Landscapes are patchy and, as the quality of a patch declines over time, individuals vary in dispersal based on their sensitivity to quality. Variation in sensitivity to habitat quality may also affect dispersal distance, ultimately producing a population that is spatially sorted by sensitivity to patch quality. We examine whether spatial sorting by sensitivity to patch quality leads to spatial sorting in other behavioral and life-history traits, such as those correlated with foraging and dispersal behaviors. We manipulated the environment experienced by female seed beetles, Callosobruchus maculatus, and allowed females to sort in experimental arrays. After 5 generations we examined behavioral and life history traits, including fecundity, habitat selection behaviors, and dispersal behaviors, that evolved to be different in females that dispersed versus did not disperse in response to low habitat quality.
Results/Conclusions
We bred 6 replicate selection lines (3 habitat sensitive and 3 non-sensitive) for two populations of beetles (total 12 lines) and maintained 5 control lines. The distance traveled by the long distance disperser lines increased each generation. After 5 generations, the long distance disperser lines had evolved a higher sensitivity to patch quality than the control lines. Females that disperse long distances have a reduced fecundity and increased acceptance of novel hosts, whereas the short distance dispersing females will have a high fecundity and low acceptance of novel hosts. These differences should lead to spatial sorting of a popultion by sensitivity to patch quality. This project aims to experimentally determine the reproductive and behavioral traits correlated with dispersal that also become spatially sorted. An understanding of how individual sensitivity to diminishing habitat quality leads to spatial sorting of populations can provide insight into the associated impacts on regional population dynamics.