Molecular dietary analyses of western capercaillies (Tetrao urogallus) reveal a diverse diet

Abstract

Conservation strategies centred around species habitat protection rely on species dietary information. One species at the focal point of conservation efforts is the herbivorous grouse, the western capercaillie (Tetrao urogallus). Traditional microhistological analysis of crop contents or faeces and/or direct observations are time-consuming and at low taxonomic resolution. Thus, limited knowledge on diet is hampering conservation efforts. Here we use non-invasive environmental DNA (eDNA) metabarcoding on DNA extracted from faeces to present the first large-scale molecular dietary analysis of capercaillies. Faecal samples were collected from seven populations located in Norway (Finnmark, Troms, Trøndelag, Innlandet) and France (Vosges, Jura, Pyrenees) (n=172). We detected 122 plant taxa belonging to 46 plant families of which 37.7% of the detected taxa could be identified at species level. The average dietary richness of each sample was 7 ± 5 SD taxa. The most frequently occurring plant groups with the highest relative read abundance (RRA) were trees and dwarf shrubs, in particular, Pinus and Vaccinium myrtillus, respectively. There was a difference in dietary composition (RRA) between samples collected from the different locations (adonis F5,86= 11.01, p <0.05) and seasons (adonis F2,03= 0.64, p <0.05). Dietary composition also differed between sexes at each location (adonis F1,47 = 2.77, p <0.05), although not significant for all data combined. In total, 35 taxa (36.84% of taxa recorded) were new capercaillie food items compared to existing knowledge. The non-invasive molecular dietary analysis applied in this study provides new ecological understanding of capercaillies diet which can have real conservation implications. The broad variety of diet items indicates that vegetation does not limit food intake. This plasticity in diet suggests that other factors including disturbed mating grounds and not diet could be the main threat to their survival.

Multi‐marker DNA metabarcoding reveals spatial and sexual variation in the diet of a scarce woodland bird

“…Spatial dietary differences observed between Hawfinch populations are consistent with similar metabarcoding studies of birds and insectivorous bats (Clare et al, 2014;Czenze et al, 2018;Shutt et al, 2020;Tournayre et al, 2021). This could indicate local dietary specialization; however, it is more probable that Hawfinch exhibit dietary plasticity and individual preference, with these patterns arising from changing availability of food resources between locations (Chua et al, 2021). The Wye Valley and north Cardiff regions occur within heterogeneous woodlands consisting of predominately beech and elm, while the north Wales region consisted of woodland supporting hornbeam and cherry.…”

“…Detailed dietary information is vital for understanding species' ecology and implementing effective conservation management plans (Chua et al, 2021). This study used a metabarcoding approach to provide the first comprehensive analysis of UK Hawfinch diet, as well as highlighting dietary differences between Hawfinch populations across the UK and between sexes.…”

Assessing flower-visiting arthropod diversity in apple orchards through environmental DNA flower metabarcoding and visual census

“…Post-OBITools sequence filtering and merging of the taxonomic assignments were carried out with R-studio 1.4.1103 (R Core Team, 2020). Following the analysis detailed in Chua et al (2021), only sequences that fulfilled the following criteria were kept: i) matched 98% of our reference database, ii) had a minimum of three reads of each taxon observed within each PCR replicate (See Supplemental information 1 Table S4), and iii) occurring in at least two PCR replicates of a sample (Ficetola et al, 2015;Rasmussen et al, 2021b) (See Supplemental information 1 Table S5). No sequences were found in the extraction blank and PCR blank when checked for possible contamination.…”

“…Metabarcoding of remnant arthropod DNA on plant samples is a relatively new tool that has just started to be used for plant-arthropod network research (Ruppert et al, 2019;Thomsen and Sigsgaard, 2019). Compared to traditional methods, metabarcoding is faster in the field, and can potentially provide a more reliable overview of apple flower visitors (Ruppert et al, 2019;Evans and Kitson, 2020), with better taxonomic resolutions, while being more cost-efficient (Yang et al, 2014;Chua et al, 2021). However, degraded DNA and unsuitable sample processing might lead to skewed results (De Barba et al, 2014;Deagle et al, 2019).…”