University of Calgary PRISM: University of Calgary's Digital Repository Graduate Studies The Vault: Electronic Theses and Dissertations 2014-01-08 The effects of structured variation in nectar standing crop on currency choice and optimal foraging by bumble bees Simspon, Paul Simspon, P. (2014). The effects of structured variation in nectar standing crop on currency choice and optimal foraging by bumble bees (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/28119 http://hdl.handle.net/11023/1247 master thesis University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca UNIVERSITY OF CALGARY The effects of structured variation in nectar standing crop on currency choice and optimal foraging by bumble bees by Paul A Simpson A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE BIOLOGICAL SCIENCES CALGARY, ALBERTA JANUARY, 2014 © PAUL SIMPSON 2014 Abstract Foragers commonly exploit patchy habitats in which resource abundance can vary within and among patches. Studies measuring resource variation tend to consider only single sources of variation, so the extent of structured resource variation and how it impacts foraging animals are unclear. A survey of nectar abundance in five plant species revealed the spectrum from only within- to solely among-plant variation. Captive bumble bees (Bombus impatiens) confronted with an increasing component of among-inflorescence nectar variation departed inflorescences in manners that diverged increasingly from expectations of the Marginal Value Theorem (MVT). Bees apparently assess inflorescence quality on a per-patch basis, changing their exploitation behavior in response to poor or rewarding inflorescences as expected from a speed-accuracy trade- off, rather than maximizing their overall average return rate. This quantitative test of the MVT demonstrates the need to incorporate responses to variation within patches in models of forager behavior. ii Acknowledgements The experience of writing this thesis has been a learning experience unlike any I have ever had; fortunately there were many in my life who were able to advise me and educate me through their own experiences along the way. First and foremost, I extend my utmost appreciation and thanks to Lawrence Harder for his Orwellian economy with words; inexhaustible patience; unbounded openness to alternatives in experimentation, theory and methodology; and sagely insight into all things statistical. These qualities invoked a change in me from a mathematician with biological inclinations and Dr. Seussian prose, to an ecologist with an appreciation for mathematics and Hemingway’s ability to tell a story. Under your guidance, Lawrence, I have learned to design studies and write in a manner that is of interest to myself, and hopefully others too. I would like to acknowledge that NSERC provided funding for this thesis through Dr. Lawrence Harder’s NSERC Discovery and Accelerator Grants. Secondly, to those who facilitated my research, I extend my heartfelt appreciation. Specifically I thank my advisory committee, Ralph Cartar and Robert Barclay, for their thoughtful comments on research proposals, research grants and graduate program applications; the sharing of data sets and lab space; and for serving as sound boards for all ideas noble and ignoble. Thanks to Lisa O’Donnell my wonderful girlfriend, lab mate, con-conspirator and first set of critical eyes. Romain Richard for encouraging me to always have another explanation. To Luke J Antosz for tirelessly watching and rewatching bumble bee videos. To field assistants: Portia Lloyd, Hazel Cameron-Inglis, and Takashi Ida for helping me to sample nectar in Kananaskis. iii Additionally, thanks to Ralph Cartar for providing me with nectar data for Penstemon confertus and Plectritis congesta, and also to Hiroshi Ishii for providing me with nectar data for Delphinium glaucum and D. bicolor. Last, but not least of all, to my wonderful family. To my parents who have been incredibly supportive, except for the times when my research objective needed to be held up to the cold, cruel light of the real world. And to my brother Josh, for his help with processing nectar samples in the lab and watching the odd bee video. iv Table of Contents Abstract ............................................................................................................................... ii! Acknowledgements ............................................................................................................ iii! Table of Contents ................................................................................................................ v! List of Tables .................................................................................................................... vii! List of Figures and Illustrations ....................................................................................... viii! Epigraph .............................................................................................................................. x! CHAPTER ONE: STRUCTURED VARIATION AND OPTIMAL FORAGING ........... 1! 1.1 General Overview ..................................................................................................... 1! 1.2 Study system ............................................................................................................. 5! 1.3 Thesis Objectives ...................................................................................................... 8! CHAPTER TWO: THE STRUCTURE OF VARIANCE IN NECTAR STANDING CROP IN NATURAL POPULATIONS ................................................................. 10! 2.1 Introduction ............................................................................................................. 10! 2.2 Materials and Methods ............................................................................................ 12! 2.2.1 Nectar Surveys ................................................................................................ 12! 2.2.1.1 Wick-sampling procedure ..................................................................... 14! 2.2.1.2 Capillary-and-refractometer procedure ................................................. 14! 2.2.1.3 Corolla volume estimation procedure ................................................... 14! 2.2.2 Statistical Analysis ......................................................................................... 15! 2.3 Results ..................................................................................................................... 16! 2.3.1 Delphinium glaucum ...................................................................................... 16! 2.3.1.1 2005 ...................................................................................................... 16! 2.3.1.2 2012 ...................................................................................................... 16! 2.3.2 Delphinium bicolor ......................................................................................... 17! 2.3.3 Chamerion angustifolium ............................................................................... 17! 2.3.4 Plectritis congesta ........................................................................................... 18! 2.3.4.1 1986 ...................................................................................................... 18! 2.3.4.2 1988 ...................................................................................................... 18! 2.3.5 Penstemon confertus ....................................................................................... 21! 2.4 Discussion ............................................................................................................... 23! CHAPTER THREE: THE EFFECT OF STRUCTURED VARIATION IN NECTAR STANDING CROP ON FORAGING BY BUMBLE BEES .................................. 28! 3.1 Introduction ............................................................................................................. 28! 3.2 Materials and Methods ............................................................................................ 34! 3.2.1 Experimental Design ...................................................................................... 34! 3.2.2 Forager Training ............................................................................................. 37! 3.2.3 Experimental Trials ........................................................................................ 38! 3.2.4 Statistical Analysis ......................................................................................... 39! 3.2.4.1 Behavioral Responses ........................................................................... 39! 3.2.4.2 Foraging Currency Maximization ......................................................... 40! 3.3 Results ..................................................................................................................... 42! 3.3.1 Behavioral Responses ..................................................................................... 42! v 3.3.1.1 Probing Time .......................................................................................