Thesis (Ph. D.)--University of Chicago, 1916. / "A Private edition distributed by the University of Chicago Libraries." "Reprinted from the Botanical gazette, Vol. LXIII, No. 4, April 1917." "Literature cited": p. 264-265.

Thesis (Ph. D.)--University of Chicago, 1916. / "A Private edition distributed by the University of Chicago Libraries." "Reprinted from the Botanical gazette, Vol. LXIII, No. 4, April 1917." "Literature cited": p. 264-265. Also available on the Internet. Also issued online.

A família Passifloraceae apresenta uma grande diversidade de estruturas glandulares: glândulas de resinas, coléteres, tricomas glandulares e nectários extraflorais (NEF\'s). Dentre estas, os NEF\'s são bastante relevantes, notadamente para fins taxonômicos e filogenéticos. Em virtude disso, numerosas pesquisas vêm abordando estudos envolvendo a descrição e a funcionalidade dessas glândulas, entretanto, foram poucos os que abordaram sua descrição em um contexto ontogenético. Portanto, o presente estudo tem por objetivo analisar a natureza e a distribuição dessas glândulas, bem como descrever os principais aspectos do seu desenvolvimento, visando a ocorrência de homologias primárias a partir dos padrões ontogenéticos. Para esse fim, analisamos as glândulas foliares maduras e ápices caulinares em representantes de Passiflora L., pertencentes aos dois subgêneros mais diversificados (Passiflora e Decaloba), a partir de técnicas usuais em anatomia vegetal, incluindo microscopia óptica e eletrônica de varredura. Realizamos também testes histoquímicos convencionais para caracterizar os exsudatos das glândulas, além do uso de Glicofitas. Constatamos que todas as glândulas são NEF\'s, devido à presença de carboidratos e outras substâncias hidrofílicas (mucilagem ácida e proteínas), além da reação positiva com a glicofita. Com efeito, os nectários extraflorais estão presentes em diferentes regiões da folha: pecíolo, lâmina foliar (dorso-laminar e marginais) e estipulas. Observamos ainda que eles apresentam uma relevante diversidade morfológica, porém, compartilham uma mesma característica anatômica: uma epiderme secretora e um parênquima nectarífero e subnectarífero. Independente da região de origem, os NEF\'s em Passiflora compartilham características estruturais comuns nos estágios iniciais do desenvolvimento: estabelecimento de uma epiderme em paliçada com divisões exclusivamente anticlinais e uma região subepidérmica caracterizada por diferentes padrões de divisões. Contudo, apesar dessa similaridade, os nectários possuem particularidades específicas em cada região de origem: os nectários dorso-laminares surgem a partir do plastrocrono 5 (p5), e tornam-se totalmente diferenciados antes da distinção do mesofilo. Os peciolares, por sua vez, desenvolvem-se basipetalmente ou acropetalmente, além de possuírem origens diferentes em relação aos domínios adaabaxial do primórdio foliar. Por fim, os nectários estipulares desenvolvem-se e amadurecem desde os primeiros plastocronos (p4). Com base nos resultados adquiridos, trouxemos novas evidências nos processos de diferenciação dessas glândulas, que podem ser potencialmente informativos nas relações filogenéticas do grupo / Passifloraceae family presents a great diversity of glandular structures: resins glands, coléteres, glandular trichomes and extrafloral nectaries (NEF\'s). Among these, the NEF\'s are quite relevant, notably for taxonomic and phylogenetic purposes. Because of this, numerous studies have been addressing studies involving the description and functionality of these glands, however, few have addressed its description in an ontogenetic context. Therefore, the present study aims to analyze the nature and distribution of these glands, as well as describe the main aspects of their development, aiming at the occurrence of primary homologies from ontogenetic patterns. Therefore, the present study aims to analyze the nature and distribution of these glands, as well as describe the main aspects of their development, aiming at the occurrence of primary homologies from ontogenetic patterns. For this purpose, we analyzed the mature leaf glands and shoots of Passiflora L., belonging to the two most diversified subgenres (Passiflora and Decaloba), using techniques usual in plant anatomy, including optical microscopy and scanning electron microscopy. We also performed conventional histochemical tests to characterize exudates of the glands, in addition to the use ribbons of glucose. We found that all glands are NEF\'s, due to the presence of carbohydrates and other hydrophilic substances (acid mucilage and proteins), in addition to the positive reaction with ribbons of glucose. In fact, NEF\'s are present in different regions of the leaf: petiole, leaf blade (dorso-laminar and marginal) and stipulate. We also observed that they present a significant morphological diversity, but they share the same anatomical characteristic: a secretory epidermis and a nectariferous and subnectariferous parenchyma. Regardless of the region of origin, the NEF\'s in Passiflora share common structural features in the early stages of development: establishment of a palisade epidermis with exclusively anticline divisions and a subepidermal region characterized by different patterns of divisions. However, in spite of this similarity, the specific peculiarities in each region of origin: dorso-laminar nectaries arise from the plastrochronous 5 (p5), and become fully differentiated before the mesophyll distinction. The peciolars, in turn, develop basipetally or acropetally, besides having different origins in relation to the ada-abaxial domains of the leaf primordia. Finally, estipules nectaries develop and mature from the first p4. Based on the results, we have brought new evidence into the processes of differentiation of these glands, which may be potentially informative in the phylogenetic relationships of the group

Made available in DSpace on 2014-06-11T19:32:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-04-30Bitstream added on 2014-06-13T21:05:17Z : No. of bitstreams: 1 possobom_ccf_me_botib.pdf: 5311682 bytes, checksum: 61049a559d97aca40ca5df2a79bf6111 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Diplopterys pubipetala é uma malpiguiácea amplamente distribuída pelo Brasil e apresenta glândulas no cálice, corola, estames e folhas, cuja estrutura, funcionamento e significado ecológico são desconhecidos. Com o objetivo de entender a dinâmica de secreção e o papel destas glândulas, foram estudados aspectos anatômicos, histoquímicos e ultraestruturais, além de registros fenológicos e do comportamento dos visitantes em uma população ocorrente em área de cerrado. As glândulas calicinais estão dispostas aos pares na face abaxial das sépalas, são conspícuas e constituídas por epiderme secretora em paliçada e parênquima especializado vascularizado por xilema e floema. As glândulas da corola ocorrem nas margens fimbriadas de todas as cinco pétalas. São diminutas e constituídas por epiderme secretora unisseriada envolvendo um pequeno grupo de células parênquimáticas vascularizadas ou não. As glândulas presentes na pétala posterior são vascularizadas e estruturalmente mais desenvolvidas do que as glândulas presentes nas pétalas laterais, não vascularizadas. Nos estames o conectivo apresenta superfície secretora constituída por células epidérmicas globulares. Constatou-se que todas as glândulas florais desempenham funções como atrativos primários ou secundários; além disto, o conectivo glandular está relacionado também com o aumento da eficiência na transferência de pólen, sendo fundamentais na manutenção da interação com os vetores de pólen e na reprodução da população de D. pubipetala estudada. Os nectários são diminutos e distribuídos na margem do limbo, sendo mais desenvolvidos os localizados na base e no ápice do limbo. Estes nectários são anatomicamente semelhantes às glândulas do cálice, entretanto são vascularizados predominantemente por floema. São ativos unicamente em folhas jovens e sua secreção representa... / Diplopterys pubipetala is a Malpighiaceae species widely distributed in Brazil and presents glands in calyx, corolla, stamens and leaves whose structural, functional and ecological aspects are unknown. In order to understand the secretion dynamic and the role of these glands, anatomical, histochemical and ultrastructural aspects were studied, besides phenological and visitors behavior records in a cerrado population. The calyx glands occur in pairs in the sepal abaxial surface and are constituted by secretory epidermis and specialized parenchyma with vascular supply of xylem and phloem. The corolla glands occur in the fimbriate margins of all the five petals. They are very small and constituted by unisseriate secretory epidermis that involves a small group of parenchyma cells vascularized or not. The posterior petal glands are vascularized and structurally more developed than lateral petal glands which are not vascularized. In the stamen, the connective shows secretory surface constituted by globular epidermal cells. All these floral glands play important roles as primary and secondary attractive; furthermore, the glandular connective is also related to the increase of pollen transfer efficiency, being essential for maintenance of the interactions with pollen vectors and in the reproduction of D. pubipetala studied population. The nectaries are very small and occur in all the margin of the leaf blade, being more developed these located in the apex and in the base. These nectaries are anatomically similar to the calyx glands, although are vascularized predominantly by phloem. They are only active in young leaves whose secretion represents a food resource for aggressive ants, suggesting the existence of benefical interactions between nectaries and ants. The histochemical tests revealed that the secretion is predominantly lipophilic in floral glands and predominantly hidrophilic in the leaf... (Complete abstract click electronic access below)

Since the early Eighteenth Century the significance of nectar secretion has been debated. Some have reasoned that it is reabsorbed into the plant and used as energy for the developing embryo while others believe it is a waste product which attracts pollinating insects. It has been suggested (Brink and Cooper, 1947) that the nutrient supply to developing ovules is a major factor in the development of seed. Also, alfalfa fields pollinated by pollen-collecting bees produce greater seed yields than those pollinated by nectar collectors (Bohart, Nye, and Levin, 1955). It is a well-known fact that more flowers are tripped by the pollen collectors, but it is debatable whether the nectar not taken by the pollinators has any influence on the quality or amount of seed set. It is then necessary to find whether the nectar not taken by bees is used by the plant before studies can be made to show its effect on seed and forage yields. The object of this study was to treat flowers of several families with C14 labeled sucrose and determine by the use of autoradiograms if sugars can be absorbed by nectaries, where the sugars are translocated, and when absorption takes place.

A ocorrência de nectários extraflorais (NEF) em espécies de Passifloraceae é muito comum e sua presença, assim como sua forma, é utilizada como característica diagnóstica para espécies do grupo. Contudo, glândulas extraflorais em Passiflora foetida L., anteriormente descritas como nectário, ao serem analisadas quanto à natureza química do exsudato, foram reconhecidas como glândulas de resina, apresentando estrutura anatômica distintas dos NEF. Desta maneira, realizamos um estudo anatômico, ultraestrutural e químico das glândulas foliares de Passiflora L., procurando estabelecer as claras diferenciações morfológicas e química dos exsudatos dos tipos glandulares presentes. Foram utilizadas técnicas de anatomia, microscopia eletrônica de varredura e transmissão. Além de testes histoquímicos para a identificação in situ das substâncias armazenadas, e técnicas de cromatografia de camada delgada e cromatografia líquida de alta eficiência para as análises de lipídios e aminoácidos, respectivamente, presentes nos exsudatos das glândulas foliares. Também foram utilizadas fitas para glicose, como auxílio para o reconhecimento de carboidratos e definição das glândulas como nectários. Os NEF apresentam formas muito variadas que foram agrupadas em nectários elevados e planos, ambos com anatomia similar. O néctar extrafloral além de ter grande quantidade de açúcares, também apresenta aminoácidos e lipídios em sua composição. Já as glândulas de resina são morfológica e anatomicamente muito distintas. Quimicamente, além de não apresentarem reação para os testes de açúcares, possuem grande quantidade de substâncias lipofílicas, incluindo uma variedade de terpenos, e presença de aminoácidos. As diferentes técnicas utilizadas nos permitiram melhor definir os tipos, e subtipos, glandulares, ressaltando as diferenças entre NEF e glândulas de resina. Novas hipóteses também foram propostas para a ocorrência de glândulas de resina no grupo, aumentando o número de espécies com esse tipo glandular / The occurrence of extrafloral nectaries (EFN) in Passifloraceae species is very common, such that their presence and their shape are widely used as a diagnostic characteristic for species within this group. However, extrafloral glands in Passiflora foetida L., previously described as nectaries, were recognized as resin glands when the chemical nature of the exudate was analyzed, showing a distinct anatomical structure from the EFN. Therefore, we carried out an extensive anatomical, ultrastructural and chemical study of the leaf glands of Passiflora L. The goal was to establish clear morphological and chemical differences among the exudates of the observed glandular types. Usual techniques of plant anatomy, including scanning and transmission electron microscopy were used. In addition to histochemical tests for the in situ identification of the stored substances, techniques of thin layer chromatography and high performance liquid chromatography were respectively employed for the analysis of lipids and amino acids present in the exudates of the foliar glands. Ribbons of glucose test were also used as an aid to the recognition of carbohydrates and the definition of glands as nectaries. The EFN showed very varied forms, which were grouped as elevated or flattened nectaries, both with similar anatomy. Additionally, to having a large amount of sugars, extrafloral nectar also had amino acids and lipids in the composition. On the other hand, resin glands were observed to be morphologically and anatomically very distinct from the EFN. Besides not reacting to sugar tests, they chemically have a large amount of lipophilic substances, including a variety of terpenes and the presence of amino acids. The different techniques used allowed us to better define the glandular types and subtypes, emphasizing the differences between EFN and resin glands. New hypotheses were also proposed for the occurrence of resin glands in the group, increasing the number of species with this glandular type

In this study poplar trees have been examined under different stress conditions. Apart from the detailed descriptions above two main conclusions might be drawn: i) A small plant like Arabidopsis thaliana is highly susceptible to stress situations that might become life-threatening compared to a tree that has extremely more biomass at its disposal. Such an organism might be able to compensate severe stress much longer than a smaller one. It seems therefore reasonable that a crop like Arabidopsis reacts earlier and faster to a massive threat. ii) In poplar both tested stress responses seemed to be regulated by hormones. The reactions to abiotic salt stress are mainly controlled by ABA, which also has a strong impact upon cold and drought stress situations. The term commonly used for ABA is “stress hormone” and is at least applicable to all abiotic stresses. In case of herbivory (biotic stress), jasmonic acid appears to be the key-player that coordinates the defence mechanism underlying extrafloral nectary and nectar production. Thus the presented work has gained a few more insights into the complex network of general stress induced processes of poplar trees. Future studies will help to understand the particular role of the intriguing indirect defence system of the extrafloral nectaries in more detail. / In dieser Arbeit wurden Pappelbäume unter verschiedenen Stressbedingungen untersucht. Zusammenfassend und zusätzlich zu den obigen Beschreibungen lassen sich zwei Schlussfolgerungen ziehen: i.) Eine kleine Pflanze wie Arabidopsis ist viel empfindlicher für Stresssituationen, die möglicherweise lebensbedrohlich werden könnten, im Gegensatz zu einem Baum mit wesentlich grösserer Biomasse . Solch ein Organismus kann schwerwiegendem Stress viel länger kompensieren als ein kleinerer Organismus. Es erscheint daher sinnvoll, dass eine Pflanze wie Arabidopsis viel früher und schneller auf eine massive Bedrohung reagiert. ii.) In Pappeln scheinen beide untersuchten Arten von Stressreaktion durch Hormone reguliert zu werden. Die Reaktionen auf abiotischen Salzstress werden hauptsächlich durch ABA kontrolliert, welches auch einen starken Einfluss auf Kälte- und Trockenstressszenarien hat. Üblicherweise wird für ABA der Ausdruck "Stress-Hormon" verwendet, was zumindest für abiotischen Stress zutreffend ist. Im Fall von Herbivorie (biotischer Stress) scheint Jasmonsäure die Schlüsselrolle zu spielen, die die Abwehrmechanismen koordiniert, die den extrafloralen Nektarien und der Nektarproduktion zu Grunde liegt. Demzufolge hat die vorliegende Arbeit ein paar neue Einsichten in das komplexe Netzwerk der Stress-induzierten Prozesse der Pappel ermöglicht. Zukünftige Studien werden dazu beitragen die besondere Rolle des faszinierendem indirektem Abwehrmechanismus der extrafloralen Nektarien en detail zu verstehen.

Borboletas neotropicais, como os licenídeos, são conhecidas pela notável diversidade, entretanto aspectos ecológicos fundamentais desse grupo taxonômico, particularmente dos imaturos, como informações sobre suas plantas hospedeiras e interações mirmecófilas são praticamente desconhecidos para a maioria das comunidades neotropicais. Além do que, o conhecimento limitado da história natural desses insetos, impede uma melhor compreensão do seu papel ecológico-evolutivo. Com isso, a presente tese teve como objetivo inicial caracterizar a comunidade de imaturos de licenídeos florívoros em uma área de cerrado descrevendo o padrão de sazonalidade, identificando as plantas hospedeiras, a amplitude de dieta e interações com formigas e inimigos naturais. A partir dessa base de informações, o objetivo seguinte foi avaliar a ocorrência de licenídeos florívoros no cerrado de acordo com fatores ligados à disponibilidade de alimento nas plantas e à presença de formigas. Adicionalmente, foram estudados diferentes sistemas de interação licenídeos-plantas-formigas com o intuito de inferir o papel da formiga sobre a seleção de plantas hospedeiras. Em suma, nosso estudo mostrou uma comunidade composta por 31 espécies de Lycaenidae registradas em 41 espécies (17 famílias) de plantas hospedeiras e caracterizada pela marcante sazonalidade, cuja ocorrência de imaturos foi maior durante a estação seca. De forma geral, a comunidade de licenídeos apresentou variação de acordo com a oferta temporal de alimento, acompanhando a fenologia de suas plantas hospedeiras disponíveis no campo. Contudo, a comunidade estudada aqui, formada por licenídeos oligófagos e polífagos teve uma tendência em utilizar plantas com menor quantidade de botões e também selecionar plantas que possuem nectários extraflorais e plantas ocupadas por formigas. Particularmente, nosso estudo revelou que a seleção de plantas hospedeiras mediadas por formigas pode variar de acordo com o sistema estudo. Licenídeos como Allosmaitia strophius e Rekoa marius utilizaram a xi presença de formigas como pista durante a seleção de plantas Heteropterys byrsonimifolia, porém os ovos presentes em ramos com formigas sofreram maior ação de parasitóides. Enquanto que Leptotes cassius mostrou selecionar inflorescências de Bionia coriacea independente da presença de Camponotus, formigas as quais mantém associações facultativas. / The Lycaenidae butterflies are known for their remarkable diversity in the Neotropics; however basic ecological features of this group, especially of the immature stages, such as information about host plants and ant-interactions (myrmecophily) are barely known for most species. Therefore the limited knowledge of lycaenids natural history restrains a better understanding of important ecological-evolutionary aspects. In this thesis we initially characterized the community of florivorous lycaenids in a Brazilian Savanna area, describing the seasonal occurrence of immatures, identifying host plants, the diet breadth and interactions with ants and natural enemies. Then, we evaluated the occurrence of the lycaenids according to factors related to resource availability (host plants) and the presence/absence of ants. In summary, we sampled 31 species of Lycaenidae in 41 plant species (17 families). Immatures were more abundant in the dry season indicating a seasonal pattern of occurrence; in addition lycaenids were related to the temporal availability of food resource, following the phenology of the host plants in the field. The oligophagous and polyphagous species were found predominately in plants which produce few flowers buds. The presence of immatures in extrafloral nectaried plants was commonplace, which was expected given that larvae can benefit from living with ants. A further detailed experimental study revealed that ant presence is a cue for female oviposition in two facultative myrmecophilous lycaenid species Allosmaitia strophius and Rekoa marius, but contrary to our predictions, ants failed to protect lycaenid eggs from parasitoids. In other study system, Leptotes cassius did not discriminate between plants with or without ants, despite the fact that larvae had stable association with ants. Our study indicates that there can be striking differences among lycaenid species with regard to association with ants and the benefits granted from these associations. So generalizations about lycaenid ant associations should be avoided and every study system must be examined with detail.

Orientador: André Olmos Simões / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-11-05T17:03:23Z (GMT). No. of bitstreams: 1 Kotovski_EmiliaRosiane_M.pdf: 8989998 bytes, checksum: 872ec26d6ded19c688d25dfd4f7f091b (MD5) Previous issue date: 2013 / Resumo: Allamanda L. é um dos 10 gêneros da tribo Plumerieae (Rauvolfioideae, Apocynaceae), sendo constituído por 15 espécies, das quais 13 nativas do Brasil. Este estudo teve por objetivo contribuir para o melhor conhecimento do gênero através do levantamento de dados morfoanatômicos (cortes anatômicos e Microscopia Eletrônica de Varredura) e testes histoquímicos de estrutura floral em antese de A. cathartica L., A. laevis Markgr., A. puberula A. DC. e A. schottii Pohl, para fornecer caracteres que auxiliem na taxonomia e filogenia da tribo. Os coléteres calicinais estão ausentes em A. cathartica e nas demais espécies, são persistentes, secretores, em número, distribuição e tipos variáveis. Desde o tipo Standard até os bífidos, ramificados e fundidos. Todos os coléteres apresentam pendúnculo não secretor, mas em A. puberula estes são mais longos e estreitos. O corpo secretor é formado por uma epiderme uniestratificada em paliçada secretora e cutícula fina, e um eixo central parenquimático não secretor no qual não foram observados laticíferos, feixes vasculares ou idioblastos. A secreção mista, composta principalmente de polissacarídeos e lipídeos, é liberada pela distensão da cutícula. Nestas espécies, a corola é dividida em duas porções denominadas tubo superior e inferior, sendo que a diferença entre o comprimento destas porções diferencia A. schottii e A. cathartica das demais espécies. Tricomas supra e infrastaminais unicelulares não ornamentados são morfologicamentes e espacialmente diferentes entre si, mas se mantêm constantes entre as espécies. O androceu é constituído por estames formados por um filete curto e antera tetrasporangiada. O filete é ornamentado por tricomas unicelulares, esparsamente distribuídos ou agrupados dependendo da espécie. As anteras apresentam duas porções estéreis: duas expansões basais das tecas dorsais, e um apêndice apical, morfologicamente distintos entre as espécies. A lignificação da antera ocorre de maneira homogênea em todo o endotécio. O anel nectarífero ao redor do ovário, difere no grau de pentalobação e na distribuição dos estômatos entre as espécies. Laticíferos articulados e feixes vasculares estão presentes e distribuídos entre o tecido parenquimático nectarífero. O ovário é sincárpico, bicarpelar, unilocular, súpero, com sutura externa visível entre os carpelos e com placentação parietal. Apenas A. laevis possui estômatos na epiderme ovariana. A cabeça do estile é morfologicamente complexa e dividida em regiões morfofuncionais, com dois apêndices apicais que diferem entre as espécies quanto à morfologia, um corpo principal cônico revestido por um anel apical de longos tricomas secretores, tricomas medianos secretores e anel basal formado por células epidérmicas justapostas não secretoras mais expansão parenquimática, formando projeções arredondadas ou acuminadas, e região receptiva localizada abaixo do anel basal. Os tricomas secretores secretam o mesmo tipo de substâncias hidro e lipofílicas. Os resultados obtidos neste estudo evidenciaram a presença de polimorfismo, principalmente no apêndice apical da antera, coléteres calicinais, nectário e apêndices apicais da cabeça do estilete entre as espécies, sendo úteis para a caracterização interespecíficas, corroborando também para o melhor conhecimento do gênero pela combinação de distintas abordagens que juntas trouxeram maior riqueza de detalhes da estrutura floral que podem auxiliar em futuros estudos taxonômicos e filogenéticos / Abstract: Allamanda L. is one of the 10 genera of the tribe Plumerieae (Rauvolfioideae, Apocynaceae), consisting of 15 species, which 13 are native to Brazil. This study aimed to contribute to a better understanding of the genus through the morphoanatomical data survey (anatomical sections and Scanning Electron Microscopy) and histochemical structure of floral anthesis in A. cathartica L., A. laevis Markgr., A. puberula A. DC. and A. schottii Pohl. The calyx colleters are absent in A. cathartica. In other species, are persistent, secretory, and variable in number, with distribution alternate in A. puberula, opposite in A. laevis and undetermined in A. schottii. The type also varies from the standard to the bifid, branched and fused. All colleters have nonsecretory peduncle, but in A. puberula these are longer and narrower. The secretory body is formed by a secretory palisade epidermis and a thin cuticle, filled with non-secretory parenchyma without laticifers, vascular bundles or idioblasts. The secretion, mainly composed of mucopolysaccharides, is released without the cuticle disruption, which suffers only distention. In these species, the corolla is divided into two portions referred to as upper and lower tube, and the difference between the lengths of these portions separate A. schottii from other species. The unicellular non-ornamented trichomes that are at the upper and lower parts of the stamens are morphologically and spatially different from each other, but remains constant among species, varying only in quantity and size. The androecium comprises a short filament, which is ornamented by unicellular trichomes, variable in length, sparsely distributed or grouped depending on species. The anther presents two sterile portions: wings, formed by the lateral expansion of thecae, which vary proportionately their size in species; and an apical appendix, morphologically distinct among species, formed by connective tissue. The lignification occurs homogeneously throughout the endothecium, including at the sterile wings. A nectary ring around the ovary occurs in all studied species, differing in the degree of lobation between them. At the epidermal tissue in this ring are present stomata, which are distributed throughout nectariferous surface in A. schottii or concentrated in the apical region of the ring from the other species. Anatomically, the nectary shows no variation in the species analyzed, being composed of a uniseriate epidermis and nectary parenchyma, which cells carry starch granules. Articulated laticifers and vascular bundles are present and distributed among the parenchyma tissue in all four species. The ovary is superior and unilocular with visible external suture between the carpels, with parietal placentation. Only A. laevis has stomata in ovarian epidermis. The style-head is morphologically complex and divided into three morphofunctional regions: 01) two apical non-secretory appendices which morphologically differ in each species; 02) a main conical body coated by an apical ring of long secretory trichomes, median secretory trichomes and a basal ring formed by juxtaposed non-secretory epidermal cells forming rounded or acuminate projections at the peripheral expansion of the parenchyma; 03) receptive region located below the basal ring, where the pollen grains that come from another flower are deposited by pollinator. The secretory trichomes of the apical ring and the median ones secrete the same type of hydro and lipophilic substance. The results showed the presence of polymorphism among species, especially in the apical appendix of anther, colleters, nectary and apical appendices of style-head, and that they are useful for the characterization within the genus. The study also collaborated to the best knowledge of the genus by combining three different approaches (SEM, anatomy and histochemistry) that brought together richer details of floral structure that can help for taxonomic purposes / Mestrado / Biologia Vegetal / Mestra em Biologia Vegetal

<p>Although we often study mutualisms (interactions in which both species benefit) at the level of the individual partners, mutualistic interactions take place in the context of populations and communities. Sharing mutualists with others in a population could result in indirect interactions in the form of mutualist-mediated competition or facilitation. In my dissertation work I asked whether intraspecific competition or facilitation for ants might occur in an extrafloral nectary-bearing (EFN) plant, and what the consequences would be for long-term population dynamics of the plant. My focal species was <italic>Colubrina spinosa</italic> (Rhamnaceae), a neotropical treelet on which I observed 69 ant species at La Selva Biological Station, Costa Rica. </p><p> Demonstrating intraspecific competition for mutualists requires that 1) neighbor densities affect mutualist visits to an individual, and 2) change in mutualist visits results in reduced benefit. To determine how mutualist density affects plant benefit, I experimentally manipulated ant abundances on plants over two years and measured growth and survival. To assess competition for mutualists, I excluded ants from conspecific neighbors and followed ant abundance on focal plants. To consider long-term facilitation, in which greater local nectar resources increase local ant abundance, I manipulated nectar resources in a two-year field experiment and estimated ant abundance on <italic>C. spinosa</italic> plants and on baits. </p><p> Considering local neighbor density both within a 1m radius and in 5x5 m plots, ant densities on <italic>C. spinosa</italic> plants showed evidence for a small-scale competition effect and a contrasting plot-level facilitation effect. The small-scale competition was sized-based; smaller plants lost ants to larger plants. Ant benefit to plants also depended on plant size. For larger plants, those with greater size-adjusted ant density had higher growth and survival than those with fewer ants than expected for their size. </p><p> To determine whether these contrasting competition and facilitation effects could impact population growth or densities, I modeled population dynamics with an integral projection model (IPM). Growth and survival were functions of ant density, which in turn depended on conspecific neighbors, plant size, and mean background ants. Results suggest that larger-scale facilitation of mutualists impacts long-term population growth more than small-scale competition. Population growth rate increased with increasing background ant density, which depended on facilitation at the 5x5m plot scale. In contrast, small-scale competition caused a redistribution of mutualist ants among plants of different sizes, but had very little effect on long-term population growth. </p><p> I thus conclude that on the scale of individuals there is evidence of intraspecific competition for ants as well as facilitation in the EFN plant <italic>C. spinosa</italic>, but only facilitation effects lead to appreciable changes in population dynamics. If mutualist-mediated facilitation effects tend to occur over long time scales in other systems as well, facilitation might prove to be more important than competition in other mutualisms.</p> / Dissertation