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How Sexual Conflict and Reproduction Drive the Sex Dependent Evolution of Life History Traits

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How Sexual Conflict and Reproduction Drive the Sex Dependent Evolution of Life History Traits How sexual conflict and reproduction drive the sex dependent evolution of life history traits Teagan Joy Gale A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy School of Biological, Earth and Environmental Sciences Evolution and Ecology Research Centre UNSW August 2018 i THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Gale First name: Teagan Other name/s: Joy Abbreviation for degree as given in the University calendar: PhD School: School of Biological, Earth and Environmental Sciences Faculty: Faculty of Science Title: How sexual conflict and reproduction drive the sex dependent evolution of life history traits Abstract: Sexual conflict is inevitable in all sexually reproducing species as males and females are selected to maximise their own fitness often at the expense of their mate. This conflict can intensify the already costly nature of reproduction for female mammals. To examine the effects of territory turnover of a dominant male to pregnant females and their resulting offspring, we exposed females to a novel male in late pregnancy. These females spent less time nursing their pups, who subsequently had a low weaning weight and suffered oxidative costs at adulthood. We believe the change in behaviour is a result of the females strategically altering their investment in relation to their perceived chances of offspring’s survival. To partition the costs of male presence and mating from those of reproduction we housed females with males of differing gonadal status and allowed half access to a refuge. We found no costs of male mating, presence or insemination, suggesting the costs associated with these behaviours may be subtler than currently predicted. However, females housed with castrated males exhibited more refuging behaviour and higher stress levels. To examine the cause of this response, we again housed females with males of differing gonadal status and supplemented each cage with the scent of an unfamiliar dominant, subordinate or castrated male. While we replicated the effect of castrated males on female stress levels, we found that this can be ameliorated after exposure to the scent of an intact male, either dominant or subordinate. This shows that the signal(s) eliciting this response in females can be transferred in soiled bedding, but that it is not due to subordination. Lastly, we investigated genetic sexual conflict to attempt to provide further evidence for Haig’s kinship theory of genomic imprinting. We used Igf2 knockout mice to explore whether paternally expressed genes in offspring reduce maternal reproductive success. We mated females to male Igf2 KO homozygotes and found that females did show reduced metabolic costs. This shows foetal/placental Igf2 upregulates maternal metabolism, imposing energetic demands on the mother in the manner predicted by Haig’s kinship hypothesis. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. ii I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). The University recognises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and require the approval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: Originality Statement ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.’ iii Authenticity Statement ‘I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.’ Copyright Statement ‘I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' iv Date 16/02/2018 Summary of Collaborators’ Contributions In all chapters and manuscripts submitted, and in preparation in which I was listed as first author, I was the primary investigator. This included being the main researcher in data collection, analysis and interpretation, and preparation of the manuscript. Professor Robert Brooks was my PhD supervisor and Dr Michael Garratt a close collaborator, who both also contributed to the design, analysis, interpretation and editing of the manuscripts. Dr Neil Youngson contributed to the designing of the Chapter 5 and provided training on dissection techniques. Professor Michael Constancia and Dr Ionel Sandovici provided genetic strains of mice necessary to conduct some of this research. v Acknowledgements In the words of Richard Feynman “Physics is like sex: sure, it may give some practical results, but that's not why we do it.” Which I feel is true for science in general. I am first and foremost grateful to have spent four years in a labour of love pursuing knowledge and chasing my curiosities. Although after this dedicated period of scholarly pursuit I have found that while I learned a great deal throughout this project, more so, I have learned just how much I don’t know. I hope that by reading this thesis I can impart the tiny fraction of knowledge I have contributed and simultaneously highlight the much larger fraction there is still to know in this field. While I considered myself lucky to end up with Rob Brooks as my supervisor in my honours year, there was no luck involved when it came to my PhD. I knew I was choosing to work under an intellectual giant who is also somehow completely down to Earth. Rob, I would like to express my sincere gratitude for everything you have done for me during my honours and PhD and for giving me so many wonderful opportunities. Your continued support, patience and immense knowledge has been integral to the success of this PhD. I also remain indebted for your belief in me, which was the only thing that gave me the confidence to undertake this journey in the first place and continued to mitigate my imposter syndrome up until the very end. My other honours supervisor, Mike Garratt, whom I also continued to work with throughout my PhD was also an essential source of assistance and guidance that I would not have been able to complete this project without. I am hugely appreciative for all your help from across the other side of the world. I would also like to take this opportunity to thank Neil Youngson, who not only responded to an email from a random PhD student from another faculty in need, but subsequently stepped in to help me with my genetics experiment without hesitation. In my daily work I have been incredibly lucky to be surrounded with the ever supporting and banterful members of the Sex lab and EERC. Thank you Amany, vi Hamish, Francesca, Dax, Jess and Justin, who helped keep my spirits high and made coming into lab everyday more enjoyable. A special thanks to Heather Try who not only helped me with my mouse work, but literally any question or request I had day or night. A massive thank you also must go to another fellow PhD student, and my now BFF, Emma Asbridge. Thank you for being one of my biggest cheer leaders, whether it was listening to conference talks numerous times or driving me to the start of my half marathon at 4:30am you were always there for me with untiring enthusiasm. You made the PhD highs higher and the lows shallower and I am truly grateful. I also need to wholeheartedly thank my boyfriend, Laurie, who has supported me and been very understanding of the enormous time investment required for this project.
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