Metacommunity ecology of the pools and ponds of the islands of the Georgian Bay

In 2011 a grant from the National Geographic Committee for Research and Exploration allowed myself and Marie-Josée Fortin (U of T, St. George) as well as graduate student Aaron Hall to initiate a survey of the aquatic habitats nested within the islands of the Georgian Bay Islands National Park.  This work was assisted by undergraduate researchers from Cal Poly.  We investigated patterns of community structure in the water-bodies on these islands which form the world’s largest freshwater archipelago.  These habitats offer a unique opportunity to use the naturally patchy and nested structure of ponds situated on islands to determine the relative contributions of processes at local and regional scale to community structure.

Effects of warming on  dispersal and connectivity

Climate change affects organisms in multiple ways, changing the distribution of suitable environments, shifting the timing of life-history activities, and affecting the conditions in which these organisms develop.  Relatively little work, however, has explored the potential for interactions between these processes.  Myself and collaborators Karen Mabry and Dan Warren are looking at one potentially critical interaction between these responses, the influence of developmental temperatures on body size and the consequent effects on dispersal.  Dispersal allows organisms to track changing environmental conditions may help populations and species avoid extinction.  However, our growing understanding of dispersal biology indicates that most dispersal is phenotype-dependent and that body size is a critical factor in determining the ability and propensity of organisms to disperse.  Body size decreases in response to climate warming may indirectly impact the ability of organisms to disperse and shift their ranges to follow the distribution of suitable habitat, most often negatively (McCauley & Mabry 2011).  We are examining the linkage between developmental temperature and dispersal behavior experimentally in dragonflies.  By experimentally manipulating the water temperatures they experience during development, we can determine the effect of these temperatures on body size, morphology, and ultimately dispersal behavior.  This work is being conducted at the Quail Ridge Reserve, part of the UC’s Natural Reserve System with additional work occurring at the Wantrup Wildlife Sanctuary in the Pope Valley.

Phenotype and context dependent dispersal

I am continuing research on how phenotype-dependent dispersal can influence habitat connectivity and the composition of local populations (McCauley et al. 2010; McCauley 2010), and on the mechanisms that shape traits related to dispersal (Benard & McCauley 2008).  Recent work in this area includes an examination of how dispersal success can be influenced by interactions between individual traits that affect dispersal capacity and conditions in the matrix habitat.  This project was conducted in collaboration with Marie-Josée Fortin and Locke Rowe.  Work on how phenotype dependent dispersal affects interactions within communities across a gradient of spatial isolation and contributes to realized connectivity will continue in both the dragonfly system and in other aquatic taxa.  I am also interested in context-dependent dispersal, such as predator-induced dispersal (McCauley & Rowe 2010), can shape connectivity across landscapes.