Research Collection Doctoral Thesis Ecological and genetic processes underlying allee effects among tree populations in the context of divergent population histories Author(s): Finger, Aline Publication Date: 2012 Permanent Link: https://doi.org/10.3929/ethz-a-7362420 Rights / License: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library DISS. ETH NO. 20153 ECOLOGICAL AND GENETIC PROCESSES UNDERLYING ALLEE EFFECTS AMONG TREE POPULATIONS IN THE CONTEXT OF DIVERGENT POPULATION HISTORIES A dissertation submitted to ETH ZURICH for the degree of Doctor of Sciences presented by ALINE FINGER Dipl. Biogeog., University of Trier born 01 March 1980 citizen of Germany accepted on the recommendation of Prof. Dr. Jaboury Ghazoul, examiner Dr. Chris Kettle, co-examiner Prof. Dr. Peter Hollingsworth, co-examiner Prof. Dr. Peter Edwards, co-examiner 2012 To My Parents “LORSQUE TU NE SAIS PAS OU TU VAS, REGARDE D'OU TU VIENS” - AFRICAN PROVERB - CONTENTS TABLE OF CONTENTS ACKNOWLEDGEMENTS ………………………………………………………………………………………. iii SUMMARY ENGLISH ………………………………………………………………………………………. 1 GERMAN ………………………………………………………………………………………. 3 CHAPTER 1: GENERAL INTRODUCTION INTRODUCTION ………………………………………………………………………………………. 5 REFERENCES ………………………………………………………………………………………. 12 CHAPTER 2: BACK FROM THE BRINK: POTENTIAL FOR GENETIC RESCUE IN A CRITICALLY ENDANGERED TREE ABSTRACT ………………………………………………………………………………………. 17 INTRODUCTION ………………………………………………………………………………………. 18 METHODS ………………………………………………………………………………………. 20 RESULTS ………………………………………………………………………………………. 25 DISCUSSION ………………………………………………………………………………………. 30 REFERENCES ………………………………………………………………………………………. 36 SUPPORTING INFORMATION..……………………………………………………………………………. 42 CHAPTER 3: FOREST FRAGMENTATION GENETICS IN A FORMERLY WIDESPREAD ISLAND ENDEMIC TREE: VATERIOPSIS SEYCHELLARUM (DIPTEROCARPACEAE) ABSTRACT ………………………………………………………………………………………. 45 INTRODUCTION ………………………………………………………………………………………. 46 METHODS ………………………………………………………………………………………. 49 RESULTS ………………………………………………………………………………………. 53 DISCUSSION ………………………………………………………………………………………. 61 REFERENCES ………………………………………………………………………………………. 68 SUPPORTING INFORMATION..……………………………………………………………………………. 74 i CONTENTS CHAPTER 4: GENETIC CONNECTIVITY OF THE MOTH POLLINATED TREE GLIONNETIA SERICEA (RUBIACEAE) IN A HIGHLY FRAGMENTED HABITAT ABSTRACT ………………………………………………………………………………………. 77 INTRODUCTION ………………………………………………………………………………………. 78 METHODS ………………………………………………………………………………………. 80 RESULTS ………………………………………………………………………………………. 86 DISCUSSION ………………………………………………………………………………………. 93 REFERENCES ………………………………………………………………………………………. 98 CHAPTER 5: VULNERABILITY OF TREE SPECIES TO THE GENETIC CONSEQUENCES OF HABITAT FRAGMENTATION: THE IMPORTANCE OF DIVERGENT POPULATION HISTORIES ABSTRACT ………………………………………………………………………………………. 101 INTRODUCTION ………………………………………………………………………………………. 103 METHODS ………………………………………………………………………………………. 106 RESULTS ………………………………………………………………………………………. 108 DISCUSSION ………………………………………………………………………………………. 116 REFERENCES ………………………………………………………………………………………. 121 CHAPTER 6: GENERAL CONCLUSION CONCLUSION ………………………………………………………………………………………. 129 REFERENCES ………………………………………………………………………………………. 135 APPENDIX: PRIMER NOTES MEDUSAGYNE OPPOSITIFOLIA …………………………………………………………………………. 139 VATERIOPSIS SEYCHELLARUM …………………………………………………………………………. 145 GLIONNETIA SERICEA ………………………………………………………………………………………. 151 APPENDIX: PICTURES ………………………………………………………………………………………. 157 CURRICULUM VITAE ………………………………………………………………………………………. 163 ii ii CONTENTS ii ACKNOWLEDGEMENTS I never thought that I would end up doing a PhD in the Seychelles when I applied for a position on Alpine plants. But as coincidences sometimes are they seemed to have decided that the right place for me to do my PhD would be the Seychelles. And many more “lucky coincidences” have kept following me since I began my thesis in 2008. First of all I would like to thank my “lucky coincidences” which followed me from the beginning till the end of my thesis in the Ecosystem Management group, my supervisors. Jaboury Ghazoul, who gave me the possibility to do the greatest PhD ever, has further been a “lucky coincidence” in that he has managed in several field trips to ward off all “Mous zonn” from me and to heroically take all the stings himself, a very special thanks for that. Chris Kettle was such an enthusiastic, motivated and well tempered supervisor from the very first day till the very last night where he did last-minute corrections at 2am without a word of complaint. So he must definitely be a “lucky coincidence”, without him this PhD would not have been so successful, and more importantly, so much fun. In the Seychelles I was harboured by my Seychellois “lucky coincidence” Christopher Kaiser-Bunbury, the most perfectly organized person I have ever met, who guided me safely through the Seychelles, its flora, fauna and politics, field work, the ecological part of science, particularly through the statistics and who was always there in times of need. An immense “lucky coincidence” was also to have, what I believe to be, the best field assistances ever, and moreover, the most enjoyable. I have had such a good time in the field with them and they taught me so much. Therefore I would like to say a big thanks to my friend Terence Valentin, the coolest Rasta ever, for keeping me safe and helping me with all the work and particularly making all the climbing so much more enjoyable. Also Damien Doudee was fantastic to have around due to his wide knowledge, his great character and dedication to the Seychelles flora, even watering our seedlings on the weekends. Thanks for that and I will never forget all these adventurous trips to Bernica. Also I am still impressed by both of your good eye-sights and mental GPSs. I also had further support from many people in the Seychelles, such as the Seychelles Island Foundation (SIF) and their members, here especially Frauke-Fleischer Dogley and Nancy Bunbury. Nancy, thanks as well for sharing my passion for nature and dogs and for being a wonderful host. Also the Plant Conservation Action group (PCA) has helped me in many ways, particularly Katy Beaver, Lindsay Chong-Seng and Bruno Senterre, for sharing their iii knowledge with me. Furthermore, I received valuable assistance from Denis Matatiken of the Botanic Garden of Mahé (now CEO of National Parks Authority) who has been a huge support due to constructive discussions, particularly his knowledge on Medusagyne and also his kindness of getting me several last minute MTA permits to take my samples back home. Also Ronley Fanchette supported and kindly helped me with MTA permits. Thanks as well to James Mougal for helping me with his experience on population locations and for joining us in the forest on some occasions as well as Steven Azemia for his support in the field. This PhD thesis was kindly approved and fully supported by Seychelles Government and I am very grateful for a thriving and mutually beneficial collaboration, particularly with Didier Dogley, at the time Principal Secretary of the Department of the Environment. My gratitude goes beyond the Seychelles as there have been further “lucky coincidences”, for example for ending up in the Ecosystem Management group and in the office of which I always forget the room number. Here I have found good friends and have been motivated by them through the whole time at ETH. Julia and Charlotte, thanks for letting me profit from your PhD experiences, and thanks for always being there for me. And Sascha, it was really nice to have you for “real scientific” discussions but also for the general PhD problem talks. I also want to thank Anna Gray for having been a great flat-mate in the Seychelles and also Bärbel Koch, our little workaholic. I’ve had fun hikes and chameleon experiences with these two, thanks for being wonderful friends since then. Last but not least I want to thank my family for being my source of energy in finding and catching all these “lucky coincidences”. More importantly they are the reason that no matter how difficult times are, I always have the certainty that nothing can go wrong. A very special thanks to Daniel, who has sacrificed his ligaments while helping me in the field, and his nerves while helping me to make nice maps. Thanks for going with me through all the ups and downs of the various PhD stages. Without you it would not have been such a nice and fruitful time, actually, it would not have been the same at all. iv SUMMARY Rare plant species are vulnerable to genetic erosion and inbreeding associated with small population size and isolation due to increasing fragmentation, though the degree to which these problems undermine population viability remains debated. The critically endangered long-lived tropical tree Medusagyne oppositifolia is an endemic to the Seychelles with a naturally patchy distribution. The species comprises 90 extant trees in four populations, with only the largest (78 trees) having successful recruitment. Whether recruitment failure in the three small populations is linked to genetic problems associated with fragmentation is not known. It could be shown that genetic diversity is high in three populations, with only the smallest having relatively low diversity. All populations have high genetic differentiation and low pollen and seed dispersal distances (< 100 m). Inter-population pollination crosses from the large donor population to a small recipient population