Association between individual genetic diversity of two oak host species and canopy arthropod community structure

Numerous oak species have wide geographical distribution and canopy dominance and they may influence the structure and functioning of the community. Therefore, they can be considered as foundation species. In the present study, we tested the potential association between individual genetic diversity of the host plant (microsatellites), host tree species (Quercus castanea and Q. crassipes), and seasonality (dry vs. rainy) with their arthropod community structure [diversity (H′), density, biomass and composition]. Forty individual oak canopies were fogged (10 individuals per species per season) in the Parque Ecológico Ciudad de México. We identified 338 arthropod morphospecies belonging to 21 orders. NMDS showed a separation of host tree species during both seasons, suggesting a different community structure between host tree species. Q. crassipes showed the highest values for H′, richness, and density in comparison with Q. castanea. In contrast, Q. castanea showed the highest values for arthropod biomass. Homozygosity by locus index (HL), a measure of individual diversity, showed that the more genetically diverse host individuals registered more H′ and density of arthropods, independently of the season. On the contrary, arthropod biomass registered an inverse pattern. This study suggests that genetic diversity of foundation species is an important element in the structuring of the canopy arthropod community.