Uncovering patterns of freshwater positive interactions using meta-analysis: Identifying the roles of common participants, invasive species and environmental context.

Positive interactions are sensitive to human activities, necessitating synthetic approaches to elucidate broad patterns and predict future changes if these interactions are altered or lost. General understanding of freshwater positive interactions has been far outpaced by knowledge of these important relationships in terrestrial and marine ecosystems. We conducted a global meta-analysis to evaluate the magnitude of positive interactions across freshwater habitats. In 340 studies, we found substantial positive effects, with facilitators increasing beneficiaries by, on average, 81% across all taxa and response variables. Mollusks in particular were commonly studied as both facilitators and beneficiaries. Amphibians were one group benefiting the most from positive interactions, yet few studies investigated amphibians. Invasive facilitators had stronger positive effects on beneficiaries than non-invasive facilitators. We compared positive effects between high- and low-stress conditions and found no difference in the magnitude of benefit in the subset of studies that manipulated stressors. Future areas of research include understudied facilitators and beneficiaries, the stress gradient hypothesis, patterns across space or time and the influence of declining taxa whose elimination would jeopardise fragile positive interaction networks. Freshwater positive interactions occur among a wide range of taxa, influence populations, communities and ecosystem processes and deserve further exploration.

Analysis of the complete organellar genomes of the economically valuable kelp Lessonia spicata (Lessoniaceae, Phaeophyceae) from Chile.

Lessonia spicata (Suhr) Santelices is the most ecologically and economically important kelp from Pacific South America. Here, we contribute to the bioinformatics and evolutionary systematics of the species by performing high throughput sequencing on L. spicata from Valparaiso, Chile. The L. spicata complete mitogenome is 37,097 base pairs (bp) in length and contains 66 genes (GenBank accession MK965907), the complete plastid genome is 130,305 bp and has 173 genes (accession MK965908), and the data assembled 7,630 bp of the nuclear ribosomal cistron (accession MK965909). The organellar genomes are similar in structure and content to others published from the Laminariales.