Welcome to the Callaway Lab
My lab is a horizontally organized group of postdoctoral, graduate student, and undergraduate collaborators. The primary focus of the research in my lab is on how organisms interact with each other, but we are interested in all aspects of ecology. These interactions include direct interactions, such as competition for resources, allelopathy, and facilitation; and indirect interactions mediated by herbivores, soil microbes, and other competitors. I continue to study facilitative interactions among plants, mostly alpine habitats and in collaboration with the international Alpine Pals research group. But because of how my graduate students have influenced my interests over the last 15 years, most of my time is now spent on exploring how exotic invaders dominate habitats despite limited opportunities for local adaption, and suppress native species which have had ample opportunities to locally adapt.
Specific interests in invasions include the role of soil biota, novel biochemical interactions with native competitors, microbes, and generalist herbivores, and using invaders to test general ideas about competition. We have generally found that naive native species are more susceptible to the chemical effects of invaders than species native to the invader's ranges. For example, three of North America's more aggressive invaders, Acroptilon repens, Centaurea stoebe and C. diffusa, show evidence for being more competitive and/or more allelopathic to North American species than species in the native ranges of the invaders.
Recently we (I) are a bit of an obsessed with biogeographic differences in the abundances and impacts of exotic invaders - in other words, actually quantifying abundances and impacts in the native and non-native ranges. While many exotics seem to behave similarly in their native and non-native ranges, we are finding finding fascinating shifts in biogeographic patterns or basic ecology (see Research) for Acroptilon repens, Centaurea stoebe, Conyza canadensis, Solidago gigantea, Ageratina adenophora, Prosopis juliflora, Thymus vulgaris, and Eucalyptus globulus.
Probably the most prominent big picture idea orginating in and being pursued in my lab is that shared evolutionary trajectories may mediate coexistence and even interdependence in communities. Thus in an invasive context, perhaps when humans introduce particular plant species to new regions they force together species with different evolutionary trajectories from different continents, providing instances of profound community disruption and an unparalleled opportunities to test long held ecological paradigms.