Macroscale Patterns of Biotic Resistance

Empirical and theoretical studies have shown that the association between native diversity and invasion (e.g., usually exotic richness) is inconsistent, varying across scales and ecosystems of study. To explain the different patterns, ecologists have proposed a number of underlying processes, focusing mostly on the role of local or regional native species richness. Yet, there are other community characteristics and mechanisms that may be involved in influencing invasibility that are currently vastly understudied. In my research, I take advantage of the advent of comprehensive databases to study macroscale patterns in the roles of lesser known community characteristics, such as beta, phylogenetic and functional diversity.

Beta diversity and biotic resistance to freshwater aquatic invasions

We sought to understand how beta diversity, the heterogeneity of species composition among assemblages, influences the observed relationship between native and exotic species richness. In addition, we sought to understand how this influence changes across scales. To do this, we obtained native and exotic richness data for the entire continental United States from the USGS nonindigenous aquatic species and NatureServe databases. We took advantage of the nested properties of these databases (HUC levels) to incorporate the influence of scale in these relationships.

Our results seem to indicate a scale-dependent effect of beta diversity on biotic resistance. Contrary to our hypothesis, we found beta diversity to have, not a negative effect, but a positive effect on biotic resistance, and only at scales with the largest spatial extent.

For the full story, please stay tuned! Manuscript is currently in preparation.

Roles of specific species traits, phylogenetic and functional diversity on biotic resistance to invasive forest pests

Non-native invasive insects are the cause of numerous ecological impacts that gravely threaten the conservation of native biodiversity. In the case of invasive insects, researchers and practitioners have focused on biotic resistance stemming from the association between non-host tree species and neighboring host trees (i.e. associational resistance). I plan to assess whether specific plant traits of non-host trees associated with host detectability or attraction of natural enemies have an effect on the number of invasive insect pests established in forests across the continental United States. Additionally, I plan to investigate the resistance effects of functional and phylogenetic diversity, as proxies for community complexity, on invasive insect richness. This research has the potential to provide novel and broadly-applicable insights into mechanisms of biotic resistance that could be highly relevant for the prioritization of resources for pest management and to ensure resistant communities in ecological restorations.