Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. Functional biodiversity of New Zealand’s marine fishes versus depth and latitude A thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Statistics at Massey University, Auckland, New Zealand Elisabeth Miro Valerie Myers June 2020 i Thesis Abstract Understanding patterns and processes governing biodiversity along broad-scale environmental gradients requires an assessment of not only taxonomic richness, but also morphological and functional traits of organisms. The deep sea is the largest habitat on earth and provides many important ecosystem services. Decreases in light, temperature, and trophic resources, along with increases in pressure that occur with greater depth, renders the deep sea one of the most constraining environments for supporting life. However, little is known about how biodiversity, and especially functional biodiversity, changes along the depth gradient. This thesis aimed to fill this gap by using a combination of traits associated with food acquisition and locomotion to quantify and characterise patterns of functional diversity across large-scale depth and latitude gradients and to investigate potential mechanisms driving biodiversity. First, to identify the major selective forces acting on morphology, I documented patterns of variation in the traits of fishes at broad spatial scales. I found that with increasing depth, fishes, on average, became larger and more elongate, and had a larger oral gape and eye size. With increasing depth, fish morphology shifted towards body shapes that enable energy-efficient undulatory swimming styles and an increased jaw-length versus mouth width to aid opportunistic feeding. Second, I investigated the role of environmental filters versus biotic interactions in shaping the functional space of communities along depth and latitude gradients by measuring the intra- and inter-specific richness, dispersion and regularity in functional trait space. I found that functional alpha diversity was ii unexpectedly high in deep-sea communities, but decreased with increasing latitude, and that competition within and among species shaped the multi- dimensional functional space for fishes at the local alpha diversity level. Third, I described spatial patterns in functional beta diversity for New Zealand marine fishes versus depth and latitude, and delineated functional bioregions. The functional turnover in fish communities was greater across depth than latitude, and latitudinal functional turnover decreased with increasing depth. I surmise that environmental filtering may be the primary driver of broad-scale patterns of beta diversity in the deep sea. Overall, this thesis contributes new knowledge regarding broad-scale functional biodiversity patterns across depth and latitude via the morphological and functional traits of New Zealand’s marine fishes. Through the measurement of individual trait variation, and the quantification of functional alpha and beta diversity, this thesis characterised variation in the traits of fishes over large spatial scales, determined the spatial turnover of functional traits, and described the relative importance of environmental versus biotic drivers in shaping the functional space of deep-sea communities. These contributions provide foundational understanding for future research on the functional diversity of marine fishes, biodiversity patterns across the depth gradient, and the monitoring of biodiversity change across New Zealand’s latitudinal and depth gradients. iii Declaration by Author The research carried out for my doctoral thesis has been used in whole or in part for this qualification only. The research is my original work, except as indicated by appropriate attribution in the text and/or acknowledgements; quotation marks have been used where required; and I take responsibility for the content and quality of this thesis. I have clearly stated the contribution by others in jointly authored works, which can be found at the end of each chapter. The “Statement of Contribution to Doctoral Thesis Containing Publications (DRC16)’, has been completed for each published article within the thesis, and is included in the electronic copy at the end of each chapter. iv Publications during candidature Peer-reviewed journal articles included in this thesis Myers, E.M.V., Anderson, M.J., Eme, D., Liggins, L. & Roberts, C.D. (2019) Changes in key traits versus depth and latitude suggest energy‐efficient locomotion, opportunistic feeding and light lead to adaptive morphologies of marine fishes. Journal of Animal Ecology, 89(2), 309-322. https://doi.org/10.1111/1365-2656.13131 Peer-reviewed journal articles not included in this thesis Eme, D., Anderson, M., Myers, E., Roberts, C. & Liggins, L. (2020) Phylogenetic measures reveal eco‐evolutionary drivers of biodiversity along a depth gradient. Ecography, 43, 1-14. https://doi.org/10.1111/ecog.04836 v Acknowledgements Deciding to move back to New Zealand to do this PhD after 16 years in Perth has been one of the best decisions of my life. It has been an amazing journey thanks to the following people and organisations. Marti, thank you for taking me on for this exciting project. You have been so supportive, kind, and have given me countless amazing opportunities. It has been a privilege to meet and learn from you weekly, and see that brain of yours whizzing away in real time. By fostering my love of biology and opening up the world of statistics you have truly set me up for an exciting and rewarding career – thank you! Your generosity with PRIMER/Permanova+ courses and software, is also deeply appreciated. The time we spent one on one using PRIMER together was a favourite part of my PhD! Also, thank you for encouraging me to present my research in Tahiti, America, Scotland, Hong Kong, and all around New Zealand. The communication and networking skills that I have learnt from these experiences have already begun to bear fruit! David, I could not have done this thesis without you! Your patience with me was seemingly inexhaustible. It was a great experience sharing an office with you and getting to draw and discuss endless scenarios on the whiteboard with you. No problem was ever too big to conquer (and we had our fair share), and I will take that lesson with me as I move into my career. I will strive to emulate your work ethic, persistence, and attention to detail, and look forward to our future collaborations. Libby, you have been such an amazing role model. Thank you for always being there for me both professionally and personally. As with David, no concern was vi ever too big or small for you. Thank you for always getting me involved with exciting projects and putting my name forward for things like the Kermadec trip (life changing), working with iwi, and always introducing me to the bigwigs at conferences! Clive, I’ve known you for almost a decade now, how time fly’s when you are having fun! My time with you and the fish team as a bright eyed 21 year old made me want to carry on with postgraduate research. I wouldn’t be here without you! Thank you for turning me into a fish-mad Ichthyologist, I am very happy to be a part of the club. Conducting my lab work at Te Papa was one of the best experiences of my PhD, and I always looked forward to it. Thank you for all of your support and friendship over the years. I look forward to many more afternoon beers at the Tutukaka fishing club, measuring the marlins together! Euan, you have been my mentor since day dot, and were the first person to see something in me as a youngster. I owe a lot to you. Thank you for always being there for me and giving me all of the wonderful opportunities that you have. I value your friendship dearly, and look forward to catching up for work and fun in Perth. Thank you to the Te Papa fish team: Andrew, Carl, Jeremy and Salme. I know every time that I can down it meant more work for you guys, but you did it with a smile. I love hanging out with you all and being an occasional member of the fish team! Thank you for the technical support and friendship over the years, and for igniting my curiosity in fishes. A special thank you to Andrew Stewart for housing me during my trips to Wellington. It was great to hanging out, talk fish, politics and everything in between. Thank you for all of the lovely meals and crafties my friend! vii Thank you to NZIAS for all of the support over the years, and for the financial support in my 4th year. Vesna, you so very helpful, prompt and caring! Mike, thanks for all of the IT support. Peter Schwerdtfeger, you brightened up my day on many occasions with our jovial encounters. You are a very funny man! Thank you for everything that you and NZIAS did for that one random deep-sea biologist in the department! Thank you Massey University for providing a great university to study at, and for the financial support in the form of a conference presentation grant, a doctoral completion bursary, and a Pūrehuroa Māori Postgraduate Award. Thank you to Tāmaki Paenga Hira, The Auckland War Memorial Museum and the Sir Hugh Kawharu Foundation for the museum scholarship award. The museum scholarship not only supported me financially, but also encouraged me to learn to kōrero I te reo Māori and find out more about my whakapapa. I am forever grateful to Haare Williams who gave me a firm push in the right direction, and told me that Māori leadership starts with korero.