Genetic Variation in Functional Traits Influences Arthropod Community Composition in Aspen (Populus tremula L.)

Abstract

We conducted a study of natural variation in functional leaf traits and herbivory in 116 clones of European aspen, Populus tremula L., the Swedish Aspen (SwAsp) collection, originating from ten degrees of latitude across Sweden and grown in a common garden. In surveys of phytophagous arthropods over two years, we found the aspen canopy supports nearly 100 morphospecies. We identified significant broad-sense heritability of plant functional traits, basic plant defence chemistry, and arthropod community traits. The majority of arthropods were specialists, those coevolved with P. tremula to tolerate and even utilize leaf defence compounds. Arthropod abundance and richness were more closely related to plant growth rates than general chemical defences and relationships were identified between the arthropod community and stem growth, leaf and petiole morphology, anthocyanins, and condensed tannins. Heritable genetic variation in plant traits in young aspen was found to structure arthropod community; however no single trait drives the preferences of arthropod folivores among young aspen genotypes. The influence of natural variation in plant traits on the arthropod community indicates the importance of maintaining genetic variation in wild trees as keystone species for biodiversity. It further suggests that aspen can be a resource for the study of mechanisms of natural resistance to herbivores.

Genotypic variability in Populus tremula L. affects how anthropogenic nitrogen enrichment influences litter decomposition

“…In a study with 31 GTs of the North American aspen, Populus tremuloides Michx., Lindroth and Hwang (1996) found that condensed tannin concentrations varied more than 2-fold between the GT expressing the lowest and the highest concentration, respectively. Also, for the related European aspen, Populus tremula L., a keystone species in the boreal region (Siitonen and Martikainen 1994;Kouki et al 2004), substantial genotypic variations in tannin concentrations have been reported (Robinson et al 2012;Bandau et al 2015). Tannins have long been recognized for their potential role in defending plants against generalist herbivores and pathogens (Kraus et al 2003;Holeski et al 2009;Barbehenn and Constabel 2011;Robinson et al 2012), but they are increasingly also acknowledged to influence soil processes, such as litter decomposition (Kraus et al 2003;Madritch et al 2006;Schweitzer et al 2008;Madritch and Lindroth 2015), through their resistance to degradation by soil microbes, as well as their ability to bind and stabilize plant proteins or microbial enzymes (Benoit and Starkey 1968;Fierer et al 2001;Kraus et al 2003 and references therein;Joanisse et al 2007).…”

Susceptibility of silver birch (Betula pendula) to herbivorous insects is associated with the size and phenology of birch – implications for climate warming

“…The latitudinal patterns in herbivore community composition found by Heimonen et al (2015a) may be explained by differences in the height growth and in the timing of growth cessation of birch along the latitudinal gradient but other unmeasured plant traits may also be associated with the herbivore community composition. Growth-related traits were also found to explain the community composition of herbivorous insects in Populus tremula (Robinson et al 2012) and in Salix hookeriana (Barbour et al 2015), and the herbivore assemblage varied strongly on two architecturally distinct morphs of Baccharis pilularis (Crutsinger et al 2014). Moreover, different herbivore species prefer certain phenological stages of their host plant, that is, leaves of different ages (Crawley & Akhteruzzaman 1988).…”

“…Based on our results, in mixed stands, the genotypes originating from high-latitude populations could be more prone to herbivore damage than those from low latitudes, due to their slower growth and earlier growth cessation. The association may not be, however, directly causal since other unmeasured plant traits may be driving the interaction between herbivores and host trees (Robinson et al 2012;Bernhardsson et al 2013). For example, lack of coevolutionary history with herbivore species could lead to weak defense against herbivores, and subsequently, to high susceptibility of high-latitude birch populations to herbivores (Cudmore et al 2010;Gandhi & Herms 2010).…”

“…On the other hand, larger plants may tolerate herbivory better than smaller ones (Byington et al 1994). Differences in plant growth are also likely to change the composition of the herbivore community (Robinson et al 2012).…”

Natural Variation as a Tool to Investigate Nutrient Use Efficiency in Plants

“…These variations could have an important impact on yield or quality of their products in crops, fruit trees and forestry management species (Saisho et al 2011;Arikita et al 2013;Eduardo et al 2010;Łata et al 2005;Robinson et al 2012). Some developmental traits, such as flowering time or seed dormancy, have drawn particular attention, partly because they are of applied interest to crop breeding, and partly because they are easy to investigate (Shindo et al 2007).…”