Host Genetics and Environment Drive Divergent Responses of Two Resource Sharing Gall-Formers on Norway Spruce: A Common Garden Analysis

E Petter Axelsson; Glenn R Iason; Riitta Julkunen-Tiitto; Thomas G Whitham

doi:10.1371/journal.pone.0142257

Host Genetics and Environment Drive Divergent Responses of Two Resource Sharing Gall-Formers on Norway Spruce: A Common Garden Analysis

PLoS One. 2015 Nov 10;10(11):e0142257. doi: 10.1371/journal.pone.0142257. eCollection 2015.

Authors

E Petter Axelsson¹, Glenn R Iason², Riitta Julkunen-Tiitto³, Thomas G Whitham⁴

Affiliations

¹ Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden.
² The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, Scotland.
³ Department of Biology, University of Eastern Finland, PO Box 111, Joensuu 80101, Finland.
⁴ Merriam-Powell Center for Environmental Research & Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, United States of America.

Abstract

A central issue in the field of community genetics is the expectation that trait variation among genotypes play a defining role in structuring associated species and in forming community phenotypes. Quantifying the existence of such community phenotypes in two common garden environments also has important consequences for our understanding of gene-by-environment interactions at the community level. The existence of community phenotypes has not been evaluated in the crowns of boreal forest trees. In this study we address the influence of tree genetics on needle chemistry and genetic x environment interactions on two gall-inducing adelgid aphids (Adelges spp. and Sacchiphantes spp.) that share the same elongating bud/shoot niche. We examine the hypothesis that the canopies of different genotypes of Norway spruce (Picea abies L.) support different community phenotypes. Three patterns emerged. First, the two gallers show clear differences in their response to host genetics and environment. Whereas genetics significantly affected the abundance of Adelges spp. galls, Sacchiphantes spp. was predominately affected by the environment suggesting that the genetic influence is stronger in Adelges spp. Second, the among family variation in genetically controlled resistance was large, i.e. fullsib families differed as much as 10 fold in susceptibility towards Adelges spp. (0.57 to 6.2 galls/branch). Also, the distribution of chemical profiles was continuous, showing both overlap as well as examples of significant differences among fullsib families. Third, despite the predicted effects of host chemistry on galls, principal component analyses using 31 different phenolic substances showed only limited association with galls and a similarity test showed that trees with similar phenolic chemical characteristics, did not host more similar communities of gallers. Nonetheless, the large genetic variation in trait expression and clear differences in how community members respond to host genetics supports our hypothesis that the canopies of Norway spruce differ in their community phenotypes.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Aphids / genetics*
Ecosystem*
Environment*
Genetic Variation*
Genotype
Phenotype*
Picea / genetics*

Grants and funding

This work was supported by King Carl XVI Gustaf’s 50-Year Fund and Fonden för skogsvetenskaplig forskning (EPA). GRI was funded by the Scottish Government's Rural and Environment Science and Analytical Services. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.