Genomic evidence for the widespread presence of GH45 cellulases among soil invertebrates.

Lignocellulose is a major component of vascular plant biomass. Its decomposition is crucial for the terrestrial carbon cycle. Microorganisms are considered primary decomposers, but evidence increases that some invertebrates may also decompose lignocellulose. We investigated the taxonomic distribution and evolutionary origins of GH45 hydrolases, important enzymes for the decomposition of cellulose and hemicellulose, in a collection of soil invertebrate genomes. We found that these genes are common in springtails and oribatid mites. Phylogenetic analysis revealed that cellulase genes were acquired early in the evolutionary history of these groups. Domain architectures and predicted 3D enzyme structures indicate that these cellulases are functional. Patterns of presence and absence of these genes across different lineages prompt further investigation into their evolutionary and ecological benefits. The ubiquity of cellulase genes suggests that soil invertebrates may play a role in lignocellulose decomposition, independently or in synergy with microorganisms. Understanding the ecological and evolutionary implications might be crucial for understanding soil food webs and the carbon cycle.

Haplotype divergence supports long-term asexuality in the oribatid mite Oppiella nova.

Sex strongly impacts genome evolution via recombination and segregation. In the absence of these processes, haplotypes within lineages of diploid organisms are predicted to accumulate mutations independently of each other and diverge over time. This so-called "Meselson effect" is regarded as a strong indicator of the long-term evolution under obligate asexuality. Here, we present genomic and transcriptomic data of three populations of the asexual oribatid mite species Oppiella nova and its sexual relative Oppiella subpectinata We document strikingly different patterns of haplotype divergence between the two species, strongly supporting Meselson effect-like evolution and long-term asexuality in O. nova: I) variation within individuals exceeds variation between populations in O. nova but vice versa in O. subpectinata; II) two O. nova sublineages feature a high proportion of lineage-specific heterozygous single-nucleotide polymorphisms (SNPs), indicating that haplotypes continued to diverge after lineage separation; III) the deepest split in gene trees generally separates the two haplotypes in O. nova, but populations in O. subpectinata; and IV) the topologies of the two haplotype trees match each other. Our findings provide positive evidence for the absence of canonical sex over evolutionary time in O. nova and suggest that asexual oribatid mites can escape the dead-end fate usually associated with asexual lineages.

[Planning, Reflecting and Evaluating Participatory Health Research: Adaptation and Piloting of the "Community Based Participatory Research (CBPR) Model" for German-Speaking Countries]. / Partizipative Gesundheitsforschung planen, reflektieren und evaluieren: Die Adaption und Erprobung des "Community Based Participatory Research (CBPR) Model" für den deutschsprachigen Raum.

Participatory research approaches are becoming increasingly established in both academic and practice settings. The participation of people with varied lived experiences and professional backgrounds can help academia and practitioners to learn from and empower each other. In the exchange of different perspectives, needs and ideas, it is possible to plan, reflect on, implement and evaluate projects in the health sector jointly and with attention to the needs of all stakeholders. The Community Based Participatory Research (CBPR) Model is often used internationally to guide participatory processes. However, an accessible translation has been lacking for application in German-speaking countries. To address this problem, a multidisciplinary working group composed of academic researchers and practitioners came together within the German-speaking Participatory Health Research Network (PartNet) to adapt the CBPR model for German-speaking countries and to test the adapted version with potential users. The adaptation was more than a translation, as the four model components "Contexts", "Partnership Processes", "Intervention & Research" and "Outcomes" as well as their associated contents are not directly applicable to the socio-structural and political contexts of the German-speaking countries. This article describes the process of adapting the model. This includes how translation drafts for German-speaking countries were first discussed in detail and then agreed upon as an initial template for testing in practice. Subsequently, various users reflected on the German-language model based on their experience of testing it in different projects, focusing on accuracy, comprehensibility and applicability. At the same time, the model was presented and discussed at conferences. The diverse feedback was incorporated into further revisions of the model. The result is a German-language version called "Modell für partizipative Gesundheitsforschung (PGF-Modell)".

Dispersal patterns of oribatid mites across habitats and seasons.

Oribatid mites are tiny arthropods that are common in all soils of the world; however, they also occur in microhabitats above the soil such as lichens, mosses, on the bark of trees and in suspended soils. For understanding oribatid mite community structure, it is important to know whether they are dispersal limited. The aim of this study was to investigate the importance of oribatid mite dispersal using Malaise traps to exclude sole passive wind-dispersal. Oribatid mite communities were collected over a 3-year period from five habitat types (coniferous forests, deciduous forests, mixed forests, meadows, bog/heathlands sites) and three seasons (spring, summer, autumn) in Sweden. Mites entered traps either by walking or by phoresy, i.e., by being attached to flying insects. We hypothesized (1) that oribatid mite communities in the traps differ between habitats, indicating habitat-limited dispersal, and (2) that oribatid mite communities differ among seasons suggesting that dispersal varies due to changing environmental conditions such as moisture or resource availability. The majority of the collected species were not typically soil-living species but rather from habitats such as trees, lichens and mosses (e.g., Carabodes labyrinthicus, Cymbaeremaeus cymba, Diapterobates humeralis and Phauloppia lucorum) indicating that walking into the traps or entering them via phoresy are of greater importance for aboveground than for soil-living species. Overall, oribatid mite communities collected in the traps likely originated from the surrounding local habitat suggesting that long distance dispersal of oribatid mites is scarce. Significant differences among seasons indicate higher dispersal during warm and dry periods of the year. Notably, 16 species of oribatid mites collected in our study were sampled for the first time in Sweden. This study also demonstrates that Malaise traps are a meaningful tool to investigate spatial and temporal patterns of oribatid mite communities.

[Ethics in participatory research-reflection on challenges and possible impairments for participants]. / Ethische Aspekte in der partizipativen Forschung ­ Reflexion von Herausforderungen und möglichen Beeinträchtigungen für Teilnehmende.

In medical research, it is established practice to discuss ethical issues, usually based on the criteria informed consent and voluntary participation, protection from harm, confidentiality, and anonymity. The discussion of ethical questions is also gaining importance in social science research. The same applies to participatory research, which is not yet very widespread in Germany. Because this approach is based on equality between all those involved, it results in relationships uncommon in nonparticipatory research. Therefore, ethical questions are raised in a different way. Partly based on an analysis of documents, a case study from participatory health research will be used to illustrate how the principle of harm reduction can be recognized. The case study shows this from the perspective of both the researchers and the peer-researchers.From the peer-researchers' perspective, there are different challenges in participatory teamwork, which can bring impairments and consequently result in a risk of harm. This can lead to disappointments, for example, when from the peer-researchers' perspective individual support during a research process is insufficient.Conclusions for dealing with ethical aspects in participatory research projects will be derived from the gathered experiences. The application of the criteria used in nonparticipatory research can be an opportunity to strengthen the discussion of ethical issues as part of participatory processes. It can also be a chance to combine the ethical discourse in participatory and qualitative social science research.

[Involving the seldom heard in participatory health research: challenges and strategies]. / "Selten Gehörte" für partizipative Gesundheitsforschung gewinnen: Herausforderungen und Strategien.

BACKGROUND: Participatory health research is gaining increasing recognition in the public health sector. The people whose lives or work are central to wicked issues around health inequalities are integrated into the projects. Including diverse forms of knowledge and perspectives has the capability of strengthening health equity in specific settings. That proffers agency to the voices of those who are seldom heard. Often, participatory health research (PHR) is done with communities. Finding the truly isolated - those who are not connected to others or to services, the seldom heard - presents a challenge for research. Without hearing the voices of those most distanced from mainstream discourse we run the risk of misunderstanding issues pertinent to their lives. This narrative overview highlights this problem and aims to contribute a solution approach for research practice. METHODS: An extensive literature review for participatory research references in the German language was used and the international literature was also screened. Furthermore, the processes of three participatory research projects were evaluated. RESULTS/DISCUSSION: The specified strategies to involve the seldom heard refer to lowered systemic barriers and improved local capacity for their participation. For example, before research can start, time should be given for a preparatory phase. This can be used to invest in relationships and co-operation to bridge the distance to research.

No Accumulation of Transposable Elements in Asexual Arthropods.

Transposable elements (TEs) and other repetitive DNA can accumulate in the absence of recombination, a process contributing to the degeneration of Y-chromosomes and other nonrecombining genome portions. A similar accumulation of repetitive DNA is expected for asexually reproducing species, given their entire genome is effectively nonrecombining. We tested this expectation by comparing the whole-genome TE loads of five asexual arthropod lineages and their sexual relatives, including asexual and sexual lineages of crustaceans (Daphnia water fleas), insects (Leptopilina wasps), and mites (Oribatida). Surprisingly, there was no evidence for increased TE load in genomes of asexual as compared to sexual lineages, neither for all classes of repetitive elements combined nor for specific TE families. Our study therefore suggests that nonrecombining genomes do not accumulate TEs like nonrecombining genomic regions of sexual lineages. Even if a slight but undetected increase of TEs were caused by asexual reproduction, it appears to be negligible compared to variance between species caused by processes unrelated to reproductive mode. It remains to be determined if molecular mechanisms underlying genome regulation in asexuals hamper TE activity. Alternatively, the differences in TE dynamics between nonrecombining genomes in asexual lineages versus nonrecombining genome portions in sexual species might stem from selection for benign TEs in asexual lineages because of the lack of genetic conflict between TEs and their hosts and/or because asexual lineages may only arise from sexual ancestors with particularly low TE loads.

Changes in the genetic structure of an invasive earthworm species (Lumbricus terrestris, Lumbricidae) along an urban - rural gradient in North America.

European earthworms were introduced to North America by European settlers about 400 years ago. Human-mediated introductions significantly contributed to the spread of European species, which commonly are used as fishing bait and are often disposed deliberately in the wild. We investigated the genetic structure of Lumbricus terrestris in a 100 km range south of Calgary, Canada, an area that likely was devoid of this species two decades ago. Genetic relationships among populations, gene flow, and migration events among populations were investigated using seven microsatellite markers and the mitochondrial 16S rDNA gene. Earthworms were collected at different distances from the city and included fishing baits from three different bait distributors. The results suggest that field populations in Alberta established rather recently and that bait and field individuals in the study area have a common origin. Genetic variance within populations decreased outside of the urban area, and the most distant populations likely originated from a single introduction event. The results emphasise the utility of molecular tools to understand the spatial extent and connectivity of populations of exotic species, in particular soil-delling species, that invade native ecosystems and to obtain information on the origin of populations. Such information is crucial for developing management and prevention strategies to limit and control establishment of non-native earthworms in North America.

Founder events and pre-glacial divergences shape the genetic structure of European Collembola species.

BACKGROUND: Climate oscillations in the Cenozoic reduced species richness and genetic diversity of terrestrial and aquatic animals and plants in central and northern Europe. The most abundant arthropods in temperate soils are Collembola that live in almost any soil-related habitat. Extant species show little morphological variation to Eocene fossils, suggesting persistence of species in stable habitats for millions of years. Collembola are able to evade adverse climatic conditions by moving into deeper soil layers and are tolerant to frost and draught. If these adaptations sufficed for surviving glacial periods remains open and needs to be investigated in a phylogeographic context, i.e. investigating spatial structure on molecular level. We investigated the molecular variation of three common species of Collembola at a pan-European scale to identify glacial refuges and post-glacial colonization patterns with three genetic markers. RESULTS: All genes revealed remarkable genetic structure between but not within populations, suggesting density dependent processes for establishment of populations (founder-takes-all principle), which is common for European animals and plants. In contrast to the post-glacial recolonization patterns of many aboveground organisms, divergence times of most geographic lineages indicate preservation of genetic structure since the Miocene. CONCLUSIONS: Collembola survived severe climatic changes including those during Quatenary glaciation and kept high genetic variance across Europe. Likely the buffering of temperature oscilliations in soil and the ability to evade adverse climatic conditions due to cold-tolerance and horizontal migration enabled Collembola to evade strong selective pressure of abiotic forces.

Convergent evolution of aquatic life by sexual and parthenogenetic oribatid mites.

Convergent evolution is one of the main drivers of traits and phenotypes in animals and plants. Here, we investigated the minimum number of independent colonisations of marine and freshwater habitats in derived oribatid mites (Brachypylina), a mainly terrestrial taxon. Furthermore, we investigated whether the reproductive mode (sexual vs. thelytokous) is associated with the habitat type (marine, freshwater) where the animals live. We hypothesized that continuous resource availability in freshwater systems fosters asexual reproduction. We used 18S rDNA sequences to construct a molecular phylogeny of oribatid mites from terrestrial, marine and freshwater habitats. The results indicate that aquatic life in oribatid mites evolved at least 3×: once in Limnozetoidea (including only freshwater taxa) and at least twice in Ameronothroidea. In Ameronothroidea the taxon Ameronothridae n. gen. (nr. Aquanothrus) colonized fresh water independently from Selenoribatidae and Fortuyniidae (mainly marine Ameronothroidea). Reproductive mode was associated neither with marine nor with freshwater life; rather, in both habitats sexual and parthenogenetic taxa occur. However, the reproductive mode was related to the stability of the habitat. Species that live underwater permanently tend to be parthenogenetic whereas taxa whose life cycle is often interrupted by flooding, such as marine oribatid mites, or by desiccation, e.g., freshwater-living Ameronothridae n. gen. (nr. Aquanothrus) (Ameronothroidea) species, are mainly sexual, indicating that continuous access to resources indeed favours parthenogenetic reproduction. Findings of our study therefore suggest that parthenogenetic reproduction is not selected for by disturbances but by unlimited access to resources.

Phylogeny and species delineation in European species of the genus Steganacarus (Acari, Oribatida) using mitochondrial and nuclear markers.

Species of the genus Steganacarus are soil-living oribatid mites (Acari, Phthiracaridae) with a ptychoid body. The phylogeny and species status of the species of Steganacarus are not resolved, some authors group all ten German species of Steganacarus within the genus Steganacarus whereas others split them into three subgenera, Steganacarus, Tropacarus and Atropacarus. Additionally, two species, S. magnus and T. carinatus, comprise morphotypes of questionable species status. We investigated the phylogeny and species status of ten European Steganacarus species, i.e. S. applicatus, S. herculeanus, S. magnus forma magna, S. magnus forma anomala, S. spinosus, Tropacarus brevipilus, T. carinatus forma carinata, T. carinatus forma pulcherrima, Atropacarus striculus and Rhacaplacarus ortizi. We used two molecular markers, a 251 bp fragment of the nuclear gene 28S rDNA (D3) and a 477 bp fragment of the mitochondrial COI region. The phylogeny based on a combined analysis of D3 and COI separated four subgenera (Steganacarus, Tropacarus and Atropacarus, Rhacaplacarus) indicating that they form monophyletic groups. The COI region separated all ten species of the genus Steganacarus and showed variation within some species often correlating with the geographic origin of the species. Resolution of the more conserved D3 region was limited, indicating that radiation events are rather recent. Overall, our results indicate that both genes alone cannot be used for phylogeny and barcoding since variation is too low in D3 and too high in COI. However, when used in combination these genes provide reliable insight into the phylogeny, radiation and species status of taxa of the genus Steganacarus.

Niche dimensions in soil oribatid mite community assembly under native and introduced tree species.

Forest soils are a critical component of terrestrial ecosystems and host a large number of animal decomposer species. One diverse and abundant decomposer taxon is oribatid mites (Acari: Oribatida), whose species composition varies with forest type and tree species composition. We used functional traits that indicate different niche dimensions, to infer assembly processes of oribatid mite communities in monocultures and mixed forests of native and introduced tree species. We found that coexisting species differed more in the resource-related niche dimension, i.e., reproductive mode and trophic guild, than in the morphological dimension, e.g., body length and width, sclerotization and concealability. These results suggest that both filtering and partitioning processes structure oribatid mite communities. In native European beech forests, but not in non-native Douglas fir forests, oribatid mites were mainly structured by filtering processes acting via traits related both to environmental tolerance and to resources. Furthermore, oribatid mite trait diversity, but not phylogenetic diversity, differed significantly between monocultures and mixed forests, demonstrating that multidimensional diversity indices provide additional information on soil biodiversity. Overall, the study provides evidence that traits representing different niche dimensions need to be considered for understanding assembly processes in soil animal communities and thereby soil biodiversity.

Convergent evolution of defense mechanisms in oribatid mites (Acari, Oribatida) shows no "ghosts of predation past".

Oribatid mites are diverse and abundant terrestrial soil arthropods that are involved in decomposition of organic matter and nutrient cycling. As indicated by fossils starting from the Devonian, they evolved varied mechanisms and structures for defense from predators. We investigated four of these defensive structures (ptychoid body, hologastry, mineralization and opisthonotal glands) and used ancestral character state reconstruction to determine whether they evolved convergently and how many times this may have happened. Phylogenetic trees based on 18S rDNA were constructed for 42 oribatid mite species and two outgroup taxa using likelihood and Bayesian algorithms. The results suggest that at least three of the four defensive structures evolved convergently several times; for opisthonotal glands convergent evolution remains equivocal. This high level of convergence indicates that predation has been an important factor throughout the evolution of oribatid mites, contributing to morphological diversity and potentially also to species richness, as there are indications that some taxa radiated after the evolution of defense structures. Despite the ancientness of oribatid mites, defense structures seems to have been rarely lost, suggesting that they still are functional and necessary to reduce predation, rather than being 'ghosts of predation past'.

"Jack-of-all-trades" is parthenogenetic.

Sex is evolutionarily more costly than parthenogenesis, evolutionary ecologists therefore wonder why sex is much more frequent than parthenogenesis in the majority of animal lineages. Intriguingly, parthenogenetic individuals and species are as common as or even more common than sexuals in some major and putative ancient animal lineages such as oribatid mites and rotifers. Here, we analyzed oribatid mites (Acari: Oribatida) as a model group because these mites are ancient (early Paleozoic), widely distributed around the globe, and include a high number of parthenogenetic species, which often co-exist with sexual oribatid mite species. There is evidence that the reproductive mode is phylogenetically conserved in oribatid mites, which makes them an ideal model to test hypotheses on the relationship between reproductive mode and species' ecological strategies. We used oribatid mites to test the frozen niche variation hypothesis; we hypothesized that parthenogenetic oribatid mites occupy narrow specialized ecological niches. We used the geographic range of species as a proxy for specialization as specialized species typically do have narrower geographic ranges than generalistic species. After correcting for phylogenetic signal in reproductive mode and demonstrating that geographic range size has no phylogenetic signal, we found that parthenogenetic lineages have a higher probability to have broader geographic ranges than sexual species arguing against the frozen niche variation hypothesis. Rather, the results suggest that parthenogenetic oribatid mite species are more generalistic than sexual species supporting the general-purpose genotype hypothesis. The reason why parthenogenetic oribatid mite species are generalists with wide geographic range sizes might be that they are of ancient origin reflecting that they adapted to varying environmental conditions during evolutionary history. Overall, our findings indicate that parthenogenetic oribatid mite species possess a widely adapted general-purpose genotype and therefore might be viewed as "Jack-of-all-trades."

TRPM3-mediated dynamic mitochondrial activity in nerve growth factor-induced latent sensitization of chronic low back pain.

ABSTRACT: The transient receptor potential ion channel TRPM3 is highly prevalent on nociceptive dorsal root ganglion (DRG) neurons, but its functions in neuronal plasticity of chronic pain remain obscure. In an animal model of nonspecific low back pain (LBP), latent spinal sensitization known as nociceptive priming is induced by nerve growth factor (NGF) injection. Here, we address the TRPM3-associated molecular basis of NGF-induced latent spinal sensitization at presynaptic level by studying TRPM3-mediated calcium transients in DRG neurons. By investigating TRPM3-expressing HEK cells, we further show the dynamic mitochondrial activity downstream of TRPM3 activation. NGF enhances TRPM3 function, attenuates TRPM3 tachyphylaxis, and slows intracellular calcium clearance; TRPM3 activation triggers more mitochondrial calcium loading than depolarization does, causing a steady-state mitochondrial calcium elevation and a delayed recovery of cytosolic calcium; mitochondrial calcium buffering accounts for approximately 40% of calcium influx subsequent to TRPM3 activation. TRPM3 activation provokes an outbreak of pulsatile superoxide production (mitoflash) that comes in the form of a surge in frequency being tunable. We suggest that mitoflash pulsations downstream of TRPM3 activation might be an early signaling event initiating pain sensitization. Tuning of mitoflash activity would be a novel bottom-up therapeutic strategy for chronic pain conditions such as LBP and beyond.

Feeding habits and multifunctional classification of soil-associated consumers from protists to vertebrates.

Soil organisms drive major ecosystem functions by mineralising carbon and releasing nutrients during decomposition processes, which supports plant growth, aboveground biodiversity and, ultimately, human nutrition. Soil ecologists often operate with functional groups to infer the effects of individual taxa on ecosystem functions and services. Simultaneous assessment of the functional roles of multiple taxa is possible using food-web reconstructions, but our knowledge of the feeding habits of many taxa is insufficient and often based on limited evidence. Over the last two decades, molecular, biochemical and isotopic tools have improved our understanding of the feeding habits of various soil organisms, yet this knowledge is still to be synthesised into a common functional framework. Here, we provide a comprehensive review of the feeding habits of consumers in soil, including protists, micro-, meso- and macrofauna (invertebrates), and soil-associated vertebrates. We have integrated existing functional group classifications with findings gained with novel methods and compiled an overarching classification across taxa focusing on key universal traits such as food resource preferences, body masses, microhabitat specialisation, protection and hunting mechanisms. Our summary highlights various strands of evidence that many functional groups commonly used in soil ecology and food-web models are feeding on multiple types of food resources. In many cases, omnivory is observed down to the species level of taxonomic resolution, challenging realism of traditional soil food-web models based on distinct resource-based energy channels. Novel methods, such as stable isotope, fatty acid and DNA gut content analyses, have revealed previously hidden facets of trophic relationships of soil consumers, such as food assimilation, multichannel feeding across trophic levels, hidden trophic niche differentiation and the importance of alternative food/prey, as well as energy transfers across ecosystem compartments. Wider adoption of such tools and the development of open interoperable platforms that assemble morphological, ecological and trophic data as traits of soil taxa will enable the refinement and expansion of the multifunctional classification of consumers in soil. The compiled multifunctional classification of soil-associated consumers will serve as a reference for ecologists working with biodiversity changes and biodiversity-ecosystem functioning relationships, making soil food-web research more accessible and reproducible.

Repeated convergent evolution of parthenogenesis in Acariformes (Acari).

The existence of old species-rich parthenogenetic taxa is a conundrum in evolutionary biology. Such taxa point to ancient parthenogenetic radiations resulting in morphologically distinct species. Ancient parthenogenetic taxa have been proposed to exist in bdelloid rotifers, darwinulid ostracods, and in several taxa of acariform mites (Acariformes, Acari), especially in oribatid mites (Oribatida, Acari). Here, we investigate the diversification of Acariformes and their ancestral mode of reproduction using 18S rRNA. Because parthenogenetic taxa tend to be more frequent in phylogenetically old taxa of Acariformes, we sequenced a wide range of members of this taxon, including early-derivative taxa of Prostigmata, Astigmata, Endeostigmata, and Oribatida. Ancestral character state reconstruction indicated that (a) Acariformes as well as Oribatida evolved from a sexual ancestor, (b) the primary mode of reproduction during evolution of Acariformes was sexual; however, species-rich parthenogenetic taxa radiated independently at least four times (in Brachychthonioidea (Oribatida), Enarthronota (Oribatida), and twice in Nothrina (Oribatida), (c) parthenogenesis additionally evolved frequently in species-poor taxa, for example, Tectocepheus, Oppiella, Rostrozetes, Limnozetes, and Atropacarus, and (d) sexual reproduction likely re-evolved at least three times from species-rich parthenogenetic clusters, in Crotonia (Nothrina), in Mesoplophora/Apoplophora (Mesoplophoridae, Enarthronota), and in Sphaerochthonius/Prototritia (Protoplophoridae, Enarthronota). We discuss possible reasons that favored the frequent diversification of parthenogenetic taxa including the continuous long-term availability of dead organic matter resources as well as generalist feeding of species as indicated by natural variations in stable isotope ratios.

Changes in diversity and community assembly of jumping spiders (Araneae: Salticidae) after rainforest conversion to rubber and oil palm plantations.

Rainforest conversion into monoculture plantations results in species loss and community shifts across animal taxa. The effect of such conversion on the role of ecophysiological properties influencing communities, and conversion effects on phylogenetic diversity and community assembly mechanisms, however, are rarely studied in the same context. Here, we compare salticid spider (Araneae: Salticidae) communities between canopies of lowland rainforest, rubber agroforest ("jungle rubber") and monoculture plantations of rubber or oil palm, sampled in a replicated plot design in Jambi Province, Sumatra, Indonesia. Overall, we collected 912 salticid spider individuals and sorted them to 70 morphospecies from 21 genera. Salticid richness was highest in jungle rubber, followed by rainforest, oil palm and rubber, but abundance of salticids did not differ between land-use systems. Community composition was similar in jungle rubber and rainforest but different from oil palm and rubber, which in turn were different from each other. The four investigated land-use systems differed in aboveground plant biomass, canopy openness and land use intensity, which explained 12% of the observed variation in canopy salticid communities. Phylogenetic diversity based on ~850 bp 28S rDNA fragments showed similar patterns as richness, that is, highest in jungle rubber, intermediate in rainforest, and lowest in the two monoculture plantations. Additionally, we found evidence for phylogenetic clustering of salticids in oil palm, suggesting that habitat filtering is an important factor shaping salticid spider communities in monoculture plantations. Overall, our study offers a comprehensive insight into the mechanisms shaping communities of arthropod top predators in canopies of tropical forest ecosystems and plantations, combining community ecology, environmental variables and phylogenetics across a land-use gradient in tropical Asia.

Arthropod colonization of land--linking molecules and fossils in oribatid mites (Acari, Oribatida).

Terrestrial fossils that document the early colonization of land are scarce for >100 my after the Cambrian explosion. This raises the question whether life on land did not exist or just did not fossilize. With a molecular dating technique, we analyzed the origin of terrestrial chelicerate microarthropods (Acari, Oribatida) which have a fossil record since the Middle Devonian that is exceptional among soil animals. Our results suggest that oribatid mites originated in the Precambrian (571+/-37 mya) and that the radiation of basal groups coincides with the gap in the terrestrial fossil record between the Cambrian explosion and the earliest fossilized records of continental ecosystems. Further, they suggest that the colonization of land started via the interstitial, approximately 150 my earlier than the oldest fossils of terrestrial ecosystems. Overall, the results imply that omnivorous and detritivorous arthropods formed a major component in early terrestrial food webs, thereby facilitating the invasion of terrestrial habitats by later colonizers of higher trophic levels.

Invasive lumbricid earthworms in North America - different life-histories but common dispersal?

AIM: Lumbricid earthworms are invasive across northern North America, causing notable changes in forest ecosystems. During their range expansion they encountered harsher climatic conditions compared to their native ranges in evolutionary short time. This study investigated if (1) dispersal barriers, (2) climatic selection, or (3) anthropogenic activities, such as fishing bait disposal, structure the dispersal of free-living earthworm populations. LOCATION: North America, forest habitats along former Wisconsinan glaciation line. TAXON: Lumbricus terrestris, L. rubellus. METHODS: Lumbricus terrestris and L. rubellus co-occur in the same habitats but differ in ecology and use Conservation approach for goblin species were sampled in five transects ranging from the east to the west coast of northern North America, including major dispersal barriers, three different climate zones, and bait shops near sampling locations. Genetic diversity and structure were compared between the two species, and the presence of free-living bait shop genotypes was assessed using four markers (COI, 16S rDNA, 12S rDNA, H3). RESULTS: Populations of both species were genetically diverse with some geographic structure, which was more pronounced in L. terrestris than in L. rubellus. Common haplotypes were present in all regions, but locally restricted haplotypes also occurred. Further, two distinct genetic clades of L. terrestris co-occurred only in the two most distant transects (Alberta and Minnesota). Genotypes identical to bait individuals were omnipresent in field populations of L. terrestris. MAIN CONCLUSIONS: Genetic diversity was high in both species, and invasive populations represented a genetic subset of European earthworms. Geographic and climatic dispersal barriers affected the less mobile species, L. rubellus, resulting in differences in genetic structure between the two species. Our results indicate common long-distance dispersal vectors and specific vectors affecting only L. terrestris. The roles of climate and anthropogenic activities are discussed, providing additional explanations of dispersal and new insights into establishment of invasive earthworms.