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Heliconius butterflies exhibit Müllerian mimicry, in which two or more unpalatable species share a mutual advantage from having a common conspicuous colour pattern. These tropical butterflies have impressive visual signals, which are under conflicting selection pressures, as they are used in choosing potential mates and defending against visual predators through aposematic coloration. As both selection pressures are likely to be strong, different elements of the signal might be adapted for different receivers. Here, I combine sensory ecology with behavioural ecology to explain Heliconius colours signals of different co-mimic pairs. I explore how mimicry in Heliconius is perceived both from the perspective of predators and conspecifics, using visual abilities of both butterflies and birds. The different visual sensitivities of avian predators, H. erato females and males make them to perceive Heliconius coloration in different ways. My work suggests that having the ability to see in the ultra-violet light range enables higher discrimination between co-mimics both for birds and butterflies. Heliconius warning colours transmit a consistent signal across time of the day and habitat in a tropical forest for avian vision. In contrast through Heliconius vision there is evidence that patterns are more conspicuous in their own habitats. All these traits could facilitate communication between co-mimics and reduce the cost of confusion in courtship while still maintaining the advantages of Müllerian mimicry against predation. I conducted a field experiment to show that attack rates on a novel distasteful butterfly reduced over time, suggesting that Heliconius wing colouration can enhance aversion among predators. Finally, I have shown that Heliconius butterflies use leaf shape as a cue to approach their host plants, demonstrating the potential for Heliconius to drive negative frequency dependent selection on the leaf shape of their Passiflora host plants. Overall these results highlight ecological interactions between Heliconius butterflies, their predators and host plants.

This study determined extrafloral nectar (EFN) amino acid composition of 31 species of the salicoid genus Passiflora known for diverse EFN morphology to characterize quantitative and qualitative variation in EFN amino acid profiles within and between species. The work was motivated by the question of whether such diversity is driven by distinct tactics used by specialists herbivores i.e. whether EFN traits attract mutualistic defenders appropriate to tactics used by specialists herbivores. The coevolutionary relationship between Passiflora and Heliconius butterflies presents an ideal system to understand how herbivore pressure can drive indirect defenses such as EFNs. EFN nectar composition might differentially favor mutualistic defenders ranging from tiny egg parasitoids to large ants and wasps. While most Passiflora species analyzed are host to several heliconiine species, our study focused on the oviposition behavior of Heliconius that impacts vulnerable new shoots. Past observations indicate that Heliconius species that deposit single eggs on host new shoots experience high mortality from eggparasitoids. By contrast, Heliconius that lay groups of eggs on new shoots, are thought to satiate local egg parasitoids. Thus, Passiflora species vulnerable to group attack may rely on attracting predators like social insects with potential of a functional response to richer resources. This study sought evidence that signals EFN traits reflect these extreme modes of Heliconius oviposition tactics. Though Passiflora subgenus classifications were a significant contributor to EFN amino acid composition (r2=0.299) pointing to a taxonomic origin of specific amino acid compositions, species classifications were a larger contributor (r2=0.526), highlighting that composition could be driven by species specific herbivore pressure. The final part of the study examined known ant defenders that patrol two species, P. auriculata and P. vitifolia, hosts to heliconiine/Heliconius species with mass egg laying strategies. Neither Passiflora species showed significant difference in EFN amino acid composition between field populations and were used to model synthetic nectars for lab-testing preferences of the ants Crematogaster laeviscula and Pseudomyrmex gracilis. Synthetic nectar trials revealed ant preferences reflective of relationships witnessed in the field and preference for higher diversity of EFN amino acid composition

One of the most taxonomically difficult groups in the passionflower genus (Passiflora, Passifloraceae) is section Dysosmia. For centuries, the taxa belonging to this group have proven difficult to classify or even name. Various authors over the years have attempted to tackle the complex task of describing the diversity in this section and have done so with varying degrees of success; often times shuffling names between species or recognizing taxa at differing ranks.Ellsworth Killip, in his 1938 monograph of the family, introduced a litany of varietal names for one of the most notoriously complicated species, Passiflora foetida, in an attempt to make sense of the staggering degree of morphological variation. His work remains a foundation for the systematics of Dysosmia as well as that of the rest of the genus to this day. The section was most recently revised by John Vanderplank in 2013, who took a more conservative approach by synonymizing many names and renaming others to more accurately reflect our changing taxonomic hypotheses. At the outset of this project 21 species and nine varieties were recognized and accepted in the section.The primary goal of this research was to use modern techniques and provide new evidence to aid in the delimitation of the taxa within section Dysosmia. An exhaustive nomenclatural study was conducted in order to ascertain the extent to which the sectional diversity has already been named. Dozens of names were subsequently typified and corrected in order to bring them into compliance with the current Code of Nomenclature.Intensive morphological studies were performed to investigate the use of macro- and micromorphological features—some of which never before assessed—for the delimitation of taxa. Robust statistical analyses revealed at least three species assemblages or lineages within section Dysosmia that were then the focus of subsequent work, particularly a conspicuous red-fruited complex. Geometric morphometric descriptors were also pursued for the purposes of classification and show promise for objective classification of an otherwise unruly group. Molecular approaches were explored to test the hypotheses of monophyly and relationships within the section but were not successful.Finally, climatic and soil data were employed to investigate a complex of taxa and delimit distinct entities at the rank of species. These data were also informative in describing habitat characteristics of the species. This is the first time that evidence of this kind has been used for taxonomic delimitation in Passiflora.The culmination of this research was a comprehensive synopsis of a portion of the section, comprising all of the red-fruited taxa, in which several new species and combinations were proposed. The current understanding of section Dysosmia brings the number of recognized taxa to 31 species and five putative varieties.

Drought and Fusarium wilt are the main constraints in growing purple passion fruit (Passiflora edulis) in Kenya. There is need for drought and Fusarium wilt-resistant rootstock. In an effort to develop a drought and Fusarium wilt resistant Passiflora rootstock, a series of experiments were conducted at The Ohio State University and Egerton University in Kenya, to study vegetative propagation, graft compatibility, drought tolerance, Fusarium wilt resistance in Passiflora species and to identify an integrated control method for Fusarium wilt. In the vegetative propagation, graft compatibility and drought tolerance studies, 20 Passiflora species were screened. Species of the subgenus Passiflora rooted in higher percentages than species of the Decaloba subgenus (81 vs 64%). Cuttings from vines and liana type species rooted in higher percentages than cuttings from annual species when treated with 0.1% indole-3-butyric acid powder (82, 73 vs 44%). Cuttings of Passiflora gerbertii L., Passiflora caerulea L. and Passiflora subpeltata Ortega. could be rooted in high percentages and were compatible rootstocks with the purple passion fruit. Passiflora incarnata, P. caerulea and P. subpeltata had higher drought-tolerance than the other species.In the Fusarium wilt resistance studies, nine Passiflora species were screened using Fusarium oxysporum f. sp. passiflorae isolates from four locations in Kenya. Passiflora edulis f. flavicarpa and P. suberosa were resistant to Fusarium wilt implying that the P. edulis f. flavicarpa plants currently being used by farmers may not be true-to-type and hence susceptible. Passiflora incarnata and P. mollisima were moderately resistant to Fusarium wilt. Passiflora suberosa, P. incarnata and P. caerulea can be improved for use as rootstock alternatives for purple passion fruit. For Fusarium resistant P. suberosa, breeding should focus on improving graft compatibility and drought tolerance. For drought-tolerant P. incarnata, improvement should focus on improving compatibility and Fusarium wilt resistance. Since P. caerulea is compatible with P. edulis and is drought-tolerant, improvement should focus on Fusarium wilt resistance.In the study the effect of irrigation and substrate type in the occurrence and suppression of Fusarium wilt in a passion fruit orchard, two substrates, native soil in Kenya and a formulated substrate comprising of 20% soil, 60% pumice and 20% decomposed bovine manure were evaluated. Substrate treatment was by pasteurization, or three chemicals; Root-guard and Rodozin (both under trials) with Terraclor Super® as a commercial control. Irrigation methods comprised of a novel integrated container-irrigation system (ICIS-pot) and black plastic mulch with integrated irrigation system (ICIS-mulch), micro irrigation (dripper), basin irrigation and no irrigation as control. Three month old seedlings were inoculated with 2.0 x 106 cfu. of Fusarium oxysporum f. sp. passiflorae macroconidia obtained from infected passion fruit plants. ICIS-pot and ICIS-mulched plots in the field and greenhouse as well as plots treated with Root-guard and Rodozin had low pathogenic Fusarium colony populations. Also ICIS-mulched plots had the highest colony populations of non-pathogenic Fusarium per gram of substrate. In the greenhouse and field, the ICIS-pot and ICIS-mulch irrigation methods significantly reduced Fusarium wilt occurrence 75 days after substrate treatment. ICIS-pot irrigated passion fruits had longer vines in the field. Thus, the use of ICIS-pot and ICIS-mulch together with either Rodozin or Root-guard treatment give short term suppression of Fusarium wilt and increase passion fruit vegetative growth.

The classification of the species of Old World species of Passiflora (subgenus Decaloba, supersection Disemma, Tetrapathaea, and Hollrungia) has been historically unresolved. Molecular and morphological data were used to examine the evolutionary relationships in this group. Two clades are supported: first, subgenus Decalobasupersection Disemma, and second, a clade representing a new subgenus with three species, Passiflora tetrandra, P. aurantioides, and P. kuranda.Supersection Disemma is monophyletic, containing an Asian section, Octandranthus, and an Australian section, Disemma. Passiflora hollrungii (section Hollrungiella) from Papua New Guinea is resolved ambiguously. In section Octandranthus three species exhibit variation in stamen and carpel number. Passiflora tonkinensis (=Passiflora moluccana var. glaberrima) and P. siamica, were investigated to determine mode of development and the mechanism behind the anomalous growth. Passiflora siamica develops additional stamens through dédoublement of a single widened stamen primordium. Passiflora moluccana var. glaberrima exhibits congenital dédoublement where stamens arise from the floral apex already doubled.The second lineage consists of P. tetrandra (= Tetrapathaea tetrandra) and P. aurantioides(= Hollrungia aurantioides). Additionally, a new species of Passiflora( P. kuranda) was identified. Tetrapathaea tetrandra, H. aurantioidesand P. kurandaform a monophyletic lineage sister to subgenus Decaloba. These species are recognized here as part of Passiflorasubgenus Tetrapathaea, raising the number of subgenera in Passiflora from four to five.A revision of subgenus Decaloba supersection Disemma is also presented. A dichotomous key to the supersection and sections is provided along with detailed morphological descriptions of each species. Information about species distributions, ecology, pollination, and herbivory are provided. Lastly, a preliminary analysis of nectary development and expression in Passiflora was completed. CRABS CLAW (CRC) was chosen as a candidate gene for an evolutionary developmental analysis of nectary evolution in Passiflora.Gene expression in both floral and extrafloral nectaries was examined in three species. CRC was expressed in all floral nectaries and none of the extrafloral nectaries. Genomic CRC was cloned and seven distinct copies are present in P. morifolia and P. tricuspis, while only two copies are present in P. perakensis.The cladograms of genomic and cDNA transcripts of CRC are congruent.