I combined comparative and experimental studies in the field and in the greenhouse to examine factors influencing reproductive success in two insect-pollinated herbs, the tristylous, selfincompatible perennial Lythrum salicaria and the self-compatible, biennial Pedicularis palustris. More specifically, I explored (i) the effects of plant population characteristics on the intensity and outcome of interactions with pollinators and seed predators, (ii) whether flower morphology affects duration of stigma receptivity, and (iii) whether damage-induced reduction in floral display reduces pollinator visitation and increases pollen limitation. As predicted, the rate of pollinator visitation tended to increase and the number of flowers probed per plant tended to decrease with increasing population size in L. salicaria, but these relationships only approached statistical significance. By taking advantage of the pollen size polymorphism that is typical of many heterostylous plants, I could show that the number of compatible pollen grains received increased with population size, and that this was associated with a reduction in pollen limitation and increased seed output per flower. The deposition of high numbers of incompatible conspecific and heterospecific pollen grains did not appear to reduce seed set. In P. palustris, fruit set and seed predation varied markedly among populations and years, but this variation could only partly be explained by variation in population size. Fruit set was positively related to population size, and seed predation was negatively related to population size, in one of three years. Similarly, the level of pollen limitation, which was quantified in two years, varied among populations, but was not related to population size, density or isolation. In L. salicaria, both the duration of stigma receptivity and the effect of prior self-pollination on seed output varied among style morphs. These differences may contribute to morph-specific differences in pollen limitation and seed production documented in the field. The results of a field experiment demonstrated that damage to the shoot apex may markedly reduce fruit production in L. salicaria, and suggested that this is mainly because damage reduces flower number. I found no evidence that a reduced floral display increased the severity of pollen limitation. Taken together, the results show that interactions with both pollinators and herbivores may markedly affect reproductive output in the two plant species, and that the intensity of both mutualistic and antagonistic interactions vary considerably in space and time. Moreover, they are consistent with the hypothesis that pollination success should depend less on population size in selfcompatible than in self-incompatible plants.

Plant-animal interactions are affected by both abundance and distribution of interacting species and the community context in which they occur. However, the relative importance of these factors is poorly known. I examined the effects of predator host range, environmental factors, host plant populations, plant traits and fruit abortion on the intensity of pre-dispersal seed predation in 46 host populations of the perennial herb Lathyrus vernus. I recorded damage by beetle pre-dispersal seed predators, mainly Apion opeticum and Bruchus atomarius with different host ranges on L. vernus as well as on two additional host plants. Local seed predator population size was mainly influenced by plant population size, current seed production and beetle population size in the previous year, but was not strongly affected by connectivity. The monophagous seed predator was less abundant and had lower densities than the oligophagous. Both predator species had a strong ability to track fluctuations in seed production; intensity of predation increased with relative increases in seed production. Oligophagous predation on L. vernus increased with the abundance of alternative hosts, but presence of L. vernus did not affect predation on alternative hosts. Abundances and trait preferences differed among three co-occurring seed predators, but were also associated with the abundance of the other species. Overall, seed predation influenced selection on flower number. I found clear indications of seed predator offence but no obvious plant defence. The pattern of fruit abortion was associated with reduced plant fitness since the seed predator had an advanced ability to locate fruits with high probability of retention. Taken together, different factors influencing abundance of the seed predator species, different preferences, and context dependent trait selection are likely to result in complex spatio-temporal variation in overall seed losses and trait selection in the common host plant.

La variabilitat de la depredació de llavors en l'espai i temps poden oferir oportunitats a les males herbes per escapar dels depredadors. Els nivells de depredació en cereals de secà van ser dels més alts mai registrats cultius extensius (46-100%). El moment de producció de les llavors de males herbes es superposava amb el període de major demanda. La distribució espacial dels nius era no aleatòria. Els nius grans estaven més regularment distribuïts, els nius petits més agrupats. Les formigues van respondre amb taxes de depredació extremadament elevades (99-100%) a totes les densitats de llavors aplicades L. (1000-20.000 llavors m-2), amb una resposta denso-independent. La mida de rodal va influir en les taxes de depredació per formigues. Va ser major en els rodals més grans (99-100%) i menor en els més petits (78-94%). Aquesta investigació va quantificar la variabilitat espaciotemporal en la depredació de llavors de cereals de secà i l'eficàcia.Summary / La variabilidad de la depredación de semillas en el tiempo y espacio ofrecen oportunidades a las malas hierbas para escapar de los depredadores. Los niveles de depredación en cereales de secano fueron entre los más altos registrados jamás en cultivos extensivos (46-100%). El momento de producción de semillas de las malas hierbas se superponía con el período de mayor demanda. La distribución espacial de los nidos era no aleatoria. Los nidos grandes estaban más regularmente distribuidos, los nidos pequeños más agrupados. Las hormigas respondieron con tasas de depredación extremadamente elevadas (99-100%) a todas las densidades de semillas aplicadas (1.000 a 20.000 semillas m-2), con respuesta denso-independiente. El tamaño de parche influyó en las tasas de depredación por hormigas. Fue mayor en los parches más grandes (99-100%) y menor en los más pequeños (78-94%). Esta investigación cuantificó la variabilidad espacio-temporal de la depredación de semillas en cereales de secano y la eficacia. / The variability of seed predation in time and space may provide opportunities to weeds to escape predation. Seed predation rates by harvester ants in dryland cereals were among the highest ever recorded on arable fields (46-100%). The timing of weed seed shed overlapped with the period of highest demand. The spatial nest arrangement appeared to be non-random. The large nests were more or less regularly distributed, small nests tended to be more clumped. Harvester ants responded with extremely high predation rates (99-100 %) to all densities of Lolium multiflorum L. seeds applied (1000-20000 seeds m-2), and the response was density independent. Patch size influenced predation rates by harvester ants. Estimated seed predation rate was highest in the largest patches (99-100%), and lowest in the smallest patches (78-94 %). The current research quantified temporal and spatial variability in seed predation in dryland cereals and the influence to the efficacy of granivory.

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Made available in DSpace on 2016-12-12T20:12:29Z (GMT). No. of bitstreams: 1 PGEF14MA016.pdf: 1107924 bytes, checksum: 90cddbcb105ffceb576c6bd738adb3c1 (MD5) Previous issue date: 2014-05-30 / The Araucaria angustifolia (Bertol.) Kuntze is certainly one of the species of largest economic and ecological importance in the Araucaria Forest. Due to the availability of their seeds for wild animals, is considered a key plant, in that relationship with animals is the warranty of his propagation. Similarly, animals using propagules as food source, work as filter, being able expand or limit the population growth of certain species based on resource availability and the anthropogenic interferences in the environment. Trying to understand the processes involved in plant-animal relationship determinants for the dispersion of this species, this study aims to assess the rates of removal and seed predation of A. angustifolia in a Araucaria Forest fragment. For this, the spatial distribution standard of the study population was evaluated, as well as removal and predation on seed in the phase secondary dispersal, the covered distances and the fate of seeds removed, and the fauna composition responsible for the use of these seeds. These evaluations were performed in the years 2012 and 2013, in four separate offering periods ranging between scarcity and abundance of the resource. The data collected showed that the study population has a high density and aggregate spatial distribution pattern, which can be regarded as a limiting factor to seed dispersal and consequently, for the recruitment of the specie. Removal rates and predation were high and can be assigned to low seed yield in years when the study was conducted. It was found, however, a lower rate of consumption of the seeds at the time of increased availability of this feature, ie the month of April. This phenomenon may be linked to an adaptive strategy of the species called Hypothesis of the Predator Satiated, where high seed production events would tend to satiate the predators, consuming fewer seeds and increasing the likelihood of their survival. The distance of availability of seeds showed no relationship with the amount of consumed seeds, which may indicate that the use of the applied method has been insufficient for this evaluation, since the Janzen-Connell model indicates that the closer the parent plant, the greater the possibility of predation, and therefore smaller the dispersion. The removal short distances and inadequate disposal sites of seeds effectively dispersed demonstrated that animals may be being inefficient in this intermediation, accommodating and reducing their mobility because of the aggregate spatial distribution pattern. The composition of the fauna was same as other similar studies recorded. It is understood that the deepening in the assessment of impacts of various human pressures exerted on Araucaria Forest, mainly by grazing of the cattle, the use of fire, the habitat fragmentation and reduction of animals by predatory hunting, is essential for the full understanding of the processes that limit and hinder the efficient seed dispersal in this formation, and which may be significantly compromising the success of the species with respect to their propagation / A Araucaria angustifolia (Bertol.) Kuntze é com certeza uma das espécies de maior importância econômica e ecológica na Floresta Ombrófila Mista. Em virtude da disponibilização de suas sementes para a fauna silvestre, é considerada uma planta-chave, tendo nessa relação com os animais a garantia de sua propagação. Da mesma forma, a fauna que utiliza esses propágulos como fonte alimentar, funciona como filtro, podendo expandir ou limitar o crescimento populacional de determinada espécie com base na disponibilidade do recurso e nas interferências antrópicas sobre o ambiente. Buscando compreender quais os processos envolvidos na relação planta-animal determinantes para a dispersão dessa espécie, este trabalho tem como objetivo avaliar as taxas de remoção e predação de sementes de A. angustifolia em um fragmento de Floresta Ombrófila Mista. Para isso, o padrão de distribuição espacial da população estudada foi avaliado, assim como a remoção e predação das sementes na fase de dispersão secundária, as distâncias percorridas e o destino das sementes removidas e a composição da fauna responsável pela utilização desses diásporos. Tais avaliações foram realizadas nos anos de 2012 e 2013, em quatro períodos distintos de oferta que variaram entre a escassez e a abundância do recurso. Os dados coletados demonstraram que a população estudada possui alta densidade e um padrão de distribuição espacial agregado, o que pode ser considerado como um fator limitante para a dispersão de sementes e consequentemente, para o recrutamento da espécie. As taxas de remoção e predação foram altas e podem ser atribuídas a baixa produtividade de sementes nos anos em que o estudo foi realizado. Constatou-se, entretanto, uma menor taxa de consumo das sementes na época de maior disponibilidade desse recurso, ou seja, o mês de abril. Esse fenômeno pode estar ligado a uma estratégia adaptativa da espécie chamada Hipótese do Predado Saciado, onde eventos de alta produção de sementes tenderiam a saciar os predadores, que assim, consumiriam menos sementes e aumentariam a probabilidade de sobrevivência das mesmas. A distância de disponibilização das sementes não demonstrou relação com a quantidade de sementes consumidas, o que pode indicar que a utilização da metodologia aplicada tenha sido insuficiente para essa avaliação, uma vez que o modelo de Janzen-Connell indica que quanto mais próximo da planta-mãe, maior a possibilidade de predação, e consequentemente, menor sua dispersão. As curtas distâncias de remoção e os locais inadequados de deposição das sementes efetivamente dispersas demonstraram que a fauna pode estar sendo ineficiente nessa intermediação, acomodando-se e reduzindo sua mobilidade em função do padrão de agregado da população. A composição da fauna registrada foi a mesma de outros relatos similares. Entende-se que o aprofundamento na avaliação dos impactos causados pelas diversas pressões humanas exercidas sobre a Floresta Ombrófila Mista, principalmente o pastoreio do gado, o uso do fogo, a fragmentação do habitat e a defaunação pela caça predatória, é imprescindível para o pleno entendimento dos processos que limitam e prejudicam a eficiente dispersão de sementes nessa formação, e que podem estar comprometendo significativamente o êxito da espécie no que tange a sua propagação

Plants can interact with many different organisms on many trophic levels in their life. In this thesis I investigated how three biotic inertactions, powdery mildew infection, caused by Podosphaera ferruginea, predispersal seed predation by Dusky Large Blue (Phengaris nausithous) and Scarce Large Blue (P. teleius) and deer grazing affect life cycle and population biology of the Great Burnet (Sanguisorba officinalis L.). I also analysed their preferences of environmental conditions. Most of studied plant populations growth rates (λ) were lower than 1 and population decreased, but quite surprisingly for more populations vegetative reproduction was more important than reproduction by seeds. All intraction mentioned above affects more generative reproduction, and thus their influence on Great Burnet population dynamics is low, even with modelled maximal possible effect. Environment conditions analysis showed that powdery mildew occurs on sites with more flowering individuals, where spreading is very easy, butterflies preferred high, well noticeable flower heads grown high above other vegetation and host ant presence. For host ants' presence model locality was only significant variable.

In the Central Coast of California, USA, wine grape growers are making efforts to identify weed control practices that promote biodiversity in their vineyards while maintaining yields. A field study was conducted in Paso Robles, CA in 2006 and 2007 evaluating the effect on Zinfandel grape-vine growth and production, groundcover plant, and ground dwelling arthropod communities of five weed control practices: 1) flumioxazin, 2) simazine, 3) cultivation, 4) cover crop, and 5) untreated control. The herbicide treatments had the lowest weed biomass followed by the cultivation, being approximately 10 and 2 times lower than the weed biomass of either the cover crop or untreated control treatments respectively. However, the differences in grape yield were not as evident. In 2006, a rainy year, the herbicides and cultivation treatments did not differ in grape yield, but the cover crop and untreated control had a reduction of approximately 20% compared with the other treatments. In 2007, a dry year, in comparison to the herbicide treatments, the grape yield reductions of cultivation were around 22%, and of the cover crop and untreated control around 48%. Although the cover crop reduced grape yield, it suppressed weed species considered important such as horseweed, panicle willowherb, scarlet pimpernel, and sowthistle. The cover crop, cultivation and untreated control had 4 to 50 times higher plant density and more than 15 times higher plant diversity compared to the herbicide treatments. The arthropod abundance differed among treatments only in 2007 being higher in the cover crop and untreated control. Also, there was a positive relationship between plant and arthropod diversity (r2 = 0.42, P = 0.02 in 2006; r2 = 0.64, P < 0.001 in 2007). Laboratory seed predation tests of the two most frequently captured carabid beetles, Calathus ruficollis and Tanystoma maculicolle, indicated their preferences for Brassica nigra and Capsella bursa-pastoris, which are considered common weed species in the region. Under field conditions, treatments with higher plant diversity and biomass favoured arthropod seed predation of these weeds, which was 20-40% in the cover crop and untreated control, doubling the predation observed in the herbicide treatments. The cultivation treatment balanced the benefits of promoting diversity while minimizing yield reductions due to weed competition. Our data indicated that the critical period of weed competition for Zinfandel grape vines occurred during budbreak-bloom period. Also, it was concluded that vines can tolerate a certain amount of weed competition, and that properly timing one pass post-emergence control tactics (e.g. cultivation or POST herbicides) could provide the necessary level of control to obtain the desired yields. However, under limited soil moisture conditions, the use of PRE herbicides could prove important to maintain vine yield and vigor. The results also illustrate how weed management practices that promote higher plant diversity and density have the potential to yield ecological services within vineyards by favoring the diversity and activity of other organisms.

Differences in taste perception between species are thought to reflect evolutionaryadaptations to dietary specializations such as seed predation. By employing a two-bottlepreference test, the purpose of the current study was to evaluate the taste responsiveness forfive food-associated carbohydrates and two steviol glycosides in four adult white-faced sakis(Pithecia pithecia). The taste preference thresholds were found to be 10 mM for sucrose, 10-40 mM for fructose, 20-30 mM for glucose and maltose, and 30-40 mM for lactose. The sakisalso showed a clear preference for rebaudioside A and stevioside over tap water atconcentrations as low as 0.04 and 0.2-0.5 mM, respectively. When given the choice betweenall binary combinations of the five carbohydrates at equimolar concentrations of 100, 200,and 300 mM, respectively, the sakis displayed the following preference pattern: sucrose &gt;fructose &gt; glucose ≥ maltose = lactose. The obtained taste preference thresholds for foodassociated carbohydrates fall into the lower range of values among primates, suggesting acomparatively high sweet-taste sensitivity in the sakis. The pattern of relative preferenceswas consistent with that reported in most tested primates. Altogether, the responsivenesstowards the sweet-tasting substances obtained in this seed predator resembles the resultsobtained in primates which act as seed dispersers. However, these results might reflect anevolutionary adaptation of white-faced sakis to exploit resources containing low sugarconcentrations such as unripe fruits and seeds.

La fixation symbiotique d'azote par l'ajonc d'Europe (Ulex europaeus) représente une source importante d'azote dans la forêt cultivée de pins maritimes des 'Landes de Gascogne'. Cette thèse a pour objectif la création d'un modèle conceptuel de dynamique de population de l'ajonc dans la région en vue de la prédiction du flux d'azote associé. Pour cela plusieurs étapes du cycle de vie de l'espèce ont été étudiées: la production et la prédation des graines, puis le recrutement de nouveaux individus depuis le stock de graines du sol. Nos résultats suggèrent que le maintien de cette espèce héliophile à l'ombre de la canopée des pins est facilité par la diminution de l'allocation de ressources à la reproduction, lui permettant de maintenir sa croissance, et par la diminution de la prédation des graines. Par ailleurs, le recrutement de nouveaux ajoncs semble influencé par des facteurs écologiques identifiables (e.g. humidité du sol). Mais ces facteurs sont fortement variables dans l'espace et dans le temps, et aucun micro habitat n'apparait comme plus favorable à la régénération de l'espèce. Ces résultats sont intégrés à un modèle conceptuel, représentant les différentes étapes du cycle de vie de l'espèce, et l'impact des opérations sylvicoles sur ces étapes. Les connaissances issues de cette thèse pourraient aussi bénéficier à d'autres problématiques liées à l'espèce (e.g. c'est une espèce invasive dans de nombreuses régions du monde) et à la compréhension de l'écologie de la régénération des espèces ligneuses. En effet, l'allocation des ressources à la reproduction pourrait être plastique et permettre une réponse adaptative à un environnement changeant; et la variabilité spatiotemporelle de la régénération des ligneux pourrait reposer sur l'existence de niches écologiques de régénération définies dans l'espace écologique. / Symbiotic nitrogen fixation by European gorse (Ulex europaeus) is a major source of nitrogen in the 'Landes de Gascogne' cultivated forest of maritime pine. This thesis aims to build a conceptual model of the population dynamic of gorse in the region, with a view to predict the associated flux of nitrogen. To achieve this, several steps of the life cycle of the species were studied: production and predation of seeds, and the recruitment of new plants from the seedbank.The results suggest that the maintenance of this light demanding species in the shade of the canopy of pines is improved by the decrease of reproductive allocation, which enable to maintain its growth, and by the decrease of the predation of seeds. The recruitment of new gorse plants seems controlled by identifiable ecological factors (e.g. soil moisture), however these factors are highly variable in space and time, and no specific micro-habitat appears to be more favourable for the species regeneration.These results are integrated into a conceptual model based on the different steps of the life cycle of the species, and taking into consideration the influence of forestry practices on these steps. Furthermore, the production of knowledge could benefit other subjects related to the species (e.g gorse is a noxious weed in many region in the world) and the understanding of the ecology of woody plants' regeneration. Allocation of resources to reproduction may be plastic and enable an adaptative response to a changing environment; and spatiotemporal variability of the regeneration of woody plants may rely on the existence of ecological regeneration niches defined in the ecological space.

Os ecossistemas de ilhas, continentais ou oceânicas, são considerados os mais sensíveis à perturbação humana. A maioria das ilhas costeiras do Brasil sofreu fortes alterações na fauna e flora silvestre. A Ilha Anchieta (Ubatuba, SP) é uma Área Protegida com um longo histórico de perturbação, tendo sido amplamente desmatada no passado e sofrido a introdução de animais. Sabe-se que a fauna possui um papel chave na composição e estrutura da comunidade vegetal, favorecendo algumas espécies e prejudicando outras. Sendo assim, a perda ou alteração dos processos de interações entre animais e plantas afetam na estrutura e composição de espécies. Este estudo analisa as interações antagônicas entre planta e animais como possíveis fatores limitantes no processo de regeneração natural em três ambientes com distintos estágios sucessionais presentes na Ilha Anchieta: campo aberto (CA) e florestas ombrófilas rala (FOR) e densa (FOD). Para isso foram testados nos três ambientes os processos pós-dispersão de sementes: a predação de sementes pós-dispersas, a germinação do banco de sementes e a herbivoria. A predação de sementes apresentou forte efeito espacial (FOD>FOR>CA) e sazonal, com maiores proporções de predação de sementes no período de escassez de alimento (estação seca). Quantitativamente o banco de sementes não representa um fator limitante, porém foi composto por uma baixa diversidade de espécies lenhosas. A capacidade de germinação do banco de sementes do solo foi similar entre os ambientes florestais apresentando menor emersão de plântulas no campo aberto, provavelmente associado ao intenso escoamento superficial no local. Adicionalmente, a mortalidade de juvenis transplantados foi de 72,27%, sendo superior nas parcelas abertas aos vertebrados para todas as espécies em todos os ambientes, demonstrando um forte efeito negativo dos herbívoros vertebrados na comunidade vegetal. Sendo assim, foram detectados distintos gargalos atuando simultaneamente na regeneração natural nos três ambientes da Ilha Anchieta, sendo necessário o estabelecimento de práticas de manejo visando minimizar os efeitos abióticos no campo aberto e floresta ombrófila rala, favorecendo as interações mutualísticas e inibindo a atividade de animais antagônicos nas florestas ombrófilas rala e densa, acelerando assim o processo de regeneração natural na Ilha Anchieta. Considerar simultaneamente os obstáculos no processo de regeneração nos auxiliará a traçar práticas de restauração e recuperação de áreas degradadas mais efetivas e viáveis economicamente. / Island ecosystems, either continental or oceanic, are considered the most sensible to anthropogenic influences. Most Brazilian coastal islands have their original fauna and flora composition altered. The Anchieta Island (southeast Brazil) is a Protected Area that suffered deforestation and introduction of alien species. It is known that the fauna plays a key role in composing and structuring the vegetal community, favoring some species and harming others. Thus, the loss or change of animal-plant interactions affects the framework and composition of species. We simultaneously analyzed the antagonistic animal-plant interactions as possible limiting factors in the natural regeneration on tree successional stages of the Anchieta Island: the old fields (OF), the early secondary forest (ESF) and old growth forest (OGF). Therefore, in each habitat we are evaluating post-dispersal seed predation processes: post-dispersal seed predation, soil seed bank, and the herbivory. We found spatial (OGF>ESF>OF) and temporal effects on seed predation, with highest rates on dry season. Quantitatively, soil seed bank did not represent a limiting factor; but qualitatively, it was composed by few woody species. Our data pointed to the absence of a viable soil seed bank in the OF, probably due to an intense runoff. The forested habitats presented similar soil bank. Moreover, the total mortality of saplings was 72.27%, being higher on the unfenced treatment for all species and in all habitats, showing a very strong negative effect of vertebrate herbivores on the vegetal community. Therefore, we are detecting distinct bottlenecks acting simultaneously in the natural regeneration process in all of the successional stages of the Anchieta Island. Our results showed that management actions are required, aiming to both minimize the abiotic effects on the old fields and in the early secondary forest and to favor the mutual interactions and inhibit the activity of antagonic animals in the old growth and early secondary forests, accelerating, this way, the natural regeneration process of the Anchieta Island. Considering simultaneously the obstacles in the regeneration process will help to define restoration and recuperation procedures of degraded areas more effective and affordable.