COMPARATIVE BIOLOGY OF TWO FORMS OF AN INVASIVE VINE, DOLICHANDRA UNGUIS-CATI (L.) LOHMANN (BIGNONIACEAE): IMPLICATIONS FOR WEED SPREAD AND BIOCONTROL JOSHUA COMRADE BURU BSc (Biological Sciences), PGDE School of Earth, Environment and Biological Sciences Science and Engineering Faculty Queensland University of Technology Brisbane, Australia A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy 2016 i Keywords Anatomy, Bignoniaceae, biodiversity, biological control agents, biomass accumulation, cat’s claw creeper, competitiveness, colonization, disturbance, ecological strategies, ecophysiology, efficacy, epidermis, fitness traits, fluctuating resource hypothesis, foliar nectaries, functional traits, intraspecific variation, invasive species, invasiveness, invasion ecology, leaf economic spectrum, long pod, Macfadyena unguis-cati, morphology, palisade mesophyll, performance, phenotypic integration, phenotypic plasticity, physiology, photosynthetic rate, plant-herbivore interactions, plant invasion, plant sexual reproduction, polyembryony, propagule pressure, relative growth rate, resource use efficiency, seed ecology, seed germination, short pod, SEM, SLA, successful colonizers, taxonomy, trait correlation, tubers, weed management, WoNS, woody vine. i Thesis Abstract Cat’s claw creeper, Dolichandra unguis-cati (Bignoniaceae) is a Weed of National Significance (WoNS) in Australia and a major environmental weed in Queensland and New South Wales states. Two forms of this weed (‘short pod’ and ‘long pod’) occur in Australia. Short pod is widely distributed in Australia, but long pod is only found in a few localities in southeast Queensland. There is a general lack of understanding why the two forms are not equally prevalent. Previous studies have shown significant differences in the flowering phenology and leaf morphology of the two forms. Despite these differences, the same biological control agents are used in the management strategies for the two forms. Preference tests have not been performed to determine whether biological control agents would choose one form over the other. The aims of this study were twofold, firstly, to use a trait-based framework to compare germination, anatomical and physiological traits between long pod and short pod. This aim included an assessment of trait responses to different water, light and nutrient resource conditions. Secondly, the study sought to test the preference of two biological control agents, Carvalhotingis visenda and Hylaeogena jureceki for the two forms under different water and nutrient resource conditions. The study found short pod to have significantly higher germination rates and higher levels of polyembryony than long pod. Short pod also exhibited significantly higher germination plasticity than long pod. Short pod foliar anatomy indicated presence of thicker leaves and significantly higher frequency of foliar nectaries than long pod. Short pod had a less compact spongy mesophyll with larger intercellular spaces than long pod. Only one type of epidermal hair (unicellular trichomes) was observed in short pod. Conversely, long pod had two types of epidermal hairs (unicellular and multicellular trichomes). The distribution of unicellular trichomes was higher in long pod than in short pod. Short pod performed better than long pod, as indicated by production of higher biomass and more tubers and branches under low nutrient resources. Short pod exhibited higher values of carbon assimilation, water use efficiency and leaf nitrogen than long pod in response to water, light and nutrient resources. However, long pod produced more biomass than short pod under high light and nutrient resource conditions. Phenotypic integration did not differ between long pod and short pod when considering all resource levels. However, short pod exhibited significantly higher ii phenotypic integration when high light and nutrients were considered separately. Short pod developed a significantly higher number of tubers than long pod in response to water, light and nutrient resources. Overall short pod performed better than long pod in response to different resource conditions. A multivariate exploration of functional traits using principal components analysis showed a clear separation of the two forms along the second axis. The second axis was influenced by shoot/root ratio, tuber development, WUE, leaf nitrogen and quantum yield of photosystem II. Biological control preference results show that C. visenda does not have a preference for any form while H. jureceki have a preference for long pod over short pod. Resource level had a significant effect on preference for both forms, with agents choosing the high nutrient plants the most. Results from this study make a significant contribution to our understanding of why short pod is the prevalent form in Australia. Short pod was shown to exhibit more traits that are associated with fast growing invaders. Higher rates of germination and polyembryony could have contributed to the spread of short pod. Higher values for relative growth rates, tuber biomass and branching shown by short pod are traits that enhance colonization success. Moreover, short pod exhibited higher phenotypic integration and greater germination plasticity in response to different levels of resources than long pod, indicating greater capacity to invade environmentally heterogenous habitats. Although long pod did not perform as well as short pod for most traits, accumulation of higher biomass under high light and nutrient conditions imply potential for colonization success by this form under disturbance scenarios. Lack of preference for either form by C. visenda implies that this agent is suitable for continual use against long pod and short pod. On the contrary, preference for long pod by H. jureceki implies a potential lack of efficacy of this agent on the more prevalent short pod form. A preference pattern by agents in the field could jeopardize biological control efforts for D. unguis- cati in Australia. More research needs to be carried out in the field to substantiate findings from this study. An evaluation of biological control method against D. unguis-cati is suggested, especially in light of occurrence of long pod and short pod. The striking differences in life history traits between long pod and short pod in this study inevitably raise questions about the taxonomy of the two forms. Differences in germination traits and frequency of polyembryony, growth patterns, tuber development and response to environmental conditions have taxonomic implications for the two forms. Differences in leaf anatomical traits such as types of hairs and nectaries have taxonomic implications for the two iii forms, and have previously been used in taxonomic resolution in Bignoniaceae. Thus, the outcomes of this study corroborate a previous hypothesis that these two forms may be different species. A phylogenetic analysis of the genus Dolichandra with extensive sampling of all possible forms of D. unguis-cati from both the native and introduced range is recommended. To test the biological species concept, we recommend studies that will test whether the two forms of D. unguis-cati can interbreed. As there were significantly higher germination rates and greater polyembryony in the short pod than long pod, flower or seed-eating biological control agents would be appropriate in the management of the short pod. iv Table of Contents Keywords ...................................................................................................................................... i Thesis Abstract ........................................................................................................................... ii Table of Contents ........................................................................................................................ v Table of Figures.......................................................................................................................... ix List of Tables ............................................................................................................................... x Acknowledgements ................................................................................................................... xv Chapter 1: General Introduction .............................................................................................. 1 1.1 Background .......................................................................................................................................... 1 1.2 Study Objectives .................................................................................................................................. 3 1.3 Thesis outline ....................................................................................................................................... 4 Chapter 1: General Introduction ................................................................................................. 4 Chapter 2: Literature Review ....................................................................................................... 4 Chapter 3: Leaf Anatomy ............................................................................................................. 4 Chapter 4: Seed Biology ................................................................................................................ 5 Chapter 5: Growth and Performance Traits .............................................................................