Landscape structure is often based on the number, size and distances between habitat patches; however, a landscape consisting of a patchwork of habitats may be perceived very differently depending on the dispersal capacity of the focal species. As dispersal range increases, separated patches become increasingly accessible until all but the most isolated patches are connected. Thus for long-range species, patches in the landscape are likely to be experienced as source-sinks; the source where patches overlap in habitat, the sinks where they are isolated. In contrast, short-range species are likely to experience landscapes as small, independent patches also known as meta-populations. We construct a theoretical framework where each member of a community experiences a shared, fragmented landscape in ways dependent on its individual dispersal capacity, and examine how perceptions of landscape structure influence the synchrony of populations and the slope of Taylor’s temporal law. We then test where along the continuum from meta-population to source-sinks each member in a real community of arthropods perceives urban garden patches as habitat using populations of aphids, ladybird beetles, and parasitoid wasps sampled regularly across an entire city landscape for three time periods.
Results/Conclusions
We show that for simulated populations parameterized using actual garden data as carrying capacities, the slope of Taylor’s temporal law increases from 1 to 2 as the sampling radius increases. This occurs due to the synchronizing effect of an environmental term, which increases as populations at large sample radii share habitat patches. At small sample radii, patches are independent sinks and experience asynchronous dynamics from random dispersal-colonization events. From survey data we find that aphid populations are sensitive to gardens at long distances and have Taylor’s law slopes nearing 2, indicating existence as source-sinks. In contrast, parasitoid wasps were sensitive to gardens at short distances with Taylor’s law slopes closer to 1, indicating existence as meta-populations. Ladybird beetles did not respond to gardens at any distance. Our results show that different organisms can perceive the same fragmented landscape very differently depending on their dispersal range, and that the slope of Taylor’s temporal law may be intricately linked to meta-population theory.