Sky islands are areas of higher elevation isolated from surrounding lowland habitats that often support unique biological communities. Arkansas houses several sky island habitats in the mountainous regions of the state (Ozark and Ouachita Mountains). While several unique insect species have been found in these areas, broad community comparisons are lacking. The objective of our study was to measure the community structure of Hymenoptera in sky islands of Arkansas and determine their similarity. We collected Hymenoptera using ground and canopy Townes-Malaise traps on Rich Mountain, Mount Magazine, and Petit Jean Mountain once a month from June through October 2017. Traps were positioned in areas of post oak (Quercus stellata) savanna habitat, the predominant habitat in these sky islands. Specimens were identified to the superfamily level and then morphotyped. We then calculated diversity metrics and compared the number of common morphospecies across sites.
Results/Conclusions
Each site showed more than 100 species of hymenoptera, with high levels of evenness (J’ > 0.85) at all sites. Each site exhibited many unique species (i.e., species found at only one sky island), in particular, Mount Magazine. Each site had few species in common, with no pair of sites having more than 16% morphospecies overlap. Low morphospecies overlap suggests that each sky island has a unique community assemblage of parasitic Hymenoptera. These sky islands are rich in hymenopteran diversity. The high degree of evenness is indicative of a community with many uncommon species and few dominant ones. Because these results suggest that sky island habitats in Arkansas each contain different communities, they may be worthy of enhanced conservation efforts.