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Diversity, Volume 12, Issue 10 (October 2020) – 45 articles

Cover Story (view full-size image): Recently, biofilm-forming diatoms received increased attention as sea turtle epibionts, and sea-turtle-associated diatom species have thus far only been reported from this substratum, suggesting a very close—possibly obligatory—relationship between these diatoms and their hosts. View this paper.
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Open AccessArticle
Diversity and Distribution Patterns of Hard Bottom Polychaete Assemblages in the North Adriatic Sea (Mediterranean)
Diversity 2020, 12(10), 408; https://doi.org/10.3390/d12100408 - 21 Oct 2020
Cited by 2 | Viewed by 694
Abstract
The knowledge on the hard bottom polychaete assemblages in the Northern Adriatic Sea, a Mediterranean region strongly affected by environmental pressures, is scarce and outdated. The objective of this paper was to update the information on polychaete diversity and depict their patterns of [...] Read more.
The knowledge on the hard bottom polychaete assemblages in the Northern Adriatic Sea, a Mediterranean region strongly affected by environmental pressures, is scarce and outdated. The objective of this paper was to update the information on polychaete diversity and depict their patterns of natural spatial variation, in relation to changes in algal coverage at increasing depth. Hard bottom benthos was quantitatively sampled by scraping off the substrate from three stations at Sveti Ivan Island (North Adriatic) at three depths (1.5 m, 5 m and 25 m). Polychaete fauna comprised 107 taxa (the majority of them identified at species level) belonging to 22 families, with the family Syllidae ranking first in terms of number of species, followed by Sabellidae, Nereididae, Eunicidae and Serpulidae. Considering the number of polychaete species and their identity, the present data differed considerably from previous studies carried out in the area. Two alien species, Lepidonotus tenuisetosus, which represented a new record for the Adriatic Sea, and Nereis persica, were recorded. The highest mean abundance, species diversity and internal structural similarity of polychaete assemblages were found at 5 m depth, characterised by complex and heterogeneous algal habitat. The DISTLM forward analysis revealed that the distribution of several algal taxa as well as some algal functional-morphological groups significantly explained the observed distribution patterns of abundance and diversity of polychaete assemblages. The diversity of the North Adriatic hard bottom polychaete fauna is largely underestimated and needs regular updating in order to detect and monitor changes of benthic communities in the area. Full article
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Open AccessEditorial
Phylogenetics of Molecular Regulators Contributing to Plant Stress Tolerance
by and
Diversity 2020, 12(10), 407; https://doi.org/10.3390/d12100407 - 21 Oct 2020
Viewed by 631
Abstract
Genetic studies on model plants and crops in the last few decades have uncovered numerous genes that play vital roles in plant tolerance to adverse environments. These genes could be used as targets for genetic engineering to improve plant tolerance to abiotic and [...] Read more.
Genetic studies on model plants and crops in the last few decades have uncovered numerous genes that play vital roles in plant tolerance to adverse environments. These genes could be used as targets for genetic engineering to improve plant tolerance to abiotic and biotic stresses. Recent advances in CRISPR-based genome editing have accelerated modern plant breeding and wild-species domestication. However, the stress regulators in many crops and horticultural cultivars and their wild species remain largely unexplored. Thus, transferring the accumulated knowledge of these molecular regulators from model plants to a wider range of other species is critical for modern plant breeding. Phylogenetic analysis is one of the powerful strategies for studying the functional conservation and diversity of homologous gene families among different species with complete genome sequences available. In addition, many transcriptome datasets of plants under stress conditions have been publicly released, providing a useful resource for addressing the stress response of given gene families. This Special Issue aims to illustrate the phylogenetics of molecular regulators with potential in contributing to plant stress tolerance and their stress response diversity in multiple non-model plants. Full article
(This article belongs to the Special Issue Phylogenetics of Stress Regulators in Plants)
Open AccessArticle
Grassland Management Affects Vegetation Structure, Bats and Their Beetle Prey
Diversity 2020, 12(10), 406; https://doi.org/10.3390/d12100406 - 21 Oct 2020
Cited by 1 | Viewed by 898
Abstract
Agricultural grasslands provide vital habitats for many species. Yet despite representing a significant proportion of European land use, they are disproportionately understudied compared to arable systems. Increases in productivity and intensification have led to changes in management practices, which are likely to affect [...] Read more.
Agricultural grasslands provide vital habitats for many species. Yet despite representing a significant proportion of European land use, they are disproportionately understudied compared to arable systems. Increases in productivity and intensification have led to changes in management practices, which are likely to affect grassland habitats and the ecological communities that they support. This study simultaneously monitored three trophic levels to assess the impacts of permanent versus temporary pasture (leys) on vegetation composition, carabid and dung beetle abundance, and the activity of beetle-feeding bats. Leys had lower abundances of soil-inhabiting dung beetles, which may be explained by the more recent exposure to tilling compared with permanent pasture. Beetle-feeding bat activity was also greater in leys, with positive relationships between E. serotinus activity and Onthophagus abundance across both pasture types. However, the lack of any positive relationships between beetle-feeding bat activity and Aphodius, a well-known prey genus, suggests that other key prey orders (Lepidoptera) may be of more influence on bat activity. As well as the management of pasture, differences in cattle management between pasture types can have a significant impact on vegetation and soil structure, which influence invertebrate communities and potentially dictate habitat suitability for bats. Full article
(This article belongs to the Section Biodiversity Conservation)
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Open AccessReview
Diversity of Feeding in Anthozoa (Cnidaria): A Systematic Review
Diversity 2020, 12(10), 405; https://doi.org/10.3390/d12100405 - 20 Oct 2020
Viewed by 864
Abstract
In this study, we performed a bibliographical review examining the scientific literature on “feeding in Anthozoa” for the period from 1890 to 2019, using the scientific database Google Scholar, supplemented with additional literature. This study categorized published scientific papers on this topic by [...] Read more.
In this study, we performed a bibliographical review examining the scientific literature on “feeding in Anthozoa” for the period from 1890 to 2019, using the scientific database Google Scholar, supplemented with additional literature. This study categorized published scientific papers on this topic by decade of publication, target taxa, variability of species studied in each order and main themes studied. As a result, 153 studies were found, and based on their content, it was observed that within Anthozoa, there has been a concentration of feeding studies on species in the orders Actiniaria (Hexacorallia), Scleractinia (Hexacorallia), and Alcyonacea (Octocorallia). This indicates that the other remaining orders of the group have been comparatively neglected with regards to their feeding aspects. Therefore, as data on feeding in some groups of Anthozoa are scarce, studies need to be carried out to fill the gaps that permeate this important benthic group, in order to better understand their ecology. Full article
(This article belongs to the Special Issue Review Papers on Marine Diversity)
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Open AccessArticle
Genetic Differentiation of an Endangered Megalobrama terminalis Population in the Heilong River within the Genus Megalobrama
Diversity 2020, 12(10), 404; https://doi.org/10.3390/d12100404 - 18 Oct 2020
Viewed by 608
Abstract
Megalobrama terminalis, which inhabits the Sino-Russian Heilong-Amur River Basin, has decreased critically since the 1960s. It has been listed in the Red Book of Endangered Fish Species by the Russian Federation in 2004. To guide the utilization and conservation programs of M. [...] Read more.
Megalobrama terminalis, which inhabits the Sino-Russian Heilong-Amur River Basin, has decreased critically since the 1960s. It has been listed in the Red Book of Endangered Fish Species by the Russian Federation in 2004. To guide the utilization and conservation programs of M. terminalis in the Heilong River (MTH), 3.1 kb of mitochondrial DNA (mtDNA) concatenated sequences and sequence-related amplified polymorphism (SRAP) markers (15 primer combinations) were applied to explore the genetic divergence and population differentiation of MTH within the genus Megalobrama. Clear genetic divergence between MTH and six other populations of the genus Megalobrama was found by haplotype network (mtDNA) and principal component (SRAP) analyses. Moreover, the STRUCTURE analysis based on SRAP data showed that MTH could be assigned to a particular cluster, whereas conspecific M. terminalis in the Qiantang River and Jinsha River Reservoir belonged to the same cluster. Analysis of molecular variance (AMOVA) and Fst statistics for the mtDNA and SRAP data revealed significant genetic variance and differentiation among all detected populations. Taken together, the results suggest that MTH has a strong genetic differentiation from other populations within the genus Megalobrama, which contributes to effective utilization in artificial cultivation and breeding of MTH. Furthermore, these results also provide a scientific basis for the management of MTH as a separate conservation unit. Full article
(This article belongs to the Special Issue Aquatic Restoration Ecology and Monitoring)
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Open AccessEditorial
Monitoring of Honey Bee Colony Losses: A Special Issue
Diversity 2020, 12(10), 403; https://doi.org/10.3390/d12100403 - 17 Oct 2020
Cited by 1 | Viewed by 729
Abstract
In recent decades, independent national and international research programs have revealed possible reasons for the death of managed honey bee colonies worldwide. Such losses are not due to a single factor, but instead are due to highly complex interactions between various internal and [...] Read more.
In recent decades, independent national and international research programs have revealed possible reasons for the death of managed honey bee colonies worldwide. Such losses are not due to a single factor, but instead are due to highly complex interactions between various internal and external influences, including pests, pathogens, honey bee stock diversity, and environmental change. Reduced honey bee vitality and nutrition, exposure to agrochemicals, and quality of colony management contribute to reduced colony survival in beekeeping operations. Our Special Issue (SI) on ‘’Monitoring of Honey Bee Colony Losses’’ aims to address specific challenges facing honey bee researchers and beekeepers. This SI includes four reviews, with one being a meta-analysis that identifies gaps in the current and future directions for research into honey bee colonies mortalities. Other review articles include studies regarding the impact of numerous factors on honey bee mortality, including external abiotic factors (e.g., winter conditions and colony management) as well as biotic factors such as attacks by Vespa velutina and Varroa destructor. Full article
(This article belongs to the Special Issue Monitoring of Honey Bee Colony Losses)
Open AccessArticle
Diel and Seasonal Variations of Vocal Behavior of the Neotropical White-Tipped Dove (Leptotila verreauxi)
Diversity 2020, 12(10), 402; https://doi.org/10.3390/d12100402 - 16 Oct 2020
Cited by 3 | Viewed by 907
Abstract
Current knowledge regarding the vocal behavior in tropical non-passerines is very limited. Here, we employed passive acoustic monitoring to study the vocal activity of the white-tipped dove (Leptotila verreauxi) at three sites over a year in the Brazilian Pantanal. The diel [...] Read more.
Current knowledge regarding the vocal behavior in tropical non-passerines is very limited. Here, we employed passive acoustic monitoring to study the vocal activity of the white-tipped dove (Leptotila verreauxi) at three sites over a year in the Brazilian Pantanal. The diel pattern of vocal activity showed a bimodal pattern, with significantly higher vocal activity after sunrise than during the other hours of the day, in agreement with prior studies on this species and other members of Columbidae. The species was vocally active throughout the year, but vocal activity was maximum during May-June and lowest during January-February. Relative air humidity was positively associated with vocal activity, which may be related to the improvement of sound transmission under more humid conditions, but it could also be related to foraging efficiency due to a higher availability of invertebrates on wetter days. Vocal activity was not related to the mean air temperature or daily rainfall. Acoustic monitoring proved to be a useful tool for monitoring this shy forest species, for which a minimum number of three monitoring days was needed to detect a reliable vocal activity rate. Future studies should evaluate its use for monitoring other species of doves and pigeons that are secretive or threatened. Full article
(This article belongs to the Section Animal Diversity)
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Open AccessCorrection
Correction: Oleas, N.H., et al. Muddy Boots Beget Wisdom: Implications for Rare or Endangered Plant Species Distribution Models. Diversity, 2019, 11, 10
Diversity 2020, 12(10), 401; https://doi.org/10.3390/d12100401 - 15 Oct 2020
Viewed by 573
Abstract
An error on our paper [...] Full article
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Open AccessReview
Visual Adaptations in Predatory and Scavenging Diurnal Raptors
Diversity 2020, 12(10), 400; https://doi.org/10.3390/d12100400 - 15 Oct 2020
Cited by 2 | Viewed by 2962
Abstract
Ecological diversity among diurnal birds of prey, or raptors, is highlighted regarding their sensory abilities. While raptors are believed to forage primarily using sight, the sensory demands of scavengers and predators differ, as reflected in their visual systems. Here, I have reviewed the [...] Read more.
Ecological diversity among diurnal birds of prey, or raptors, is highlighted regarding their sensory abilities. While raptors are believed to forage primarily using sight, the sensory demands of scavengers and predators differ, as reflected in their visual systems. Here, I have reviewed the visual specialisations of predatory and scavenging diurnal raptors, focusing on (1) the anatomy of the eye and (2) the use of vision in foraging. Predators have larger eyes than scavengers relative to their body mass, potentially highlighting the higher importance of vision in these species. Scavengers possess one centrally positioned fovea that allows for the detection of carrion at a distance. In addition to the central fovea, predators have a second, temporally positioned fovea that views the frontal visual field, possibly for prey capture. Spatial resolution does not differ between predators and scavengers. In contrast, the organisation of the visual fields reflects important divergences, with enhanced binocularity in predators opposed to an enlarged field of view in scavengers. Predators also have a larger blind spot above the head. The diversity of visual system specializations according to the foraging ecology displayed by these birds suggests a complex interplay between visual anatomy and ecology, often unrelatedly of phylogeny. Full article
(This article belongs to the Special Issue Ecology of Predation and Scavenging and the Interface)
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Open AccessCommunication
Implementing and Monitoring the Use of Artificial Canopy Bridges by Mammals and Birds in an Indonesian Agroforestry Environment
Diversity 2020, 12(10), 399; https://doi.org/10.3390/d12100399 - 15 Oct 2020
Cited by 2 | Viewed by 1612
Abstract
Deforestation is a major threat to biodiversity, particularly within tropical forest habitats. Some of the fastest diminishing tropical forest habitats in the world occur in Indonesia, where fragmentation is severely impacting biodiversity, including on the island of Java, which holds many endemic species. [...] Read more.
Deforestation is a major threat to biodiversity, particularly within tropical forest habitats. Some of the fastest diminishing tropical forest habitats in the world occur in Indonesia, where fragmentation is severely impacting biodiversity, including on the island of Java, which holds many endemic species. Extreme fragmentation on the western part of the island, especially due to small-scale agriculture, impacts animal movement and increases mortality risk for mainly arboreal taxa. To mitigate this risk in an agroforest environment in Garut District, West Java, we installed 10 canopy bridges and monitored them through camera trapping between 2017 and 2019. Five of the monitored bridges were made of waterlines and five of rubber hose. We recorded Javan palm civets using the waterline bridges 938 times, while Javan slow lorises used the waterlines 1079 times and the rubber bridges 358 times. At least 19 other species used the bridges for crossing or perching. Our results demonstrate that relatively simple and cost-effective materials can be used to mitigate the effects of habitat fragmentation. We also recommend the use of camera traps to monitor the effectiveness of these interventions. Full article
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Open AccessArticle
Spatio-Temporal Distribution of Carabids Influenced by Small-Scale Admixture of Oak Trees in Pine Stands
Diversity 2020, 12(10), 398; https://doi.org/10.3390/d12100398 - 15 Oct 2020
Cited by 1 | Viewed by 946
Abstract
In a region with poor soil fertility, low annual precipitation and large areas of homogenous Pinus sylvestris L. forests, conservation of old sessile oak (Quercus petraea (Matt.) Liebl.) trees is one option to enrich structure and species richness. We studied the affinities [...] Read more.
In a region with poor soil fertility, low annual precipitation and large areas of homogenous Pinus sylvestris L. forests, conservation of old sessile oak (Quercus petraea (Matt.) Liebl.) trees is one option to enrich structure and species richness. We studied the affinities of Carabus coriaceus, C. violaceus, C. hortensis and C. arvensis for specific tree species and the resultant intra- and interspecific interactions. We focused on their temporal and spatial distributions. Pitfall traps were used as a surface-related capture method on a grid over an area of three hectares. Generalised linear models and generalised linear geostatistical models were used to analyse carabid activity densities related to distance-dependent spatial effects corresponding to tree zones (oak, oak–pine, pine). The results demonstrated significant spatial affinities among these carabids, especially for females and during the period of highest activity. Individuals of C. coriaceus showed a tendency to the oak zone and C. hortensis exhibited a significant affinity to the oak–pine mixture. Imagines of C. arvensis and C. violaceus were more closely related to pine. The observed temporal and spatial coexistence of the different Carabus species reveals that single admixed old oak trees can support greater diversity within pine-dominated forests. Full article
(This article belongs to the Special Issue Interactions between Oaks and Insects)
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Open AccessArticle
Can Functional Traits Explain Plant Coexistence? A Case Study with Tropical Lianas and Trees
Diversity 2020, 12(10), 397; https://doi.org/10.3390/d12100397 - 14 Oct 2020
Cited by 1 | Viewed by 684
Abstract
Organisms are adapted to their environment through a suite of anatomical, morphological, and physiological traits. These functional traits are commonly thought to determine an organism’s tolerance to environmental conditions. However, the differences in functional traits among co-occurring species, and whether trait differences mediate [...] Read more.
Organisms are adapted to their environment through a suite of anatomical, morphological, and physiological traits. These functional traits are commonly thought to determine an organism’s tolerance to environmental conditions. However, the differences in functional traits among co-occurring species, and whether trait differences mediate competition and coexistence is still poorly understood. Here we review studies comparing functional traits in two co-occurring tropical woody plant guilds, lianas and trees, to understand whether competing plant guilds differ in functional traits and how these differences may help to explain tropical woody plant coexistence. We examined 36 separate studies that compared a total of 140 different functional traits of co-occurring lianas and trees. We conducted a meta-analysis for ten of these functional traits, those that were present in at least five studies. We found that the mean trait value between lianas and trees differed significantly in four of the ten functional traits. Lianas differed from trees mainly in functional traits related to a faster resource acquisition life history strategy. However, the lack of difference in the remaining six functional traits indicates that lianas are not restricted to the fast end of the plant life–history continuum. Differences in functional traits between lianas and trees suggest these plant guilds may coexist in tropical forests by specializing in different life–history strategies, but there is still a significant overlap in the life–history strategies between these two competing guilds. Full article
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Open AccessFeature PaperArticle
Responses of Ground-Dwelling Spider (Arachnida: Araneae) Communities to Wildfire in Three Habitats in Northern New Mexico, USA, with Notes on Mites and Harvestmen (Arachnida: Acari, Opiliones)
Diversity 2020, 12(10), 396; https://doi.org/10.3390/d12100396 - 14 Oct 2020
Viewed by 661
Abstract
Catastrophic wildfire is increasingly common in forests of the western United States because climate change is increasing ambient temperatures and periods of drought. In 2011, the Las Conchas wildfire burned in the Santa Fe National Forest of New Mexico, including portions of ponderosa [...] Read more.
Catastrophic wildfire is increasingly common in forests of the western United States because climate change is increasing ambient temperatures and periods of drought. In 2011, the Las Conchas wildfire burned in the Santa Fe National Forest of New Mexico, including portions of ponderosa pine and mixed-conifer forests, and grasslands in the Valles Caldera National Preserve, a large, high-elevation volcanic caldera. Following the fire, Caldera staff began monitoring abiotic, plant, and animal responses. In this study, ground-dwelling arachnids were collected in pitfall traps in burned and unburned habitats from 2011–2015. Permutational multivariate analysis of variance (PERMANOVA) mostly at the genus level with some higher taxon levels showed significant fire, year, and interaction effects. Abundance was at or near unburned levels by 2014, but species composition changed in burned areas. Pardosa and Haplodrassus were dominant genera across habitats. Linyphiids were strong indicators of unburned sites. Harvestmen were among the dominant species in the forest habitats, and erythraeid mites were abundant in the burned ponderosa pine forest and the grassland. Years were not significantly autocorrelated, unsurprising given the interannual variation in precipitation in this generally arid region. Although fire is a common feature of these habitats, future fires may be outside of historical patterns, preventing spider communities from re-establishing fully. Full article
(This article belongs to the Special Issue Forest Spider Communities Diversity)
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Open AccessArticle
Diversity of Olfactory Responses and Skills in Astyanax Mexicanus Cavefish Populations Inhabiting different Caves
Diversity 2020, 12(10), 395; https://doi.org/10.3390/d12100395 - 13 Oct 2020
Cited by 3 | Viewed by 818
Abstract
Animals in many phyla are adapted to and thrive in the constant darkness of subterranean environments. To do so, cave animals have presumably evolved mechano- and chemosensory compensations to the loss of vision, as is the case for the blind characiform cavefish, Astyanax [...] Read more.
Animals in many phyla are adapted to and thrive in the constant darkness of subterranean environments. To do so, cave animals have presumably evolved mechano- and chemosensory compensations to the loss of vision, as is the case for the blind characiform cavefish, Astyanax mexicanus. Here, we systematically assessed the olfactory capacities of cavefish and surface fish of this species in the lab as well as in the wild, in five different caves in northeastern Mexico, using an olfactory setup specially developed to test and record olfactory responses during fieldwork. Overall cavefish showed lower (i.e., better) olfactory detection thresholds than surface fish. However, wild adult cavefish from the Pachón, Sabinos, Tinaja, Chica and Subterráneo caves showed highly variable responses to the three different odorant molecules they were exposed to. Pachón and Subterráneo cavefish showed the highest olfactory capacities, and Chica cavefish showed no response to the odors presented. We discuss these data with regard to the environmental conditions in which these different cavefish populations live. Our experiments in natural settings document the diversity of cave environments inhabited by a single species of cavefish, A. mexicanus, and highlight the complexity of the plastic and genetic mechanisms that underlie cave adaptation. Full article
(This article belongs to the Special Issue Cave Communities: From the Surface Border to the Deep Darkness)
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Open AccessArticle
Prioritizing Management of Non-Native Eurasian Watermilfoil Using Species Occurrence and Abundance Predictions
Diversity 2020, 12(10), 394; https://doi.org/10.3390/d12100394 - 13 Oct 2020
Viewed by 698
Abstract
Prioritizing the prevention and control of non-native invasive species requires understanding where introductions are likely to occur and cause harm. We developed predictive models for Eurasian watermilfoil (EWM) (Myriophyllum spicatum L.) occurrence and abundance to produce a smart prioritization tool for EWM [...] Read more.
Prioritizing the prevention and control of non-native invasive species requires understanding where introductions are likely to occur and cause harm. We developed predictive models for Eurasian watermilfoil (EWM) (Myriophyllum spicatum L.) occurrence and abundance to produce a smart prioritization tool for EWM management. We used generalized linear models (GLMs) to predict species occurrence and extended beta regression models to predict abundance from data collected on 657 Wisconsin lakes. Species occurrence was positively related to the nearby density of vehicle roads, maximum air temperature, lake surface area, and maximum lake depth. Species occurrence was negatively related to near-surface lithological calcium oxide content, annual air temperature range, and average distance to all known source populations. EWM abundance was positively associated with conductivity, maximum air temperature, mean distance to source, and soil erodibility, and negatively related to % surface rock calcium oxide content and annual temperature range. We extended the models to generate occurrence and predictions for all lakes in Wisconsin greater than 1 ha (N = 9825), then prioritized prevention and management, placing highest priority on lakes likely to experience EWM introductions and support abundant populations. This modelling effort revealed that, although EWM has been present for several decades, many lakes are still vulnerable to introduction. Full article
(This article belongs to the Special Issue Ecology of Invasive Aquatic Plants)
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Open AccessArticle
Patterns of Rotifer Diversity in the Chihuahuan Desert
Diversity 2020, 12(10), 393; https://doi.org/10.3390/d12100393 - 13 Oct 2020
Cited by 1 | Viewed by 748
Abstract
Desert aquatic systems are widely separated, lack hydrologic connections, and are subject to drought. However, they provide unique settings to investigate distributional patterns of micrometazoans, including rotifers. Thus, to understand rotifer biodiversity we sampled 236 sites across an array of habitats including rock [...] Read more.
Desert aquatic systems are widely separated, lack hydrologic connections, and are subject to drought. However, they provide unique settings to investigate distributional patterns of micrometazoans, including rotifers. Thus, to understand rotifer biodiversity we sampled 236 sites across an array of habitats including rock pools, springs, tanks, flowing waters, playas, lakes, and reservoirs in the Chihuahuan Desert of the USA (n = 202) and Mexico (n = 34) over a period of >20 years. This allowed us to calculate diversity indices and examine geographic patterns in rotifer community composition. Of ~1850 recognized rotifer species, we recorded 246 taxa (~13%), with greatest diversity in springs (n = 175), lakes (n = 112), and rock pools (n = 72). Sampling effort was positively related to observed richness in springs, lakes, rivers, and tanks. Nestedness analyses indicated that rotifers in these sites, and most subsets thereof, were highly nested (support from 4 null models). Distance was positively correlated with species composition dissimilarity on small spatial scales. We predicted species richness for unsampled locations using empirical Bayesian kriging. These findings provide a better understanding of regional rotifer diversity in aridlands and provide information on potential biodiversity hotspots for aquatic scientists and resource managers. Full article
(This article belongs to the Special Issue Biodiversity of Rotifers)
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Open AccessFeature PaperArticle
Definition of Core Bacterial Taxa in Different Root Compartments of Dactylis glomerata, Grown in Soil under Different Levels of Land Use Intensity
Diversity 2020, 12(10), 392; https://doi.org/10.3390/d12100392 - 13 Oct 2020
Cited by 2 | Viewed by 765
Abstract
Plant-associated bacterial assemblages are critical for plant fitness. Thus, identifying a consistent plant-associated core microbiome is important for predicting community responses to environmental changes. Our target was to identify the core bacterial microbiome of orchard grass Dactylis glomerata L. and to assess the [...] Read more.
Plant-associated bacterial assemblages are critical for plant fitness. Thus, identifying a consistent plant-associated core microbiome is important for predicting community responses to environmental changes. Our target was to identify the core bacterial microbiome of orchard grass Dactylis glomerata L. and to assess the part that is most sensitive to land management. Dactylis glomerata L. samples were collected from grassland sites with contrasting land use intensities but comparable soil properties at three different timepoints. To assess the plant-associated bacterial community structure in the compartments rhizosphere, bulk soil and endosphere, a molecular barcoding approach based on high throughput 16S rRNA amplicon sequencing was used. A distinct composition of plant-associated core bacterial communities independent of land use intensity was identified. Pseudomonas, Rhizobium and Bradyrhizobium were ubiquitously found in the root bacterial core microbiome. In the rhizosphere, the majority of assigned genera were Rhodoplanes, Methylibium, Kaistobacter and Bradyrhizobium. Due to the frequent occurrence of plant-promoting abilities in the genera found in the plant-associated core bacterial communities, our study helps to identify “healthy” plant-associated bacterial core communities. The variable part of the plant-associated microbiome, represented by the fluctuation of taxa at the different sampling timepoints, was increased under low land use intensity. This higher compositional variation in samples from plots with low land use intensity indicates a more selective recruitment of bacteria with traits required at different timepoints of plant development compared to samples from plots with high land use intensity. Full article
(This article belongs to the Special Issue Plant-Soil Interactions)
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Open AccessArticle
Seascape Configuration and Fine-Scale Habitat Complexity Shape Parrotfish Distribution and Function across a Coral Reef Lagoon
Diversity 2020, 12(10), 391; https://doi.org/10.3390/d12100391 - 13 Oct 2020
Cited by 1 | Viewed by 1362
Abstract
Structural complexity spanning fine to broad spatial scales can influence the distribution and activity of key organisms within marine ecosystems. However, the relative importance of hard (e.g., corals) and/or soft (e.g., macroalgae) structural complexity for marine organisms is often unclear. This study shows [...] Read more.
Structural complexity spanning fine to broad spatial scales can influence the distribution and activity of key organisms within marine ecosystems. However, the relative importance of hard (e.g., corals) and/or soft (e.g., macroalgae) structural complexity for marine organisms is often unclear. This study shows how both broad-scale (seascape configuration of coral structure) and fine-scale habitat complexity (structure height, number of holes, and presence of macroalgae) can influence the abundance and spatial ecology of reef fish. Underwater visual census of fish, surveys of habitats, remote underwater videos, and behavioral observations by following individual fish were used to quantify fine-scale habitat characteristics (e.g., complexity, coral structure height, macroalgae presence) and the abundance, size structure, and behavior (rates of herbivory, tortuosity ratios and total distance travelled) of abundant parrotfish. Both seascape configuration and macroalgae influenced the patterns of fish abundance and rates of herbivory. However, these relationships varied with trophic groups and ontogenetic stages. Abundance of adult and intermediate-phase parrotfishes was positively influenced by densely aggregated coral structures, whereas juvenile abundance was positively influenced by the presence of macroalgae. Foraging path and bite rates of an abundant parrotfish, Chlorurus spilurus, were not influenced by coral structure configuration or height, but the presence of macroalgae increased the bite rates of all juvenile parrotfish. Our results suggest that a combination of seascape configuration, fine-scale habitat complexity, and microhabitat selectivity influence reef fish community structure and foraging behavior, thus altering herbivory. However, these relationships can differ among functional groups of fish and life-history stages. Information on these fish–habitat interactions is critical for identifying habitats that facilitate ecological functions and ensures the successful management and conservation of essential habitats. Full article
(This article belongs to the Special Issue Biodiversity and Ecology of Herbivorous Fish)
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Open AccessEditorial
Diversity, Interaction, and Bioprospecting of Plant-Associated Microbiomes
Diversity 2020, 12(10), 390; https://doi.org/10.3390/d12100390 - 13 Oct 2020
Viewed by 601
Abstract
Plant-associated microbiomes have been suggested as pivotal for the growth and health of natural vegetation and agronomic plants. In this sense, plant-associated microbiomes harbor a huge diversity of microorganisms (such as bacteria and fungi) which can modulate the plant host response against pathogens [...] Read more.
Plant-associated microbiomes have been suggested as pivotal for the growth and health of natural vegetation and agronomic plants. In this sense, plant-associated microbiomes harbor a huge diversity of microorganisms (such as bacteria and fungi) which can modulate the plant host response against pathogens and changing environmental conditions through a complex network of genetic, biochemical, physical, and metabolomics interactions. Advances on next-generation omic technologies have opened the possibility to unravel this complex microbial diversity and their interactive networks as never described before. In parallel, the develop of novel culture-dependent methods are also crucial to the study of the biology of members of plant-associated microbiomes and their bioprospecting as sources of bioactive compounds, or as tools to improve the productivity of agriculture. This Special Issue aims to motivate and collect recent studies which are focused on exploring the diversity and ecology of plant-associated microbiomes and their genetic and metabolic interactions with other microorganisms or their plant hosts, as well as their potential biotechnological applications in diverse fields, such as inoculants for agriculture. Full article
Open AccessFeature PaperArticle
Filling the Gap and Improving Conservation: How IUCN Red Lists and Historical Scientific Data Can Shed More Light on Threatened Sharks in the Italian Seas
Diversity 2020, 12(10), 389; https://doi.org/10.3390/d12100389 - 10 Oct 2020
Cited by 3 | Viewed by 1107
Abstract
Chondrichthyans are one of the most threatened marine taxa worldwide. This is also the case in the Mediterranean Sea, which is considered an extinction hotspot for rays and sharks. The central position of the Italian peninsula makes it an ideal location for studying [...] Read more.
Chondrichthyans are one of the most threatened marine taxa worldwide. This is also the case in the Mediterranean Sea, which is considered an extinction hotspot for rays and sharks. The central position of the Italian peninsula makes it an ideal location for studying the status and changes of this sea. There is a lack of biological, ecological and historical data when assessing shark populations, which is also highlighted in the Red List of Threatened Species compiled by the International Union for the Conservation of Nature (IUCN). Historical data can provide important information to better understand how chondrichthyan populations have changed over time. This study aims to provide a clearer understanding of the changes in distribution and abundance of eight shark species in the Italian seas that are currently classified as at risk of extinction by the IUCN. In this respect, a bibliographic review was conducted on items from the 19th century to the first half of the 20th century, focusing on the selected species. The results show that all sharks were considered common until the beginning of the 20th century but have declined since, with a clear negative trend, mainly in the past 70 years. The strong local decline has been attributed to overexploitation, bycatch, habitat loss, depletion of prey items and environmental pollution. Furthermore, historical data also allow us to avoid the issue of a ‘shifting baseline’, in which contemporary abundances are assumed to be “normal”. Using historical data to further our knowledge of the marine environment is becoming increasingly common, and is fundamental in understanding human impact and evaluating mitigation measures to manage and conserve marine species and environments. Full article
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Open AccessArticle
Evaluation of Metabarcoding Primers for Analysis of Soil Nematode Communities
Diversity 2020, 12(10), 388; https://doi.org/10.3390/d12100388 - 09 Oct 2020
Cited by 1 | Viewed by 1378
Abstract
While recent advances in next-generation sequencing technologies have accelerated research in microbial ecology, the application of high throughput approaches to study the ecology of nematodes remains unresolved due to several issues, e.g., whether to include an initial nematode extraction step or not, the [...] Read more.
While recent advances in next-generation sequencing technologies have accelerated research in microbial ecology, the application of high throughput approaches to study the ecology of nematodes remains unresolved due to several issues, e.g., whether to include an initial nematode extraction step or not, the lack of consensus on the best performing primer combination, and the absence of a curated nematode reference database. The objective of this method development study was to compare different primer sets to identify the most suitable primer set for the metabarcoding of nematodes without initial nematode extraction. We tested four primer sets for amplicon sequencing: JB3/JB5 (mitochondrial, I3-M11 partition of COI gene), SSU_04F/SSU_22R (18S rRNA, V1-V2 regions), and Nemf/18Sr2b (18S rRNA, V6-V8 regions) from earlier studies, as well as MMSF/MMSR (18S rRNA, V4-V5 regions), a newly developed primer set. We used DNA from 22 nematode taxa, 10 mock communities, 20 soil samples, 4 root samples, and one bulk soil. We amplified the target regions from the DNA samples with the four different primer combinations and sequenced the amplicons on an Illumina MiSeq sequencing platform. We found that the Nemf/18Sr2b primer set was superior for detecting soil nematodes compared to the other primer sets based on our sequencing results and on the annotation of our sequence reads at the genus and species ranks. This primer set generated 74% reads of Nematoda origin in the soil samples. Additionally, this primer set did well with the mock communities, detecting all the included specimens. It also worked better in the root samples than the other primer set that was tested. Therefore, we suggest that the Nemf/18Sr2b primer set could be used to study rhizosphere soil and root associated nematodes, and this can be done without an initial nematode extraction step. Full article
(This article belongs to the Special Issue Soil Nematodes Research)
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Open AccessCommunication
Transferability of Microsatellite Markers Developed in Oenothera spp. to the Invasive Species Oenothera drummondii Hook. (Onagraceae)
Diversity 2020, 12(10), 387; https://doi.org/10.3390/d12100387 - 08 Oct 2020
Viewed by 723
Abstract
Oenothera drummondii Hook. (Onagraceae) has life-history traits that make it an invasive species. Native populations are distributed along the coastal dunes from North Carolina in the United States to Tabasco in the Gulf of Mexico. It has been reported as an invasive species [...] Read more.
Oenothera drummondii Hook. (Onagraceae) has life-history traits that make it an invasive species. Native populations are distributed along the coastal dunes from North Carolina in the United States to Tabasco in the Gulf of Mexico. It has been reported as an invasive species in Spain, Israel, and China, where this species can successfully colonize and dominate if the environmental conditions are appropriate. In South Africa, Australia, New Zealand, and France, it is reported to be naturalized. In this study, 28 microsatellite markers developed for other Oenothera species were evaluated for cross-amplification in O. drummondii. Nine primers showed consistent amplification and were polymorphic. Polymorphism was assessed in three populations from both native and invaded areas. Results indicated generalized low genetic variability. Three loci showed significant deviations from the Hardy Weinberg equilibrium, associated with null alleles’ presence. The observed heterozygosity and inbreeding coefficient reflected a generalized excess of homozygotes, particularly in the invaded population “El Dique”, likely due to allele fixation. High genetic differentiation was found between the three populations. These results highlight the accuracy of these markers for future population genetic studies in O. drummondii. Full article
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Open AccessArticle
Megadiversity in the Ant Genus Melophorus: The M. rufoniger Heterick, Castalanelli and Shattuck Species Group in the Top End of Australia’s Northern Territory
Diversity 2020, 12(10), 386; https://doi.org/10.3390/d12100386 - 08 Oct 2020
Viewed by 581
Abstract
This study contributes to an understanding of megadiversity in the arid-adapted ant genus Melophorus by presenting an integrated genetic, morphological and distributional analysis of diversity within the M. rufoniger group in the 400,000 km2 Top End (northern region) of Australia’s Northern Territory. [...] Read more.
This study contributes to an understanding of megadiversity in the arid-adapted ant genus Melophorus by presenting an integrated genetic, morphological and distributional analysis of diversity within the M. rufoniger group in the 400,000 km2 Top End (northern region) of Australia’s Northern Territory. An earlier study of the Top End’s ant fauna lists eleven species from the M. rufoniger group, but a recent revision of Melophorus described the taxon as a single species occurring throughout most of the Australian mainland. CO1 sequences were obtained for 120 Top End specimens of the M. rufoniger group, along with a specimen from just outside the Top End. We recognize a total of 30 species among the sequenced specimens from the Top End, based on marked CO1 divergence (mean > 9%) in association with morphological differentiation and/or sympatric distribution. The sequenced specimen from just outside the Top End represents an additional species. Our unpublished CO1 data from other specimens from elsewhere in monsoonal Australia indicate that all but two of the 30 sequenced Top End species are endemic to the region, and that such diversity and endemism are similar in both the Kimberley region of far northern Western Australia and in North Queensland. The total number of species in the M. rufoniger group is potentially more than the 93 total species of Melophorus recognized in the recent revision. It has previously been estimated that Melophorus contains at least 1000 species, but our findings suggest that this is a conservative estimate. Full article
(This article belongs to the Special Issue Diversity, Biogeography and Community Ecology of Ants)
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Open AccessArticle
An Assessment of the Influence of Host Species, Age, and Thallus Part on Kelp-Associated Diatoms
Diversity 2020, 12(10), 385; https://doi.org/10.3390/d12100385 - 08 Oct 2020
Viewed by 684
Abstract
Diatom community composition and abundances on different thallus parts of adult and juvenile specimens of Eckloniamaxima and Laminariapallida were examined in False Bay, South Africa, using light and scanning electron microscopy. Altogether, 288 thallus portions were analysed. Diatom abundances ranged from [...] Read more.
Diatom community composition and abundances on different thallus parts of adult and juvenile specimens of Eckloniamaxima and Laminariapallida were examined in False Bay, South Africa, using light and scanning electron microscopy. Altogether, 288 thallus portions were analysed. Diatom abundances ranged from 0 to 404 cells mm−2 and were generally higher on E. maxima and juvenile thalli than L. pallida and adult specimens. Moreover, diatom abundances differed between the various thallus parts, being highest on the upper blade and lowest on the primary blade. A total of 48 diatom taxa belonging to 28 genera were found. Gomphoseptatum Medlin, Nagumoea Witkowski and Kociolek, Cocconeis Ehrenberg, and Navicula Bory were the most frequently occurring genera, being present in 84%, 65%, 62.5%, and 45% of the analysed samples, respectively. Among these, Cocconeis and Gomphoseptatum were the most abundant, contributing 50% and 27% of total diatom cells counted collectively across all samples. Permutational multivariate analysis of variance (PERMANOVA) revealed that all investigated main factors (kelp species and age and thallus part), as well as their two- and three-way interactions, except for the interaction between the host species and age, were significant. The high residual variance (72%) indicated that the sum of other unexamined factors contributed the largest component of the variation observed in the kelp-associated diatom communities, and grazing and possible defence strategies utilised by kelps are proposed as processes playing an important role in the structuring of epiphytic diatom communities. Possible endophytism of tissue-boring diatoms colonizing both kelp species is briefly discussed. Full article
(This article belongs to the Special Issue Taxonomy, Ecology and Biogeography of Diatoms)
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Open AccessArticle
Richness of Primary Producers and Consumer Abundance Mediate Epiphyte Loads in a Tropical Seagrass System
Diversity 2020, 12(10), 384; https://doi.org/10.3390/d12100384 - 07 Oct 2020
Cited by 3 | Viewed by 841
Abstract
Consumer communities play an important role in maintaining ecosystem structure and function. In seagrass systems, algal regulation by mesograzers provides a critical maintenance function which promotes seagrass productivity. Consumer communities also represent a key link in trophic energy transfer and buffer negative effects [...] Read more.
Consumer communities play an important role in maintaining ecosystem structure and function. In seagrass systems, algal regulation by mesograzers provides a critical maintenance function which promotes seagrass productivity. Consumer communities also represent a key link in trophic energy transfer and buffer negative effects to seagrasses associated with eutrophication. Such interactions are well documented in the literature regarding temperate systems, however, it is not clear if the same relationships exist in tropical systems. This study aimed to identify if the invertebrate communities within a tropical, multispecies seagrass meadow moderated epiphyte abundance under natural conditions by comparing algal abundance across two sites at Green Island, Australia. At each site, paired plots were established where invertebrate assemblages were perturbed via insecticide manipulation and compared to unmanipulated plots. An 89% increase in epiphyte abundance was seen after six weeks of experimental invertebrate reductions within the system. Using generalised linear mixed-effect models and path analysis, we found that the abundance of invertebrates was negatively correlated with epiphyte load on seagrass leaves. Habitat species richness was seen to be positively correlated with invertebrate abundance. These findings mirrored those of temperate systems, suggesting this mechanism operates similarly across latitudinal gradients. Full article
(This article belongs to the Special Issue Biodiversity in Seagrass Ecosystems)
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Open AccessArticle
Diatom Diversity on the Skin of Frozen Historic Loggerhead Sea Turtle Specimens
Diversity 2020, 12(10), 383; https://doi.org/10.3390/d12100383 - 05 Oct 2020
Viewed by 839
Abstract
In recent years, biofilm-forming diatoms have received increased attention as sea turtle epibionts. However, most of the research has focused on carapace-associated taxa and communities, while less is known about diatoms growing on sea turtle skin. The current study investigated diatom diversity on [...] Read more.
In recent years, biofilm-forming diatoms have received increased attention as sea turtle epibionts. However, most of the research has focused on carapace-associated taxa and communities, while less is known about diatoms growing on sea turtle skin. The current study investigated diatom diversity on the skin of loggerhead sea turtle heads detached from the carcasses found along the Adriatic coast between 1995 and 2004 and stored frozen for a prolonged period of time. By using both light and scanning electron microscopy we have found diatom frustules in 7 out of 14 analysed sea turtle samples. Altogether, 113 diatom taxa were recorded, with a minimum of seven and a maximum of 35 taxa per sample. Eight taxa, Achnanthes elongata, Berkeleya cf. fennica, Chelonicola sp., Licmophora hyalina, Nagumoea sp., Navicula sp., Nitzschia cf. lanceolata, and Poulinea lepidochelicola exceeded 5% of relative abundance in any one sample. The presumably obligately epizoic diatom taxa, A. elongata, Chelonicola sp., and P. lepidochelicola, dominated in six loggerhead samples, contributing up to 97.1% of the total diatom abundance. These observations suggest that on the sea turtle skin highly specialised taxa gain even greater ecological advantage and dominance over the co-occurring benthic forms than in the carapace biofilms. The suitability of frozen sea turtle skin specimens for diatom analysis and limitations of this approach are discussed. Full article
(This article belongs to the Special Issue Taxonomy, Ecology and Biogeography of Diatoms)
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Open AccessArticle
Strategy for the Removal of Satellite Bacteria from the Cultivated Diatom
Diversity 2020, 12(10), 382; https://doi.org/10.3390/d12100382 - 03 Oct 2020
Viewed by 650
Abstract
Multiple ecological and genetic studies of diatom algae require an axenic culture. However, algae-associated bacterial biofilms often form in diatom-produced mucus, both during creation of monoclonal cultures from single cells and during biomass growth, and they may be difficult to remove. In this [...] Read more.
Multiple ecological and genetic studies of diatom algae require an axenic culture. However, algae-associated bacterial biofilms often form in diatom-produced mucus, both during creation of monoclonal cultures from single cells and during biomass growth, and they may be difficult to remove. In this work, we describe a protocol for removing associated bacteria from a monoclonal culture of Ulnaria danica isolated from Lake Baikal. The axenization strategy involves selecting the latent phase of diatom growth, multiple washes to remove extracellular polymeric substances and bacterial cells, filter deposition, and treatment with antibiotics that are not toxic for diatoms. The absence of bacteria during these stages was controlled by light microscopy with Alcian blue staining for mucus, epifluorescent microscopy with DAPI (4′,6-diamino-2-phenylindole) staining for bacterial DNA, and scanning electron microscopy of the diatom cell surface. High-throughput sequencing of a 16S rRNA fragment, amplified with universal bacterial primers, from total DNA of a final culture failed to detect any bacterial contamination, confirming successful axenization. A detailed comparative description of all stages of our protocol may prove useful in developing axenic cultures of other diatoms for various ecological and genetic studies. Full article
(This article belongs to the Special Issue Taxonomy, Ecology and Biogeography of Diatoms)
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Open AccessArticle
Inter-Habitat Variability in Parrotfish Bioerosion Rates and Grazing Pressure on an Indian Ocean Reef Platform
Diversity 2020, 12(10), 381; https://doi.org/10.3390/d12100381 - 02 Oct 2020
Cited by 1 | Viewed by 771
Abstract
Parrotfish perform a variety of vital ecological functions on coral reefs, but we have little understanding of how these vary spatially as a result of inter-habitat variability in species assemblages. Here, we examine how two key ecological functions that result from parrotfish feeding, [...] Read more.
Parrotfish perform a variety of vital ecological functions on coral reefs, but we have little understanding of how these vary spatially as a result of inter-habitat variability in species assemblages. Here, we examine how two key ecological functions that result from parrotfish feeding, bioerosion and substrate grazing, vary between habitats over a reef scale in the central Maldives. Eight distinct habitats were delineated in early 2015, prior to the 2016 bleaching event, each supporting a unique parrotfish assemblage. Bioerosion rates varied from 0 to 0.84 ± 0.12 kg m−2 yr−1 but were highest in the coral rubble- and Pocillopora spp.-dominated habitat. Grazing pressure also varied markedly between habitats but followed a different inter-habitat pattern from that of bioerosion, with different contributing species. Total parrotfish grazing pressure ranged from 0 to ~264 ± 16% available substrate grazed yr-1 in the branching Acropora spp.-dominated habitat. Despite the importance of these functions in influencing reef-scale physical structure and ecological health, the highest rates occurred over less than 30% of the platform area. The results presented here provide new insights into within-reef variability in parrotfish ecological functions and demonstrate the importance of considering how these interact to influence reef geo-ecology. Full article
(This article belongs to the Special Issue Biodiversity and Ecology of Herbivorous Fish)
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Open AccessArticle
In or Out of the Checklist? DNA Barcoding and Distribution Modelling Unveil a New Species of Crocidura Shrew for Italy
Diversity 2020, 12(10), 380; https://doi.org/10.3390/d12100380 - 02 Oct 2020
Cited by 1 | Viewed by 706
Abstract
The genus Crocidura (Eulipotyphla, Soricidae) is the most speciose genus amongst mammals, i.e., it includes the highest number of species. Different species are distinguished by skull morphology, which often prevents the identification of individuals in the field and limits research on these species’ [...] Read more.
The genus Crocidura (Eulipotyphla, Soricidae) is the most speciose genus amongst mammals, i.e., it includes the highest number of species. Different species are distinguished by skull morphology, which often prevents the identification of individuals in the field and limits research on these species’ ecology and biology. We combined species distribution models and molecular analyses to assess the distribution of cryptic Crocidura shrews in Italy, confirming the occurrence of the greater white-toothed shrew Crocidura russula in the northwest of the country. The molecular identification ascertained the species’ presence in two distinct Italian regions. Accordingly, species distribution modelling highlighted the occurrence of areas suitable for C. russula in the westernmost part of northern Italy. Our results confirm the role of Italy as a mammal hotspot in the Mediterranean; additionally, they also show the need to include C. russula in Italian faunal checklists. To conclude, we highlight the usefulness of combining different approaches to explore the presence of cryptic species outside their known ranges. Since the similar, smaller C. suaveolens may be displaced by the larger C. russula through competitive exclusion, the latter might be the species actually present where C. suaveolens had been reported previously. A comprehensive and detailed survey is therefore required to assess the current distribution of these species. Full article
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Open AccessArticle
Site-Level Variation in Parrotfish Grazing and Bioerosion as a Function of Species-Specific Feeding Metrics
Diversity 2020, 12(10), 379; https://doi.org/10.3390/d12100379 - 02 Oct 2020
Viewed by 979
Abstract
Parrotfish provide important ecological functions on coral reefs, including the provision of new settlement space through grazing and the generation of sediment through bioerosion of reef substrate. Estimating these functions at an ecosystem level depends on accurately quantifying the functional impact of individuals, [...] Read more.
Parrotfish provide important ecological functions on coral reefs, including the provision of new settlement space through grazing and the generation of sediment through bioerosion of reef substrate. Estimating these functions at an ecosystem level depends on accurately quantifying the functional impact of individuals, yet parrotfish feeding metrics are only available for a limited range of sites, species and size classes. We quantified bite rates, proportion of bites leaving scars and scar sizes in situ for the dominant excavator (Cetoscarus ocellatus, Chlorurus strongylocephalus, Ch. sordidus) and scraper species (Scarus rubroviolaceus, S. frenatus, S. niger, S. tricolor, S. scaber, S. psittacus) in the central Indian Ocean. This includes the first record of scar frequencies and sizes for the latter three species. Bite rates varied with species and life phase and decreased with body size. The proportion of bites leaving scars and scar sizes differed among species and increased with body size. Species-level allometric relationships between body size and each of these feeding metrics were used to parameterize annual individual grazing and bioerosion rates which increase non-linearly with body size. Large individuals of C. ocellatus, Ch. strongylocephalus and S. rubroviolaceus can graze 200–400 m2 and erode >500 kg of reef substrate annually. Smaller species graze 1–100 m2 yr−1 and erode 0.2–30 kg yr−1. We used these individual functional rates to quantify community grazing and bioerosion levels at 15 sites across the Maldives and the Chagos Archipelago. Although parrotfish density was 2.6 times higher on Maldivian reefs, average grazing (3.9 ± 1.4 m2 m−2 reef yr−1) and bioerosion levels (3.1 ± 1.2 kg m−2 reef yr−1) were about 15% lower than in the Chagos Archipelago (4.5 ± 2.3 and 3.7 ± 3.0, respectively), due to the dominance of small species and individuals in the Maldives (90% <30 cm length). This demonstrates that large-bodied species and individuals contribute disproportionally to both grazing and bioerosion. Across all sites, grazing increased by 66 ± 5 m2 ha−1 and bioerosion by 109 ± 9 kg ha−1 for every kg increase in parrotfish biomass. However, for a given level of parrotfish biomass, grazing and bioerosion levels were higher on Maldivian reefs than in the Chagos Archipelago. This suggests that small-bodied fish assemblages can maintain ecosystem functions, but only if key species are present in sufficiently high numbers. Full article
(This article belongs to the Special Issue Biodiversity and Ecology of Herbivorous Fish)
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