Aim Species richness of insect herbivores feeding on exotic plants increases with abundance as well as range size of the host in the area of introduction. The formation of these herbivore assemblages requires a certain amount of time, and the richness of insect faunas should also increase with the length of time an exotic plant has been present in the introduced range.Location Central Europe.
Freshwater macro‐organismic environmental DNA (eDNA) is gaining increasing popularity in detecting invasive species, assessing community assemblages, and in mapping the distribution of taxa that are rare or otherwise difficult to monitor. The objectives of this article are to review the targets of published freshwater eDNA research in relation to aquatic conservation with a focus on geographic regions covered, as well as the habitats and species investigated.
The analysis of 272 peer‐reviewed articles published between 2005 and 2018 revealed that 57% of the 238 primary research papers have a focus on conservation science, mostly addressing invasive and endangered species, followed by 23% papers investigating methodological developments and 11% biodiversity surveys also using eDNA metabarcoding. A strong geographical pattern emerged, with Africa, South America, and the tropics being under‐represented. Taxonomic coverage was dominated by 123 fish species, followed by 29 amphibian and 28 mollusc species. Freshwater arthropods (27 taxa) were under‐represented in relation to their estimated species richness.
Taxonomic bias towards certain species such as fishes observed in freshwater eDNA research is pervasive in biodiversity research and conservation sciences, and thus is not surprising. Geographical representation was biased, with a few industrialized countries from the Northern Hemisphere contributing 72% of the studies. Both findings parallel biases known from other research areas, such as marine eDNA analysis, taxonomy, or invasion biology.
The application of eDNA in freshwater conservation will benefit from the development of general standards and guidelines that are necessary to integrate freshwater macrobial eDNA techniques in existing monitoring frameworks. To aid future freshwater conservation, our suggestions are to harmonize eDNA methods for comparable and easier implementation worldwide, and to increase international cooperation and funding for under‐represented geographical regions and neglected taxa. This is especially crucial for the known biodiversity hotspots in developing countries where rapid changes occur to freshwater habitats and biodiversity.
Reliable quantitative methods for sampling invertebrate communities are critical for effective freshwater biomonitoring. We tested a range of devices and protocols for sampling benthic macroinvertebrates in shallow tropical lakes; this is the first time this has been attempted in Southeast Asia. First, a pilot study to identify a suitable artificial substrate and colonisation period was conducted. Coconut brushes combined with split palm fronds attracted the greatest macroinvertebrate abundance and richness. A colonisation period of 4 wk was sufficient to capture the key macroinvertebrate families and orders. Second, the sampling efficiencies of 7 artificial substrate sampler designs and 2 hydraulic suction devices were compared in rocky and soft-sediment littoral habitats of a reservoir in Singapore. Among the 9 different sampling techniques tested, the samplers containing coconut brushes and split palm fronds again were the most effective at capturing the greatest total abundance and family richness of benthic macroinvertebrates. Variation in community structure among sampler types was largely explained by the abundance of Chironomidae and Polymitarcyidae (Ephemeroptera). Results were similar between sites dominated by 'rocky' and 'vegetated' littoral habitats. This project identified a sampling device suitable for biomonitoring Singapore's lentic environment, with protocols likely to apply to shallow tropical lentic systems elsewhere.
Several revisions of the genus Pleurothallis have been proposed. Luer has proposed that Pleurothallis species in subgenus Scopula be segregated into the genera Colombiana and Ancipitia. Szlachetko and Margonska (2001) proposed the genus Zosterophyllanthos for Pleurothallis subsection Macrophyllae-Fasciculatae. As an alternative, Luer (2005) proposed the genus Acronia by uniting Pleurothallis subsection Macrophyllae-Fasciculatae with subsections Acroniae and Amphygiae. The molecular phylogenetic studies by Pridgeon and Chase (2001), however, suggested that these taxonomic revisions might not be justified. We report here a more detailed phylogenetic analysis of the genus Pleurothallis, with emphasis on subsection Macrophyllae-Fasciculatae, with data primarily from nuclear ITS sequencing, supplemented with preliminary data from plastid DNA (rpoB2, rpoC1, and ycf1) sequencing. Some initial, tentative conclusions can be drawn. In the strict consensus maximum-parsimony tree of ITS data, many of the clades collapse, leaving a polytomy with a single, highly supported node that tentatively could be used to delimit the genus Pleurothallis. Such a tree would argue for an expanded concept of the genus Pleurothallis, in which the groups Ancipitia, Colombiana, and Acronia/Zosterophyllanthos, if shown to be monophyletic, are relegated to subgenera.
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