Variations in terrestrial arthropod DNA metabarcoding methods recovers 1 robust beta diversity but variable richness and site indicators based on 2 exact sequence variants 3 4 Abstract 24Terrestrial arthropod fauna have been suggested as a key indicator of 25 ecological integrity in forest systems. Because phenotypic identification is 26 expert-limited, a shift towards DNA metabarcoding could improve scalability and 27 democratize the use of forest floor arthropods for biomonitoring applications. The 28 objective of this study was to establish the level of field sampling and DNA 29 extraction replication needed for soil arthropod biodiversity assessments. 30Processing individually collected field samples recovered significantly higher 31 richness (539-596 ESVs) than pooling the same number of field samples (126-32 154 ESVs), and we found no significant richness differences when using 1 or 3 33 pooled DNA extractions. Variations in the number of individual or composite 34 samples or DNA extractions resulted in similar sample clustering based on 35 community dissimilarities. Though our ability to identify taxa to species rank was 36 limited, we were able to use arthropod COI metabarcodes from forest soil to 37 assess richness, distinguish among sites, and recover site indicators based on 38 unnamed exact sequence variants. Our results highlight the need to continue 39 DNA barcoding of local taxa during COI metabarcoding studies to help build 40 reference databases. All together, these sampling considerations support the 41 use of soil arthropod COI metabarcoding as a scalable method for biomonitoring. 42Soil arthropod fauna have been suggested as a key indicator of faunal 46 community structure. 1-3 These organisms are essential to ecological processes 47 that include organic matter decomposition, nutrient cycling, and soil structural 48 development (e.g. micropore formation that improves aeration porosity and water 49 infiltration rates). 1,2 Community shifts in soil arthropods in response to 50 anthropogenic and natural disturbance have been documented in numerous 51 studies. 3-7 52Typically, soil arthropods are sampled by trapping (e.g. pitfall traps) or 53 they are extracted directly from soil (e.g. Tullgren funnels). Because of the large 54 numbers of individuals that are sampled in even small studies, and because of 55 the relative difficulty of identifying soil fauna, phenotypic identification is often 56 expert-and time-limited. There are also significant issues of low recovery 57 efficiency and bias in the recovery of soil fauna for phenotypic identification. A 58 shift towards DNA metabarcoding could improve scalability and facilitate the use 59 of soil arthropods for biomonitoring applications. DNA metabarcoding is currently 60 the method of choice for highly scalable biodiversity studies. 8 Although the use 61 of COI metabarcoding to survey whole-community freshwater and Malaise trap 62 arthropods is becoming fairly routine 9,10 , the use of COI metabarcoding to survey 63 whole-community forest soil art...

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Engzell and Tropf (2019) find a positive association between intergenerational mobility and heritability for educational attainment. However, we cannot be confident of the relationship between these two variables until this question is revisited with: a) samples which contain data on both twins and their parents/offspring, b) models which precision-weight those samples, and c) models which test the consistency of the relationship across scientifically salient subgroups.