Ploidy level in the genus Leucanthemum correlates with resistance to a specialist herbivore

Sonja Stutz,Kamil Konowalik,Christoph Oberprieler,Hariet L Hinz,Heinz Müller‐Schärer,Urs Schaffner

doi:10.1002/ecs2.1460

Abstract

AbstractPolyploidy is considered to be a major source of genetic diversity in plants. Genome duplication has been shown repeatedly to be associated with changes in biotic interactions, but little is known about whether species traits such as herbivore resistance consistently change with increasing ploidy level among closely related plant species. We tested whether larval survival and performance of the specialist root‐mining moth Dichrorampha aeratana are influenced by the ploidy level of plant species in the genus Leucanthemum by experimentally infesting 16 different taxa with ploidy levels ranging from diploid to dodecaploid. We found that survival of D. aeratana larvae consistently decreased with increasing ploidy level, irrespective of whether phylogenetic distance among taxa was taken into account or not. The mass of larvae and the proportion of adults emerging from last‐instar larvae, however, did not consistently change with increasing ploidy level. Root biomass and dry matter content of the Leucanthemum taxa were neither correlated with ploidy level nor correlated with survival or mass of D. aeratana larvae. In summary, our results provide evidence that in the genus Leucanthemum, resistance to the specialist root herbivore D. aeratana consistently increases with increasing plant ploidy level, but it remains unclear which characteristics associated with polyploidy account for the higher herbivore resistance.

Highlights

The phylogenetic distance matrix was based on sequence variation at nine nuclear DNA loci (markers A39, B12, B20, C12, C20, C33, D18, D23, and D27 of Chapman et al (2007) and on five intergenic spacer regions of the chloroplast genome, the latter being concatenated into a single alignment (see Konowalik et al (2015) for details of the sequencing procedure in diploid taxa, which was applied to the polyploid taxa of the present study)
Our calculation of pairwise phylogenetic distances among taxa followed the Matrix Representation with Parsimony (MRP) method (Baum 1992, Ragan 1992, Bininda-Emonds 2004), which is often used to reconstruct supertrees based on supermatrices resulting from coding multiple underlying phylogenetic trees (e.g. Johnson et al (2012))
All ten underlying gene trees were transformed into multilabelled trees by giving all accessions and all alleles of a particular taxon the same label, coding the gene tree topologies as 0/1 matrices, and merging the matrices into a single matrix by using a script provided by Johnson et al (2012)