Diversity, Volume 11, Issue 6 (June 2019) – 14 articles

The rhizosphere and the phyllosphere represent two different epiphytic compartments of host plant, which are closely related to plant growth, health, and productivity. However, the understanding of the diversity, composition, and assembly of the bacterial communities in different epiphytic microenvironments of large emerged macrophytes has remained elusive, especially the abundant and rare taxa across rhizosphere and phyllosphere communities. In this study, we collected samples of two different epiphytic compartments (rhizosphere and phyllosphere) of Phragmites australis. Both 16S rRNA gene-based high-throughput sequencing and null-model analysis were employed to determine the difference in the composition and assembly of above-mentioned epiphytic bacterial communities. Our results indicated that bacterial communities of rhizosphere exhibited higher diversity and richness than those of phyllosphere. Deterministic processes dominated the assembly of bacterial community in both compartments, and stochastic processes contributed a certain proportion (30.30%) in the assembly of phyllosphere bacterial community. We also found that rare taxa contributed more significantly to the alpha- and beta-diversity of bacterial community than those of abundant taxa. The obtained data are useful for better understanding the bacterial community of different epiphytic compartments of P. australis. Full article

Few long-term demographic studies have been conducted on freshwater turtles of South America, despite the need for this type of inquiry to investigate natural variation and strengthen conservation efforts for these species. In this study, we examined the variation in demography of the Chocoan River Turtle (Rhinoclemmys nasuta) based on a population from an island locality in the Colombian Pacific region between 2005 and 2017. We calculated survival, recapture, and transition probabilities, and the effects of stream substrate and El Niño–Southern Oscillation (ENSO) phases (El Niño, Neutral, La Niña) on these variables using a multi-state model. We found differences in survival probabilities between ENSO phases, likely as a consequence of an increase in flood events. In addition, we found support for survival being greater in muddy streams than rocky streams, possibly because it is easier to escape or hide in mud substrates. Recapture probabilities varied by life stages; differences in the probability of recapture between size classes were associated with the high fidelity to territories by adults. The present increases in frequency and severity of El Niño and La Niña may exacerbate the consequences of climatic regimes on natural populations of turtles by increasing the mortality caused by drastic phenomena such as floods. Full article

Natural water reservoirs are very valuable floristic sites, with springs particularly important for the preservation of floral biodiversity. This paper presents, as a case study, a community of water plants that is new to limnocrene karst springs in Europe: Potametum alpini (Potametea), found in Poland. The paper provides the floristic composition and ecological requirements of this plant association, which is rare and endangered in Europe. According to our knowledge, the habitat data presented here are unique as they are published for the first time for this plant community, and thus it is currently not possible to compare them with data from other authors. Our study confirms the importance of rare microhabitats for global biodiversity. Research on as yet unknown physical and chemical factors limiting the range and development of patches of different plant associations should be conducted intensively, because plant communities, including rare, endangered and protected examples, are an important element of biodiversity at both continental and local scales. All the issues discussed in the paper (rare microhabitats, endangered aquatic plant communities, global biodiversity) are important because they are related to the conservation and management of inland waters. Full article

Epiphytic algae in mangrove forests contribute to high productivity in these unique mangrove ecosystems. A general survey of mangrove-associated macroalgae was conducted during February–March (dry season) and November–December (wet season) in the Sundarbans Mangrove Forest, Bangladesh. Different macroalgae were collected from mangrove pneumatophores, roots, and branches of trees. During this survey, a small and inconspicuous species of Chondria was encountered from the upper-middle of the intertidal zone in the Malancha River (22°5′11.37″ N and 89°13′12.37″ E). External–internal anatomical traits were examined and the sample was identified as Chondria intertexta Silva, a new record for the algal flora of Bangladesh. Furthermore, its geographical distribution and some other ecological notes are also discussed. Full article

Diversity of secondary lichen metabolites and their relationship to substrate and environmental parameters were studied in saxicolous lichens in the Middle and South Urals of Russia. Atranorin, usnic acid, gyrophoric acid, zeorin, norstictic acid, antraquinones and stictic acid were found in 73, 42, 41, 37, 36, 35 and 32 species, respectively, of 543 taxa collected. One hundred and ninety six species (i.e., 36% of total species documented) contained no secondary metabolites. Spectra of secondary metabolites of crustose lichens varied on different rock types, while in fruticose and foliose groups only those species without lichen acids were dependent on the substrate type. In Canonical Correspondence Analysis, secondary lichen metabolites were subdivided into groups depending on the concentration of Ca and metals in the substrate. Gyrophoric, lobaric, psoromic, rhizocarpic and stictic acids were common in crustose lichens in metal-poor habitats; species with antraquinones and lichens without any secondary metabolites were most abundant on limestone (alkalic and metal-poor), while other common lichen metabolites had no to minimal dependence on the chemistry of the substrate. The two additional abiotic factors affecting the composition of secondary metabolites were the maximum temperature of the warmest month and elevation. Our results suggest a range of possible relationships exist among lichen acids, rocks and climatic parameters. Furthermore, the same metabolite may affect both accumulation of metals and stress tolerance under unfavorable conditions. Full article

Fusarium is one of the most diverse fungal genera affecting several crops around the world. This study describes the phylogeny of Fusarium species associated with grains of sorghum and finger millet from different parts of Ethiopia. Forty-two sorghum and 34 finger millet grain samples were mycologically analysed. All of the sorghum and more than 40% of the finger millet grain samples were contaminated by the Fusarium species. The Fusarium load was higher in sorghum grains than that in finger millet grains. In addition, 67 test isolates were phylogenetically analysed using EF-1α and β-tubulin gene primers. Results revealed the presence of eight phylogenetic placements within the genus Fusarium, where 22 of the isolates showed a close phylogenetic relation to the F. incarnatum–equiseti species complex. Nevertheless, they possess a distinct shape of apical cells of macroconidia, justifying the presence of new species within the Fusarium genus. The new species was the most dominant, represented by 33% of the test isolates. The current work can be seen as an important addition to the knowledge of the biodiversity of fungal species that exists within the Fusarium genus. It also reports a previously unknown Fusarium species that needs to be investigated further for toxin production potential. Full article

Dipodomys microps, the chisel-toothed kangaroo rat, is heralded as one of few mammalian herbivores capable of dietary specialization. Throughout its range, the diet of D. microps is thought to consist primarily of Atriplex confertifolia (saltbush), a C₄ plant, and sparing amounts of C₃ plants. Using stable isotopes of carbon and nitrogen as natural diet tracers, we asked whether D. microps is an obligate specialist on saltbush. We analyzed hair samples of D. microps for isotopes from historic and recent museum specimens (N = 66). A subset of samples (N = 17) from 2017 that were associated with field notes on plant abundances were further evaluated to test how local saltbush abundance affects its inclusion in the diet of D. microps. Overall, we found that the chisel-toothed kangaroo rat facultatively specializes on saltbush and that the degree of specialization has varied over time and space. Moreover, saltbush abundance dictates its inclusion in the diet. Furthermore, roughly a quarter of the diet is comprised of insects, and over the past century, insects have become more prevalent and saltbush less prevalent in the diet. We suggest that environmental factors such as climate change and rangeland expansion have caused D. microps to include more C₃ plants and insects. Full article

The pet trade in aquatic animals is known to be one of the main sources of non-native species worldwide. Freshwater decapod crustaceans have increased in popularity as ornamentals in the last two decades. Freshwater crabs of the genus Limnopilos were discovered by hobby aquarists and introduced on the market in 2008. They are generally considered interesting additions to an aquarium, but information about their living requirements are scarce. Additionally, their invasive potential is not known. Here, we present a survey of the availability of Limnopilos crabs on the market in Europe and North America and analyzed the invasive potential of all species from the genus based on climate matching from a global perspective. The only species recorded in the pet trade is L. naiyanetri, but future introduction of other species is discussed. Certain tropical regions were identified as the most suitable for the potential establishment of Limnopilos crabs including the northern part of South America, and L. microrhynchus was evaluated as the highest risk species. In this pilot study, we also suggest some points to be answered regarding further improving the risk assessment and also recommend continuous monitoring of the market for ornamental decapods. Full article

Two subspecies of European beech (Fagus sylvatica L.) can be found in southeast Europe: Fagus sylvatica ssp. sylvatica L. and Fagus sylvatica ssp. orientalis (Lipsky) Greut. & Burd. (Fagus orientalis Lipsky). In a previous study, based on genetic diversity patterns and morphological characters, indications of hybridization between both subspecies were found in northeastern Greece, a known contact zone of F. sylvatica and F. orientalis. Nevertheless, potential genetic admixture has not been investigated systematically before. Here, we investigated genetic diversity and genetic structure of 14 beech populations originating from Greece and Turkey as well as of two reference F. sylvatica populations from Germany based on nine expressed sequence tag-simple sequence repeat (EST-SSR) markers. Very low genetic differentiation was detected among F. sylvatica populations (mean G_ST: 0.005) as well as among F. orientalis populations (mean G_ST: 0.008), but substantial differentiation was detected between populations of the two subspecies (mean G_ST: 0.122). Indications for hybridization between both subspecies were revealed for one population in Greece. One of the genetic markers showed specific allele frequencies for F. sylvatica and F. orientalis and may be used as a diagnostic marker in future studies to discriminate both subspecies. Full article

Organisms that modify the availability of abiotic resources for other species can alter the structure and function of ecological communities through multiple pathways. In Florida Bay, red grouper (Epinephelus morio) engineer habitats by excavating sediment and detritus from karst solution holes and are also predators that consume a variety of benthic crustaceans and fish, some of which colonize engineered habitats. The effect of red grouper on these communities is complex as colonizing species interact with red grouper in different ways, including both direct (e.g., predator–prey) and indirect interactions. Here, I present the results of an experiment designed to test the direct effects of red grouper on faunal communities associated with Florida Bay solution holes by excluding red grouper from solution holes for four weeks. Red grouper presence generally had positive effects on the abundance, richness, and diversity of faunal communities associated with engineered habitats. Few strong interactions were observed between red grouper and colonizing species, mainly juvenile coral reef fishes. These results suggest that by acting as both a predator and habitat engineer, red grouper shape unique communities, distinct from those of surrounding areas, and influence the composition of communities associated with manipulated habitats. Full article

Variation in nutrient excretion rates and stoichiometric ratios (e.g., nitrogen to phosphorus) by consumers can have substantial effects on aquatic ecosystem function. While phylogenetic signals within an assemblage often explain variation in nutrient recycling rates and stoichiometry, the phylogenetically conserved traits that underlie this phenomenon remain unclear. In particular, variation in nutrient excretion stoichiometry across a phylogeny might be driven by phylogenetic patterns in either diet or body stoichiometry. We examined the relative importance of these traits in explaining variation in nutrient recycling rates and stoichiometry in a diverse family of Neotropical-armored catfishes, Loricariidae, in Panamanian streams. We found significant variation in nutrient mineralization traits among species and subfamilies, but variation in nutrient excretion stoichiometry among species was best explained by trophic position rather than body stoichiometry. The variation in trophic position among Panamanian species was consistent with variation in the trophic niche of their genera across South America, suggesting that phylogenetic patterns underpin the evolution of trophic and nutrient excretion traits among these species. Such geographical variation in nutrient mineralization patterns among closely related species may be common, given that trophic variation in fish lineages occurs widely. These results suggest that information on trophic trait evolution within lineages will advance our understanding of the functional contribution of animals to biogeochemical cycling. Full article

Critical loads of atmospheric deposition help decision-makers identify levels of air pollution harmful to ecosystem components. But when critical loads are exceeded, how can the accompanying ecological risk be quantified? We use a 90% quantile regression to model relationships between nitrogen and sulfur deposition and epiphytic macrolichens, focusing on responses of concern to managers of US forests: Species richness and abundance and diversity of functional groups with integral ecological roles. Analyses utilized national-scale lichen survey data, sensitivity ratings, and modeled deposition and climate data. We propose 20, 50, and 80% declines in these responses as cut-offs for low, moderate, and high ecological risk from deposition. Critical loads (low risk cut-off) for total species richness, sensitive species richness, forage lichen abundance and cyanolichen abundance, respectively, were 3.5, 3.1, 1.9, and 1.3 kg N and 6.0, 2.5, 2.6, and 2.3 kg S ha⁻¹ yr⁻¹. High environmental risk (80% decline), excluding total species richness, occurred at 14.8, 10.4, and 6.6 kg N and 14.1, 13, and 11 kg S ha⁻¹ yr⁻¹. These risks were further characterized in relation to geography, species of conservation concern, number of species affected, recovery timeframes, climate, and effects on interdependent biota, nutrient cycling, and ecosystem services. Full article

Wetlands play an important role in the feeding, breeding, and lives of birds. However, available habitats for bird species are changing due to intensifying human activity, especially in the context of China’s mass urbanization. Urban sprawl has taken over the wetlands along the lakes in the past decades, which places tremendous pressure on wetland ecosystems and, therefore, on bird communities. However, the ways urban land cover pattern along the urban-rural gradient affects bird communities is still unclear. To investigate the influence of land cover pattern on the α and β diversity of birds in the urban-rural gradient we chose 31 sites distributed within the wetlands around the Dianchi Lake in Yunnan, China. We calculated the species richness to indicate α diversity and used the Morisita–Horn index to indicate β diversity. Meanwhile, we assessed the land cover pattern of each site by measuring the proportion of emergent plants, floating plants, submerged plants, ponds, forests, lawns, roads, agricultural lands and built lands in a quadrat of 1 square kilometer. Simple linear regressions, model selection, and an averaging approach based on corrected Akaike information criterion (AICc) were used to test the effects of land cover pattern on bird diversity. Using one-way ANOVA and Tukey’s HSD (honestly significant difference) test, we compared the difference between α and β diversity, respectively, along the urban-rural gradient. Based on our analyses, urban and suburban wetland birds were significantly homogeneous. The community structure in rural wetlands, however, was significantly different from that of the suburban and urban areas. According to our research, the land cover patterns that influenced bird species richness were the built lands acreage, submerged plants acreage, ponds acreage, and the edge density of emergent plants. Meanwhile, of these variables, the built lands acreage, ponds acreage and edge density of emergent plants were significantly different in urban, suburban, and rural wetlands. Therefore, to maintain high biodiversity in wetlands affected by urbanization, we must pay more attention to the land cover patterns. Full article

Coral reefs are under increasing pressure from a variety of stressors, highlighting the need for information about the status of coral reef communities including the distribution, abundance and composition of juvenile and adult coral assemblages. This information is currently limited for the Great Barrier Reef (GBR) and is necessary for understanding the impacts of disturbances and the system’s potential for recovery. This study reports juvenile and adult hard coral abundance and composition from 122 reefs on the GBR during a period of limited acute disturbance. The data represent baseline observations for juvenile hard coral assemblages spanning the longitudinal cross-shelf gradient of the GBR and 12 degrees of latitude and augment reported distribution of adult coral assemblages over the same scale with inclusion of additional reefs. Juvenile and adult coral assemblages reflected broad differences imposed by the gradient of environmental conditions across the GBR. The mean density of juvenile hard corals was lower in the inshore reefs (5.51 m²) than at either the mid-shelf (11.8 m²) or outer shelf reefs (11.2 m²). The composition of juvenile and adult coral assemblages covaried overall, although there were different relationships between these two life stages across the continental shelf and among community types. Dissimilarity between juvenile and adult coral assemblages was greater on inshore and outer shelf reefs than on reefs in the mid-shelf, although, there were differences in community types both within these shelf positions and those that spanned mid- and outer shelf reefs. Dissimilarity was greatest for Inshore branching Acropora and high for Southern Acropora communities, although very high coral cover and very low juvenile densities at these reefs precluded interpretation beyond the clear competitive dominance of Acropora on those reefs. Dissimilarity was also high between juvenile and adult coral assemblages of Turbid inshore communities suggesting water quality pressures, along with synergistic effects of other stressors, pose ongoing selective pressures beyond the juvenile stage. Conversely, relatively low dissimilarity between juvenile and adult coral assemblages on mid-shelf and lower latitude outer shelf reefs suggests pressures beyond those influencing settlement and early post-settlement survival were having less influence on the composition of adult coral assemblages. Full article