Conservation Biology of Bats: Invasive Threats, Research Effort, and Extinction Risk
Total Page:16
File Type:pdf, Size:1020Kb
University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2017 Conservation Biology of Bats: Invasive Threats, Research Effort, and Extinction Risk Jessica Nicole Welch University of Tennessee, Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Ecology and Evolutionary Biology Commons Recommended Citation Welch, Jessica Nicole, "Conservation Biology of Bats: Invasive Threats, Research Effort, and Extinction Risk. " PhD diss., University of Tennessee, 2017. https://trace.tennessee.edu/utk_graddiss/4508 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Jessica Nicole Welch entitled "Conservation Biology of Bats: Invasive Threats, Research Effort, and Extinction Risk." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Ecology and Evolutionary Biology. Daniel Simberloff, Gary McCracken, Major Professor We have read this dissertation and recommend its acceptance: Brian O'Meara, Alison Boyer, Mike McKinney Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Conservation Biology of Bats: Invasive Threats, Research Effort, and Extinction Risk A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Jessica Nicole Welch May 2017 Copyright © 2017 by Jessica Nicole Welch. All rights reserved. ii ABSTRACT Global conservation for bats is needed: 15 percent of species are listed as extinct or threatened, signifying that they are at a high risk of extinction. An additional 17 percent are designated data-deficient, denoting that a threat category has not been assigned owing to insufficient knowledge on species abundance or distribution. In this dissertation, I use methods from both ecology and evolution to contribute to the study of bat conservation. Firstly, I review the impacts of biological invasion on bats, and provide examples of threats from each of four broad categories: predation, pathogens, competition, and indirect interactions. Overall, detailed accounts of invasive species threatening bats are lacking, but the most persuasive cases occur on islands. Secondly, I provide a case study of the endangered Pacific sheath-tailed bat (Emballonura semicaudata rotensis) to illustrate the importance of investigating indirect effects of invasion on species of conservation concern. The results imply that the impact of an invasive shrub on the persistence of the bat has been underestimated and that it is unclear how a feral ungulate alters bat habitat aside from reducing understory vegetation. Thirdly, I describe the state of academic literature for most of the bat clade, and provide ranked prioritization of bats for research based upon species vulnerability and evolutionary irreplaceability. Lastly, I use evolutionary comparative methods to identify species of conservation concern. Given simulations using important correlates of bat extinction risk, I predict that 31 data-deficient bats are threatened by endangerment. Overall, my work will benefit bat conservation by highlighting gaps in knowledge and elucidating research priorities that will be useful for directing conservation action. iii TABLE OF CONTENTS INTRODUCTION.....................................................................................................................................1 References.............................................................................................................................................................4 CHAPTER I: The threat of invasive species to bats: A review.................................................5 Abstract..................................................................................................................................................................6 Introduction.........................................................................................................................................................7 Methods..................................................................................................................................................................8 Results and Discussion....................................................................................................................................8 Conclusion..........................................................................................................................................................20 References..........................................................................................................................................................23 Appendix.............................................................................................................................................................35 CHAPTER II: Indirect impacts of invaders: A case study of the Pacific sheath-tailed bat (Emballonura semicaudata rotensis)...........................................................................................41 Abstract...............................................................................................................................................................42 Introduction.......................................................................................................................................................43 Methods...............................................................................................................................................................44 Results and Discussion.................................................................................................................................48 Conclusion..........................................................................................................................................................50 References..........................................................................................................................................................52 Appendix A: Figures.......................................................................................................................................56 Appendix B: Supplementary Methods....................................................................................................58 Appendix C: Supplementary Tables and Figures...............................................................................63 CHAPTER III: Prioritizing bats for research effort..................................................................75 Abstract...............................................................................................................................................................76 Introduction.......................................................................................................................................................77 Methods...............................................................................................................................................................78 Results..................................................................................................................................................................80 Discussion...........................................................................................................................................................82 iv References..........................................................................................................................................................85 Appendix.............................................................................................................................................................88 CHAPTER IV: Predicting extinction risk for data-deficient bats......................................103 Abstract.............................................................................................................................................................104 Introduction....................................................................................................................................................105 Methods............................................................................................................................................................106 Results ..............................................................................................................................................................108 Discussion........................................................................................................................................................111 References.......................................................................................................................................................114 Appendix..........................................................................................................................................................116