Estimates Of Species Richness Research Articles

A race against extinction: The challenge to overcome the Linnean amphibian shortfall in tropical biodiversity hotspots

AbstractAimThere is an urgent need to explore, characterize, describe and preserve as many species as possible to prevent their decline. Tropical biodiversity hotspots harbour most of the known land diversity and vast amounts of undiscovered and undescribed species. Here, we quantify the taxonomically unassessed amphibian species richness in Madagascar, one of the best‐studied and explored tropical hotspots worldwide, to identify knowledge gaps and conservation implications.LocationMadagascar.Time PeriodPresent.Major Taxa StudiedAmphibians.MethodsWe used the Madagascar amphibian fauna as a model to unveil neglected diversity by analysing 10,873 mitochondrial sequences using species delimitation algorithms and incorporating all previously published bioacoustics, distributional, morphological and nuclear data with an integrative approach.ResultsBesides the currently described 413 species, we identified 408 divergent lineages. Among this, 310 fit the category of candidate species pending a taxonomic assessment, while 98 are considered deep conspecific lineages. These figures suggest that species richness could be twice as high as represented in the current taxonomy. Geographically, most of these candidate species occur in well‐studied areas within the island.Main ConclusionsDespite being one of the best‐studied and explored tropical countries worldwide for amphibians, we found that many species are awaiting a taxonomic assessment in Madagascar. Paradoxically, this unassessed diversity concentrates on highly explored regions, emphasizing the importance of exploring and inventorying new areas. Our results highlight the magnitude of the Linnean and Wallacean shortfalls, affecting both species richness estimates and the distribution ranges and biogeographic setting known for this fauna. Current conservation efforts should consider this novel diversity and unexplored areas as they will likely harbour yet many new species to be discovered. We expect similar patterns across less studied tropical realms and encourage researchers to perform such studies in different clades before this neglected biodiversity becomes irremediably lost.

Distribution of Sarcophagidae (Diptera, Oestroidea) in Brazilian biomes: richness, endemism, and sampling gaps

ABSTRACT Sarcophagid experts have made several efforts to associate biodiversity data and comprehend where each species occurs, but comprehensive faunal inventories remain scarce. Our aim was to provide a list of distributional patterns and endemic species and allow assessment of the sampling effort conducted within Brazilian biomes. We produced a dataset of Brazilian sarcophagids and overlaid with a biome map, to investigate distributional patterns, endemism and to build species accumulation curves. Additionally, we calculated nonparametric asymptotic species richness estimators and extrapolation of species diversity (Hill numbers). Our dataset comprised 288 sarcophagid species, which 21 were identified as endemic. The biomes with the highest species richness were the Atlantic Rainforest and the Amazon Forest, and no biome exhibited a stabilized asymptotic curve. This is the first proposal of listing Sarcophagidae species by biomes and essential to understand the spatial distribution of this family in Brazil. We present maps and richness estimators that allow identifying gaps and guiding survey planning.

Rodent diversity in an elevation gradient from grassland to pine forest in the Chihuahuan desert ecoregion in North-Western Mexico

Diversity patterns of rodent communities across elevational ranges have been analyzed in the Chihuahuan Desert. However, detailed local variations in community composition and species turnover across these ranges are unknown. Anthropogenic pressures in a landscape differ depending on ecosystem type, and therefore, effective conservation initiatives must incorporate an understanding of where these biotic transitions occur. We estimated the rodent diversity in a prairie-to-mountain continuum of four ecosystem types in the Chihuahuan Desert: oak forest (Quercus spp.), pine forest (Pinus spp.), grasslands, and scrublands. We hypothesized that solid habitat associations of the rodent community in each ecosystem are strong drivers that differentiate community groups across ecosystem types. We speculated that the inherent differences between prairie and mountain ecosystems will likely yield a more significant species turnover than between communities within ecosystem types. We studied the rodent communities in each of the four ecosystem types during the dry, wet, and winter seasons in the Janos Biosphere Reserve in Chihuahua, Mexico, across an elevational range from 1,300 to 2,600 m asl. The grassland rodent communities were subdivided into two groups: those with and those without black-tailed prairie dogs (Cynomys ludovicianus). We estimated species richness, number of dominant species, and species turnover for each ecosystem type across the elevational range. Our study revealed that while the prairie and mountain ecosystems support two distinctly different rodent communities, there were significant differences in community composition in each ecosystem type, except the grassland communities, where the presence/absence of the prairie dogs did not appear to influence community composition. The rodent community in the scrublands was the most species-rich and included all the grassland species and a species shared with oak and pine forests. In contrast, the mountain oak and pine forests were less diverse ecosystems dominated by habitat specialists.

Ecology and molecular analysis of sand flies in Bambuí, Minas Gerais, Brazil: Implications for leishmaniasis surveillance.

Leishmaniasis stands out as a public health problem in the state of Minas Gerais, Brazil, especially in the Midwest region. However, the entomological aspects in several municipalities remain unknown. Therefore, this study aimed to investigate the sand fly fauna in Bambuí, encompassing ecological dynamics and molecular detection of Leishmania. Monthly collections were conducted using CDC light traps from September 2018 to August 2020 across 16 selected points with urban and rural characteristics, chosen based on the coverage area of the Municipal Health Department and the occurrence of canine and human visceral leishmaniasis (VL) cases. Ecological indices of the sand fly population (Chao1, Shannon, Simpson and Pielou) were assessed, and sand fly abundance was correlated to climatic variables (humidity, temperature and rainfall). A total of 8838 specimens representing 17 species within nine genera were collected (estimated species richness by Chao 1 estimator = 17; SE ± 1.8). Predominantly, Lutzomyia longipalpis, Nyssomyia whitmani and Evandromyia cortelezzii constituted approximately 98% of all captured sand flies. While species richness and diversity displayed variations throughout the study, a positive correlation emerged between temperature (p < 0.0001; r = 0.7767), monthly rainfall (p < 0.0001; r = 0.7810) and sand fly abundance. Molecular analysis revealed Leishmania DNA in 2.05% of female sand flies, with the presence of Leishmania infantum in Lu. longipalpis and both Le. infantum and Leishmania braziliensis in Ev. cortelezzii. The entomological data, coupled with the occurrence of autochthonous cases of canine visceral leishmaniasis, offer valuable insights for evidence-based strategies to prevent leishmaniasis in Bambuí.

Optimising species detection probability and sampling effort in lake fish eDNA surveys

Environmental DNA (eDNA) metabarcoding is transforming biodiversity monitoring in aquatic environments. Such an approach has been developed and deployed for monitoring lake fish communities in Great Britain, where the method has repeatedly shown a comparable or better performance than conventional approaches. Previous analyses indicated that 20 water samples per lake are sufficient to reliably estimate fish species richness, but it is unclear how reduced eDNA sampling effort affects richness, or other biodiversity estimates and metrics. As the number of samples strongly influences the cost of monitoring programmes, it is essential that sampling effort is optimised for a specific monitoring objective. The aim of this project was to explore the effect of reduced eDNA sampling effort on biodiversity metrics (namely species richness and community composition) using algorithmic and statistical resampling techniques of a data set from 101 lakes, covering a wide spectrum of lake types and ecological quality. The results showed that reliable estimation of lake fish species richness could, in fact, usually be achieved with a much lower number of samples. For example, in almost 90% of lakes, 95% of complete fish richness could be detected with only 10 water samples, regardless of lake area. Similarly, other measures of alpha and beta-diversity were not greatly affected by a reduction in sample size from 20 to 10 samples. We also found that there is no significant difference in detected species richness between shoreline and offshore sampling transects, allowing for simplified field logistics. This could potentially allow the effective sampling of a larger number of lakes within a given monitoring budget. However, rare species were more often missed with fewer samples, with potential implications for monitoring of invasive or endangered species. These results should inform the design of eDNA sampling strategies, so that these can be optimised to achieve specific monitoring goals.

Diversity and Distribution of Monocot Understory Herbs during Tropical Forest Succession in Northeastern Costa Rica

Broad-leaved monocot herbs form one of the most common and diverse growth forms of Neotropical plants. Their significance and frequency of occurrence is particularly notable in the understories of tropical rainforests, where they form a dominant element. We assessed and quantified changes in the cover and diversity of understory herb communities in a chronosequence of 1 ha permanent plots established as part of a multidisciplinary study on tropical forest regeneration in the Atlantic lowlands of northeastern Costa Rica. Sampled were two young stands cleared 12 years ago, two secondary forests with 21 and 39 of years of recovery since clearance, and two stands in old-growth primary forest. Changes in species composition during succession were assessed using Chao’s Jaccard similarity index. Observed species richness ranged from 15 to 26 species in individual plots, with the greatest number of species in the 21-year intermediate-age and fewest in the young 12-year plots. Herb species sampled represented 6 families, 15 genera, and 39 species, with the Araceae contributing the largest number of species. Ten species were sampled in all six stands, while fourteen species were found exclusively in one plot. Herb density (ramets m−2) showed a hump-shade trend, with peak density in the intermediate stands and a lower level in mature and young secondary forests. Mean herb cover in 25 m2 quadrats ranged from 2.0% (young stand) to 22.7% (intermediate-age stand) and differed significantly both among stand types and among sites. Both observed and estimated species richness increased along the chronosequence as a whole, with the highest number of species in primary forest, although only slightly higher than in intermediate-age stands. Over half of the species exhibited some degree of clonal growth, with the extent of clonal spread varying among species and forest stands. Although we did not find a clear pattern between clonality and forest age, we observed a greater number of clonal patches in secondary over primary forest stands.

Slugs Count: Assessing citizen scientist engagement and development, and the accuracy of their identifications

Abstract How accurately can citizen science participants identify species, and can the information they provide be used to calculate accurate estimates of species richness, abundance and diversity measures? In this paper, we address these questions using data from a citizen science project assessing slug species diversity in gardens. Sixty participants were selected from over 2700 applicants across Britain to sample their gardens regularly for slugs following a standardised method. All slugs collected during the 30‐min search were posted to the lead investigator for verification throughout the 12‐month project. The resulting data were analysed to explore how accurate participants were in identifying slugs and whether this improved over the study period. Prior experience in slug identification was evaluated as a predictor of accuracy. Participants overestimated slug abundance and species richness, which led to overestimates in species diversity indices, illustrating the importance of verification in citizen science projects involving identification. Accuracy of slug identifications increased significantly over time in quantitative analysis of ecological data. However, self‐defined prior experience of identifying slugs before participation was not a good predictor of participant accuracy. Participants reported perceived improvement in slug identification skills to an evaluation survey after the project. However, confidence in identifying and explaining identification of slugs was lower than confidence in understanding and explaining other new science topics. This citizen science approach, including expert verification of physical specimens, illustrates how this method can be used successfully to provide accurate data on species' abundance and richness, alongside improving identification skills among the public for an understudied taxon. Continued engagement and feedback for participants is key in retaining citizen science participation in a project of this type, particularly if the taxon is challenging to identify correctly to species. Read the free Plain Language Summary for this article on the Journal blog.

Two listeners detect slightly more birds than a single listener when interpreting acoustic recordings

ABSTRACT Acoustic recorders are increasingly important for monitoring bird populations and have potential to augment existing monitoring programs such as the North American Breeding Bird Survey (BBS). An advantage of acoustic recordings is that they can be reviewed multiple times by multiple experts, potentially yielding improved estimates of species abundance and community richness. Yet, few studies have examined how frequently successive listeners disagree on acoustic interpretations and how strongly estimates of species richness and abundance are altered when multiple experts review each recording. We assigned multiple expert listeners to interpret recordings at 690 BBS stops, and subsequently assigned second listeners to conduct a review of first listeners’ interpretations. We examined the extent to which listeners agreed with each other and quantified the effect of disagreements on resultant estimates of species occurrence, abundance, and stop-level richness. We also compared estimates from acoustic recordings to those obtained during simultaneous field surveys. Estimates were highly correlated for number of species per stop (r = 0.92) and detection probabilities of species (r = 0.97) based on first and second-listener data. Second listeners disagreed with ~9% of first listeners’ interpretations and added an average of ~15% additional species and 16% additional birds not reported by first listeners. Estimates based on acoustic recordings were also highly correlated with those obtained from field surveys, though listeners were unable to count flocks. A single expert reviewer can provide a reasonable approximation of the relative abundance and species composition of birds available for acoustic detection during BBSs. However, acoustic review by multiple listeners may still be important for species that are rare, difficult to identify, or of high conservation concern.

Species richness and evenness of European bird communities show differentiated responses to measures of productivity.

Understanding patterns of species diversity is crucial for ecological research and conservation, and this understanding may be improved by studying patterns in the two components of species diversity, species richness and evenness of abundance of species. Variation in species richness and evenness has previously been linked to variation in total abundance of communities as well as productivity gradients. Exploring both components of species diversity is essential because these components could be unrelated or driven by different mechanisms. The aim of this study was to investigate the relationship between species richness and evenness in European bird communities along an extensive latitudinal gradient. We examined their relationships with latitude and Net Primary Productivity, which determines energy and matter availability for heterotrophs, as well as their responses to territory densities (i.e. the number of territories per area) and community biomass (i.e. the bird biomass per area). We applied a multivariate Poisson log-normal distribution to unique long-term, high-quality time-series data, allowing us to estimate species richness of the community as well as the variance of this distribution, which acts as an inverse measure of evenness. Evenness in the distribution of abundance of species in the community was independent of species richness. Species richness increased with increasing community biomass, as well as with increasing density. Since both measures of abundance were explained by NPP, species richness was partially explained by energy-diversity theory (i.e. the more energy, the more species sustained by the ecosystem). However, species richness did not increase linearly with NPP but rather showed a unimodal relationship. Evenness was not explained either by productivity nor by any of the aspects of community abundance. This study highlights the importance of considering both richness and evenness to gain a better understanding of variation in species diversity. We encourage the study of both components of species diversity in future studies, as well as use of simulation studies to verify observed patterns between richness and evenness.

Estimating bee distributions and their functional range to map important areas for protecting bee species and their functions

The decline of wild bee populations causes the decline of bee-pollinated plant populations through the deterioration of pollination services. Since high bee species richness generally involves high functional group diversity, protecting areas of high bee species richness will help to maintain pollination services for plants. However, those areas do not always include the habitats of bee species with specialized functions that expand the range of plants being pollinated. To map important areas for protecting native bee species and their functions, we estimated the distributions and functional range of 13 bumble bee species and 1 honey bee species in Japan. The distributions were estimated from an ensemble of six species distribution models using bee occurrence data and environmental data. The functional range of bee species was estimated by combining the estimated distributions and proboscis length, which frequently corresponds to the floral shape of the plant species they pollinate. The estimated species richness was high in western Hokkaido and the estimated functional range was wide in central Honshu. Our method is useful to see whether areas important for high species richness of pollinators differ from those for rare species or their functions.

Fungi and deadwood diversity: A test of the area‐heterogeneity trade‐off hypothesis

Abstract Environmental heterogeneity is one of the most fundamental drivers of species diversity. For decades, ecologists have suggested that heterogeneity–diversity relationships are generally positive. But today, a greater variety of heterogeneity–diversity relationships is discussed. In this study, we contrasted two hypotheses for wood‐inhabiting fungi: The classical heterogeneity–diversity hypothesis, which predicts positive relationships due to an increase in niche dimensionality with increasing heterogeneity. And the more recently stated area‐heterogeneity trade‐off hypothesis, that predicts a unimodal pattern due to an inherent trade‐off between the number of occupied niches and the effective area per species. It allows positive and negative relationships only as special cases. We sampled 3715 deadwood objects on 135 plots along a forest structure gradient in the Black Forest, Germany, and recorded 284 wood‐inhabiting fungal species. To assess heterogeneity of deadwood structures, we calculated two multidimensional structural diversity indices: Structural richness was used as a measure of available niche space, and structural divergence as a measure of multivariate variance within that niche space. Those indices were then related to species richness estimates for rare, common and dominant species using the framework of Hill numbers. We found a linear, positive effect of structural richness and a unimodal effect for structural divergence on estimated species diversity. Structural richness, but not structural divergence, was strongly correlated with the number of sampled deadwood objects. No clear differences between the responses of rare, common and dominant species to the two heterogeneity gradients were found. We also estimated the mean abundance as a proxy for mean population size, which decreased significantly with structural richness but was non‐significantly related to structural divergence. Synthesis. In general, the results of this study suggest a unimodal heterogeneity–diversity relationship for deadwood‐inhabiting fungi and are thereby in line with the area‐heterogeneity trade‐off hypothesis. Thus, the negative effect of heterogeneity should lead to lower species richness and a higher risk of stochastic extinctions at high levels of heterogeneity. However, as deadwood amount and deadwood diversity are often strongly correlated, we argue that the positive effect of resource availability on species richness may mask the negative effect of structural heterogeneity in some cases.

Diversity, habitat and activity patterns of mesocarnivore assemblages in an Afrotropical protected forest savannah mosaic of Central Cameroon

AbstractLittle is known about the diversity and ecology of mesocarnivores in the Mpem and Djim National Parks in central Cameroon. Therefore, we undertook a rapid assessment using camera traps from September 2021 to December 2021. The main objective of our study was to collect data on the diversity, abundance and relative frequency of mesocarnivores per habitat type and their activity period using camera traps with a distance sampling method. In 1700 trap nights, we recorded 53 events of seven mesocarnivores, all belonging to the family of Viveridae, Herpesdidae and Felidae which yield 3.12 mesocarnivores per 100 days. The black‐legged mongoose (Bdeogale nigripes, Pucheran, 1855) exhibited the highest capture rate (CR, 0.88). The long‐nosed mongoose (Xenogale naso, Winton, 1901) was found in all habitats class and was the more active mesocarnivore. The Shannon‐Weaver diversity index (H) showed a high diversity of species in the community with high diversity in the near primary forest. We obtained a lower dominance of one species over the other, a lower richness and a more even distribution of species between habitats. Our results suggest a possible spatio‐temporal niche partitioning between the species recorded, with blotched genet (Genetta maculata, Gray, 1830), showing no clear peak of activity. However, the rarefaction curve indicates that the effort expended was insufficient, suggesting that additional sampling is required to obtain a reasonable estimate of species richness within our community. The activity patterns of the recorded mesocarnivores were generally similar to those reported elsewhere but suggest some behavioural flexibility. Although all these species are listed as Least Concern by the IUCN, the low number of recorded events may indicate that mesocarnivores may be threatened in this area if effective conservation strategies are not implemented.

Environmental DNA reveals ecologically relevant spatial and temporal variation in fish assemblages between estuaries and seasons

Estuarine ecosystems are threatened by numerous anthropogenic pressures. Fish assemblages are a dominant component of estuarine macrofauna and serve as indicators for the health of these transitional water ecosystems. Environmental DNA (eDNA) metabarcoding is increasingly used to assess the biodiversity of fishes in estuaries. However, there is a need to further establish how effective eDNA metabarcoding can be relative to conventional fish sampling methods across multiple estuaries and seasons. This study compared fish assemblages detected via eDNA metabarcoding of surface water samples to contemporary sampling with conventional fishing gears in three temperate estuaries (UK), during early summer and autumn. Most species caught by fishing were detected by eDNA. Species richness estimates from eDNA were two to ten times higher than estimates based on fishing, and included taxa of conservation importance and a non-native species. The eDNA assemblage composition was significantly different to the assemblage detected by seine nets. Importantly, eDNA methods could effectively discriminate between fish assemblages of different estuaries and seasons. Fish assemblages in estuaries are often not monitored due to resource constraints. The dynamic nature of estuaries may make fishing gear deployment difficult and inconsistent. The findings indicate that eDNA metabarcoding is suited to gathering large amounts of information on fish biodiversity, at a relatively low sampling effort, compared to established fishing methods. Therefore, eDNA shows promise as an assessment tool for fish assemblage structure and ecosystem health in estuarine environments, with application to statutory monitoring.

Different diversity patterns of butterfly and moth assemblages between deciduous and evergreen broad-leaf forests

In this study, we compared the diversity and abundance of two groups of Lepidopteran insects—butterflies and moths—across deciduous (DBL) and evergreen broad-leaved (EBL) tree communities in warm temperate forests. Over three years (from 2018 to 2020) at the Wando Arboretum, we used transect and point methods to sample butterflies and light traps to sample moths. Our findings revealed that the total estimated species richness was higher in EBL compared to DBL. Non-metric multidimensional scaling (NMDS) analysis confirmed distinct moth assemblages between the two tree communities, while butterfly assemblages did not exhibit such separation. The seasonal diversity patterns of butterflies in both forests differed significantly, whereas those of moths exhibited a similar trend with a peak in June. Beta diversity components indicated high turnover rates in moth assemblages across both tree communities and high nestedness in butterfly assemblages within the DBL. Although the diet breadth of butterflies and moths did not significantly differ between the two tree communities, the number of butterfly species per host plant was higher in DBL and that of moths was higher in EBL. Considering the ongoing vegetation transition from DBL to EBL, changes in forest structure—such as canopy openness and tree density—may adversely impact insect communities within DBL.

Data coverage, biases, and trends in a global citizen‐science resource for monitoring avian diversity

AbstractAimUnderstanding and addressing the global biodiversity crisis requires ecological information compiled continuously from across the globe. Data from citizen science initiatives are useful for quantifying species' ecological niches and geographical distributions but can be difficult to apply towards biodiversity monitoring. The presence of fixed geographical locations reduces the opportunistic nature of citizen science data, allowing for more reliable and nuanced trend estimation. The eBird citizen‐science program contains predefined locations whose bird assemblages are sampled across years (‘hotspots’). For hotspots to function as a biodiversity monitoring resource, issues related to data coverage, biases, and trends need to be addressed.LocationGlobal.MethodsWe estimated the survey completeness of species richness at 300,500 eBird hotspots during 2002–2022. We documented sampling biases at eBird hotspot and non‐hotspot locations during 2022 based on protection status, temperature, precipitation, and landcover.ResultsA total of 10,410 bird species (ca. 96.9% of total) were recorded at hotspots. The number of hotspots, checklists, and participants and the quality of species richness estimates increased worldwide with the Nearctic containing the strongest and most consistent trends. Compared to non‐hotspots, hotspots oversampled areas with higher protection status. Hotspots and non‐hotspots oversampled warmer and wetter locations in the Antarctic, Nearctic, and Palearctic, and cooler locations in the Afrotropics, Australasia, and the Neotropics. Hotspots and especially non‐hotspots oversampled urban areas. Hotspots and non‐hotspots undersampled shrublands in Australasia. Hotspots and especially non‐hotspots undersampled forests in the Afrotropics, Indomalaya, Neotropics, and Oceania.Main ConclusionsHotspots have captured a large component of the world's avian diversity but have done so inconsistently across space and time. Data quantity and quality are increasing in many regions, but the presence of regionally specific sampling biases and spatial uncertainty in hotspot locations should be addressed when applying the data.

Nested plot designs used in forest inventory do not accurately capture tree species richness in Southwestern European forests

Key messageNested plot designs with concentric plots with increasing radii and size threshold underestimate tree species richness with respect to full census sampling with no tree size restrictions. Regeneration emerged as the most relevant pool for tree species richness estimation.ContextNested or concentric plot designs, where trees are sampled according to their size and position, are common in National Forest Inventories (NFI) to reduce the sampling effort. However, this could bias the estimation of tree diversity such as species richness.AimsThe main goal of this study is to quantify the effect of the nested plot designs with increasing radii and diameter at breast height threshold on the number of tree species as well as to provide values for mean tree species richness per plot at the forest-type level using the Spanish NFI.MethodsWe compared tree species richness according to the Spanish NFI nested plot design (radii ranging from 5 to 25 m with increasing minimum threshold in dbh from 7.5 to 42.5 cm as well as the regeneration compartment) with the richness estimate based on a full census (without restrictions in the location or size) in the Spanish NFI 25 m radius plot.ResultsOur results confirmed the underestimation of tree species richness (around 32.5%) when using the nested design. The species omitted in the nested design sampling are often subordinates, typically with small diameters. Regeneration emerged as the main pool for tree species richness estimation. This pattern holds across the main forest types, indicating that it is a generalized rather than regional or local phenomenon.ConclusionWe strongly recommend using full census data for assessing tree species richness whenever available, as relying solely on nested designs can significantly underestimate tree species richness.

First Account of Epibiotic Diatom Taxa from the Carapaces of Green Swimming Crab Callinectes bellicosus (Stimpson 1859) (Decapoda, Portunidae)

Diatoms are among the most common epibionts and have been recorded on the surfaces of various living substrates, either plants or animals. However, studies on them are still scarce in view of the many substrata available. In this study, epibiotic diatoms living on Callinectes bellicosus were identified for the first time from a subtropical coastal lagoon in Northwest Mexico. We tested the null hypothesis that the diatom flora living on the carapaces of C. bellicosus would not be similar to that recorded for mangrove sediments, its typical habitat. The epibiotic diatoms were brushed off from the carapaces of two specimens, acid-cleaned, mounted in synthetic resin, and identified based on frustule morphology. This way, 106 taxa from 46 genera were recorded, including 25 singletons, and 6 new records for the Mexican northwest region. The best-represented genera were Nitzschia (10 taxa), Mastogloia (9), Diploneis (8), Navicula (7), Amphora (5), Cocconeis (5), Tryblionella (4), and Gyrosigma (4). Species composition included 93% of local taxa, thus refuting the proposed hypothesis and supporting the alternate one. Although the estimated species richness was lower than that in sediments, it deems the green crab carapace a favorable substrate for the growth of benthic diatoms.

Of sea, rivers and symbiosis: Diversity, systematics, biogeography and evolution of the deeply diverging florideophycean order Hildenbrandiales (Rhodophyta)

The Hildenbrandiales, a typically saxicolous red algal order, is an early diverging florideophycean group with global significance in marine and freshwater ecosystems across diverse temperature zones. To comprehensively elucidate the diversity, phylogeny, biogeography, and evolution of this order, we conducted a thorough re-examination employing molecular data derived from nearly 700 specimens. Employing a species delimitation method, we identified Evolutionary Species Units (ESUs) within the Hildenbrandiales aiming to enhance our understanding of species diversity and generate the first time-calibrated tree and ancestral area reconstruction for this order. Mitochondrial cox1 and chloroplast rbcL markers were used to infer species boundaries, and subsequent phylogenetic reconstructions involved concatenated sequences of cox1, rbcL, and 18S rDNA. Time calibration of the resulting phylogenetic tree used a fossil record from a Triassic purportedly freshwater Hildenbrandia species and three secondary time points from the literature. Our species delimitation analysis revealed an astounding 97 distinct ESUs, quintupling the known diversity within this order. Our time-calibration analysis placed the origin of Hildenbrandiales (crown age) in the Ediacaran period, with freshwater species emerging as a monophyletic group during the later Permian to early Triassic. Phylogenetic reconstructions identified seven major clades, experiencing early diversification during the Silurian to Carboniferous period. Two major evolutionary events—colonization of freshwater habitats and obligate systemic symbiosis with a marine fungus—marked this order, leading to significant morphological alterations without a commensurate increase in species diversification. Despite the remarkable newly discovered diversity, the extant taxon diversity appears relatively constrained when viewed against an evolutionary timeline spanning over 800 million years. This limitation may stem from restricted geographic sampling or the prevalence of asexual reproduction. However, species richness estimation and rarefaction analyses suggest a substantially larger diversity yet to be uncovered—potentially four times greater. These findings drastically reshape our understanding of the deeply diverging florideophycean order Hildenbrandiales species diversity, and contribute valuable insights into this order's evolutionary history and ecological adaptations. Supported by phylogenetic, ecological and morphological evidence, we established the genus Riverina gen. nov. to accommodate freshwater species of Hildenbrandiales, which form a monophyletic clade in our analyses. This marks the first step toward refining the taxonomy of the Hildenbrandiales, an order demanding thorough revisions, notably with the creation of several genera to address the polyphyletic status of Hildenbrandia. However, the limited diagnostic features pose a challenge, necessitating a fresh approach to defining genera. A potential solution lies in embracing a molecular systematic perspective, which can offer precise delineations of taxonomic boundaries.

Wetland Creation and Reforestation of Legacy Surface Mines in the Central Appalachian Region (USA): A Potential Climate-Adaptation Approach for Pond-Breeding Amphibians?

Habitat restoration and creation within human-altered landscapes can buffer the impacts of climate change on wildlife. The Forestry Reclamation Approach (FRA) is a coal surface mine reclamation practice that enhances reforestation through soil decompaction and the planting of native trees. Recently, wetland creation has been coupled with FRA to increase habitat available for wildlife, including amphibians. Our objective was to evaluate the response of pond-breeding amphibians to the FRA by comparing species occupancy, richness, and abundance across two FRA age-classes (2–5-year and 8–11-year reclaimed forests), traditionally reclaimed sites that were left to naturally regenerate after mining, and in mature, unmined forests in the Monongahela National Forest (West Virginia, USA). We found that species richness and occupancy estimates did not differ across treatment types. Spotted Salamanders (Ambystoma maculatum) and Eastern Newts (Notophthalmus viridescens) had the greatest estimated abundances in wetlands in the older FRA treatment. Additionally, larger wetlands had greater abundances of Eastern Newts, Wood Frogs (Lithobates sylvaticus), and Green Frogs (L. clamitans) compared to smaller wetlands. Our results suggest that wetland creation and reforestation increases the number of breeding sites and promotes microhabitat and microclimate conditions that likely maximize the resilience of pond-breeding amphibians to anticipated climate changes in the study area.

Controlling the effects of sampling bias in biodiversity models

AbstractAimSampling bias and gaps have a direct influence on the perceived patterns of biodiversity, hence limiting our ability to make well‐informed decisions about biodiversity conservation. Yet most methods either disregard or underestimate the effects of sampling bias and gaps in modelling biodiversity patterns. Our objective is to test the sensitivity of commonly used methods for modelling biodiversity dimensions (richness, endemism, and beta diversity) to sampling bias and collection gaps, and as a way to mitigate those effects we introduce a novel approach that employs the sampling effort to minimize the effects of collection bias and gaps in biodiversity models.LocationSouth America.MethodsHere, we use controlled simulations of virtual species distribution and sampling effort to test the sensitivity to sampling bias and collection gaps by commonly used methods, that is, species distribution models (SDMs), spatial interpolation (SI), and environmental prediction (EP), for estimating species richness, endemism, and beta diversity. Our research contributes to advancing biodiversity modelling by introducing a novel approach, named uniform sampling from sampling effort (USSE), that employs the sampling effort to minimize the effects of collection bias and gaps.Results and Main ConclusionsEP with USSE has proven effective in accurately predicting species richness, especially in scenarios in which the sampling effort does not coincide with the biodiversity niches. It outperformed SI and SDMs. The latter performed poorly, yielding the lowest predictive score. In estimating endemism and beta diversity, all methods yielded similar results, without statistically significant differences. For estimating beta diversity, the generalized dissimilarity model proved to be a robust method, even in face of biased sampling. Controlled simulations are key to testing biodiversity methods. These tests can isolate confounding factors inherent to real‐world data, enabling robust methodological assessments. Although fieldwork and curation of collections must remain indispensable, novel biodiversity methods could help overcome the limitations of sampling biases, helping expedite conservation actions much needed.