In the United Nations Decade on Ecosystem Restoration¹, large knowledge gaps persist on how to increase biodiversity and ecosystem functioning in cash crop-dominated tropical landscapes². Here, we present findings from a large-scale, 5-year ecosystem restoration experiment in an oil palm landscape enriched with 52 tree islands, encompassing assessments of ten indicators of biodiversity and 19 indicators of ecosystem functioning. Overall, indicators of biodiversity and ecosystem functioning, as well as multidiversity and ecosystem multifunctionality, were higher in tree islands compared to conventionally managed oil palm. Larger tree islands led to larger gains in multidiversity through changes in vegetation structure. Furthermore, tree enrichment did not decrease landscape-scale oil palm yield. Our results demonstrate that enriching oil palm-dominated landscapes with tree islands is a promising ecological restoration strategy, yet should not replace the protection of remaining forests.

Complete mitochondrial (mt) genomes and the gene rearrangements therein are increasingly used as molecular markers for investigating phylogenetic relationships, especially for elucidating deep splits. Contributing to the complete mt genomes of arthropods, especially Arachnida, available so far, we provide the first complete mt genome of a sarcoptiform mite species, the sexually reproducing oribatid mite Steganacarus magnus (Acari, Oribatida) which was determined by sequencing of long PCR products.

Microarthropod communities in the soil and on the bark of trees were investigated along an elevation gradient (1,850, 2,000, 2,150, 2,300 m) in a tropical montane rain forest in southern Ecuador. We hypothesised that the density of microarthropods declines with depth in soil and increases with increasing altitude mainly due to the availability of resources, i.e. organic matter. In addition, we expected bark and soil communities to differ strongly, since the bark of trees is more exposed to harsher factors. In contrast to our hypothesis, the density of major microarthropod groups (Collembola, Oribatida, Gamasina, Uropodina) was generally low and decreased with altitude. However, as we predicted the density of each of the groups decreased with soil depth. Density of microarthropods on tree bark was lower than in soil. Overall, 43 species of oribatid mites were found, with the most abundant higher taxa being Poronota, pycnonotic Apheredermata, Mixonomata and Eupheredermata. The oribatid mite community on bark did not differ significantly from that in soil. The number of oribatid mite species declined with altitude (24, 23, 17 and 13 species at 1,850, 2,000, 2,150 and 2,300 m, respectively). Rarefaction curves indicate that overall about 50 oribatid mite species are to be expected along the studied altitudinal gradient. Results of this study indicate (1) that microarthropods may be limited by the quality of resources at high altitudes and by the amount of resources at deeper soil layers, and (2) that the bark of trees and the soil are habitats of similar quality for oribatid mites.

Significance: Putatively ancient asexual species pose a challenge to theory because they appear to escape the predicted negative long-term consequences of asexuality. Although long-term asexuality is difficult to demonstrate, specific signatures of haplotype divergence, called the “Meselson effect,” are regarded as strong support for long-term asexuality. Here, we provide evidence for the Meselson effect in an asexual oribatid mite species,Oppiella nova, and we show that the effect is not caused by hybridization or polyploidization. Our findings provide conclusive evidence for the long-term absence of sex inO. novaand suggest that asexual oribatid mites can escape the dead-end fate usually associated with asexual reproduction.

The dominance of sex in Metazoa is enigmatic. Sexual species allocate resources to the production of males, while potentially facing negative effects such as the loss of well‐adapted genotypes due to recombination, and exposure to diseases and predators during mating. Two major hypotheses have been put forward to explain the advantages of parthenogenetic versus sexual reproduction in animals, that is, the Red Queen hypothesis and the Tangled Bank/Structured Resource Theory of Sex. The Red Queen hypothesis assumes that antagonistic predator—prey/ parasite–host interactions favor sex. The Structured Resource Theory of Sex predicts sexual reproduction to be favored if resources are in short supply and aggregated in space. In soil, a remarkable number of invertebrates reproduce by parthenogenesis, and this pattern is most pronounced in oribatid mites (Oribatida, Acari). Oribatid mites are abundant in virtually any soil across very different habitats, and include many sexual and parthenogenetic (thelytokous) species. Thereby, they represent an ideal model group to investigate the role of sexual versus parthenogenetic reproduction across different ecosystems and habitats. Here, we compiled data on oribatid mite communities from different ecosystems and habitats across biomes, including tropical rainforests, temperate forests, grasslands, arable fields, salt marshes, bogs, caves, and deadwood. Based on the compiled dataset, we analyzed if the percentage of parthenogenetic species and the percentage of individuals of parthenogenetic species are related to total oribatid mite density, species number, and other potential driving factors of the reproductive mode including altitude and latitude. We then interpret the results in support of either the Red Queen hypothesis or the Structured Resource Theory of Sex. Overall, the data showed that high density of oribatid mites, indicating abundance of resources, is associated with high frequency of parthenogenesis supporting predictions of the Structured Resource Theory of Sex rather than the Red Queen hypothesis.