Rapid reorganization of global biodiversity

Gaps and opportunities in modelling human influence on species distributions in the Anthropocene

Understanding species distributions is a global priority for mitigating environmental pressures from human activities. Ample studies have identified key environmental (climate and habitat) predictors and the spatial scales at which they influence species distributions. However, regarding human influence, such understandings are largely lacking. Here, to advance knowledge concerning human influence on species distributions, we systematically reviewed species distribution modelling (SDM) articles and assessed current modelling efforts. We searched 12,854 articles and found only 1,429 articles using human predictors within SDMs. Collectively, these studies of >58,000 species used 2,307 unique human predictors, suggesting that in contrast to environmental predictors, there is no 'rule of thumb' for human predictor selection in SDMs. The number of human predictors used across studies also varied (usually one to four per study). Moreover, nearly half the articles projecting to future climates held human predictors constant over time, risking false optimism about the effects of human activities compared with climate change. Advances in using human predictors in SDMs are paramount for accurately informing and advancing policy, conservation, management and ecology. We show considerable gaps in including human predictors to understand current and future species distributions in the Anthropocene, opening opportunities for new inquiries. We pose 15 questions to advance ecological theory, methods and real-world applications.

Synthesis reveals approximately balanced biotic differentiation and homogenization

It is commonly thought that the biodiversity crisis includes widespread declines in the spatial variation of species composition, called biotic homogenization. Using a typology relating homogenization and differentiation to local and regional diversity changes, we synthesize patterns across 461 metacommunities surveyed for 10 to 91 years, and 64 species checklists (13 to 500+ years). Across all datasets, we found that no change was the most common outcome, but with many instances of homogenization and differentiation. A weak homogenizing trend of a 0.3% increase in species shared among communities/year on average was driven by increased numbers of widespread (high occupancy) species and strongly associated with checklist data that have longer durations and large spatial scales. At smaller spatial and temporal scales, we show that homogenization and differentiation can be driven by changes in the number and spatial distributions of both rare and common species. The multiscale perspective introduced here can help identify scale-dependent drivers underpinning biotic differentiation and homogenization.

Impacts of landscape pattern on plants diversity and richness of 20 restored wetlands in Chaohu Lakeside of China

The recovery of wetland function and biodiversity conservation aroused considerable interest in the past decades. Although many advances have been achieved in revealing disturbing factors on plants diversity, the knowledge of biodiversity manipulation, landscape configuration and ecosystem process in restored wetlands remains incomplete. To address this issue, the landscape of 20 restored wetlands' vegetation was classified into five vegetation formations including: upland plants, wet grassland, emergent plants, floating plants and submerged plants. Meanwhile, the configuration of landscape, plants' function traits and the structure of plants communities of each wetland were analyzed. A total of 142 herbaceous plants were identified from 399 samples of 20 lakeside wetlands. The top five predominant species were Typha orientalis, Alternanthera philoxeroides, Phragmites australis, Echinochloa caudata, and Erigeron canadensis. The highest of diversity index was observed in upland plants with Shannon-Wiener index (H) of 0.92 while higher richness of plants was obtained in wet grassland with species of 88. In dry year, the immigration of upland xerophyte and obligated aquatic species to facultative area increased the biodiversity of the ecotone. Meanwhile, this change may also aggravate the diffusion risk of exotic invasive species Erigeron canadensis. Additionally, the results indicated that number and evenness of landscape outweighed Shannon diversity index (SHDI) of wetlands in shaping the richness and diversity of wetland plants. Whereas, the high value of maximum proportion of landscape (Pmax) have reduced the landscape evenness and species richness. A suggested Pmax of <0.5 was benefit for the stability and biodiversity of restored wetlands.

Can we meaningfully estimate the impacts of climate on zooplankton biodiversity? A review on uses and limitations of marine time series

Climate events compromise ecosystems functioning and services. Marine zooplankton play a key role linking primary producers and higher consumers, in the carbon export to deeper regions, and respond quickly to environmental change. We conducted a systematic review to assess the effects of climate on marine zooplankton diversity. We describe the major findings, uses and limitations raised in the literature from worldwide time series ≥5 years. Thirty-five studies were included and only 6 presented extractable data (i.e., those that could be extracted from images) for the most studied group (i.e., copepods). Responses to climate were conflicting, and studies were mostly restricted to the global north, applied richness, alpha- and beta-diversity equally, and had a large number of unresolved taxonomic identification. Standardized open long-term data would meaningfully help unveiling assemblage reorganization and allow meta-analyses to improve our understanding of the effects of climate change and variability on zooplankton biodiversity.

Monitoring mosquito richness in an understudied area: can environmental DNA metabarcoding be a complementary approach to adult trapping?

Mosquito surveillance programmes are essential to assess the risks of local vector-borne disease outbreaks as well as for early detection of mosquito invasion events. Surveys are usually performed with traditional sampling tools (i.e., ovitraps and dipping method for immature stages or light or decoy traps for adults). Over the past decade, numerous studies have highlighted that environmental DNA (eDNA) sampling can enhance invertebrate species detection and provide community composition metrics. However, the usefulness of eDNA for detection of mosquito species has, to date, been largely neglected. Here, we sampled water from potential larval breeding sites along a gradient of anthropogenic perturbations, from the core of an oil palm plantation to the rainforest on São Tomé Island (Gulf of Guinea, Africa). We showed that (i) species of mosquitoes could be detected via metabarcoding mostly when larvae were visible, (ii) larvae species richness was greater using eDNA than visual identification and (iii) new mosquito species were also detected by the eDNA approach. We provide a critical discussion of the pros and cons of eDNA metabarcoding for monitoring mosquito species diversity and recommendations for future research directions that could facilitate the adoption of eDNA as a tool for assessing insect vector communities.

Measuring biodiversity from DNA in the air

The crisis of declining biodiversity¹ exceeds our current ability to monitor changes in ecosystems. Rapid terrestrial biomonitoring approaches are essential to quantify the causes and consequences of global change. Environmental DNA² has revolutionized aquatic ecology,³ permitting population monitoring⁴ and remote diversity assessments matching or outperforming conventional methods of community sampling.^3-5 Despite this model, similar methods have not been widely adopted in terrestrial ecosystems. Here, we demonstrate that DNA from terrestrial animals can be filtered, amplified, and then sequenced from air samples collected in natural settings representing a powerful tool for terrestrial ecology. We collected air samples at a zoological park, where spatially confined non-native species allowed us to track DNA sources. We show that DNA can be collected from air and used to identify species and their ecological interactions. Air samples contained DNA from 25 species of mammals and birds, including 17 known terrestrial resident zoo species. We also identified food items from air sampled in enclosures and detected taxa native to the local area, including the Eurasian hedgehog, endangered in the United Kingdom. Our data demonstrate that airborne eDNA concentrates around recently inhabited areas but disperses away from sources, suggesting an ecology to airborne eDNA and the potential for sampling at a distance. Our findings demonstrate the profound potential of air as a source of DNA for global terrestrial biomonitoring.

The complexity of global change and its effects on insects

Global change includes multiple overlapping and interacting drivers: 1) climate change, 2) land use change, 3) novel chemicals, and 4) the increased global transport of organisms. Recent studies have documented the complex and counterintuitive effects of these drivers on the behavior, life histories, distributions, and abundances of insects. This complexity arises from the indeterminacy of indirect, non-additive and combined effects. While there is wide consensus that global change is reorganizing communities, the available data are limited. As the pace of anthropogenic changes outstrips our ability to document its impacts, ongoing change may lead to increasingly unpredictable outcomes. This complexity and uncertainty argue for renewed efforts to address the fundamental drivers of global change.

Changes in the analysis of temporal community dynamics data: a 29-year literature review

BACKGROUND

Understanding how biological communities change over time is of increasing importance as Earth moves into the Anthropocene. A wide variety of methods are used for multivariate community analysis and are variously applied to research that aims to characterise temporal dynamics in community composition. Understanding these methods and how they are applied is useful for determining best practice in community ecology.

METHODOLOGY

We reviewed the ecological literature from 1990 to 2018 that used multivariate methods to address questions of temporal community dynamics. For each paper that fulfilled our search criteria, we recorded the types of multivariate analysis used to characterise temporal community dynamics in addition to the research aim, habitat type, location, taxon and the experimental design.

RESULTS

Most studies had relatively few temporal replicates; the median number was seven time points. Nearly 70% of studies applied more than one analysis method; descriptive methods such as bar graphs and ordination were the most commonly applied methods. Surprisingly, the types of analyses used were only related to the number of temporal replicates, but not to research aim or any other aspects of experimental design such as taxon, or habitat or year of study.

CONCLUSIONS

This review reveals that most studies interested in understanding community dynamics use relatively short time series meaning that several, more sophisticated, temporal analyses are not widely applicable. However, newer methods using multivariate dissimilarities are growing in popularity and many can be applied to time series of any length.

Cross-continental analysis of coastal biodiversity change

Whereas the anthropogenic impact on marine biodiversity is undebated, the quantification and prediction of this change are not trivial. Simple traditional measures of biodiversity (e.g. richness, diversity indices) do not capture the magnitude and direction of changes in species or functional composition. In this paper, we apply recently developed methods for measuring biodiversity turnover to time-series data of four broad taxonomic groups from two coastal regions: the southern North Sea (Germany) and the South African coast. Both areas share geomorphological features and ecosystem types, allowing for a critical assessment of the most informative metrics of biodiversity change across organism groups. We found little evidence for directional trends in univariate metrics of diversity for either the effective number of taxa or the amount of richness change. However, turnover in composition was high (on average nearly 30% of identities when addressing presence or absence of species) and even higher when taking the relative dominance of species into account. This turnover accumulated over time at similar rates across regions and organism groups. We conclude that biodiversity metrics responsive to turnover provide a more accurate reflection of community change relative to conventional metrics (absolute richness or relative abundance) and are spatially broadly applicable. This article is part of the theme issue 'Integrative research perspectives on marine conservation'.

Integrative research perspectives on marine conservation

Whereas the conservation and management of biodiversity has become a key issue in environmental sciences and policy in general, the conservation of marine biodiversity faces additional challenges such as the challenges of accessing field sites (e.g. polar, deep sea), knowledge gaps regarding biodiversity trends, high mobility of many organisms in fluid environments, and ecosystem-specific obstacles to stakeholder engagement and governance. This issue comprises contributions from a diverse international group of scientists in a benchmarking volume for a common research agenda on marine conservation. We begin by addressing information gaps on marine biodiversity trends through novel approaches and technologies, then linking such information to ecosystem functioning through a focus on traits. We then leverage the knowledge of these relationships to inform theory aiming at predicting the future composition and functioning of marine communities. Finally, we elucidate the linkages between marine ecosystems and human societies by examining economic, management and governance approaches that contribute to effective marine conservation in practice. This article is part of the theme issue 'Integrative research perspectives on marine conservation'.

The World Coral Conservatory (WCC): A Noah's ark for corals to support survival of reef ecosystems

Global change causes widespread decline of coral reefs. In order to counter the anticipated disappearance of coral reefs by the end of this century, many initiatives are emerging, including creation of marine protected areas (MPAs), reef restoration projects, and assisted evolution initiatives. Such efforts, although critically important, are locally constrained. We propose to build a “Noah's Ark” biological repository for corals that taps into the network of the world’s public aquaria and coral reef scientists. Public aquaria will serve not only as a reservoir for the purpose of conservation, restoration, and research of reef-building corals but also as a laboratory for the implementation of operations for the selection of stress-resilient and resistant genotypes. The proposed project will provide a global dimension to coral reef education and protection as a result of the involvement of a network of public and private aquaria.

Global change is causing a widespread decline in coral reefs. This Community Page article proposes to build the World Coral Conservatory, a “Noah's Ark” biological repository that taps into the network of the world’s public aquaria and coral reef scientists, in order to preserve the fast-disappearing biodiversity of coral reefs.