Community heritability, repeatability, and stability: The arthropod community of Populus angustifolia over 3 years

Abstract. Recent studies have shown that intraspecific genetic variation can affect biodiversity and ecosystem processes and a few studies have shown that these phenotypes can be heritable (i.e., related individuals support similar communities and ecosystem processes).  Because heritability studies of community composition are few, limited to a subset of the community, and are limited to a single field season, it is important to expand such studies to examine full communities and to quantify heritability across years to better understand the repeatability of such findings.  In our observational and common garden studies of 103 arthropod species on Populus angustifolia, we found 4 major patterns:  1). Both field and common garden studies show extensive variation in community richness, abundance and composition among individual tree genotypes.  2). Common garden studies using replicated clones of the same tree genotypes show that the arthropod community phenotype is a heritable trait (broad-sense heritability, H²_C = 0.66).  In other words, different tree genotypes support different arthropod communities regardless of where they are growing in a randomized common garden.  3). Broad-sense heritability is highly repeatable; i.e., over each of three consecutive years, broad-sense heritability of arthropod community composition ranged from H²_C = 0.63 to 0.68.  4). There is a strong genetic component to “community stability” in which community phenotypes were consistent across years (r²=0.83) yet there was no genetic by time interaction.  5). These findings place community traits such as species richness, abundance and composition within a genetic and evolutionary framework and have important conservation implications.