of park plantation canopy on the understory and herbaceous layer of the park. There were 30 plant species in the tree layer of the park plantation. The most common species were Robinia pseudoacacia L., Acer platanoides L., A. negundo L., Gleditsia triacanthos L., Aesculus hippocastanum L., Populus carolinensis Moench. The variance-to-mean ratio revealed that 13 tree species were randomly distributed throughout the park, and 14 species were aggregated. The number of occurrences of a given tree species per site and variance-to-mean ratio were positively correlated. The numerous tree species showed a tendency of aggregated distribution within the park. Sixteen plant species were found in the understory. Among them, the most abundant species were Acer platanoides L., A. negundo L., A. pseudoplatanus L., Sambucus nigra L., Robinia pseudoacacia L. Eight species were found to be randomly distributed over the park area, and eight species showed an aggregate distribution. The number of species encountered in the understory and variance-to-mean ratio were positively correlated. In the herbaceous stand, 99 plant species were found, of which Chelidonium majus L., Viola odorata L., Impatiens parviflora DC., Parthenocissus quinquefolia (L.) Planch., Geum urbanum L. predominated. The variance-to-mean ratio of all species was significantly less than unity, indicating regular spatial distribution. The values of alpha- and gamma-diversity of the plant community in separate layers are very different. The highest gamma diversity was found for the herbaceous stand, while the diversity of the tree stand and understory was significantly lower. Alpha biodiversity of the tree stand and the understory did not practically differ. Beta diversity values between the layers are very close, and beta diversity is practically equal for tree stand and herbaceous layer. Thus, we can assume that the mechanisms of species turnover for the plant communities of different layers are determined by the common causes. The spatial broad-scale component was able to explain 8.2% of community variation, the medium-scale component was able to explain 4.2% of community variation, and the fine-scale component was able to explain 0.7% of community variation. The understory is the most sensitive to the environmental factors, the herbaceous stand is somewhat less sensitive, and the tree stand is the least sensitive to the environmental factors. The environmental factors in this study are represented by a set of variables. The spatial variation of the stand is predominantly influenced by the factors of trophicity and moisture of the edaphotope. These same factors also act on the herbaceous stand and understory, but along with them are included the environmental variables, which are determined by the architectonics of the crown space and thus the light regime, which is regulated by the tree stand. It is important to note that the variation of the communities of the different layers of the park plantation is subject to spatial patterns. The herbaceous and understory variation is more spatially structured than the tree stand variation. The spatial patterns can arise as a result of the influence of spatially structured environmental factors and as a result of factors of a neutral nature. The latter aspect of variation is best described by the pure spatial component of community variation.

Lower alpha, higher beta, and similar gamma diversity of saproxylic beetles in unmanaged compared to managed Norway spruce stands.

Strong anthropogenic pressures on global forests necessitate that managed forests be evaluated as habitat for biodiversity. The complex pattern of habitat types created in forestry systems is ideal for analyses through the theoretical framework of alpha (local), gamma (total) and beta (compositional) diversity. Here I use saproxylic beetles, a species-rich threatened group, to compare four Norway spruce-dominated habitats representative of the boreal forest landscape of northern Europe: unmanaged semi-natural stands, nature reserves, unthinned middle-aged production stands and commercially thinned production stands. The beetles (in total 38 085 individuals of 312 species), including red-listed ones and three feeding guilds (wood consumers, fungivores and predators) were studied in 53 stands in central-southern Sweden, in two regions with differing amounts of conservation forest. Alpha diversity of saproxylic, but not red-listed, beetles was higher in the thinned stands than in the semi-natural stands, and did not differ for the other forest types. Beta diversity of saproxylic beetles was higher in unmanaged semi-natural stands than in the other forest types, but species composition did not differ noticeably. Furthermore, red-listed saproxylic beetles had higher gamma diversity in unmanaged semi-natural stands in the region with more conservation forest, but not in the one with less such forest. The local factors dead wood volume and dead wood diversity did not influence alpha diversity of beetles, but increasing canopy openness had a minor negative influence on saproxylic and red-listed beetles. While the local scale (alpha diversity) indicates the potential for managed forests to house many saproxylic beetle species associated with spruce forests in this boreal landscape, the larger scales (beta and gamma diversity) indicate the value of unmanaged forests for the conservation of the entire saproxylic beetle fauna. These results show the importance of analyses at multiple levels of diversity (alpha, beta, gamma) for identifying patterns relevant to conservation.

Are springs hotspots of benthic invertebrate diversity? Biodiversity and conservation priority of rheocrene springs in the karst landscape

Abstract Springs are perceived by human society as essential sources of drinking water, but on the other hand they represent peculiar and vulnerable ecosystems. They differ from other watercourses in the relatively high stability of their physicochemical conditions. As a result, springs represent ecosystems with an insular character, usually inhabited by specific aquatic communities. Although springs are generally considered species‐rich habitats across the world, they have been outside scientific and conservation interest in the karst mountains of the Western Carpathians. This study, therefore, examined the diversity of spring benthic macroinvertebrates and compared it with that of other watercourses of the Western Carpathian riverine landscape. The results of the study showed that, in contrast to rhithral streams, individual karst springs often had low species richness, and therefore they cannot be considered biodiversity hotspots. However, their metacommunity diversity is characterized by high taxonomic turnover, resulting in high gamma diversity. This means that the individual springs often harbour unique macroinvertebrate communities, so they are worthy of protection. However, the present level of spring habitat protection is insufficient as even springs located in protected areas are often captured as sources of drinking water and hydromorphologically or otherwise disturbed. A simple method to evaluate the spring conservation priority (CP) was developed to find a better trade‐off between their use and protection. It uses the number of Red List, endemic and crenal taxa, as well as the total species richness at each site. Based on this classification method, 16% of the springs studied reached very high CP, 39% high CP, 33% moderate CP and 12% low CP. The proposed management recommendations based on findings of conservation priority of the Western Carpathian karst springs can significantly contribute to their more effective protection and the creation of a legislative framework relating to spring habitat protection in general.

Contrasting biodiversity and food web structure of three temporary freshwater habitats in a tropical biodiversity hotspot

Abstract In many biomes, a variety of different small freshwater habitats, such as pools and phytotelmata can occur together in the same habitat matrix. However, both the biodiversity and the functioning of these ecosystems remain poorly known. Three freshwater habitat types in a tropical West African biodiversity hotspot were studied. The study demonstrated that animal communities in water‐filled tree holes, temporary ponds and granite rock pools were strongly differentiated with exclusive faunas despite their spatial proximity and similar disturbance in the form of seasonal drought. In particular, granite rock pools stood out with a high gamma diversity. Rock pools were also functionally different from the other two habitat types. The three habitats had contrasting predator assemblages, a differential reliance on primary production and different concentrations of available nutrients. The work illustrates that the biodiversity and functions of small temporary freshwater habitats can be strongly differentiated. This shows the unique and potentially complementary roles that these habitats can fulfil in mediating fluxes of energy and nutrients and preserving aquatic biodiversity in landscapes. Temporary aquatic habitats are typically overlooked in conservation policy and local management plans despite being threatened by habitat transformation. In addition, livestock can threaten savanna ponds, wood exploitation can threaten tree holes, and mining and sediment disruption can threaten rock pools. Hence, better knowledge about the ecological functioning of these ecosystems is vital to the implementation of effective conservation strategies.

Optimizing tropical forest bird surveys using passive acoustic monitoring and high temporal resolution sampling

AbstractEstimation of avian biodiversity is a cornerstone measure of ecosystem condition. Surveys conducted using autonomous recorders are often more efficient at estimating diversity than traditional point‐count surveys. However, there is limited research into the optimal temporal resolution for sampling—the trade‐off between the number of samples and sample duration when sampling a survey window with a fixed survey effort—despite autonomous recorders allowing easy repeat sampling compared to traditional survey methods. We assess whether the additional temporal coverage from high temporal resolution (HTR) sampling, consisting of 240 15‐s samples spread randomly across a survey window detects higher alpha and gamma diversity than low temporal resolution (LTR) sampling of four 15‐min samples at the same locations. We do so using an acoustic dataset collected from 29 locations in a region of very high avian biodiversity—the eastern Brazilian Amazon. We find HTR sampling outperforms LTR sampling in every metric considered, with HTR sampling predicted to detect approximately 50% higher alpha diversity, and 10% higher gamma diversity. This effect is primarily driven by increased coverage of variation in detectability across the morning, with the earliest period containing a distinct community that is often under sampled using LTR sampling. LTR sampling produced almost four times as many false absences for species presence. Additionally, LTR sampling incorrectly found 70 species (34%) at only a single forest type when they were in fact present in multiple forest types, while the use of HTR sampling reduced this to just two species (0.9%). When considering multiple independent detections of species, HTR sampling detected three times more uncommon species than LTR sampling. We conclude that high temporal resolution sampling of passive‐acoustic monitoring‐based surveys should be considered the primary method for estimating the species richness of bird communities in tropical forests.

Matrix composition mediates effects of habitat fragmentation: a modelling study

ContextHabitat loss has clear negative effects on biodiversity, but whether fragmentation per se (FPS), excluding habitat loss does is debatable. A contribution to this debate may be that many fragmentation studies tend to use landscapes of fragmented focal-habitat and a single vastly different species-poor intervening land cover (the matrix).ObjectivesHow does matrix composition influence the effect of FPS on biodiversity?.MethodsUsing an individual-based model to investigate the effect of different configurations of the matrix on the relationship between FPS and biodiversity of the focal-habitat. We manipulated the number and quality of land cover types in the matrix, and their similarity to the focal-habitat.ResultsExtremely different matrix, caused an order of magnitude stronger effect of FPS on alpha- and gamma-diversity and beta-diversity to decline. Low FPS led to high gamma-diversity. Increasing FPS caused a dramatic decline to low diversity. In contrast landscapes with a more similar matrix had lower diversity under low FPS declining little with increasing FPS. Having few matrix types caused beta-diversity to decline in general compared to landscapes with a larger numbers.ConclusionsThe effects of FPS on biodiversity may change depending on the number of matrix types and their similarity to the focal-habitat. We recommend that fragmentation studies should consider a greater variety of landscapes to help assess in which cases FPS does not have a negative impact and allow better predictions of the impacts of fragmentation. We show the importance of having a diversity of matrix land cover types and improving the hospitability of the matrix for species dependent on the focal-habitat.

Species packing and the latitudinal gradient in beta-diversity.

The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogues. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographical heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.

Conserving ecological functions of frog communities in Borneo requires diverse forest landscapes

Recent studies suggest that differences in species composition across habitat types lead to increased multifunctionality on the regional scale. However, data about species turnover—and especially complementarity in the functional composition—across neighbouring habitat types from natural communities are rare. We studied frog communities in lowland rainforest in Malaysian Borneo and compared the species composition and functional-trait composition of different habitat types (alluvial forest, limestone forest, kerangas). Forest types differed strongly in their species composition and, to a lesser extent, in their functional-trait composition. We also compared functional-trait combinations of frogs directly across the forest types and identified six clusters of functionally similar species: three were found in all forest types, the others were absent from at least one forest type. The complementarity in species and functional-trait composition between the forest resulted in high regional gamma diversity, and most of this regional functional diversity was unique to individual forest types. Moreover, the strict separation in species composition suggests that even functionally similar frog species from different forest types cannot easily replace each other in case of local extinctions. The maintenance of ecological functions fulfilled by frogs on the landscape scale therefore requires the conservation of all forest-specific frog communities.

Effects of anthropogenic land-use on scorpions (Arachnida: Scorpiones) in Neotropical forests

Changes in land-cover driven by human activities is one of the main causes of disturbances on natural communities but the impact of this factor on scorpions assemblages remains scarcely know. Here we analyzed the scorpion fauna in five tropical forests and their respective neighboring non-natural matrix (planted forests or crops) in Brazil (n = 4) and Mexico (n = 1), aiming to understand how different species of scorpions respond to land-use changes. Scorpions were actively collected with the help of a UV flashlight. A total of 461 individuals were sampled, belonging to nine species and seven genera distributed in three families Buthidae, Bothriuridae and Diplocentridae. Differences in assemblages between environments were found, with higher gamma diversity in undisturbed environments where species showed the highest abundance. A higher species turnover was found in disturbed environments. Based on these results, we suggest a differential sensitive reaction to habitat alterations amongst scorpions species.

Are the patterns of zooplankton community structure different between lakes and reservoirs? A local and regional assessment across tropical ecosystems

Lakes and reservoirs present contrasting differences regarding origin, age and trophic state that may influence their biological communities. In the face of the inevitably rising number of reservoirs worldwide, our objective was to investigate the differences in zooplankton community structure and diversity patterns from 98 tropical shallow lakes and reservoirs (northeast Brazil). We tested the hypothesis that reservoirs have less diverse communities, which could be associated with ecosystem age or high productivity (a typical local pattern). The results show that most reservoirs are eutrophic ecosystems that hold distinct zooplankton communities in comparison with lakes. Despite their higher productivity, reservoirs played an essential role in subsidizing zooplankton diversity as they had higher gamma diversity because of the number of exclusive species, especially for the Rotifera group. The zooplankton density and biomass were also higher in the reservoirs, but this pattern was not associated with higher species dominance. Lakes also played a central role in zooplankton diversity, having a distinct species composition. Jointly, lakes and reservoirs help to maintain the zooplankton species pool at a regional level, suggesting the importance of complementarity in community composition between artificial and natural aquatic ecosystems on large-scale patterns of zooplankton biodiversity.

Landforms contribute to plant biodiversity at alpha, beta and gamma levels

AbstractAimGeodiversity underpins biodiversity, but the contribution of specific geofeatures or landforms has rarely been explored. In this study, we use multiple vascular plant species diversity measures on alpha, beta and gamma levels to explore the linkage between biodiversity and co‐located landforms (e.g. gullies, dunes and lake shores). We hypothesize that biodiversity will be positively related to geodiversity, which is founded on distinct landforms. Additionally, we propose that different landforms will sustain different amounts of biodiversity and that high alpha and gamma diversity values are related to landform‐driven moisture availability whereas high beta diversity relates especially to landform‐specific microtopographic variation.LocationRokua UNESCO Global Geopark area, Finland.TaxonVascular plants.MethodsWe compare vascular plant species richness measures, Shannon's and Simpson's diversity indices, rarity‐weighted richness and local contribution to beta diversity at altogether three levels of biodiversity (alpha, beta and gamma) for different landforms. Landform information is compiled from aerial photos, spatial data layers and targeted field surveys. We compare results to control habitat (i.e. sites without any distinct landforms) within the study area.ResultsVascular plant diversity was higher on landforms than in control habitat. There was also notable variation between species diversity of different landforms. Moisture‐rich gullies and river shores were especially diverse at all three levels, whereas aapa mires hosted most unique species composition (highest beta diversity). Beta diversity patterns were rather comparable with alpha and gamma diversity patterns, which contradict our hypothesis.Main conclusionsThis study quantitatively established a strong connection between terrestrial plant communities and multiple landforms. Our results highlighted the landform‐controlled variation in soil moisture, microclimate and microtopography in enhancing plant species diversity. Based on the results, we promote the inclusion of landform‐based geodiversity information in conservation management and in further biogeographical studies.

Influence of Habitat Heterogeneity on Structure and Composition of a Chrysomelidae (Coleoptera) Assemblage in a Temperate Forest in Northeast Mexico

Disturbance in natural areas occurs as a result of various processes on various spatio-temporal scales, generating a heterogeneous mosaic of environmental characteristics. The effect of such change on diversity patterns has been explained by the hypothesis of habitat heterogeneity. Modifications in abiotic and biotic factors such as plant density influence the composition and structure of assemblages of phytophagous insects. Response of the leaf beetle (Coleoptera: Chrysomelidae) assemblage to such changes was evaluated in an oak (Quercus spp.) forest in the Altas Cumbres Natural Protected Area, Victoria, Tamaulipas, Mexico. The delimited mosaic was classified into four categories according to the length of time since the last disturbance: 1 year, 10 years, 30 years, and 40 years. Disturbance time categories were delimited using remote sensing techniques from LANDSAT satellite scenes. Leaf beetles were sampled each month from February to April 2016 in 10 plots per category. The numbers of herbaceous and shrubby plants in each plot were counted with the aim of estimating the plant density of each category and relating values with differences among communities of Chrysomelidae. In total, 1,056 individuals of six subfamilies and 37 species were obtained, with Centralaphthona sp. 1 the most abundant. Thirteen species were specialists, while Helocassis crucipennis (Boheman, 1855) occurred in the most niches. Leaf beetles preferred high plant densities and were most abundant and had most species richness in the category of 10 years since the last disturbance. The community had aggregate spatial distribution that might reflect significant biological patterns. Alpha diversity indices indicated the 10-year category was most even, with Hypolampsis sp. 1 the dominant species. In contrast, least evenness was in the 1-year category where Centralaphthona sp. 1 was dominant; the species might indicate permanent disturbance. The community had low species turnover among the categories of disturbance and is therefore expected to have high gamma diversity. Inventory of the study area had 82.4% completeness; however, categories of 10 and 30 years required more sampling effort. Results supported the hypothesis of habitat heterogeneity, because observed community patterns did not occur by chance. This suggested that environmental heterogeneity because of disturbance positively influenced composition and community structure of Chrysomelidae, and observed patterns responded to intra- and interspecific interactions.

Spatial, biogeographic and environmental predictors of diversity in Amazonian Zygoptera

Abstract Our objectives were to assess how turnover and nestedness contribute to beta‐diversity patterns of the Zygoptera in Amazonian streams, and to relate these components of beta diversity to environmental, spatial and biogeographic predictors. Our first hypothesis is that the turnover is the most important component of beta‐diversity patterns due to the historical isolation of all or part of the areas located in the interfluves of the major Amazonian rivers. Our second hypothesis is that the interaction between environmental conditions and the area of endemism (biogeography) would be the most important predictor of beta‐diversity patterns. To test these hypotheses, we compiled data on the Zygoptera communities from 172 Amazonian streams. We used three sets of predictor variables: (i) environmental variables, (ii) area of endemism (biogeographic) and (iii) spatial filters. The turnover explained 99.36% of the beta diversity, corroborating our first hypothesis. Together, environmental and biogeographic variables were the best predictors of beta‐diversity patterns. For turnover, however, the biogeographic variables were the best predictors, contrary to our second hypothesis. We found high gamma diversity, but low alpha diversity in the Zygoptera communities. This paradox is explained by the high turnover among sites within the study landscape. This pattern of diversity is related to both historical biogeographic factors and the spatial structuring of environmental conditions in the Amazon region. In the light of our results (high turnover and beta diversity), and their correspondence with areas of endemism, adequate conservation of Amazonian Zygoptera diversity will depend on the establishment of so‐called mega‐reserves throughout the major Amazonian interfluves and, whenever possible, in the areas with adequate environmental conditions for the greatest possible number of species, otherwise, most species may be at a constant risk of extinction.

The variability in the hydrosedimentological regime supports high phytoplankton diversity in floodplain: a 12-year survey of the Upper Paraná River

<p>The alpha, beta, and gamma diversity are important tools for conservation studies, and the distribution of species in space and time is essential to provided insights regarding diversity patterns and processes that modify the ecosystem and the community responses to such changes. Thus, a long-term ecological date was used to evaluate in 12 biotopes the phytoplankton composition and diversity within selected habitats (alpha diversity), between habitats (beta diversity) and across the upper Paraná River floodplain (gamma diversity). We evaluate the environmental variability of the hydrosedimentological cycles (limnophase and potamophase) during 12 years, associated with the water level variability and with the environmental heterogeneity as drivers of the phytoplankton composition and diversity in the upper Paraná River floodplain. Remarkable gamma diversity was recorded especially in limnophase, however, years with intense flood presented high gamma diversity, and years with extreme drought presented low gamma diversity, although without significant differences. The alpha diversity was significantly different on spatial and temporal scales. The beta diversity showed high values, however with low temporal variability and without correlation with the hydrosedimentological regime of the Paraná River. Overall, these results indicate that the variability in the hydrosedimentological regime associated with the periodicity, duration, and amplitude of limnophase and potamophase, and the pattern of mosaic of habitats in this floodplain are essential for sustaining much of the diversity phytoplankton diversity and ecosystem integrity, and that this approach is relevant and proved be useful to understand floodplain systems and associated phytoplankton community.</p>

Wartime scars or reservoirs of biodiversity? The value of bomb crater ponds in aquatic conservation

Considering the ongoing loss of aquatic habitats, anthropogenic ponds are gaining importance as substitute habitats. It is therefore important to assess their functioning in comparison to their natural precursors. Here we assess the biodiversity value of sodic bomb crater ponds by comparing their gamma diversity to that of natural reference habitats, astatic soda pans, and assess their importance on the landscape level by studying alpha and beta diversity. We studied aquatic organisms ranging from algae to vertebrates in a dense cluster of 54 sodic bomb crater ponds in Central Europe. Despite the overall small area of the pond cluster, gamma diversity was comparable to that found in surveys of natural habitats that encompassed much wider spatial and temporal scales. We also found a considerable number of species shared with reference habitats, indicating that these anthropogenic habitats function as important refuge sites for several species that are associated with the endangered soda pans. Moreover, we found a number of regionally or worldwide rare species. Among the components of beta diversity, species replacement dominated community assembly. Individual ponds contributed similarly to beta diversity in terms of replacement, being equally important for maintaining high gamma diversity and emphasising the role of the pond network rather than individual ponds. This pattern was seen in all studied groups. Bomb crater ponds therefore acted as important contributors to aquatic biodiversity. Considering the tremendous losses of ponds throughout Europe, anthropogenic ponds should be taken into consideration in nature conservation, especially when occurring in pond networks.

Do tropical rain forest soils have greater nematode diversity than High Arctic tundra? A metagenetic comparison of Malaysia and Svalbard

AbstractAimLatitudinal differences in diversity have long fascinated ecologists. It is unclear whether small soil animals such as nematodes show latitudinal differences in diversity. Based on hypotheses concerning the basis for greater tropical diversity, and by analogy with other groups, we predicted (1) greater alpha diversity in the equatorial tropics than the High Arctic, (2) greater beta and gamma diversity in the tropics. We also predicted (3) no species overlap between the tropics and the High Arctic, and (4) lower abundance of root feeding and insect parasitic nematodes in the high Arctic.LocationWe sampled at three sites in equatorial rain forest in Malaysia at 2° N and three sites in High Arctic tundra in Svalbard at 79° N.MethodsIn Malaysia and Svalbard, three sets of 1‐m2 samples were taken, in interrupted grids. Nematodes were extracted using a Baermann funnel. Bulk DNA was amplified by polymerase chain reaction for the 18S rRNA gene, followed by 454‐pyrosequencing.ResultsComparing operational taxonomic unit (OTU)‐based nematode communities (99% sequence similarity), averaged alpha diversity per 1‐m2 quadrat showed no difference between Malaysia and Svalbard. However, the classic beta diversity and gamma diversity of nematodes was higher for Malaysia.Main conclusionsThere was, surprisingly, no difference in the alpha diversity of nematodes between Malaysia and Svalbard. However, for beta and gamma diversity, diversity was higher in Malaysia. There was also considerable OTU overlap between the two regions, suggesting that very broad climatic niches are common in nematode ecology. Plant root feeders and insect parasites were relatively more common in Svalbard. Overall, we found a mixed and complex picture in terms of agreement with what would be predicted on the basis of ecological theory and observations on other groups. While further confirmatory studies would be beneficial, there is a need to incorporate these new findings in the formulation of hypotheses and tests for the underlying causes of latitudinal trends.

Does the habitat structure control the distribution and diversity of the Odonatofauna?

The statement that the habitat complexity and structure govern the abundance and diversity of biological communities has been widely investigated. In this context, we assumed the hypothesis of habitat heterogeneity, that is, the higher habitat complexity leads to greater diversity of Odonata. In addition, we analyzed the influence of habitat structure on the distribution of this community, and evaluated the effects of abiotic variables. Odonata larvae were collected with sieves and by electrofishing in ten neotropical streams belonging to the Pirapó River basin. Forty species of Odonata were registered, which were distributed in eight families, Libellulidae stood out with the highest richness. The high gamma diversity and distribution of Odonata were associated with habitat heterogeneity in these streams. However, the abiotic variables also seem to affect the distribution of Odonata species, in view of the impact of the land use in the vicinity of streams.