Biogeography, Population Genetics, and Community Structure of North American Bumble Bees Jonathan Berenguer Koch
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Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-2015 Biogeography, Population Genetics, and Community Structure of North American Bumble Bees Jonathan Berenguer Koch Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Biology Commons Recommended Citation Koch, Jonathan Berenguer, "Biogeography, Population Genetics, and Community Structure of North American Bumble Bees" (2015). All Graduate Theses and Dissertations. 4577. https://digitalcommons.usu.edu/etd/4577 This Dissertation is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. i BIOGEOGRAPHY, POPULATION GENETICS, AND COMMUNITY STRUCTURE OF NORTH AMERICAN BUMBLE BEES by Jonathan Berenguer Koch A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Ecology Approved: _____________________________ _____________________________ James P. Pitts James P. Strange Major Professor Project Advisor _____________________________ _____________________________ Terry Griswold Karen Mock Committee Member Committee Member _____________________________ _____________________________ Joseph S. Wilson Mark McLellan Committee Member Vice President for Research and Dean of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2015 ii Copyright © Jonathan Berenguer Koch 2015 All Rights Reserved iii ABSTRACT Biogeography, Population Genetics, and Community Structure of North American Bumble Bees by Jonathan Berenguer Koch, Doctor of Philosophy Utah State University, 2015 Major Professor: James P. Pitts Project Adviser: James P. Strange Department: Biology This dissertation examines patterns of population genetic diversity and structure across multiple bumble bee species in North America. In Chapter 2 I examine the biogeography and population genetic diversity of the Hunt bumble bee, Bombus huntii (Hymenoptera: Apidae), a species currently in development as a pollinator for commercial agriculture. In Chapter 3 I test the single species hypothesis for Bombus californicus and B. fervidus with ecological, morphological, and molecular data. At present there is disagreement as to whether they constitute one or two species, leading to confusion in taxonomic keys, with conservation planning, and even in popular field guides. In Chapter 4, I characterize patterns of phenotypic color variation in bumble bee communities distributed across an elevation gradient in Yosemite National Park, California. In Chapters 5 and 6, I examine patterns of population genetic structure and diversity of four bumble bee species distributed in the Pacific Northwest, and document the range extension of B. sylvicola into Olympic National Park. The results of my iv dissertation research suggests that (1) Pleistocene climate variability predicts contemporary population genetic structure and divergence, (2) there is clear divergence between B. californicus and B. fervidus, despite convergence of color phenotypes, (3) bumble bee community structure is predicted by Müllerian mimicry at narrow spatial scales, and (4) bumble bees inhabiting specialized bioclimatic niches, specifically alpine environments, exhibit significant isolation by distance at regional spatial scales. I anticipate that the results of my studies will not only yield effective conservation strategies of bumble bee pollinators, but also advance the study of Quaternary invertebrate phylogeography and population genetic diversity. (232 pages) v PUBLIC ABSTRACT Biogeography, Population Genetics, and Community Structure of North American Bumble Bees Jonathan B. Koch In 2011, several wild North American bumble bee pollinator species were reported to have declined by up to 96% in relative abundance in comparison to historic estimates, and one species was speculated to be extinct. None of these species have yet been documented to have recovered from these declines and additional species are now suggested to be at risk. Imperiled species in particular show increased specificity to narrow climatic envelopes, as opposed to putatively stable species. My dissertation describes patterns of population genetic diversity, structure, and gene flow pathways associated with climate variation and historical biogeography of bumble bees distributed in western North America. The results of my dissertation research suggests that (1) historic climate variability predicts contemporary patterns of population genetic structure and divergence in an economically important species, (2) color variability in bumble bees is likely associated with lineage diversification and phylogeography, (3) bumble bee community structure across evolutionary time is likely driven by Müllerian mimicry at narrow spatial scales, and (4) bumble bees inhabiting specialized ecological niches are associated with high levels of genetic fixation at regional spatial scales in the Pacific Northwest. The results of my research directly contribute to current efforts to effectively manage, conserve, and advocate for wild bumble bee pollinators in the context of global change. vi DEDICATION For my mother and father, the first two people who taught me the value of an education. vii FRONTISPIECE viii ACKNOWLEDGMENTS I extend my biggest Mahalo to my mentor, Jamie Strange, for encouraging me to pursue a Ph. D. after I completed my MS at Utah State University (USU). You have provided amazing guidance, constructive criticism, direction, and opportunity during my entire tenure at USU. I would also like to thank Dr. James Pitts, my major professor for providing invaluable insight on Hymenoptera evolution over the past seven years. I am especially appreciative for the thoughtful and inspiring conversations with my committee members, Dr. Terry Griswold, Dr. Karen Mock, and Dr. Joseph Wilson. I especially would like to thank Dr. Terry Griswold for the hours of fantastic bee conversations and opportunities to collaborate on projects. I am grateful to Joyce Knoblett, Harold Ikerd, Ellen Klinger, Byron Love, Emily Sadler, and Amber Tripodi for being invaluable sources of information and expertise on bee biology, ecology, molecular techniques, and analyses. My dissertation would have not been possible without your encouragement and contributions. I thank all those who have contributed specimens to my dissertation research and conducted field research with me: Sam Droege, Amber Tripodi, Paul Johnson, Steven Highland, David Drons, Terry Griswold, Chris Looney, Jenny Geib, Jessamyn Manson, Monica Kohler, Lori Spears, Rémy Vandame, Philippe Sagot, Esteban Pineda, Knute Gunderson, Jason Long, Brandon Hopkins, Elinor Lichtenberg, Steven Sheppard, Craig Huntzinger, Houston Judd, Joan Meiners, and Elaine Evans. I thank the USDA-ARS Bee Lab for hosting me over these past several years. I have learned so much about bees from the individuals in this unique lab, and I am appreciative for the wonderful conversations and collaborations that have resulted during my stint as a “Bee Labber”. A special thank you goes out to ix undergraduate research volunteers Hattie Cadreact, Taylor Peacock, and Cody Darrington for their assistance in lab and museum work. Funding for this research was provided largely by the United States Department of Agriculture- Agricultural Research Service (USDA-ARS). Additional sources of funding included a grant from the USU Ecology Center and the North Coast and Cascades Science Learning Center (#NPS P13PG00149/FSN). I am honored to have also received funding from the Pollinator Partnership and the U.S. Fish and Wildlife Service, which culminated in the field guide “Bumble Bees of the Western United States”. Travel to a diversity of conferences and workshops would have not been possible without the USU Graduate Research Office, Entomological Society of America, Ecological Society of America SEEDS Program, and the USU Ecology Center. I would especially like to thank my mother and father for teaching me the value of an education, and the importance of working hard. I thank my younger brothers, Joshua B. Koch and Jacob B. Koch and my sisters Erika Angela B. K. Santiago and Jaime Rose Kealohalani B. K. Rapal for being brave, understanding, and above all loving. I would like to thank my Hānai Logan Family, whom have enriched my life in ways that cannot be described in words. To Juanita Rodriguez, Jaime Florez, Cecilia Waichert, Rodrigo Ferriera, Mercedes Roman, Jane Li, Molly Rightmeyer, and Victor Gonzalez: thank you all for the amazing times in Logan, UT and beyond. You are all fantastic friends and scientists. I am grateful to the Strange Family: Jamie, Ellen, Sylvie, and Amelia, and the late Jennifer Strange. Since I first arrived in Logan, your family has shown such amazing aloha and hospitality. I would also like to acknowledge the mentors and teachers in my life: Aunty Lisa-Anne Tsuruda (Waiʻanae High School), Mr. Steven Schick (Waiʻanae x High School), Mrs. Tess Kaji (Waiʻanae High School), Mrs. Shannon Kam (Waiʻanae High School), Mahealani Jones (University of Hawaiʻi at Hilo), Dr. Heather Sahli (University of Hawaiʻi at Hilo), Dr. Kathryn Besio (University of Hawaiʻi at Hilo), Dr. Michael Steinberg (University of Hawaiʻi at Hilo), Dr. Sonya and James Juvik (University of Hawaiʻi at Hilo), and Ms. Sharon Ziegler-Chong (University of Hawaiʻi at Hilo). Without these individuals,