Results
We found a total of 251 ant species, which represented about 85% of the
diversity estimated across the entire study region (HDI range = [294,
327]; Fig. 2A). Approximately 45% of all species were observed at
individual patches (observed range = [37, 80]; estimated range =
[84, 177]; Fig. 2B-D). The large number of unobserved species,
especially in individual patches, results from low detection of most ant
species at individual Winkler extractors (Fig. 3A). Due to the larger
number of patches and extractors across the entire landscape, the chance
of detecting a rare species at least once increases with greater
sampling effort (e.g. if Mycetomoellerius sp.6, one of the rarest
species, is present, detection changes from ~1% at the
Winkler extractor scale to ~9% at the patch scale, and
to ~89% at the landscape scale). Even when considering
detection errors, most species were rare across the landscape and
occurred in fewer than 50% of all forest fragments (occupancy
< 0.5 in Fig. 3B). These results demonstrate that any naïve
counting of species (without the use of occupancy models or other
corrections) would find more species at the landscape scale than at the
local patches due to detection issues alone, even if no real changes in
diversity occurred.
Estimates of regional species richness using the 500-m buffers or cattle
intrusion as predictors in occupancy models provided almost identical
results. Therefore, we were unable to detect an effect of the
surrounding habitat amount on local diversity above and beyond what
would be predicted by patch area alone (or the Species-Area
Relationship). One additional species was estimated to be undetected in
the landscape when cattle was used as a predictor when comparing with
model with area as a predictor. Using the same sampling protocol,
species were easier to detect in the smaller patches (i.e. smaller
patches tend to more easily represented).