Data from a given population (i.e. weevils sampled at a given site from a given host species) across years are not necessarily independent.
Because we found differences between populations of weevils sampled from different hosts, we also tested for preference differences between weevils that could use different hosts in their field site.
At sites MA53 and MS16 there was no trend for a difference in preference between weevils sampled from the two hosts (MA53: F1;14 = 0.004, P = 0.95; MS16: F1;49 = 0.027, P = 0.87), and at site MS27 there was a large and significant trend for weevils from one host genus to prefer that same genus in experimental preference trials (F1 21 = 5.12, P = 0.034).
Populations CS20, MS16, CS8, and CS12 : weevils were sampled from Cynara flowerheads in Sardinia; OS4, OS2, OS21, OS14 :weevils were sampled from Onopordum flowerheads in Sardinia: OA22 and OA23 : weevils were sampled from Onopordum flowerheads in Corsica.
Already, the Weevil and Canopy samples show different symbiont profiles.
Because of the unpredictability of host phenology, not all populations were in the right stage for sampling for weevil attacks when visited.
A total of 5,174 scaffolds were shared by both samples (5.8% of Weevil scaffolds; 4.7% of Canopy scaffolds), showing that thousands of similar scaffolds can also be recovered between pools of different species composition.
It was only marginally higher (non-significant) in root feeding weevils and millipede detritivores, possibly due to low sample sizes.
Trees without trial holes from weevils were excluded from the second analysis; leaving the sample size at 548.
Hence, the Canopy sample covers a much wider phyletic spectrum than Weevil, which is taxonomically nested within the former.
