Island biogeography at the meso-scale: distance from forest edge affects choice of patch size by ovipositing treefrogs

Diversity in habitat patches is partly driven by variation in patch size,
which affects extinction, and isolation, which affects immigration. Patch
size also affects immigration as a component of patch quality. In wetland
ecosystems, where variation in patch size and inter-patch distance is
ubiquitous, relationships between size and isolation may involve
trade-offs. We assayed treefrog oviposition at three patch sizes in arrays
of two types, one where size increased with distance from forest
(dispersed), and one with all patches equidistant from forest
(equidistant), testing directly for an interaction between patch size and
distance, which was highly significant. Medium patches in dispersed arrays
received more eggs than those in equidistant arrays as use of typically
preferred larger patches was reduced in dispersed arrays. Our results
demonstrate a habitat selection trade-off between preferred large and
less-preferred medium patches across small-scale variation in isolation.
Such patch size/isolation relationships are critical to community assembly
and to understanding how diversity is maintained within a metapopulation
and metacommunity framework, especially as wetland habitat becomes
increasingly rare and fragmented. These results bring lessons of Island
Biogeography, writ large, to bear on questions at small scales where
ecologists often work, and where habitat restoration is most often
focused.