MIAMI UNIVERSITY The Graduate School Certificate for Approving the Dissertation We hereby approve the Dissertation of Kaitlin U. Campbell Candidate for the Degree DOCTOR OF PHILOSOPHY ______________________________________ Thomas O. Crist, Director ______________________________________ Melany C. Fisk, Reader ______________________________________ Hans Klompen, Reader ______________________________________ Ann L. Rypstra, Reader ______________________________________ John K. Maingi, Graduate School Representative ABSTRACT BIODIVERSITY OF ANTS AND ASSOCIATED MITES IN CONSTRUCTED GRASSLANDS AT MULTIPLE SPATIAL SCALES by Kaitlin U. Campbell The goals of this dissertation were to examine how patch and landscape level processes structure ant communities in agricultural landscapes and determine the relative roles of patch and host-level factors in determining ant-associated mite diversity and community composition. In Chapter 1, I examined ant richness, species frequencies, and community composition in 23 warm season constructed grasslands that varied in both patch and landscape level characteristics. Ant species richness was greater in older sites with sandier soils, while community composition was structured by soil texture, management, and urban land use. Frequency analyses for 14 ant species showed a wide range of responses to both patch and landscape components of the environment including age, management, soil texture, and surrounding land use. My findings support the use of ants as environmental indicators of disturbance in agricultural landscapes and show that diversity in constructed grasslands is structured by both patch and landscape level processes. In Chapter 2, I determined the relative importance of host and habitat for an ant-dependent commensalism (phoretic mites). I found that large, cosmopolitan, and abundant ant species support a greater proportion of the mite diversity. Additionally, I found that patch level characteristics, or environmental context (area, age, soil texture, and litter depth), of the host can alter the associated mite diversity. In Chapter 3, predictions of theory, herbivore resource hypotheses, and spatial parasitology were used to identify the extent of the ecological neighborhood for mites associated with ants. My results indicate that commensal mite communities are consistent with the Resource Size Hypothesis and are sensitive to ecological neighborhoods at multiple hierarchical levels including individual host ants, the host ant colony, surrounding nest community, and habitat type, but do not vary significantly among sites. In the final chapter, I examined the importance of spatial arrangement of ant nests for mite dispersal among nests in a homogenous environment and the role of seasonal synchrony with hosts. I found significant spatial autocorrelation for mite communities at the closest distance class and evidence of increased mite abundance and richness during periods of ant colony reproduction. Together, these studies demonstrate that processes at multiple temporal and spatial scales contribute to biodiversity and community assembly within conservation habitatsand that the context of ant hosts can modify their roles as biodiversity regulators. BIODIVERSITY OF ANTS AND ASSOCIATED MITES IN CONSTRUCTED GRASSLANDS AT MULTIPLE SPATIAL SCALES A DISSERTATION Presented to the Faculty of Miami University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Biology by Kaitlin U. Campbell The Graduate School Miami University Oxford, Ohio 2015 Dissertation Director: Thomas O. Crist © Kaitlin U. Campbell 2015 TABLE OF CONTENTS Table of Contents General Introduction ....................................................................................................................... 1 1 References ............................................................................................................................... 5 Chapter 1: Differential responses of grassland ant species at patch and landscape levels ............ 8 1 Abstract ................................................................................................................................... 8 2 Introduction ............................................................................................................................. 9 3 Methods ................................................................................................................................ 13 3.1 Study Sites ..................................................................................................................... 13 3.2 Ant Community Sampling .............................................................................................. 13 3.3 Vegetation Sampling ..................................................................................................... 14 3.4 Soil Analysis ................................................................................................................... 14 3.5 Additional Patch-level Variables .................................................................................... 15 3.6 Landscape Analysis ........................................................................................................ 15 3.7 Statistical analysis .......................................................................................................... 16 4 Results ................................................................................................................................... 17 4.1 Ant Species Composition ............................................................................................... 19 5 Discussion .............................................................................................................................. 20 5.1 Relative Role of Patch and Landscape-level Predictors ................................................. 20 5.2 Anthropogenic and Uncommon Specialist Responses .................................................. 20 5.3 Landscape-level Responses ........................................................................................... 21 5.4 Management Practices .................................................................................................. 22 5.5 Soil Characteristics......................................................................................................... 22 5.6 Vegetation ..................................................................................................................... 23 5.7 Conclusions .................................................................................................................... 23 6 References ............................................................................................................................. 25 Chapter 2: Host traits and environmental context structure ant-dependent mite communities 39 1 Abstract ................................................................................................................................. 39 2 Introduction ........................................................................................................................... 39 3 Methods ................................................................................................................................ 43 3.1 Study Sites ..................................................................................................................... 43 3.2 Ant and Mite Collections ............................................................................................... 44 3.3 Environmental variables ................................................................................................ 45 iii 3.4 Statistical Analysis ......................................................................................................... 45 3.5 Community Composition Analyses ................................................................................ 47 4 Results ................................................................................................................................... 47 4.1 Overall Mite Species Richness and Abundance ............................................................. 48 4.2 Richness and Abundance of Heterostigmata and Astigmata ........................................ 48 4.3 Mites on Common Host Species .................................................................................... 49 4.4 Mite Community Composition ...................................................................................... 49 5 Discussion .............................................................................................................................. 50 5.1 Host Identity vs. Environment ....................................................................................... 50 5.2 Host Suitability, Frequency, and Richness ..................................................................... 50 5.3 Disturbance, Soil Resources, and Patch Characteristics ................................................ 51 5.4 Conclusions .................................................................................................................... 52 6 References ............................................................................................................................. 53 Chapter 3: Merging spatial parasitology and herbivore theory to identify ecology relevant spatial scales for commensal organisms ..................................................................................................