Cryptic Dispersal Networks Connect Habitat Patches in ways not Captured by Distance

Abstract

Species interact with the physical world in complex ways, and life history strategies might cause species to differ in how they experience connectedness of the same landscape. As a consequence, dispersal limitation might be present but not captured by distance-based measures of connectivity. To test these ideas, we surveyed plant communities that associate with serpentine soils but differ in dispersal mode (gravity, animal, or wind), and used satellite imagery to quantify forms of landscape connectivity associated with each dispersal mode. Our data yielded two key insights: First, dispersal limitation appeared to be absent using a conventional distance-based measure of connectivity, but emerged after considering forms of landscape connectivity relevant to each dispersal mode. Second, the landscape variables that emerged as important to each dispersal mode were generally consistent with our predictions based on putative dispersal vectors, and included interactive effects that allude to the altered efficacy of animal dispersal in invaded landscapes. Our results have broad implications for understanding how ecological communities reorganize as landscapes are fragmented, patches are lost, and the function of dispersal life histories is altered.