PARENT SESSION
Oral Session # 88: Plant Ecology VII: Communities.
Presiding: N Turrill Welch
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 100.
Host plant genetic diversity affects arthropod diversity at multiple scales.
Wimp, Gina*,1, Young, William1, Woolbright, Scott1, Martinsen, Greg1, Keim, Paul1, Whitham, Thomas1, 1 Northern Arizona University, Flagstaff, Arizona
ABSTRACT- We examined the hypothesis that genetic diversity in a dominant tree has higher-level effects on the structure and diversity of the dependent arthropod community. Plant hybridizing systems are ideal systems in which we can test these predictions because they represent some of the most genetically diverse systems where gene flow is occurring. Hybridizing systems therefore provide an important step between inter- and intraspecific host plant diversity in determining the level at which arthropod communities might be responding to genetic differences among their host plants. We chose a hybrid cottonwood system (Populus angustifolia x P. fremontii), and used clones of known genetic composition in a common garden to address individual tree-level effects, combined with stand-level comparisons in the wild to address landscape-level effects of host plant genetic diversity on arthropod communities. In a common garden analysis of 66 different arthropod species, we found that genetic diversity among different cottonwood species and hybrid types affected the structure of arthropod communities via changes in arthropod composition. We therefore predicted that changes in arthropod composition among cottonwood species and hybrid types would lead to the greatest levels of arthropod diversity where cottonwood genetic diversity was also greatest. When we tested this prediction using an analysis of 11 different cottonwood stands and 210 arthropod species, our results supported this prediction. We found a significant, positive relationship between cottonwood stand genetic diversity and arthropod diversity such that genetic diversity among cottonwood stands accounted for 59% of the variation in arthropod diversity. Because these findings demonstrate the community-level consequences of genetic diversity, they argue for the consideration of genetic-based approaches to the theory of community organization and conservation biology.
Key words: genetics, hybrid, community, arthropod