A defining feature of the non-flying mammal pollinated (NMP) syndrome is inflorescence crypsis whereby flowers are close to the ground and somewhat hidden within the canopy. A number of species in the Cape Proteaceae are NMP, two of which were chosen as focal species for this study: Protea amplexicaulis and Protea humiflora. This study investigated the two previously suggested hypotheses for crypsis: hidden flowers are more difficult for nectarivorous birds to access, or hidden flowers provide greater cover for small mammal pollinators from aerial predators. Using remote triggered cameras, P. amplexicaulis and P. humiflora inflorescences were observed over the 2017 flowering period, noting visitation by birds and small mammals and assessing the legitimacy of birds as pollinators. In the literature, bird visitation to exposed inflorescences is suggested to be rare, but this study showed that it is considerable. Observations of camera footage suggest that birds are in fact illegitimate pollinators and thus nectar rob. Bird visitation to exposed inflorescences was more than tenfold that of hidden inflorescences, suggesting that crypsis is likely a strategy to avoid nectar robbing by birds. Both P. amplexicaulis and P. humiflora have been observed to retain dead leaves, which may contribute to their cryptic nature. Alternative hypotheses for dead leaf retention in Proteaceae – that it may increase flammability or result in a below canopy spike in nutrients post fire (selfish fertilization) – were assessed and rejected. Sampling of eight local Protea species showed that dead leaf retention is not a consequence of prolonged live leaf retention, with P. amplexicaulis retaining dead leaves for up to 6 years. The removal of dead leaves in 30 P. amplexicaulis individuals resulted in a significant decrease in the number of inflorescences hidden from aerial view, thus suggesting that dead leaf retention may be a strategy to enhance crypsis and thus forms part of the NMP syndrome. This research expands on the knowledge of the NMP syndrome; providing evidence in support of an anti- nectar robbing crypsis function, discovering a novel crypsis adaptation regarding dead leaf retention, and casting doubt on the Restricted Distributions hypothesis for the evolution of the syndrome.

While pollinators and leaf herbivores have been a focus of research for decades, floral antagonists have been studied significantly less. Since floral antagonists can be as common as leaf herbivores and have strong impacts on plant reproduction, it is important to understand the role of floral antagonists in the ecology and evolution of flowers. I conducted four experiments to better understand the relationship between plants, floral traits, floral antagonists, and other plant-insect interactions. First, I manipulated resources (light and soil nutrients) that are known to have impacts on plants and floral traits to test how they affect floral antagonists and other plant-insect interactions. Plentiful resources increased the proportion of floral antagonists to visit flowers, but also increase tolerance of floral antagonists. Second, I manipulated flower bud gallers, a species-specific floral herbivore that destroys flowers, to test how it affected other plant-insect interactions, floral traits, and plant reproduction. Plants with flower bud gallers tended to have more pollinator visits, but this effect is due to a shared preference by gallers and pollinators for similar plants. Third, I manipulated florivory to examine how it affects subsequent plant-arthropod interactions, floral traits, and plant reproduction. Florivory had systemic effects on other plant-insect interactions, including leaf herbivores, and shifted the plant mating system towards more selfing. Additionally, I tested how several floral antagonists respond to floral attractive and defense traits to understand which floral traits are important in mediating antagonisms. Finally, I manipulated florivory, pollination, and nectar robbing to test for effects of multiple floral interactions on subsequent plant-insect interactions, floral traits, and plant reproduction. There were significant many-way interactions between the three treatments on subsequent plant-insect interactions and reproduction, indicating that the effect of one interaction depends on what other interactions are present. Understanding the role that floral antagonists play in plant ecology can help scientists determine which interactions are most important, and may help determine why some floral traits exist in their current state. Together, this work represents some of the most comprehensive research on the community consequences of floral antagonists, as well as the interplay between floral traits and floral interactions.

Orientador: Elza Maria Guimarães Santos / Resumo: A limitação de pólen é um dos fatores que mais afeta a produção de frutos e sementes de muitas populações naturais. Cerca de 60% das angiospermas apresentam baixo sucesso reprodutivo decorrente da transferência ineficiente dos grãos de pólen pelos polinizadores. Assim, o objetivo geral desse estudo foi avaliar diversos aspectos ligados à limitação de pólen em Zeyheria montana (Bignoniaceae), uma espécie ornitófila e autoincompatível. Ao longo do período de florescimento, com ampla variação do anúncio floral, nós avaliamos o efeito do padrão de forrageamento dos polinizadores dentro e entre plantas sobre o sucesso reprodutivo das mesmas. Avaliamos também as estratégias de forrageamento empregadas por cada espécie de polinizador e o efeito do roubo de néctar sobre a produção de frutos. Além disso, estimamos o tamanho do genoma das plantas com a finalidade de avaliar se havia variações intrapopulacional no nível de ploidia que pudessem estar associadas ao baixo sucesso reprodutivo. Em geral, nós demonstramos que a baixa qualidade do pólen transferido pelos polinizadores é o principal fator limitante do sucesso reprodutivo de Z. montana. Esse efeito ocorre principalmente no pico do florescimento, quando o anúncio floral é mais intenso, e os polinizadores tendem visitar um maior número de flores sequenciais dentro da mesma planta transferindo pólen incompatível. Além disso, o padrão de movimento entre plantas também não se mostrou eficiente, visto que os polinizadores frequentemen... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Pollen limitation is one of the factors that most affects the fruits and seeds production of many natural populations. Around 60% of angiosperms have low reproductive success due to inefficient pollen grains transfer among flowers by pollinators. Thus, the general goal of this study was to evaluate several aspects related to pollen limitation in Zeyheria montana (Bignoniaceae), an ornithophilous and self-incompatible species. Throughout the flowering period, with wide variation in floral display, we evaluated the effect of the pollinators’ foraging pattern within and between plants on their reproductive success. We also evaluated the foraging strategies employed by each pollinator species and the effect of nectar robbing on fruit production. In addition, we estimated the plants’ genome size in order to evaluate whether there were intrapopulation variations in the ploidy level that could be associated with the low reproductive success. In general, we demonstrated that the low pollen quality transferred by pollinators is the main limiting factor of the reproductive success. This effect occurs mainly at the flowering peak, when the floral display is more intense, and pollinators tend to visit a larger number of sequential flowers within the plant transferring incompatible pollen. In addition, the movement pattern between plants also was not efficient, since pollinators often visited nearby plants that possibly were more related. Although some hummingbirds species alternate their... (Complete abstract click electronic access below) / Doutor