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It is widely acknowledged that biodiversity change is affecting human well-being by altering the supply of Nature's Contributions to People (NCP). Nevertheless, the role of individual species in this relationship remains obscure. In this article, we present a framework that combines the cascade model from ecosystem services research with network theory from community ecology. This allows us to quantitatively link NCP demanded by people to the networks of interacting species that underpin them. We show that this “network cascade” framework can reveal the number, identity and importance of the individual species that drive NCP and of the environmental conditions that support them. This information is highly valuable in demonstrating the importance of biodiversity in supporting human well-being and can help inform the management of biodiversity in social-ecological systems.
Tree-related microhabitats (TReMs) have been proposed as important indicators of biodiversity to guide forest management. However, their application has been limited mostly to temperate ecosystems, and it is largely unknown how the diversity of TReMs varies along environmental gradients. In this study, we assessed the diversity of TReMs on 180 individual trees and 44 plots alongside a large environmental gradient on Kilimanjaro, Tanzania. We used a typology adjusted to tropical ecosystems and a tree-climbing protocol to obtain quantitative information on TreMs on large trees and dense canopies. We computed the diversity of TReMs for each individual tree and plot and tested how TReM diversity was associated with properties of individual trees and environmental conditions in terms of climate and human impact. We further used non-metric multidimensional scaling (NMDS) to investigate the composition of TReM assemblages alongside the environmental gradients. We found that diameter at breast height (DBH) and height of the first branch were the most important determinants of TReM diversity on individual trees, with higher DBH and lower first branch height promoting TReM diversity. At the plot level, we found that TReM diversity increased with mean annual temperature and decreased with human impact. The composition of TReMs showed high turnover across ecosystem types, with a stark difference between forest and non-forest ecosystems. Climate and the intensity of human impact were associated with TReM composition. Our study is a first test of how TReM diversity and composition vary along environmental gradients in tropical ecosystems. The importance of tree size and architecture in fostering microhabitat diversity underlines the importance of large veteran trees in tropical ecosystems. Because diversity and composition of TReMs are sensitive to climate and land-use effects, our study suggests that TReMs can be used to efficiently monitor consequences of global change for tropical biodiversity.
Tree-related microhabitats (TReMs) have been proposed as important indicators of biodiversity to guide forest management. However, their application has been limited mostly to temperate ecosystems, and it is largely unknown how the diversity of TReMs varies along environmental gradients. In this study, we assessed the diversity of TReMs on 180 individual trees and 46 plots alongside a large environmental gradient on Kilimanjaro, Tanzania. We used a typology adjusted to tropical ecosystems and a tree-climbing protocol to obtain quantitative information on TreMs on large trees and dense canopies. We computed the diversity of TReMs for each individual tree and plot and tested how TReM diversity was associated with properties of individual trees and environmental conditions in terms of climate and human impact. We further used non-metric multidimensional scaling (NMDS) to investigate the composition of TReM assemblages alongside the environmental gradients. We found that diameter at breast height (DBH) and height of the first branch were the most important determinants of TReM diversity on individual trees, with higher DBH and lower first branch height promoting TReM diversity. At the plot level, we found that TReM diversity increased with mean annual temperature and decreased with human impact. The composition of TReMs showed high turnover across ecosystem types, with a stark difference between forest and non-forest ecosystems. Climate and the intensity of human impact were associated with TReM composition. Our study is a first test of how TReM diversity and composition vary along environmental gradients in tropical ecosystems. The importance of tree size and architecture in fostering microhabitat diversity underlines the importance of large veteran trees in tropical ecosystems. Because diversity and composition of TReMs are sensitive to climate and land-use effects, our study suggests that TReMs can be used to efficiently monitor consequences of global change for tropical biodiversity.
New U–Pb ages of detrital and igneous zircons of the Uppermost Unit of Crete shed light on its provenance and on Eohellenic to Eoalpine imprints in the eastern Mediterranean. The detrital zircons of all nappes show Variscan ages and are characterized by a Minoan-type age spectrum, which is typical for the NE margin of Gondwana. Parts of the metasedimentary rocks are unexpectedly young. Their detrital zircon ages continue via the Permian until the Late Triassic, Middle Jurassic and Early Cretaceous. The high-grade metamorphic rocks of the Asterousia crystalline complex are likely equivalents of the low-grade metamorphic trench and fore-arc deposits of the Vatos nappe pointing to Late Cretaceous slab roll back. The presence of both late Permian detrital zircons and Late Cretaceous arc-type granitoids suggest that the Uppermost Unit of Crete is derived from the late Permian/Late Cretaceous magmatic belt situated north of the Sava–Vardar–Izmir–Ankara Suture in the Strandja–Rhodope area. To achieve their recent position on Crete, the nappes had to travel more than 500 km. The traveling path is well tracked by rocks of the Upper Cycladic Unit, which are similar to those of the Uppermost Unit of Crete. The large displacement of the Cretan nappes was controlled not only by nappe transport, but probably also by dextral strike–slip along the North Anatolian Fault Zone and related counterclockwise rotation of the Anatolian block since the Eocene.
The taxonomic status of recently described Isophya taxa from Serbia (Tettigoniidae, Phaneropterinae)
(2024)
During recent decades, increasing research of the taxonomy of the genus Isophya resulted in taxonomic descriptions of several new species. The delimitation of these species is mainly based on oscillographic song analysis of the male song in combination with morphological characters, such as the shape of male cerci, tegmina and ovipositor. In the present paper, we used an integrative taxonomic approach in order to resolve the status of four recently described Isophya taxa from Serbia. Based on our molecular and bioacoustic analyses, all analyzed taxa belong to a single species: Isophya modestior. The majority of the morphological characters used to differentiate the taxa showed strong intra- and interpopulational variability, proving that describing new species within the genus Isophya should not rely on morphological characters alone, but needs to consider bioacoustic analyses as the main tool and a larger series of specimens.
Keystone mutualisms, such as corals, lichens or mycorrhizae, sustain fundamental ecosystem functions. Range dynamics of these symbioses are, however, inherently difficult to predict because host species may switch between different symbiont partners in different environments, thereby altering the range of the mutualism as a functional unit. Biogeographic models of mutualisms thus have to consider both the ecological amplitudes of various symbiont partners and the abiotic conditions that trigger symbiont replacement. To address this challenge, we here investigate 'symbiont turnover zones'--defined as demarcated regions where symbiont replacement is most likely to occur, as indicated by overlapping abundances of symbiont ecotypes. Mapping the distribution of algal symbionts from two species of lichen-forming fungi along four independent altitudinal gradients, we detected an abrupt and consistent β-diversity turnover suggesting parallel niche partitioning. Modelling contrasting environmental response functions obtained from latitudinal distributions of algal ecotypes consistently predicted a confined altitudinal turnover zone. In all gradients this symbiont turnover zone is characterized by approximately 12°C average annual temperature and approximately 5°C mean temperature of the coldest quarter, marking the transition from Mediterranean to cool temperate bioregions. Integrating the conditions of symbiont turnover into biogeographic models of mutualisms is an important step towards a comprehensive understanding of biodiversity dynamics under ongoing environmental change.
Highlights
• BaP exposure increases the mutation rate of C. riparius.
• BaP exposure is detrimental for the fitness and the population dynamics of C. riparius.
• Multi-generational studies are essential to assess evolutionary implications of anthropogenic substances on biodiversity.
Abstract
The release of polycyclic aromatic hydrocarbons (PAHs) into the environment is posing a threat to ecosystems and human health. Benzo(a)pyrene (BaP) is considered a biomarker of PAH exposure and is classified as a Group 1 carcinogen. However, it was not known whether BaP is mutagenic, i.e. induces inherited germline mutations. In this study, we used a recently established method, which combines short-term mutation accumulation lines (MAL) with whole genome sequencing (WGS) to assess mutagenicity in the non-biting midge Chironomus riparius. The mutagenicity analysis was supplemented by an evaluation of the development of population fitness in three successive generations in the case of chronic exposure to BaP at a high concentration (100 μg/L). In addition, the level of ROS-induced oxidative stress was examined in vivo. Exposure to the higher BaP concentration led to an increase in germline mutations relative to the control, while the lower concentration showed no mentionable effect. Against expectations, BaP exposure decreased ROS-level compared to the control and is thus probably not responsible for the increased mutation rate. Likewise, the higher BaP concentration decreased fitness measured as population growth rate per day (PGR) significantly over all generations, without signs of rapid evolutionary adaptations. Our results thus highlighted that high BaP exposure may influence the evolutionary trajectory of organisms.
Tree-related microhabitats (TreMs) describe the microhabitats that a tree can provide for a multitude of other taxonomic groups and have been proposed as an important indicator for forest biodiversity (Asbeck et al., 2021). So far, the focus of TreM studies has been on temperate forests, although many trees in the tropics harbour exceptionally high numbers of TreMs. In this study, TreMs in the lowland tropical forests of the Choco (Ecuador) and in the mountain tropical forests of Mount Kilimanjaro (Tanzania) were surveyed. Our results extend the existing typology of TreMs of Larrieu et al. (2018) to include tropical forests and enabled a comparison of the relative recordings and diversity of TreMs between tropical and temperate forests. A new TreM form, Root formations, and three new TreM groups, concavities build by fruits or leaves, dendrotelms, and root formations, were established. In total, 15 new TreM types in five different TreM groups were specified. The relative recordings of most TreMs were similar between tropical and temperate forests. However, ivy and lianas, and ferns were more common in the lowland rainforest than in temperate forests, and bark microsoil, limb breakage, and foliose and fruticose lichens in tropical montane forest than in lowland rainforest. Mountain tropical forests hosted the highest diversity for common and dominant TreM types, and lowland tropical forest the highest diversity for rare TreMs. Our extended typology of tree-related microhabitats can support studies of forest-dwelling biodiversity in tropical forests. Specifically, given the ongoing threat to tropical forests, TreMs can serve as an additional tool allowing rapid assessments of biodiversity in these hyperdiverse ecosystems.
Establishing management programs to preserve the benthic communities along the NW Pacific and the Arctic Ocean (AO) requires a deep understanding of the composition of communities and their responses to environmental stressors. In this study, we thus examine patterns of benthic community composition and patterns of species richness along the NW Pacific and Arctic Seas and investigate the most important environmental drivers of those patterns. Overall we found a trend of decreasing species richness toward higher latitudes and deeper waters, peaking in coastal waters of the eastern Philippines. The most dominant taxa along the entire study area were Arthropoda, Mollusca, Cnidaria, Echinodermata, and Annelida. We found that depth, not temperature, was the main driver of community composition along the NW Pacific and neighboring Arctic Seas. Depth has been previously suggested as a factor driving species distribution in benthic fauna. Following depth, the most influential environmental drivers of community composition along the NW Pacific and the Arctic Ocean were silicate, light, and currents. For example, silicate in Hexactinellida, Holothuroidea, and Ophiuroidea; and light in Cephalopoda and Gymnolaemata had the highest correlations with community composition. In this study, based on a combination of new samples and open-access data, we show that different benthic communities might respond differently to future climatic changes based on their taxon-specific biological, physiological, and ecological characteristics. International conservation efforts and habitat preservation should take an adaptive approach and apply measures that take the differences among benthic communities in responding to future climate change into account. This facilitates implementing appropriate conservation management strategies and sustainable utilization of the NW Pacific and Arctic marine ecosystems.
Peracarid data were collected in the Southern Ocean and South Atlantic Ocean. Sampling was performed during nine different expeditions on board of RRS James Clark Ross and RV Polarstern, using epibenthic sledges (EBS) at depth ranging between 160–6348 m at 109 locations. The correlation between environmental variables and peracarid abundance was investigated. Abundance data comprise a total of 128570 peracarids (52366 were amphipods, 28516 were cumaceans, 36142 isopods, 5676 mysidaceans and 5870 were tanaidaceans). The presented data are useful to investigate the composition and abundance patterns of peracarid orders at a wide depth range and spatial scale in the Southern Ocean. They can also be reused to compare their abundance with that of other taxa in broader ecological surveys.
Bird-mediated seed dispersal is crucial for the regeneration and viability of ecosystems, often resulting in complex mutualistic species networks. Yet, how this mutualism drives the evolution of seed dispersing birds is still poorly understood. In the present study we combine whole genome re-sequencing analyses and morphometric data to assess the evolutionary processes that shaped the diversification of the Eurasian nutcracker (Nucifraga), a seed disperser known for its mutualism with pines (Pinus). Our results show that the divergence and phylogeographic patterns of nutcrackers resemble those of other non-mutualistic passerine birds and suggest that their early diversification was shaped by similar biogeographic and climatic processes. The limited variation in foraging traits indicates that local adaptation to pines likely played a minor role. Our study shows that close mutualistic relationships between bird and plant species might not necessarily act as a primary driver of evolution and diversification in resource-specialized birds.
From hunting and foraging to clearing land for agriculture, humans modify forest biodiversity, landscapes, and climate. Forests constantly undergo disturbance–recovery dynamics and understanding them is a major objective of ecologists and conservationists. Chronosequences are a useful tool for understanding global restoration efforts. They represent a space-for-time substitution approach suited for the quantification of the resistance of ecosystem properties to withstand disturbance and the resilience of these properties until reaching pre-disturbance levels. Here we introduce a newly established chronosequence with 62 plots (50 ⍰ 50 m) in active cacao plantations and pastures, early and late regeneration, and mature old-growth forests, across a 200 km2 area in the extremely wet Chocó rainforest. Our chronosequence covers by far the largest total area of plots compared to others in the Neotropics. Plots ranged from 159–615 masl in a forested landscape with 74 ± 2.8 % forest cover within a 1-km radius including substantial old-growth forest cover. Land-use legacy and regeneration time were not confounded by elevation. We tested how six forest structure variables (maximum tree height and DBH, basal area, number of stems, vertical vegetation heterogeneity, and light availability), aboveground biomass (AGB), and rarefied tree species richness change along our chronosequence. Forest structure variables, AGB, and tree species richness increased with regeneration time and are predicted to reach similar levels to those in old-growth forests after ca. 30–116, 202, and 108 yrs, respectively. Compared to previous work in the Neotropics, old-growth forests in Canandé accumulate high AGB that takes one of the largest time spans reported until total recovery. Our chronosequence comprises one of the largest tree species pools, covers the largest total area of regenerating and old-growth forests, and has higher forest cover than other Neotropical chronosequences. Hence, our chronosequence can be used to determine the time for recovery and stability (resistance and resilience) of different taxa and ecosystem functions, including species interaction networks. This integrative effort will ultimately help to understand how one of the most diverse forests on the planet recovers from large-scale disturbances.
Background: Genome sequencing of all known eukaryotes on Earth promises unprecedented advances in biological sciences and in biodiversity-related applied fields such as environmental management and natural product research. Advances in long-read DNA sequencing make it feasible to generate high-quality genomes for many non–genetic model species. However, long-read sequencing today relies on sizable quantities of high-quality, high molecular weight DNA, which is mostly obtained from fresh tissues. This is a challenge for biodiversity genomics of most metazoan species, which are tiny and need to be preserved immediately after collection. Here we present de novo genomes of 2 species of submillimeter Collembola. For each, we prepared the sequencing library from high molecular weight DNA extracted from a single specimen and using a novel ultra-low input protocol from Pacific Biosciences. This protocol requires a DNA input of only 5 ng, permitted by a whole-genome amplification step.
Results: The 2 assembled genomes have N50 values >5.5 and 8.5 Mb, respectively, and both contain ∼96% of BUSCO genes. Thus, they are highly contiguous and complete. The genomes are supported by an integrative taxonomy approach including placement in a genome-based phylogeny of Collembola and designation of a neotype for 1 of the species. Higher heterozygosity values are recorded in the more mobile species. Both species are devoid of the biosynthetic pathway for β-lactam antibiotics known in several Collembola, confirming the tight correlation of antibiotic synthesis with the species way of life.
Conclusions: It is now possible to generate high-quality genomes from single specimens of minute, field-preserved metazoans, exceeding the minimum contig N50 (1 Mb) required by the Earth BioGenome Project.
The snake pipefish, Entelurus aequoreus (Linnaeus, 1758), is a slender, up to 60 cm long, northern Atlantic fish that dwells in open seagrass habitats and has recently expanded its distribution range. The snake pipefish is part of the family Syngnathidae (seahorses and pipefish) that has undergone several characteristic morphological changes, such as loss of pelvic fins and elongated snout. Here, we present a highly contiguous, near chromosome-scale genome of the snake pipefish assembled as part of a university master’s course. The final assembly has a length of 1.6 Gbp in 7,391 scaffolds, a scaffold and contig N50 of 62.3 Mbp and 45.0 Mbp and L50 of 12 and 14, respectively. The largest 28 scaffolds (>21 Mbp) span 89.7% of the assembly length. A BUSCO completeness score of 94.1% and a mapping rate above 98% suggest a high assembly completeness. Repetitive elements cover 74.93% of the genome, one of the highest proportions so far identified in vertebrate genomes. Demographic modeling using the PSMC framework indicates a peak in effective population size (50 – 100 kya) during the last interglacial period and suggests that the species might largely benefit from warmer water conditions, as seen today. Our updated snake pipefish assembly forms an important foundation for further analysis of the morphological and molecular changes unique to the family Syngnathidae.
Highlights
• Genomes for all five Natrix species, two represented by two distinct subspecies each, were sequenced.
• Two genomes were de-novo assembled to their 1.7 Gb length with a contig N50 of 4.6 Mbp and 1.5 Mbp.
• Evidence for interspecific hybridization, both between allopatric and widely sympatric species.
• Fossil-calibrated molecular clock using genomes indicates that species are ancient several million-year-old lineages.
• Our findings imply that speciation took place despite continued gene flow.
Abstract
Understanding speciation is one of the cornerstones of biological diversity research. Currently, speciation is often understood as a continuous process of divergence that continues until genetic or other incompatibilities minimize or prevent interbreeding. The Palearctic snake genus Natrix is an ideal group to study speciation, as it comprises taxa representing distinct stages of the speciation process, ranging from widely interbreeding parapatric taxa through parapatric species with very limited gene flow in narrow hybrid zones to widely sympatric species. To understand the evolution of reproductive isolation through time, we have sequenced the genomes of all five species within this genus and two additional subspecies. We used both long-read and short-read methods to sequence and de-novo-assemble two high-quality genomes (Natrix h. helvetica, Natrix n. natrix) to their 1.7 Gb length with a contig N50 of 4.6 Mbp and 1.5 Mbp, respectively, and used these as references to assemble the remaining short-read-based genomes. Our phylogenomic analyses yielded a well-supported dated phylogeny and evidence for a surprisingly complex history of interspecific gene flow, including between widely sympatric species. Furthermore, evidence for gene flow was also found for currently allopatric species pairs. Genetic exchange among these well-defined, distinct, and several million-year-old reptile species emphasizes that speciation and maintenance of species distinctness can occur despite continued genetic exchange.
In the vast abyssal plains northwest of Iceland, white glass sponges of the genus Caulophacus Schulze, 1886 were inhabited by reddish Bythocaris G.O. Sars, 1870 shrimps and pinkish amphipods. After in situ observations at 3700 m depth, in -1°C waters by a remotely operated vehicle, members of this assemblage were collected and preserved for molecular studies. Based on integrative taxonomic analyses, the amphipods were identified as a new species of the genus Halirages Boeck, 1871 – Halirages spongiae sp. nov. Lörz, Nack & Tandberg –, as described in detail below. Part of our integrative approach was to establish reference DNA barcodes for known species of Halirages. However, our investigation of material of Calliopiidae G.O. Sars, 1895 collected around Iceland and Norway revealed slight morphological discrepancies in all the described species of Halirages. Except for Halirages fulvocinctus (M. Sars, 1858), none of the encountered specimens of Calliopiidae fully matched a current species description. We illuminate the morphological characteristics of nine operational taxonomic units, which also represented clades in COI and 28S. We set the Icelandic samples in the context of Halirages from Canada and Norway. A key to the world species of Halirages is provided.
Highlights
• Protocol for extracting and analyzing pollen grains from fossil insects
• Individual fossil grains can be analyzed using a combined approach
• Simple and fast TEM embedding and sectioning protocol
• Protocol enables a taxonomic assignment of pollen
Summary
This protocol explains how to extract pollen from fossil insects with subsequent descriptions of pollen treatment. We also describe how to document morphological and ultrastructural features with light-microscopy and electron microscopy. It enables a taxonomic assignment of pollen that can be used to interpret flower-insect interactions, foraging and feeding behavior of insects, and the paleoenvironment. The protocol is limited by the state of the fossil, the presence/absence of pollen on fossil specimens, and the availability of extant pollen for comparison.
Highlights
• Seed size mediates seedling recruitment in tropical forests and pastures.
• Large-seeded species recruited better than small-seeded species in the forest.
• Recruitment of large-seeded species in pastures was limited by surface temperature.
• Large-seeded species should be protected against drought in regenerating pastures.
Abstract
Seedling recruitment is a key process of plant regeneration that often depends on plant functional traits, such as seed size. To optimize forest restoration efforts, we need to better understand how seedling recruitment of different seed sizes varies along environmental gradients with strong variation in abiotic and biotic factors. To understand these interacting effects, we conducted a sowing experiment with different-sized seeds in forests and pastures in the tropical mountains of southern Ecuador. We quantified seedling recruitment in relation to temperature, soil moisture and biotic pressures. We sowed seeds of five tree species of varying seed size at three elevations (1000, 2000 and 3000 m a.s.l.) in primary forest and pastures. We tested (1) how habitat type influences the recruitment of seedlings belonging to three small- and two large-seeded species, and (2) how abiotic and biotic factors limit seedling recruitment of species with different seed sizes. We found that seedlings of the two large-seeded species recruited better than seedlings of the three small-seeded species, but only in the forest habitat. Seedling recruitment of large seeds was primarily limited by high surface temperature, which explains lower recruitment of large seeds in pastures compared to forests. Our study shows that seed size can be a key trait mediating variability in seedling recruitment in tropical ecosystems. We conclude that restoration measures should aim to mitigate extreme temperatures in tropical pastures to aid the natural regeneration of large-seeded tree species.
The tremendous diversity of life in the ocean has proven to be a rich source of inspiration for drug discovery, with success rates for marine natural products up to 4 times higher than other naturally derived compounds. Yet the marine biodiscovery pipeline is characterized by chronic underfunding, bottlenecks and, ultimately, untapped potential. For instance, a lack of taxonomic capacity means that, on average, 20 years pass between the discovery of new organisms and the formal publication of scientific names, a prerequisite to proceed with detecting and isolating promising bioactive metabolites. The need for “edge” research that can spur novel lines of discovery and lengthy high-risk drug discovery processes, are poorly matched with research grant cycles. Here we propose five concrete pathways to broaden the biodiscovery pipeline and open the social and economic potential of the ocean genome for global benefit: (1) investing in fundamental research, even when the links to industry are not immediately apparent; (2) cultivating equitable collaborations between academia and industry that share both risks and benefits for these foundational research stages; (3) providing new opportunities for early-career researchers and under-represented groups to engage in high-risk research without risking their careers; (4) sharing data with global networks; and (5) protecting genetic diversity at its source through strong conservation efforts. The treasures of the ocean have provided fundamental breakthroughs in human health and still remain under-utilised for human benefit, yet that potential may be lost if we allow the biodiscovery pipeline to become blocked in a search for quick-fix solutions.
Mollusca is the second-largest animal phylum with over 100,000 species among eight distinct taxonomic classes. Across 1000 living species in the class Polyplacophora, chitons have a relatively constrained morphology but with some notable deviations. Several genera possess “shell eyes”, true eyes with a lens and retina that are embedded within the dorsal shells, which represent the most recent evolution of animal eyes. The phylogeny of major chiton clades is mostly well established, in a set of superfamily and higher-level taxa supported by various approaches including multiple gene markers, mitogenome-phylogeny and phylotranscritomic approaches as well as morphological studies. However, one critical lineage has remained unclear: Schizochiton was controversially suggested as a potential independent origin of chiton shell eyes. Here, with the draft genome sequencing of Schizochiton incisus (superfamily Schizochitonoidea) plus assembly of transcriptome data from other polyplacophorans, we present phylogenetic reconstructions using both mitochondrial genomes and phylogenomic approaches with multiple methods. Phylogenetic trees from mitogenomic data are inconsistent, reflecting larger scale confounding factors in molluscan mitogenomes. A consistent robust topology was generated with protein coding genes using different models and methods. Our results support Schizochitonoidea is a sister group to other Chitonoidea in Chitonina, in agreement with established classification. This suggests that the earliest origin of shell eyes is in Schizochitonoidea, which were also gained secondarily in other genera in Chitonoidea. Our results have generated a holistic review of the internal relationship within Polyplacophora, and a better understanding on the evolution of Polyplacophora.