Carry-over effects in space: Beyond single species studies and towards metacommunity dynamics
Van Allen, Benjamin G
Rudolf, Volker H. W.
Doctor of Philosophy
The behavioral and physical traits of adults can be strongly influenced by conditions experienced during development. Consequently, variation in natal habitat quality across a landscape and through time can also lead to differences in the traits of adults. When individuals move across the landscape, this could create carry-over effects where differences in the natal habitat quality of colonizers influence population dynamics and species interactions in new habitats. I studied how these carry-over effects, which are known to alter individual traits and population dynamics, scale up to larger effects on community and metacommunity (multiple communities across a landscape connected by dispersing individuals) dynamics. I tested these questions on carry-over effects in a spatial context using a Tribolium spp. flour beetle system with habitat patches of flour. I generated carry-over effects by using flour types which predictably alter the traits of flour beetles who develop in them. The first chapter identified that carry-over effects which alter population dynamics occur in this system. It also discovered novel and powerful mechanisms for carry-over effects to influence population dynamics. The second chapter shows how carry-over effects and population density interact to affect dispersal decisions, which is important for understanding how carry-over effects will propagate across landscapes. The third chapter shows that carry-over effects can decisively alter competitive dynamics and outcomes, but that how may not be immediately predictable from their influence on single population dynamics. Finally, my fourth chapter manipulated whether carry-over effects occurred across multi-patch landscapes to test whether they influence species dynamics across a metacommunity. This final chapter shows that at the landscape scale, carry-over effects can have even more strong emergent effects. For example, carry-over effects increased population sizes across landscapes by ~10% while dramatically promoting different species under different conditions of dispersal and habitat arrangement. Thus, the influences of carry-over effects on population and community dynamics at the landscape level may be strong, but context dependent on other spatial processes. Further work to understand how landscape habitat patterns and dispersal shape the influence of carry-over effects on metacommunity dynamics could improve understanding of natural population and community dynamics.
Carry-over effects; Natal habitat effects