Ecological Impacts of a Trait-mediated Cascade By Hsun-Yi Hsieh A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Natural Resources and Environment) in the University of Michigan 2015 Doctoral Committee: Professor Ivette Perfecto, Chair Professor Bradley Cardinale Professor Mark D Hunter Professor John H. Vandermeer ! ! ! © Hsun-Yi Hsieh All rights reserved 2015 ! ! DEDICATED TO LIFE ! ii! Table of Contents Dedication ……………………………………………………………………………………......ii List of Figures ............................................................................................................................... vi List of Tables .............................................................................................................................. viii List of Appendices……………………………………………………………………………… ix Abstract .......................................................................................................................................... x Chapter 1 Introduction ................................................................................................................ 1 References ...................................................................................................................................... 5 Chapter 2 Trait-Mediated Indirect Effects of Phorid Flies on Ants ...................................... 10 2.1. Abstract ................................................................................................................................. 10 2.2. Introduction .......................................................................................................................... 10 2.3. Direct Density Effects of Phorid Parasitization on Ants .................................................. 11 2.4. Trait-mediated Effects on Ant Foraging Activity, Resource Acquisition, and Defense 12 2.4.1. Number of Foragers .......................................................................................................... 12 2.4.2. Size of Foragers ................................................................................................................. 13 2.4.3. Acquisition of Food Resources ......................................................................................... 13 2.4.4. Compensatory Factors ...................................................................................................... 14 2.5. Phorid Parasitoids and Competition within Ant Assemblages ........................................ 15 2.5.1. Exploitative and Interference Competition .................................................................... 15 2.5.2. Factors That Interact with Phorid Parasitoids to Affect Competition ........................ 17 2.5.3. Competitive Dominance Hierarchies and Species Coexistence .................................... 19 2.6. Trait-mediated Cascades: The Case of Azteca sericeasur in the Coffee Agroecosystem 20 2.7. Conclusions ........................................................................................................................... 24 References .................................................................................................................................... 26 Chapter 3 Cascading trait-mediated interactions induced by ant pheromones ................... 37 3.1. Abstract ................................................................................................................................. 37 ! iii! 3.2. Introduction .......................................................................................................................... 37 3.2.1.The study system: the first TMII unit .............................................................................. 39 3.2.2. The study system: the second TMII unit ........................................................................ 40 3.3. Materials and Methods ........................................................................................................ 41 3.3.1. Olfactometer bioassays ..................................................................................................... 42 3.3.2. Oviposition experiment .................................................................................................... 43 3.4. Data analyses ........................................................................................................................ 44 3.5. Results ................................................................................................................................... 44 3.6. Discussions ............................................................................................................................ 45 3.6 Acknowledgments ................................................................................................................. 49 3.7. Authors’ Contributions ....................................................................................................... 49 References .................................................................................................................................... 50 Chapter 4 Effects of trait–mediated indirect interactions on a consumer-resources system ....................................................................................................................................................... 59 4.1. Abstract ................................................................................................................................. 59 4.2. Introduction .......................................................................................................................... 60 4.3. Materials and Methods ........................................................................................................ 63 4.3.1. Study site ............................................................................................................................ 63 4.3.2. Behavioral experiments .................................................................................................... 63 4.3.3. Azya orbigera parasitism experiments ........................................................................... 64 4.3.4. Source of insects used for the experiments ..................................................................... 65 4.3.5. Field surveys ...................................................................................................................... 65 4.4. Data Analyses ....................................................................................................................... 66 4.4.1. Ant behavior ...................................................................................................................... 66 4.4.2. Beetle parasitism experiments- effect of TMIIs on parasitism of A. orbigera ............ 66 4.4.3. Beetle parasitism experiments - effect of TMIIs on survivors’ sex ratio ..................... 67 4.4.4. Beetle parasitism experiments – per capita survival probability with regard to sex . 68 4.4.5. Field surveys ...................................................................................................................... 69 4.5. Results ................................................................................................................................... 69 4.5.1. Ants are aggressive towards parasitoid wasps and the presence of phorid flies reduce that aggressiveness ...................................................................................................................... 69 4.5.2. One TMII does not affect beetle parasitism but two interacting TMIIs do ................ 69 ! iv! 4.5.3. One TMII does not affect survivor’s sex ratio but two interacting TMIIs do ............ 70 4.5.4. TMIIs affect fitness of male vs. female individuals ........................................................ 70 4.5.5. Field surveys: female biased population in areas with high phorid attack intensity . 71 4.6. Discussions ............................................................................................................................ 71 References .................................................................................................................................... 77 Chapter 5 Community-wide impacts of interactive trait-mediated interactions: A case study in neotropic coffee agroecosystems ................................................................................. 89 5.1 Abstract .................................................................................................................................. 89 5.2 Introduction ........................................................................................................................... 89 5.3 Methods .................................................................................................................................. 91 5.3.1. Study sites and field experiments .................................................................................... 91 5.4. Data analyses ........................................................................................................................ 92 5.5. Results ................................................................................................................................... 93 5.5.1. Responses of total arthropods and particular orders .................................................... 93 5.5.2. Responses of Morphospecies ...........................................................................................