Monica Paola Higuera
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Pollination biology and transcriptomics of Cleomaceae species exhibiting different pollination systems by Monica Paola Higuera A thesis submitted in partial fulfillment of the requirements for the degree of Doctor in Philosophy in Systematics & Evolution Department of Biological Sciences University of Alberta © Monica Paola Higuera, 2018 Abstract Pollinator mediated-selection is responsible for much of the phenotypic diversity exhibited by flowers. Flowering plants that attract a diverse range of pollinators represent a generalist pollination system in which selection is exerted by many different pollinators. However, generalist pollination systems are difficult to study. They are frequently overlooked, because directional selection may be limited and diffuse selection exerted by pollinators in floral traits is hard to test. Thus, specialist flowering plants attract specific pollinator guilds, which mediates directional or stabilizing selection on floral traits. Selection by a guild of pollinators, such as bees, birds or bats, has led to the convergence of floral phenotypes, known as pollination syndromes. Flowering plants associated to pollination syndromes belong to a specialist pollination system. While, flowering plants that attract a diverse range of pollinators represent a generalist pollination system in which selection is exerted by many different pollinators. However, generalist pollination systems are difficult to study. They are frequently overlooked, because directional selection may be limited and diffuse selection exerted by pollinators in floral traits is hard to asses. One way to understand the evolution of floral traits and pollination systems involves exploring the genes encoding floral traits subject to pollinator-mediated selection. One good family for exploration of these topics is the Cleomaceae, which exhibits variation in floral traits, has species displaying generalist and specialist pollination systems and is an emerging model system for studying floral evolution. In this thesis, I used natural history of Cleomaceae species and molecular methods to compare the pollination biology and genes encoding floral traits from plants exhibiting generalized or specialized floral traits. I observed plants with floral traits that could be subject to pollinator-mediated selection such as color, and nectar glands, ii and then I used transcriptomics to identify candidate genes that may be responsible for differences in these floral traits. My thesis begins by proposing a comprehensive framework that incorporates both ecological and genetic pollination studies, which I have defined as integrative pollination studies. I reviewed genetic techniques used to explore genes underlying floral traits and discuss the use of next generation sequencing to study pollination. Second, I studied the pollination biology of two Cleomaceae species present in Alberta, which differ in main floral traits: Cleomella serrulata (Pursh) E.H. Roalson and J.C. Hall and Polanisia dodecandra (L.) DC to determine their pollination systems. I determined that both species have a generalist pollination system, but there were differences in the richness and composition of pollinators between them, due to main differences in floral traits and population locations. To examine differences in the floral evolution of species exhibiting generalized and specialized floral traits, I identified putative candidate genes responsible for pollinator attraction, then I studied the floral transcriptome of these two generalist species, along with the specialist Melidiscus giganteus (L.) Raf. Despite phylogenetic distance, the generalist species C. serrulata and P. dodecandra shared more transcripts when compare with M. giganteus. I then examined putative candidate genes for key floral traits and found differences in genes coding for color and nectary traits between generalist and specialist species that could be subjected to selection by pollinators. However, the genes coding for floral traits in specialist and generalist species were similar overall. Finally, I aimed to down-regulate candidate genes important for pollinator attraction to obtain plants with modified phenotypes that could be used in pollinators preference tests. I tested the feasibility of the virus-inducing gene silencing (VIGS) technique in P. dodecandra. Unfortunately, this species was not amenable to this technique, but it was iii feasible in Cleome violacea L., which may be a good candidate species for further pollination studies. Overall, my results indicate that species exhibiting generalized and specialized floral traits were similar in terms of gene repertoires despite being pollinated by different pollinators and despite phylogenetic distance. The generalist species were pollinated by different pollinator assemblages although the populations were located nearby. Though the floral transcriptomes of the generalist species were more similar to each other than to that of the specialist, generalists and specialist were alike in terms of gene repertoires. Taken together, this thesis advances our understanding of the pollination biology and genetics of the floral traits in Cleomaceae. I recommend that Cleomaceae be used as a comprehensive model to study the transitions between generalist and specialist pollination systems, and to study the evolution of floral traits important for pollinator attraction. iv Preface Chapter 3 of this thesis has been published as “Higuera-Díaz M, Manson JS, Hall JC. 2015. Pollination biology of Cleomella serrulata and Polanisia dodecandra in a protected natural prairie in southern Alberta, Canada”, at Botany 93: 745-757. I collected the data, analyzed and wrote the manuscript. JS Manson and JC Hall helped with experimental design, manuscript editing, and revisions. v Dedication To my husband who always hold my hand, my beautiful daughter Suanti and my family vi Acknowledgements I would like to thank my supervisors Dr. Jocelyn C. Hall and Dr. Jessamyn Manson for their guidance and their support during my PhD studies, but also, I am very grateful for the support that they provided me, when I endured the most sad and difficult moments in my life. Without your help and support, I would not have been able to continue my doctoral studies. You were the best supervisors for me, many thanks for your mentoring, support and patience during the last six years. I also want to thank to Dr. James Cahill for being in my committee, many thanks for your guidance and support on my project, also many thanks for made me think broadly and for challenge me, and of course, I would like to thank you for introducing me to your students, and for adopting me in your lab meetings and celebrations, it was a great experience for me. I would like to thank Dr. Mike Deyholos for being in my committee for 2 years and for his support on my project. I want to thank Dr. Felix Sperling, Janet Sperling, José Díaz and Lucy Díaz for their support during my arrival to Edmonton, many thanks for your hospitality and for making me feel at home. I am also very grateful to my lab mates and also good friends Kelsey Bernard, Melanie Patchell, Shane Carey, Peter Mankowski, Mariano Avino, Ashton Sturm, Angela Phung, Monica Khöler, and Michael Foisy. Many thanks for your support and your friendship during this process. I also want to thank my very good friends who were my support in happy and sad moments: Gisela Stötz, Gregory Peck, Tan Bao, Jared Bernard, William Torres, Orión Reyes, Isabel Barrios, Guillermo Bueno, Alec Carrigy, Gian Carlo Gianoli, Fred Noddin, Caroline Whitehouse, Sandra Durán, Charlotte Brown, Margarete Dettlaff, Megan Ljubotina, Leonardo Galindo, Angélica Quesada, Javier Luque, Kecia Kerr, Claudia Ayala, Jaime Pinzón, Jenny Fonseca, and Nicolas Abarca. Many thanks for all the happy moments and for taking care of me and my daughter when she was born. My research would not have been possible without the people that help me in the field, many thanks to Jared Bernard Jenny Kleininger for their hard work during the field seasons. Thanks to Drew Taylor, range biologist at Suffield CFB, for his logistical help during my project. Many thanks to Cory Sheffield, Ashton Sturm, Felix Sperling, Gary Anweiler, Matthias Buck and Tyler Cobb for help with insect identification. Many thanks to Dorothy Fabijan for assistance with plant voucher preparation. I would also like to thank vii Corey Davis and Troy Locke for their advice during my project, and many, many thanks to Kerrin Mendler, Leonardo Galindo and Dr. Mike Deyholos for their bioinformatics help. Last but not least, I want to thank my life partner Giovanny Fagua for all his support, love and care, my cute baby Suanti for her smile and happiness that encourage me every day, to my family Stella, Francisco, Andrea, Gustavo, Vero, and Diego for their encouragement and support. Finally, many, many thanks to my mom and my mother in law for taking care of my baby, while, I was finishing my thesis. My PhD studies had the financial support of the Administrative Department of Science, Technology and Innovation of Colombia (COLCIENCIAS, “Generación del Bicentenario” scholarship). My research was funded for a ACA Grant in Biodiversity (supported by the Alberta Conservation Association), and a NSERC Discovery Grant held by Dr. Jocelyn C. Hall. viii TABLE OF CONTENTS Chapter 1: Introduction ....................................................................................................... 1 1.1. Genetic studies of pollination systems .......................................................................