PS 85-37
Diversity patterns of shrub dwelling spiders of Colorado grasslands

Friday, August 14, 2015
Exhibit Hall, Baltimore Convention Center
Eric Knutson, BSPM, Colorado State University, Fort Collins

Understanding the patterns that underline species distribution, by comparing habitat heterogeneity and community organization can illustrate the factors shaping metapopulations. Recent advances in species distribution models (SDMs) may allow ecologists to test ecological variation to elude to local dispersal and niche width in new, spatially explicit ways. Spiders are a diverse taxonomic group and fill important niches of grassland ecosystems. However, relatively little is known about arboreal species in grassland systems. Arboreal spiders, as generalist predators, inhabiting numerous microhabitats with uncommon dispersal methods, make a unique ecological system to study population diversity and community interactions. To assess the factors responsible for diversity variation, data was collected for a multi-year biodiversity study within selected Colorado National Grassland sites with a focus on life history of shrub dwelling spiders. Sampling locations were selected at each site spanning a large range of vegetation and topography intervals. This study predicted that at the highest level, beta diversity would contribute more to overall regional diversity than the lower hierarchal levels, due to more habitat heterogeneity at the landscape level. 


In this study, 32 spider species were collected at at Pawnee and Comanche National Grasslands of eastern Colorado along sampling corridors of vegetation representing dominant shrubland plant species. Preliminary 2014 data indicates that shrub species offer unique structural or temporal factors to spider communities in grasslands. A predictive model was constructed of spider distribution within a study area assessing environmental factors that have the strongest effect in the distribution of spider species richness. I also assessed the importance of the spatial scale to identify patterns of spider diversity. The spider diversity documented at these locations highlight the importance of higher detail to specific shrubland habitat in grasslands, suggesting the nation’s grassland biodiversity is poorly-characterized.