Living with Fire: Ecology and Genetics of the Dasyurid Mammal Dasykaluta Rosamondae
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Living with fire: Ecology and genetics of the dasyurid mammal Dasykaluta rosamondae Genevieve Louise Tavani Hayes Bachelor of Science (Wildlife Management) Hons This thesis is presented for the degree of Doctor of Philosophy of The University of Western Australia School of Biological Sciences 2018 Thesis Declaration I, Genevieve Louise Tavani Hayes, certify that: This thesis has been substantially accomplished during enrolment in the degree. This thesis does not contain material which has been accepted for the award of any other degree or diploma in my name, in any university or other tertiary institution. No part of this work will, in the future, be used in a submission in my name, for any other degree or diploma in any university or other tertiary institution without the prior approval of The University of Western Australia and where applicable, any partner institution responsible for the joint-award of this degree. This thesis does not contain any material previously published or written by another person, except where due reference has been made in the text. The work(s) are not in any way a violation or infringement of any copyright, trademark, patent, or other rights whatsoever of any person. The research involving animal data reported in this thesis was assessed and approved by The University of Western Australia Animal Ethics Committee. Approval #: RA/3/100/1235. The following approvals were obtained prior to commencing the relevant work described in this thesis: Health and Safety Induction, Permission to Use Animals (PUA), Program in Animal Welfare, Ethics and Science (PAWES), Department of Parks and Wildlife Regulation 4: Permission to enter DPaW lands and/or waters for the purpose of undertaking research (licence numbers: CE004035 and CE004508) and Department of Parks and Wildlife Regulation 17: Licence to take fauna for scientific purposes (licence numbers: SF009353 and SF009924). The work described in this thesis was funded by The University of Western Australia and an ARC Future Fellowship awarded to DO Fisher (FT110100191). This thesis contains published work and/or work prepared for publication, some of which has been co-authored. Signature: Date: 18 August 2017 ii Summary The dasyurids are a group of Australian mammals with relatively few threatened species. This is rare for mammals in Australia, where over 30% of the world’s terrestrial mammal extinctions have occurred since 1600 AD, and may be a consequence of their unusual and ‘fast’ life histories. The kaluta, Dasykaluta rosamondae, is a small dasyurid, common in the broader Pilbara region of north- western Australia. In my study, I examined the ecology of kalutas to determine whether their current conservation status is appropriate and whether management actions are required to ensure the persistence of this species. Specifically, I assessed life history characteristics, patterns of paternity, responses to fire, diet, and population structure at broad and fine scales. My study was conducted in Millstream Chichester National Park (MCNP) between July 2013 and December 2014. In total, I captured 131 individual kalutas (54 males, 77 females) at a trap success rate of 3.8%. Sex ratios varied over the year, with an equal sex ratio in winter compared with only females in summer following male die-off. Adult males were significantly larger than adult females and were also in better condition. Kalutas were cathemeral, with activity times ranging from crepuscular in summer to more diurnal in winter. I confirmed that males were obligately semelparous and that females were polyandrous, with litters sired by up to three males. Intraspecific positive testis allometry was demonstrated in adult males, consistent with sperm competition occurring in this species. Populations of kalutas were larger on sites that had not been burnt for a long time and had higher spinifex (Triodia) cover than they were on sites that had been recently burnt and had less spinifex cover. Capture success of kalutas was significantly influenced by spinifex cover, but not time since fire. Spinifex hummocks were significantly smaller on recently burnt sites than the other sites, but no difference was found in spinifex size and cover between intermediate aged and long unburnt sites, suggesting that there was a threshold for the effect of time since fire on spinifex size. These findings suggest that the frequency of fire is not as important for kaluta persistence as the occurrence of spinifex of sufficient size. I used DNA barcoding to study the diet of the kaluta; this new technology is revolutionising the diet analysis of cryptic species. My data revealed that kaluta diet consisted predominantly of termites, as well as another small dasyurid species (Pseudantechinus sp.), spiders and centipedes. The diet analysis did not identify any differences in diet between the sexes, sites of differing fire age or between seasons. Lastly, I used microsatellite genotyping to study the population structure of kalutas across their range as well as on a fine scale within MCNP. I found at the broad scale no genetic structuring was evident in kalutas, while at the local scale both males and females exhibit clear population structure and individuals are more closely related than by chance up to distances of 8 km. These genetic results indicate different dispersal patterns, and highlight the importance of assessing structure at both broad and local scales in conservation genetic studies. iii Together, the results of my comprehensive study of the demography, ecology, mating system, diet and genetics of the kaluta will inform future management actions for a species inhabiting a region likely to experience substantial changes as the global climate warms. My findings suggest fire management that encourages less frequent, less intense fires would support this species, with patches of long unburnt habitat a vital niche for their long-term survival. My results suggest that the current conservation status of kalutas is appropriate. I advise caution, however, since the kaluta has the potential to quickly become threatened, particularly through the negative impact of fire frequency, which is likely to increase under a warming climate. My data are consistent with the pattern of dasyurid species with fast life histories being more robust to the threats that have driven other small mammal species to extinction. iv Table of Contents Summary ............................................................................................................................................................... iii Acknowledgements .............................................................................................................................................. vi Authorship Declaration: Co-authored Publications ......................................................................................... vii Prologue ................................................................................................................................................................. 1 Chapter 1 Life history and activity schedules of a small dasyurid Dasykaluta rosamondae in the Pilbara region of Western Australia ............................................................................................................................................... 7 1.1 Abstract......................................................................................................................................................... 8 1.2 Introduction .................................................................................................................................................. 9 1.3 Methods ...................................................................................................................................................... 11 1.4 Results......................................................................................................................................................... 14 1.5 Discussion ................................................................................................................................................... 17 Chapter 2 Multiple paternity and male semelparity confirmed in an arid-zone dasyurid, Dasykaluta rosamondae .......................................................................................................................................................... 21 2.1 Abstract....................................................................................................................................................... 22 2.2 Introduction ................................................................................................................................................ 23 2.3 Methods ...................................................................................................................................................... 24 2.4 Results......................................................................................................................................................... 27 2.5 Discussion ................................................................................................................................................... 30 Chapter 3 Fire and decreased Triodia cover negatively affect the small, Pilbara region endemic dasyurid Dasykaluta rosamondae ....................................................................................................................................... 33 3.1 Abstract......................................................................................................................................................