I studied evolutionary history in the angiosperm order Apiales, with a special emphasis on interactions between form, time, and space. Four broad categories of problems were addressed: interfamilial relationships in Apiales, the assignment of genera traditionally assigned to the Apiaceae subfamily Hydrocotyloideae, the estimation of divergence times of the major clades, and the reconstruction of the biogeographic history of Apiales. We used molecular markers with different evolutionary properties and rates derived from the plastid (trnD-trnT and rpl16), nuclear (RPB2), and mitochondrial (nad1 intron 2) genomes, from more than 250 species representing all major clades in the order. The nuclear RPB2 region exhibited evidence of at least six duplication events in Apiales and provided a rich source of information for understanding the origins of polyploid lineages, especially in Araliaceae. Sequence comparisons among the copies show that exon regions are highly conserved. All copies appear to be functional but may have undergone subfunctionalization. Phylogenetic analyses of the three genomes suggest that Hydrocotyloideae should be divided into as many as six evolutionary lineages, but that most taxa should be included in subfamilies Azorelloideae and Mackinlayoideae. Relationships among and within the major clades of Azorelloideae need further analyses since many genera appeared non-monophyletic (e.g., Azorella, Schizeilema, and Eremocharis). Mackinlayoideae appeared as the earliest diverging lineage of Apiaceae, but the plastid and nuclear trees were incongruent in the placement of the Platysace clade relative to Mackinlayoideae and the rest of Apiaceae. Among the remaining clades of suborder Apiineae, Myodocapaceae appeared sister to Apiaceae in both plastid and nuclear trees, preceded by the divergence of Araliaceae and then Pittosporaceae. At the base of the gene trees in Apiales, Griseliniaceae and Torricelliaceae formed successive sisters to Apiineae. The placement of Pennantiaceae as sister to the rest of Apiales was confirmed by plastid data, but was not found in the nuclear trees. The order appears to have originated in the Cretaceous, with Apiineae having an age of c. 100 Mya. Australasia appears to be the most likely center of origin for Apiineae and most of its major clades, except Azorelloideae (South America) and Apioideae-Saniculoideae (sub-Saharan Africa).

Doctor of Philosophy (PhD) / A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.

Doctor of Philosophy (PhD) / A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.

<p>This thesis deals with evolutionary relationships within the asterids, a group of plants comprising about one-third of all flowering plants.</p><p>Two new families are recognised: Pennantiaceae and Stemonuraceae. The woody <i>Pennantia</i> from New Zealand and Australia is the sole genus of Pennantiaceae. Stemonuraceae consist of a dozen woody genera with a pantropical distribution and a centre of diversity in South East Asia and the Malesian islands. They are characterised by long hairs on their stamens and/or fleshy appendages on their fruits. Both families were formerly included in Icacinaceae. While Pennantiaceae are unrelated to any of the former Icacinaceae and placed in the order Apiales, other former Icacinaceae genera are related to <i>Cardiopteris</i>, a twining herb from South East Asia and Malesia. The monogeneric family Cardiopteridaceae is enlarged as to include also these. Cardiopteridaceae and Stemonuraceae are sister groups and placed in Aquifoliales. The three other families of Aquifoliales are monogeneric and closely related. The Asian Helwingiaceae and the Central/South American Phyllonomaceae are suggested to be merged into Aquifoliaceae (hollies). The genera of Icacinaceae in the traditional sense not placed in any of the above families (all euasterids II) are members of early diverging lineages of the euasterids I and possibly included in the order Garryales.</p><p>The three woody Australasian families Alseuosmiaceae, Argophyllaceae, and Phellinaceae are confirmed as members of Asterales, despite traditional placements not close to that order. They are, moreover, supported as each other’s closest relatives.</p><p>The results are based mainly on parsimony analysis of DNA sequence data, but morphological studies have revealed characters in support for the molecularly based conclusions. The gene that has provided most new information is the chloroplast <i>ndh</i>F gene. The results are, however, drawn from combined analyses of sequences from one or several additional genes (<i>atp</i>B, <i>mat</i>K, <i>rbc</i>L, <i>18S</i> rDNA). The data have also been explored with Bayesian analysis, a statistical, model-based method that most recently has been developed for phylogeny reconstruction.</p>

This thesis deals with evolutionary relationships within the asterids, a group of plants comprising about one-third of all flowering plants. Two new families are recognised: Pennantiaceae and Stemonuraceae. The woody Pennantia from New Zealand and Australia is the sole genus of Pennantiaceae. Stemonuraceae consist of a dozen woody genera with a pantropical distribution and a centre of diversity in South East Asia and the Malesian islands. They are characterised by long hairs on their stamens and/or fleshy appendages on their fruits. Both families were formerly included in Icacinaceae. While Pennantiaceae are unrelated to any of the former Icacinaceae and placed in the order Apiales, other former Icacinaceae genera are related to Cardiopteris, a twining herb from South East Asia and Malesia. The monogeneric family Cardiopteridaceae is enlarged as to include also these. Cardiopteridaceae and Stemonuraceae are sister groups and placed in Aquifoliales. The three other families of Aquifoliales are monogeneric and closely related. The Asian Helwingiaceae and the Central/South American Phyllonomaceae are suggested to be merged into Aquifoliaceae (hollies). The genera of Icacinaceae in the traditional sense not placed in any of the above families (all euasterids II) are members of early diverging lineages of the euasterids I and possibly included in the order Garryales. The three woody Australasian families Alseuosmiaceae, Argophyllaceae, and Phellinaceae are confirmed as members of Asterales, despite traditional placements not close to that order. They are, moreover, supported as each other’s closest relatives. The results are based mainly on parsimony analysis of DNA sequence data, but morphological studies have revealed characters in support for the molecularly based conclusions. The gene that has provided most new information is the chloroplast ndhF gene. The results are, however, drawn from combined analyses of sequences from one or several additional genes (atpB, matK, rbcL, 18S rDNA). The data have also been explored with Bayesian analysis, a statistical, model-based method that most recently has been developed for phylogeny reconstruction.