http://researchcommons.waikato.ac.nz/ Research Commons at the University of Waikato Copyright Statement: The digital copy of this thesis is protected by the Copyright Act 1994 (New Zealand). The thesis may be consulted by you, provided you comply with the provisions of the Act and the following conditions of use: Any use you make of these documents or images must be for research or private study purposes only, and you may not make them available to any other person. Authors control the copyright of their thesis. You will recognise the author’s right to be identified as the author of the thesis, and due acknowledgement will be made to the author where appropriate. You will obtain the author’s permission before publishing any material from the thesis. Population Genetics and Photobiont Selectivity in Antarctic Lichens A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at The University of Waikato by Tracey C. Burgess-Jones 2013 Abstract This thesis examines population genetic structure and migration indices of an Antarctic endemic lichen Buellia frigida as well as algal selectivity of the lichens Buellia frigida, Umbilicaria aprina and Umbilicaria decussata in the Ross Sea Region of Antarctica. My aim was to determine where current populations may have originated (i.e. ancient or recent introductions to Antarctica) and if the level of algal selectivity potentially affects colonisation. Chapter 2 reviews historical climate change in Antarctica, particularly in the Ross Sea Region, and introduces the basic characteristics of lichens. It also outlines how molecular analyses of lichen can aid in determining the genetic structure of populations and add to the growing data set which highlights sites in the Ross Sea Region (e.g. Dry Valleys) as glacial refugia. To examine population differentiation between populations in this region it was necessary to develop polymorphic markers capable of delineating individuals. Chapter 3 focuses on the development of five microsatellite markers for this purpose. The initial data for these microsatellites suggested they were suitable for individual genotyping and characterization of B. frigida population structure being mycobiont specific with a high degree of polymorphism. A method of decreasing inhibiting factors present in lichen cells is also provided. In Chapter 4 regional genetic differentiation was revealed by an analysis using microsatellite markers developed in Chapter 3 over 11 populations ii in five regions of the Ross Sea Region. The identification of three populations with high allelic richness and sites of high dispersal indicated three regions as putative refugia (Terra Nova Bay, Dry Valleys and Beardmore Glacier). Terra Nova Bay has not previously been highlighted putatively as refugia. Limited mixing between adjacent geographical areas (such as the Dry Valleys and Ross Island) was identified, with migration likely to be influenced by wind currents. The photobionts of the lichens Buellia frigida, Umbilicaria aprina and Umbilicaria decussata were examined using ITS rDNA sequence analysis in chapter 5. This identified that over a latitudinal gradient of roughly 10˚, there was a single haplotype present in the majority (>95%) of samples. This haplotype was nearly identical to haplotypes from as far afield as Svalbard showing a consistency in photobiont selection over a very wide geographical range and may be micro-climate specific. Other haplotypes present were specific to single geographical areas, and mutation may play the major role in this. Collectively, these findings suggest that despite potentially high dispersal of propagules, populations of lichen species in the Ross Dependency show differentiation among locations and are potentially limited in their dispersal to different habitats. This may be the result of high selectivity for the photobiont. I conclude that lichen populations in the Ross Sea Region have originated from ancient, refugial populations rather than being populated via recent dispersal from northern continents. Dispersal within this region is likely to be restricted by ice-covered areas and relichenisation is potentially limited to particular photobiont strains which iii are suited to the micro-climatic conditions found in this region. In order to minimise the consequences of anthropological disturbance, we recommend the continued protection of areas (e.g. Dry Valleys) housing high lichen and photobiont diversity. iv Acknowledgements Firstly and foremost I thank my supervisors Ian Hogg, Dick Wilkins and Allan Green, for their help and advice in countless situations. From advice on what coffee maker to take to Antarctica, the precise lab work required to develop microsatellite markers and run polyacrylamide gels, and how to write a sentence, you held all the answers. Thank you Ian, in particular, for getting me through the last stages when I thought it would never end, and reassuring me that the light at the end of the tunnel was not, in fact, a train. A special thanks to you Dick Wilkins, for getting me back on track in the lab when I was lost, and also for exposing me to radiation. I see things much more clearly now. And for always I will thank you Allan Green for sending me to Antarctica on a project that HAS to collect samples from a great many sites! Thank you to the people in the C2.03 lab, in particular Gregg, Ali, Richard and Helen, you have provided lightened moments when I was feeling dismal, those belly laughs have been invaluable stress relief. Thank you Ray Cursons for continuing to share your office with me, the words that come from your direction have been interesting and informative. And thank you Olivia for not only providing light moments, and a running companion, but for running such a smooth and trouble free lab. Also to the people who really keep the biological department running, Gloria, Vicki and Gillian. The often appreciated but sometimes understated help you give is immense. Thank you for all those years. v Thank you to Phil Ross for pointing me in the right direction for microsatellite analysis, and Chrissen Gemmill for clarifying why some use Bayesian and some use Likelihood! And a big thank you to Angela McGaughran for the taking up the challenge of critiquing and giving advice on the first draft. I do owe you! Thank you to my long suffering family and friends, of whom some have only known me during the restrictive years of being a PhD student (yes it has been that long). You have supported, encouraged and given me reasons to keep looking ahead (past the train). Thanks Catherine, Claire, Deb, Mark, Niki, Penny, Steve and Tara your friendship and belief in me have been a blessing. My sister Lynda, you are fabulous, and thanks for keeping me sane when I was close to the edge! Thanks Mum for giving me the stamina to see this through, and for always believing in me, no matter what. John and Doreen, thank you, you truly are the best in-laws a girl could hope for. Finally I wish to thank my husband Colin, for his patience, his encouragement and the fun we have together. My two daughters, Chris and Alexia, and my little pixie Aaliyah, every day you make my heart sing. vi Table of Contents Abstract ....................................................................................................... ii Acknowledgements .................................................................................... v Table of Contents ...................................................................................... vii List of Tables.............................................................................................. x List of Figures ........................................................................................... xii Chapter 1:Thesis Introduction .................................................................... 1 1.1 Introduction ................................................................................... 1 1.2 Thesis Organisation ...................................................................... 6 Chapter 2: General Introduction ................................................................. 9 2.1 Introduction ................................................................................... 9 2.2 Antarctic Glacial history .............................................................. 11 2.2.1 Ross Sea Glacial History .................................................. 12 2.3 Lichens ....................................................................................... 15 2.4 What are Lichens? ...................................................................... 16 2.5 The name of a Lichen ................................................................. 17 2.6 Structure ..................................................................................... 17 2.7 Relichenisation and Dispersal ..................................................... 19 2.8 Selectivity and Specificity in Lichens. ......................................... 21 2.9 Population Genetics of Lichens .................................................. 24 2.10 Taxonomy of the Targeted Lichens ......................................... 27 2.10.1 Mycobiont .......................................................................... 27 vii 2.10.1.1 Endemic Species: Buellia frigida Darb. (1910).................. 28 2.10.1.2 Bi-polar Species: Umbilicaria aprina Nyl. (1869) ............... 29 2.10.1.3 Cosmopolitan Species: Umbilicaria decussata (Vill.) Zahlbr. (1942) ...............................................................