@article{li_he_campbell_colborn_jackson_martin_monagan_ong_perfecto_2017, title={From endogenous to exogenous pattern formation: Invasive plant species changes the spatial distribution of a native ant}, volume={23}, ISSN={["1365-2486"]}, DOI={10.1111/gcb.13671}, abstractNote={AbstractInvasive species are a significant threat to global biodiversity, but our understanding of how invasive species impact native communities across space and time remains limited. Based on observations in an old field in Southeast Michigan spanning 35 years, our study documents significant impacts of habitat change, likely driven by the invasion of the shrub, Elaeagnus umbellata, on the nest distribution patterns and population demographics of a native ant species, Formica obscuripes. Landcover change in aerial photographs indicates that E. umbellata expanded aggressively, transforming a large proportion of the original open field into dense shrubland. By comparing the ant's landcover preferences before and after the invasion, we demonstrate that this species experienced a significant unfavorable change in its foraging areas. We also find that shrub landcover significantly moderates aggression between nests, suggesting nests are more related where there is more E. umbellata. This may represent a shift in reproductive strategy from queen flights, reported in the past, to asexual nest budding. Our results suggest that E. umbellata may affect the spatial distribution of F. obscuripes by shifting the drivers of nest pattern formation from an endogenous process (queen flights), which led to a uniform pattern, to a process that is both endogenous (nest budding) and exogenous (loss of preferred habitat), resulting in a significantly different clustered pattern. The number and sizes of F. obscuripes nests in our study site are projected to decrease in the next 40 years, although further study of this population's colony structures is needed to understand the extent of this decrease. Elaeagnus umbellata is a common invasive shrub, and similar impacts on native species might occur in its invasive range, or in areas with similar shrub invasions.}, number={6}, journal={GLOBAL CHANGE BIOLOGY}, author={Li, Kevin and He, Yifan and Campbell, Susanna K. and Colborn, A. Shawn and Jackson, Eliot L. and Martin, Austin and Monagan, Ivan V., Jr. and Ong, Theresa Wei Ying and Perfecto, Ivette}, year={2017}, month={Jun}, pages={2250–2261} }
 @article{bradham_nelson_kelly_pomales_scruton_dignam_misenheimer_li_obenour_thomas_2017, title={Relationship Between Total and Bioaccessible Lead on Children's Blood Lead Levels in Urban Residential Philadelphia Soils}, volume={51}, ISSN={["1520-5851"]}, DOI={10.1021/acs.est.7b02058}, abstractNote={Relationships between total soil or bioaccessible lead (Pb), measured using an in vitro bioaccessibility assay, and children's blood lead levels (BLL) were investigated in an urban neighborhood in Philadelphia, PA, with a history of soil Pb contamination. Soil samples from 38 homes were analyzed to determine whether accounting for the bioaccessible Pb fraction improves statistical relationships with children's BLLs. Total soil Pb concentration ranged from 58 to 2821 mg/kg; the bioaccessible Pb concentration ranged from 47 to 2567 mg/kg. Children's BLLs ranged from 0.3 to 9.8 μg/dL. Hierarchical models were used to compare relationships between total or bioaccessible Pb in soil and children's BLLs. Total soil Pb concentration as the predictor accounted for 23% of the variability in child BLL; bioaccessible soil Pb concentration as the predictor accounted for 26% of BLL variability. A bootstrapping analysis confirmed a significant increase in R2 for the model using bioaccessible soil Pb concentration as the predictor with 99.0% of bootstraps showing a positive increase. Estimated increases of 1.3 μg/dL and 1.5 μg/dL in BLL per 1000 mg/kg Pb in soil were observed for this study area using total and bioaccessible Pb concentrations, respectively. Children's age did not contribute significantly to the prediction of BLLs.}, number={17}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Bradham, Karen D. and Nelson, Clay M. and Kelly, Jack and Pomales, Ana and Scruton, Karen and Dignam, Tim and Misenheimer, John C. and Li, Kevin and Obenour, Daniel R. and Thomas, David J.}, year={2017}, month={Sep}, pages={10005–10011} }