Mycorrhizal fungi are soil-borne organisms that form symbiotic associations with the majority of land plants. These fungi gather and exchange mineral nutrients with plants for photosynthetically derived carbohydrates. Mycorrhizal fungi can also confer other benefits onto plants, e.g. defense against pathogens, improved water relations, tolerance to heavy metal toxicity and herbivory. The influence of mycorrhizal fungi on plant mineral nutrition and response to stress suggests that these organisms may have a role to play sustainable agriculture as well as in bioremediation and ecosystem restoration. In contributing to this important research, I investigated host-specific interactions between mycorrhizal fungi and the sex morphs of the gynodioecious perennial herb Polemonium foliosissimum (Polemoniaceae) and their mycorrhizal associates in the field. I hypothesized that the genders of this species differed in their associations with mycorrhizal fungi in benefits received. I performed a full factorial simulated herbivory experiment and evaluated the extent of mycorrhizal colonization in the roots as well as the concentrations of nutrients in leaf tissue. Mycorrhizal colonization and leaf nutrient concentrations did not differ between the genders nor were influenced by the experimental treatments. This suggests that the genders of Polemonium foliosissimum do not interact differently with mycorrhizal fungi, and thus do not represent different "hosts". Also, I investigated local adaptation of mycorrhizal associations by exploring the effect of large herbivore grazing on plant-mycorrhizal associations. I hypothesized that grazing by large herbivores results in locally adapted symbioses that enhance plant response to herbivory. I grew the perennial bunchgrass Themeda triandra (Poaceae) in inoculum prepared from soils collected from three field exclosures with differing histories of large herbivore exclusion in the Kenya Long Term Exclosure Experiment. I conducted a full factorial simulated herbivory experiment in which plants were subject to two clipping events over the course of 5-months, and evaluated plant regrowth as well as mycorrhizal colonization for plants in the experiment. Plants grown in inoculum from exclosures in which large herbivores have had access produced more root mass when mycorrhizal fungi were present. Further, I found equivalent biomass production of clipped and non-clipped plants in inoculum prepared from the exclosure with only native large herbivore access while equivalent biomass production was not found in the substrate prepared from areas with a history of large herbivore exclusion. This suggests that mycorrhizal fungi mediate plant growth and response to herbivory in this system.

Species of Valerianaceae in South America represent one of the best examples of rapid diversification on a continental scale. The phylogeny of Valerianaceae has received a lot of attention within the last 10 years, but relationships among the South American species are fairly unresolved. Results from previous studies have not been well resolved with traditional genetic markers, most likely due to its recent and rapid radiation. Species in this clade exhibit a variety mating systems and inflorescence types. For the first part of this research I used several traditional plastid markers, and 3 new low copy nuclear markers to better resolve the phylogeny and then explore mating system evolution within the clade. For the second part of this research I collected high-throughput “next-generation” genomic sequence data from reduced representation libraries obtained using genotyping-by-sequencing (GBS) protocols, along with several phylogenetic methods, to try to further resolve the phylogeny of this group.

Co-occurring species of flowering plants may compete for pollination, which can cause character displacement by altering natural selection on floral traits. In a gynodioecious species, competition for pollination may also affect the evolution of sexual dimorphism of floral traits by influencing sex-specific selection. I demonstrated that Mimulus ringens did not affect seed set of gynodioecious Lobelia siphilitica, indicating that it is not a competitor for pollination. The presence of M. ringens did not alter selection upon most floral traits of L. siphilitica. I detected sex-specific selection upon five floral traits, supporting the hypothesis that sexual dimorphism evolves in response to sex-specific selection, rather than pleiotropic effects. My results also suggest that the presence of a co-flowering species may provide a context for sex-specific selection, and therefore, influence sexual dimorphism. Thus, my results suggest a link between the fields of study of competition for pollination and the evolution of sexual dimorphism. / NSERC, OGS, Ontario Innovation Trust, Canada Fund for Innovation

Orientador: Simone de Pádua Teixeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-18T14:54:49Z (GMT). No. of bitstreams: 1 Basso-Alves_JoaoPaulo_M.pdf: 5360673 bytes, checksum: dcedc4cbe8765f92aca350ab0d6cfac5 (MD5) Previous issue date: 2011 / Resumo: A ausência de um dos verticilos reprodutivos em algumas flores pode decorrer da perda ou supressão de primórdios, o que pode ser elucidado por meio de estudos morfológicos do desenvolvimento floral. Ficus L. é um ótimo modelo para estes estudos, uma vez que possui representantes com sistemas sexuais diversos. Assim, o presente trabalho teve por objetivo comparar a morfologia da flor em desenvolvimento em Ficus citrifolia (monóica), F. hispida (ginodióica), F. racemosa (monóica secundária) e F. religiosa (monóica), a fim compreender as vias ontogenéticas que promovem a condição flor imperfeita. Para tal, sicônios em diversos estádios de desenvolvimento foram coletados, fixados em FAA 50, dissecados em lupa e preparados para observações de superfície em microscopia eletrônica de varredura (MEV) e histológicas em microscopia de luz. A organização dos meristemas florais e das flores no interior do sicônio é muito congesta na maioria das espécies estudadas, sendo menos acentuada em F. hispida (ginodióica). Diferenças no tempo de emergência dos meristemas e de alongamento do pedicelo em flores carpeladas foram observadas nas espécies monóicas (F. citrifolia, F. racemosa e F. religiosa) e parecem ser cruciais para a formação da heterostilia incompleta, típica de espécies monóicas deste gênero. As flores carpeladas de todas as espécies exibiram formação de sinestigma ao final do desenvolvimento (exceto aquelas do sicônio produtores de galha em F. hispida). Nossos dados, comparados aos de literatura, indicam que a ausência de estames nas flores carpeladas, tanto em espécies monóicas quanto em ginodióicas de Ficus, deve-se a um processo de perda, ou seja, os primórdios de estames não são iniciados no meristema floral. As flores estaminadas de F. hispida apresentaram supressão carpelar. A perda de primórdios estaminais é difundida no gênero e em Moraceae; já o carpelo pode ser perdido ou suprimido nestes grupos. Aspectos do desenvolvimento floral também são discutidos em relação à reprodução e biologia floral de Ficus / Abstract: The absence of reproductive organs in some flowers may ontogenetically arise by organ loss or suppression. Ficus L. is an interesting model for floral developmental studies, due to its diversity in sexual systems. The aim of this study was to compare the morphology of the floral development in Ficus citrifolia (monoecious), F. hispida (gynodioecious), F. racemosa (secondary monoecious) and F. religiosa (monoecious), to help understanding the ontogenetic pathways that promote the condition "imperfect flower". Thus, figs at various developmental stages were collected, fixed in FAA 50 and prepared for surface (scanning electron microscopy) and histological observations (light microscopy). The organization of the floral meristem and flowers inside the syconium is quite compressed, although F. hispida (gynodioecious) exhibits a less compressed floral arrangement inside the syconium. Variation in meristem inception time and pedicel elongation were observed in carpellate flowers of monoecious species (F. citrifolia, F. racemosa and F. religiosa) and should be crucial for establishment of incomplete heterostyly. The carpellate flowers of all species showed a sinstigma in the later developmental stages (except the gall-producing syconium in F. hispida). The staminate flowers of F. hispida showed carpel suppression. Our data, compared with those in the literature, indicate that the absence of stamens in carpellate flowers is due to loss of stamen primordium, both in gynodioecious and monoecious species. This condition is present in the genus and in Moraceae as a whole, while the carpel primordium may be lost or suppressed in this group. Aspects of floral development observed in Ficus are discussed in relation to their systematic and reproductive biology / Mestrado / Biologia Vegetal / Mestre em Biologia Vegetal

Abstract Most plants grow in association with arbuscular mycorrhizal (AM) fungi in their roots forming the so-called AM symbiosis. AM symbiosis is usually beneficial to the host as it improves plant survival and performance. However, AM symbiosis also entails a cost to the plant in terms of the carbon allocated to the fungus. In sexually dimorphic plants, more than one type of individual can be recognised with regard to their sexual expression or gender. The cost of reproduction in these plants will differ in relation to the relative investment in male versus female function, as the female and the male sexual functions incur different costs. This different cost of reproduction may be translated into differences in other plant functions between the sexes as all functions are connected through trade-offs. Therefore, since sexes differ in resource needs and allocation patterns, and AM mediate resource acquisition and allocation patterns through imposing both costs and benefits to the plant, the sexes of dimorphic plant species may possess, at least theoretically, a different relationship with their AM roots symbionts. In this thesis, I have investigated whether the sexes in sexually dimorphic plant species differ in their mycorrhizal relationship, and if so, in which ways. Several plant life history traits were studied in the dioecious species Antennaria dioica and also in the gynodioecious Geranium sylvaticum using greenhouse, common-garden and field experiments. Resource acquisition, resource allocation, and both plant and fungal benefits from AM symbiosis were considered. Mainly beneficial effects of AM symbiosis were observed in both sexes of the two dimorphic plant species for most of the studied plant life history traits. Overall, both partners benefited from the AM association. However, several sex-specific benefits were detected which were not uniformly present in all experiments for any given trait. Moreover, the responses observed in certain life history traits were dependent on both the AM fungal and plant species involved in the symbiosis. Remarkably, plants gained sex-specific benefits from the same species of AM fungi and the fungal benefit differed depending on the sex of the host plant. In addition, mycorrhizal benefits were lost under certain environmental conditions. To summarise, the results obtained in this study highlight the complexity of AM interactions. My results suggest that the plant-mycorrhizal fungus relationship may differ depending on the sex of the host plant. Through sex-specific effects on survival, growth and reproduction of the hosts, AM fungi may play a role in the evolution of the life histories in the studied species. In addition, sex-specific relationships between plants and their mycorrhizal symbionts may have potential important consequences for the population dynamics of the sexual morphs and the coevolution of the mycorrhizal relationship.

No description available.

<p>In this thesis, I examined variation in sex expression and mating patterns in the sexually polymorphic, wind-pollinated herb <i>Plantago maritima</i>. With a combination of field studies, greenhouse experiments, and genetic analyses, I (a) examined factors influencing sex ratio variation in gynodioecious plants (in which hermaphrodites and females coexist), (b) discovered variation in breeding system, (c) investigated density-dependence of seed production, and (d) documented genetic variation within and among populations close to the northern range margin in Europe. </p><p>In a survey of 104 <i>P. maritima</i> populations, I documented considerable variation in sex ratio (range 0-70% females, median 6.3% females). As predicted, females were more frequently missing from small than from large populations, and the variance in sex ratio increased with decreasing population size. Among twelve populations sampled for seed production, the frequency of females was positively related to relative fecundity of females and negatively related to population size. The results suggest that the local sex ratio is influenced both by the relative fecundity of females and hermaphrodites, and by stochastic processes in small populations.</p><p>A comparative field study showed that plant fecundity decreased with increasing distance to nearest pollen donor both within and among populations in an archipelago in southern Sweden, where self-incompatibility was confirmed in controlled crosses. In contrast, plant fecundity was overall higher and was not density-dependent in the Skeppsvik archipelago in northern Sweden, where controlled crosses showed that plants are self-compatible. The results were consistent with the prediction that evolution of self-fertility should reduce density-dependence of pollination success.</p><p>I quantified the genetic structure within and among populations from eastern Sweden and western Finland based on variation at four polymorphic microsatellite loci. The genetic diversity was low in northern Sweden, which may be the result of a history of small population sizes and periods of frequent self-fertilization.</p>

In this thesis, I examined variation in sex expression and mating patterns in the sexually polymorphic, wind-pollinated herb Plantago maritima. With a combination of field studies, greenhouse experiments, and genetic analyses, I (a) examined factors influencing sex ratio variation in gynodioecious plants (in which hermaphrodites and females coexist), (b) discovered variation in breeding system, (c) investigated density-dependence of seed production, and (d) documented genetic variation within and among populations close to the northern range margin in Europe. In a survey of 104 P. maritima populations, I documented considerable variation in sex ratio (range 0-70% females, median 6.3% females). As predicted, females were more frequently missing from small than from large populations, and the variance in sex ratio increased with decreasing population size. Among twelve populations sampled for seed production, the frequency of females was positively related to relative fecundity of females and negatively related to population size. The results suggest that the local sex ratio is influenced both by the relative fecundity of females and hermaphrodites, and by stochastic processes in small populations. A comparative field study showed that plant fecundity decreased with increasing distance to nearest pollen donor both within and among populations in an archipelago in southern Sweden, where self-incompatibility was confirmed in controlled crosses. In contrast, plant fecundity was overall higher and was not density-dependent in the Skeppsvik archipelago in northern Sweden, where controlled crosses showed that plants are self-compatible. The results were consistent with the prediction that evolution of self-fertility should reduce density-dependence of pollination success. I quantified the genetic structure within and among populations from eastern Sweden and western Finland based on variation at four polymorphic microsatellite loci. The genetic diversity was low in northern Sweden, which may be the result of a history of small population sizes and periods of frequent self-fertilization.

No description available.

Chez les plantes à fleurs, la gynodioécie -- système dans lequel coexistent des individus femelles et des individus hermaphrodites -- est le système de reproduction le plus commun après l'hermaphrodisme. La question de l'évolution et surtout du maintien de la gynodioécie et du polymorphisme génétique sous-jacent a intrigué les chercheurs depuis le 19e siecle. Aujourd'hui, les grands principes de son évolution sont posés mais beaucoup de zones d'ombres persistent. Durant ma thèse, j'ai exploré trois aspects de la gynodioécie en utilisant une approche expérimentale chez l'espèce Silene nutans et une approche théorique. Je me suis en premier lieu intéressée au déterminisme génétique de la gynodioécie grâce à la réalisation de croisements contrôlés qui m'ont permis de montrer que le déterminisme génétique du sexe était cytonucléaire, c'est à dire contrôlé par plusieurs gènes de stérilité mâle cytoplasmique (CMS) et plusieurs restaurateurs nucléaires de fertilité. En parallèle, j'ai porté une attention particulière aux plantes gynomonoïques -- celles où coexistent sur le même pied des fleurs pistillés (femelles) et des fleurs parfaites (hermaphrodites) -- fréquentes chez Silene nutans comme chez d'autres espèces gynodioïques. J'ai montré que les caractéristiques reproductrices et florales de ce troisième phénotype sexuel étaient souvent intermédiaires entre celles des femelles et des hermaphrodites mais pouvaient dépendre de la proportion de fleurs pistillées sur la plante. Par ailleurs et contrairement à ce qui avait été suggéré, la plasticité du phénotype gynomonoïque s'est révélée être relativement réduite, suggérant un déterminisme génétique dont la caractérisation est encore en cours. La troisième partie de ma thèse a été motivée par les preuves récentes d'hétéroplasmie -- coexistence de différents génomes mitochondriaux au sein d'un individu -- et de la transmission occasionnelle du génome mitochondrial par le pollen chez Silene vulgaris. J'ai montré théoriquement que la présence d'un gène de stérilité mâle cytoplasmique favorisait l'évolution de la fuite paternelle de mitochondries. J'ai également vérifié expérimentalement l'hérédité mitochondriale chez Silene nutans par le génotypage des descendances de croisements contrôlés. / In flowering plants, gynodioecy -- a system in which females and hermaphrodites coexist within populations -- is the most common sexual system after hermaphroditism. The evolution and maintenance of gynodiocy and its underlying polymorphism have puzzled evolutionary biologists since the 19th century. The main principles of its evolution are well known but some points remain vague. During my PhD, I explored three aspects of gynodioecy using an experimental approach in the species Silene nutans and a theoretical approach. First, I studied the genetic determination of gynodioecy using controlled crosses that showed that the genetic determination of sex was cytonuclear, i.e. controlled by several cytoplasmic male sterility (CMS) genes and several nuclear restorers of fertility. Second, I focused on gynomonoecious plants -- those that carry both pistillate (female) flowers and perfect (hermaphrodite) flowers -- that are frequently found in Silene nutans as in other gynodioecious species. I showed that the floral and reproductive traits of this third sex phenotype were often intermediate between those of females and hermaphrodites but varied with varying proportions of pistillate flowers on the plant. Contrary to what was previously thought, the plasticity of the gynomoneocious phenotype was found to be limited, suggesting a genetic determination whose characterization is still in progress. The third part of my PhD was motivated by recent evidences of heteroplasmy -- the coexistence of different mitochondrial genomes within an individual -- and occasional transmission of the mitochondrial genome through pollen in Silene vulgaris. I showed theoretically that the occurrence of a cytoplasmic male sterility gene can favor the evolution of paternal leakage of mitochondria. I also investigated mitochondrial inheritance in Silene nutans by genotyping progenies from controlled crosses.