Impacts of environmental variation on the fitness of the pygmy bluetongue lizard Tiliqua adelaidensis

Author: Leili Shamiminoori

Shamiminoori, Leili, 2015 Impacts of environmental variation on the fitness of the pygmy bluetongue lizard Tiliqua adelaidensis, Flinders University, School of Biological Sciences

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Abstract

The alarming rate of species extinction has urged ecologists and conservation managers to identify species at risk, obtain information on the causes of decline and find efficient techniques to reverse or halt the declining trend. This thesis explores two potential indicators of population stress, individual body condition and levels of asymmetry in an endangered Australian lizard, Tiliqua adelaidensis, the pygmy bluetongue lizard. The pygmy bluetongue lizard is an endangered scincid lizard that is endemic to mid-North region of South Australia. There are currently 31 known populations, in a small geographic range and all restricted to small fragments of native grassland. For endangered species, identifying the causes of changes in the level of fitness overtime is an essential component of conservation management of that population. Chapter 1 introduces the general topic of monitoring populations, and particularly populations of endangered species for fitness. Chapter 2 introduces the study species, the study sites and the general methodology used in the study. The results chapters are all published or submitted manuscripts. Because they have more than one author, the terminology used is in the plural “we” and “our” instead of the singular “I” and “my”, although the majority of the practical work and analysis was conducted by me. Chapter 3 and 4 of the thesis explore the changes in the body condition of both adult and neonate pygmy bluetongue lizards. We considered the relative importance of phenotypic (plain and patterned morphs), temporal (sampling year and activity period), biological (sex) and climatic factors (rainfall and temperature) that can affect the body condition of lizards. Our results indicated that body condition changed significantly over sampling years in both adults and neonates. In addition, in adults, body condition was different between early (September- December) and late (January-April) activity periods within a season. In neonates, we also looked at the relationship between presence/absence of mothers and the size of litter on body condition of lizards. None of those factors showed any association with neonate body condition. The substantial annual variation in body condition of pygmy bluetongue lizards can provide important insights into the persistence of these fragile populations of this enigmatic species. Chapter 5 and 6 of this thesis investigate the relationship between the level of symmetry in the head scales of adult (Chapter 5) and neonate (Chapter 6) pygmy bluetongue lizards and two parameters of their fitness, body condition and jaw width. We developed an index of symmetry using the digital photos of the head scales of lizards. The results of this section demonstrated a negative relationship between jaw width and the symmetry index in adult lizards over sampling years. More symmetrical lizards had narrower jaws. We provide some possible explanations of this relationship. However, body condition did not correlation with the symmetry index. For the long-term conservation of pygmy bluetongue lizards, the findings of this study can assist in monitoring the fragmented populations and to identify any deteriorating trend in the body condition. Further study needs to explore the underlying causes of the changes in the body condition in this species. In addition, in order to use symmetry index as an indicator of fitness, future studies need to look at symmetry index in multiple traits in pygmy bluetongue lizards in order to shed light on the association between asymmetry and fitness in this species. This thesis also contains two published papers as appendices (I, II) which are collaborative effort between my study and Damien Tohl’s (School of Computing Science, Engineering and Mathematics, Flinders University) PhD thesis in image analysis. The collaboration resulted in development of the Symmetry Index of head scalation (Appendix I) and an automated photo identification technique (Appendix II) for pygmy bluetongue lizards

Keywords: conservation biology, endangered species, body condition, fitness, fluctuating asymmetry, Tiliqua adelaidensis
Subject: Biological Sciences thesis

Thesis type: Doctor of Philosophy
Completed: 2015
School: School of Biological Sciences
Supervisor: Professor Michael Bull