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Early blight (Alternaria solani Sorauer)is a major foliar disease of potatoes in most growing regions of the world and is underestimated in South Africa. This project studies the epidemiology and control of the disease in South Africa. A decision support system (DSS) for early blight in South Africa was developed and evaluated in field trials. This early blight DSS is the first such system to be developed in South Africa and once incorporated with the late blight model, will represent innovative technology for use in the South African potato industry. Trends in weather variables and concentrations of airborne conidia of A. solani were monitored. Distinct seasonal variation was noted. Peaks in spore concentration coincided with periods favourable for spore formation and dispersal; most notable was diurnal periodicity and interrupted wetting periods. The results obtained from these measurements will be useful in improving early blight DSSs for southern Africa. Isolates of A. solani from various potato-growing regions in South Africa were characterized using virulence, vegetative compatibility (VC) and random amplified microsatellite (RAMS) primers. Neither the virulence assays nor VC tests sufficiently characterised the population. Analysis of RAMS profiles revealed 27% genetic diversity among the isolates. This value is similar to diversity values obtained by previous authors studying A. solani, however, it is relatively high for an asexually reproducing fungus. There was no evidence for geographical clustering of isolates, indicating that isolates are widespread across South Africa. A survey on control practices and grower perceptions of early blight in South Africa was conducted using a questionnaire. These questionnaires were distributed to growers from 10 potato-growing regions in South Africa. Results highlighted the most popular control methods and cultivars in the South African potato industry. The majority of respondents indicated that they would use an accurate, cost-effective early blight DSS, and that more research is necessary on early blight in South Africa. A survey on control practices and grower perceptions of early blight in South Africa was conducted using a questionnaire. These questionnaires were distributed to growers from 10 potato-growing regions in South Africa. Results highlighted the most popular control methods and cultivars in the South African potato industry. The majority of respondents indicated that they would use an accurate, cost-effective early blight DSS, and that more research is necessary on early blight in South Africa. Estimated crop losses ranged from 1% - 60%, with an average of approximately 20%. This is the first comprehensive epidemiological study to be conducted on early blight in South Africa and has highlighted the need for further research. / Thesis (DPhil (Plant Pathology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Le commerce mondial et les mouvements humains accroissent les probabilités de transport à longue distance de propagules, et leur introduction dans de nouvelles aires géographiques. Dans certains cas, des espèces récemment établies peuvent devenir dominantes dans la communauté envahie. Malgré les menaces sur les communautés natives et le fonctionnement des écosystèmes, les invasions biologiques constituent des expériences naturelles qui permettent d’étudier les processus éco-évolutifs en temps réel, notamment l’impact de nouvelles interactions biotiques sur la composition et la dynamique des communautés, l’adaptation rapide à de nouvelles conditions environnementales, ou la dispersion en limite de répartition. Les îles océaniques sont particulièrement sensibles aux invasions biologiques en raison de la faible diversité de leurs communautés natives. Dans les terres australes françaises, le carabique marcheur Merizodus soledadinus, natif de Patagonie, a été accidentellement introduit à Kerguelen en 1913. La présente étude vise à comprendre les principaux mécanismes à l’origine du succès invasif de cet insecte aux Iles Kerguelen. Un large ensemble de méthodes ont été utilisée pour explorer les traits écologiques de M. soledadinus, des populations à la molécule. Les analyses génétiques confortent l’hypothèse historique d’un unique évènement d’introduction dans un seul site des Iles Kerguelen. Les populations échantillonnées le long du gradient d’invasion ne montrent pas de structuration génétique. Les traits phénotypiques mesurés montrent une forte différentiation entre les individus selon le temps de résidence des populations, confirmant l’hypothèse de tri spatial des populations au cours de l’expansion géographique. Nous avons démontré que l’expansion géographique et la sélection d’habitats par M. soledadinus est principalement gouvernée par la disponibilité en eau, comme le suggère par la forte sensibilité des adultes au stress hydrique. En parallèle, la colonisation d’habitats en altitude dépend des conditions thermiques, qui semblent être contraignantes pour cet insecte à partir de 200m d’altitude. La colonisation d’habitats d’altitude progresse pourtant, probablement assistée par le changement climatique. Pour finir, les adultes M. soledadinus sont longévifs et actifs toute l’année. Les connaissances apportées sur l’écologie de M. soledadinus et sur la dynamique de son expansion géographique suggèrent la poursuite de la colonisation de l’archipel par ce prédateur. L’ensemble de ces connaissances pourraient être utiles à la paramétrisation d’un modèle d’expansion géographique, qui permettrait de définir les routes de dispersion et les taux d’expansion, dans l’objectif d’assister les mesures de gestion par les agents de la Réserve naturelle des Terres Australes et Antarctiques Françaises. / Global trade and human movements increase the likelihood of long-distance transportation of propagules and their subsequent introduction into new geographic regions. In some instances, newly established species can become dominant in invaded communities, at the expense of native species. Besides threatening invaded communities and ecosystem functions, biological invasions constitute natural experiments that allow to study eco-evolutionary processes in real time, including the occurrence of new biotic interactions affecting community composition, rapid adaptation to novel environmental conditions, or dispersal evolution at range margins. Because of their impoverished native communities, oceanic islands’ ecosystems are particularly sensitive to biological invasions, and the French subantarctic islands are no exception. For instance, the flightless predatory carabid beetle Merizodus soledadinus is native from the southern tip of South America, and has been accidentally introduced to the Kerguelen Islands in 1913. In the present work, we aimed at understanding the main mechanisms underlying the invasive success of this insect at the Kerguelen Islands. Using a vast array of methodologies, ecological features of M. soledadinus were investigated with analytical procedures scaling from population to molecule through the individual level. Genetic investigations support the historically-based hypothesis of a single introduction event at a unique location of the Kerguelen Islands. No genetic structure was observed among individuals sampled from different populations along the invasion gradient. We tested the hypothesis of spatial sorting of populations during range expansion, by exploring phenotypic changes among individuals sampled along the invasion gradient. The measured phenotypic traits revealed major differentiation of adults according to the residence time of their populations, confirming the occurrence of spatial sorting of populations during geographic expansion. We also demonstrated that the geographic expansion of M. soledadinus, and microhabitat selection, are primarily governed by the availability of water resources, as suggested by the high sensitivity to water stress of adults of this ground beetle. In parallel, colonisation of altitudinal habitats is governed by thermal conditions, which seem to be physiologically constraining from 200m asl onwards. As the altitudinal distribution of M. soledadinus still extends, we concluded that ongoing climatic changes play a pivotal role in this expansion. Finally, adults of this ground beetle are long-lived and active year-round. The ecological knowledge of M. soledadinus characteristics and spatial expansion dynamics suggest that the colonisation process of the Kerguelen archipelago by this species will continue. Altogether, these data could be used for parametrising range expansion models that would delineate dispersal pathways and expansion rates, in the objective to assist stakeholders’ management decisions.

A high proportion of amphibian species are threatened with extinction globally, and habitat loss and degradation are the most frequently implicated causes. Rapid deforestation for the establishment of agricultural production is a primary driver of habitat loss in tropical zones where amphibian diversity is highest. Land-cover change affects native assemblages, in part, through the reduction of habitat area and the reduction of movement among remnant populations. Decreased gene flow contributes to loss of genetic diversity, which limits the ability of local populations to respond to further environmental changes. The focus of this dissertation is on the degree to which common land uses in Sarapiquí, Costa Rica impede the movement of two common amphibian species. First, I used field experiments, including displacement trials, and a behavioral landscape ecology framework to investigate the resistance of pastures to movement of Oophaga pumilio. Results from experiments demonstrate that pastures do impede movement of O. pumilio relative to forest. Microclimatic effects on movement performance as well as limited perceptual ranges likely contribute to reduced return rates through pastures. Next, I linked local processes to landscape scale estimates of resistance. I conducted experiments to measure habitat-specific costs to movement for O. pumilio and Craugastor bransfodrii, and then used experimental results to parameterize connectivity models. Model validation indicated highest support for resistance estimates generated from responses to land-use specific microclimates for both species and to predator encounters for O. pumilio. Finally, I used abundance and experiment-derived resistance estimates to analyze the effects of prevalent land uses on population genetic structure of the two focal species. While O. pumilio did not exhibit a strong response to landscape heterogeneity and was primarily structured by distances among sites, C. bransfordii genetic variation was explained by resistance estimates from abundance and experiment data. Collectivity, this work demonstrates that common land uses can offer different levels of resistance to amphibian movements in Sarapiquí and illustrates the value of investigating local scales processes to inform interpretation of landscape-scale patterns.

Plants depend on a wide variety of vectors, both biotic and abiotic, to move their seeds to locations away from parent plants. The stages between seed production and seedling establishment in the plant life cycle are under the influence of a complex set of ecological and evolutionary factors (Wang and Smith 2002). In ecological time scales, seed dispersal has been shown to influence both plant population and community dynamics (Howe and Miriti 2004, Seidler and Plotkin 2006). The evolutionary effects are seen in the way these interactions influence the fruiting season, fruit crop size, fruit size, nutritive value of fruit or seed and other strategies adopted by the plant to ensure effective dispersal of their seeds (Howe and Smallwood 1982, Schupp 1993). Most seed dispersal research has focussed on arboreal frugivores such as birds, primates and bats. In comparison, terrestrial frugivores such as ruminants, elephants and rodents are poorly researched. Large-bodied terrestrial frugivores are key to the dispersal of several large-seeded plants and are also capable of dispersing seeds to long distances (> 1 km). Given that large mammals have witnessed tremendous declines in their abundances and ranges in historical times, plants that depend upon them for long distance dispersal might have limited ability to move across fragmented landscapes under changing climates. However, very little is understood about seed dispersal by large mammals or about seed dispersal characteristics of tropical dry forests which support among the highest biomass of large terrestrial mammals. Tropical dry forests are among the most endangered tropical ecosystems (Janzen 1988). It has also been forecast that tropical dry forests in the Indian subcontinent will witness significant changes in temperature and rainfall regimes in the coming decades (Ravindranath et al. 2006). However, compared to tropical moist forests which have received most of the scientific interest, theory, methodology and base line information about seed dispersal in dry forests is poorly developed. To address some of these lacunae, I examined seed dispersal at both population and community-scales in the tropical dry forests of Mudumalai Wildlife Sanctuary from 2005 -2007. Mudumlai is located within a relatively large contiguous stretch of tropical dry forests in southern India and has an intact and abundant frugivore assemblage. In addition, the Mudumalai Forest Dynamics Plot (MFDP), a large 50 hectare plot has been monitored for recruitment, mortality and diameter growth of woody plants for the last twenty years. The plot is an invaluable resource for seed dispersal studies since it provides us an opportunity to link seed dispersal with plant population and community dynamics. In the first part of the thesis (Chapters 3 and 4), I focus on evaluating the effectiveness of ruminants as seed dispersers and then examine factors that influence frugivory by ruminants. This work was carried out at the population level, for the tree Phyllanthus emblica. The fruits of P. emblica are important non-timber forest produce from Asian dry tropics and understanding the quantity of fruit consumed by frugivores has implications for sustainable harvest practices of this resource (Shahabuddin and Prasad 2004). In the second part of the thesis (Chapters 5 and 6), I characterized seed dispersal at the community-scale for woody plants on the MFDP. Community-wide characterization of seed dispersal at sites harboring an intact faunal assemblage is critical to identify plants dependent on endangered dispersers. The second half of the thesis focuses on examining the associations between dispersal mode and fruit characteristics, and also between dispersal mode and spatial patterning of woody plants. Evaluating the effectiveness of ruminants as seed dispersers: Disperser effectiveness is defined as the contribution a disperser makes to the future reproduction of a plant. Evaluating disperser effectiveness involves addressing both quantitative aspects such as frequency of visits, quantity of fruit consumed, diversity of species dispersed, and, qualitative components such as the treatment given in mouth and gut and the suitability of seed deposition sites for germination (Schupp 1993, Dennis and Westcott 2006). Information on quantity and quality of seed dispersal services provided by ruminants is very limited. This is because techniques such as tree watches or fruit traps adapted from avian frugivore studies are ill suited to study terrestrial frugivores, and conventional camera traps provide little quantitative information on the quantity of fruit consumed by frugivores. The quantity of dispersal services provided by ruminants for P. emblica was assessed using a novel camera trap technique. Time-delay was programmed into the camera trap units (4 pictures taken 2 minutes apart) to tell apart frugivores from visitors (by comparing number of fruit remaining in the time-delay picture sequence). During a two year study using this technique, six terrestrial mammals were identified as frugivores of P. emblica. Additionally, seven mammals and one bird species visited fruiting trees but did not consume fallen fruit. Two ruminants, the Indian chevrotain Moschiola indica and chital Axis axis, were the most frequent frugivores of P. emblica and these ruminants accounted for over 95% of fruit removal, while murid rodents accounted for less than 1%. The quality of dispersal services provided by ruminants was examined using a combination of feeding trials (with captive animals) and germination experiments for large-seeded species dispersed by ruminants in tropical dry forests, including P. emblica. Ruminants regurgitated well-protected seeds larger than 5 mm, after retaining them in the rumen for 2–50 h. Though germination success was lowered after rumen retention, it was not too low (> 15%), and would still ensure dispersal if suitable micro-habitats could be found. Given the daily home-range of chital (14–20 ha in tropical dry forests (Mishra 1982)), and their seed retention times (2–50 h), movement of chital during the 1–2 d period when seeds remain in the rumen can potentially disperse seeds to distances over 1 km. Thus, our research shows that ruminants account for most of the fruit removal and are the principal primary dispersers of P. emblica. Factors influencing frugivory by ruminants: Fruit removal, the quantity of fruits consumed by frugivores, is highly variable within plant populations. Understanding factors influencing this selection operated by frugivores helps link frugivore behavior with plant demography. The outcome of such selection operated by frugivores has been examined mostly for interactions involving avian frugivores. The extension of this theory to terrestrial frugivores, which are presented with fruit on the ground, is not well understood. In addition, factors influencing fruit removal have been examined mostly with respect to changing spatial contexts such as crop size and fruiting neighborhoods. The influence of varying temporal contexts on frugivore choice, and their possible demographic and evolutionary consequences is poorly understood. We examined if temporal variation in fruit availability across a hierarchy of nested temporal levels (interannual, intraseasonal, 120 h, 24 h) altered fruit removal of P. emblica on the MFDP. The interactions between P. emblica and its primary disperser (ruminants) was mediated by another frugivore (a primate, langur), which made large quantities of fruit available on the ground to ruminants. The direction and strength of crop size and neighborhood effects on this interaction varied with changing temporal contexts. Fruit availability was higher in the first of the two study years, and at the start of the season in both years. Fruit persistence on trees, determined by primate foraging, was influenced by crop size and conspecific neighborhood densities only in the high fruit availability year. Fruit removal by ruminants was influenced by crop size in both years and neighborhood densities only in the high availability year. In both years, these effects were stronger at the start of the season. Intraseasonal reduction in fruit availability diminished inequalities in fruit removal by ruminants and the influence of crop size and fruiting neighborhoods. Temporal asymmetry in frugivore-mediated selection could reduce the potential for co-evolution between frugivores and plants by diluting selective pressures. Langurs determined the length of time fruit persisted on individual trees, and, also influenced the quantity and duration of fruit availability for the primary dispersers, ruminants. Such inter-dependencies formed between disparate animal consumers add additional levels of complexity to plant–frugivore mutualistic networks and can have potential reproductive consequences for specific individuals within populations. Seed dispersal within a tropical dry forest community: Megafauna are considered to be important seed dispersers, but their contribution has mostly been examined in isolation, with limited reference to other frugivores within communities. Community-wide characterization of seed dispersal at sites harboring an intact fauna is essential to evaluate the role of megafauna in dispersal, examine dispersal syndromes and assess the vulnerability of plant communities to disperser declines and climate change. Dispersal modes were inventoried for 92% of species and fruit traits for 84% of the woody plant community on the MFDP. Fruit–frugivore interactions were identified using a combination of camera traps, tree watches and opportunistic observations. Though 60% of the species were animal-dispersed, mechanically-dispersed species were more dominant and constituted nearly 70% of the stand. Bird-dispersed species were very rare and constituted less than 10% of the stand cumulatively. In comparison, bird-dispersed species account for ~ 50% of the stand in moist forests of tropical Asia. Three broad dispersal modes were identified – mechanical, mammal and bird-mammal, and these displayed strong associations with fruit traits. Among the 11 frequently-observed frugivore groups, the three largest frugivores, deer, bear and elephant, together dispersed 40% of the community. There was low overlap in fruit diets between these three megafaunal groups, though diets of deer and bear overlapped with different groups of small and medium-sized frugivores. Deer and bear displayed significant associations with fruit traits, while elephant did not. Among the fleshy fruits, large fruits and large-seeded fruits had fewer dispersers compared to smaller, multi-seeded fruits. Although the largest fleshy fruits and seeds were often dispersed by megafauna, few were exclusively dependent on megafauna. The three megafaunal groups were the only potential long distance dispersers for 25% of the community. For a better understanding of the impacts of megafaunal extinctions, even rare events of dispersal by megafauna should be considered since these could prove important for plants lacking other long distance dispersers. Given that these megafauna and several medium-sized frugivores are rare in degraded areas of tropical Asia (Corlett 2007, Karanth et al. 2010), one fourth of the plant community at Mudumalai could have limited ability to disperse across fragmented landscapes in response to changing climates. Seed dispersal and spatial patterns in tropical dry forests: To address the relevance of seed dispersal to plant community structure, the linkages between dispersal mode and spatial aggregation of trees were examined for the woody plant community on the MFDP. For plants, seed arrival patterns vary depending upon their dispersal mode and form the primary matrix upon which further forces shape spatial patterns. Spatial patterns were examined via the pair correlation function (statistic) and statistics derived from cluster models (Matern process). Considering only trees that had 10 individuals (48 species), it was found that tropical dry forest trees exhibited extensive spatial aggregation. The degree of spatial aggregation at Mudumalai was remarkably similar to wet forests in tropical Asia. Species with limited-dispersal (mechanically-dispersed species) were more aggregated than those with more frequent long-distance dispersal (animal-dispersed species) at smaller spatial scales (< 50 m). Animal-dispersed species had larger cluster radius, with bird-dispersed species having the largest radii. These results are in concordance with Siedler & Plotkin (2006) and Li et al. (2009) who find that mechanically-dispersed species are more aggregated than animal-dispersed species. These results demonstrate that seed dispersal has a strong influence on the spatial patterning of plant communities. Conclusion: At the population level, our results imply that P. emblica is mainly dependent on ruminants for seed dispersal. In tropical dry forest sites such as Mudumalai, up to 15% of the species are dispersed by ruminants, with langurs mediating the ruminant-plant interaction similar to P. emblica. The observed fruit removal patterns for P. emblica reiterate the fact that all fruiting individuals in a population are not equally attractive to frugivores, especially when fruits are abundant. Alterations of such complex fruit-frugivore interactions through human-mediated changes of fruit or frugivore densities (through fruit harvests or hunting of large mammalian frugivores such as ruminants), can feed back into the seed dispersal loop and affect several downstream ecological and evolutionary processes. At the community-scale, the dispersal profile of woody plants in Mudumalai’s tropical dry forests differed considerably from tropical moist sites, with a greater representation of mammal and mechanically-dispersed species. However, the linkages between seed dispersal and spatial patterns of trees at Mudumalai are similar to tropical moist forests. Extensions of the models developed from this site harbouring an intact faunal assemblage to other tropical dry forests would enable rapid characterization of dispersal profiles and identification of plant species dependent on endangered fauna for seed dispersal that should be prioritized for restoration programs.

Pour expliquer les faibles taux d'endémisme rencontrés chez les mousses en Macaronésie, deux hypothèses ont été successivement testées et invalidées au cours de mon doctorat chez deux genres de mousses d'occurrence macaronésienne, phylogénétiquement proches, Hedenasiastrum et Rhynchostegiella. Une première hypothèse suggérait que les mousses sont des organismes à faible potentiel évolutif peu enclins à former des espèces endémiques. Si une apparente stase morphologique de plus de 40 millions d'années a été reconstruite chez Hedenasiastrum, genre monotypique endémique de Madère, le grand nombre de convergences phénotypiques et les taux très élevés de diversification insulaire dans le genre Rhynchostegiella, infirment très fortement cette hypothèse. Ces études tendent ainsi à mettre en valeur la nature hyper adaptable des mousses et la diversité des processus évolutifs pouvant se mettre en place pour des espèces proches, dans une même région biogéographique. Une seconde hypothèse évoquait des flux de gènes intenses entre continents et îles, bloquant la spéciation insulaire ; hypothèse à son tour réfutée par le grand nombre d'évènements de spéciation in situ dans les îles, révélé par nos analyses de reconstruction d'aires ancestrales. Ce travail dévoile au final que la généralisation des colonisations inverses des îles vers le continent, pourrait être un des facteurs majeur expliquant les faibles taux d'endémisme macaronésiens chez les mousses. Plus que des puits de diversité, les îles seraient ainsi une source importante de biodiversité pour le continent chez les organismes capables de dispersion longue distance. / To explain the low rates of endemism encountered in Macaronesian mosses, two hypotheses have been successfully tested and invalidated during my PhD in two genera of mosses of the subfamily Helicodontioideae occurring in Macaronesia Islands, respectively Hedenasiastrum and Rhynchostegiella. The first hypothesis suggested that mosses are low evolutionary potential organisms, reluctant to form endemic species; if an apparent morphological stasis over 40 million years was reconstructed in Hedenasiastrum, a monotypic genus endemic of Madeira, the large number of phenotypic convergences and high rates of insular diversification in the genus Rhynchostegiella, strongly refute this hypothesis. Thereby these studies tend to emphasize the hyper-adaptability of mosses and the diversity of evolutionary processes that can occur in closely related species in the same biogeographic region. The second hypothesis evoked too intense gene flow between mainland and islands, preventing speciation on islands; a hypothesis invalidated by the high number of in situ event of speciation on islands revealed by our analysis of ancestral area reconstruction. Finally this work reveals generalized reverse colonization from islands to mainland after in situ speciation, as one of major factor responsible for low rates of endemism in the Macaronesian mosses. Islands may thus appear for organisms with high dispersal ability as inexhaustible sources of diversity.

Orientador: Wesley Rodrigues Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T19:16:14Z (GMT). No. of bitstreams: 1 Zaniratto_CristianePatricia_M.pdf: 6906690 bytes, checksum: 61183ae4c09cd06d8858d6ee6aa85be7 (MD5) Previous issue date: 2015 / Resumo: A degradação em florestas tropicais afeta as relações mutualísticas entre plantas e frugívoros, o que é refletido na chuva de sementes. Devido ao comportamento alimentar e à alta capacidade de deslocamento, aves e morcegos frugívoros são importantes agentes no processo de restauração, pois transportam propágulos de fontes bem preservadas para áreas impactadas. Este trabalho avaliou a chuva de sementes zoocóricas em um mosaico fisionômico de restauração de Mata Atlântica no estado de São Paulo, considerando a contribuição de aves e morcegos, bem como a influência de fatores ambientais sobre a chuva de sementes. As sementes foram analisadas quanto ao sistema de dispersão (ornitocóricas e quiropterocóricas), grupo sucessional (pioneiras e não pioneiras) e origem (espécies do plantio e colonizadoras). Também foi comparada a chuva de sementes entre áreas com diferentes fisionomias. A estação chuvosa apresentou maior abundância e riqueza de propágulos, indicando uma maior disponibilidade de recursos para a fauna durante esse período. As variáveis ambientais não explicaram a abundância total de sementes, a abundância de sementes quiropterocóricas e a abundância de sementes pioneiras. Esses resultados foram influenciados por algumas espécies amplamente coletadas em todos os pontos de amostragem, o que dificultou a formação de um padrão. A abundância de sementes ornitocóricas foi explicada por uma relação positiva com a densidade de plantas zoocóricas, sugerindo que essas espécies constitui um fator de atração importante para a avifauna. A abundância de sementes não pioneiras foi relacionada negativamente à abertura de dossel e positivamente à densidade de sub-bosque. A riqueza total e a riqueza de sementes ornitocóricas relacionaram-se negativamente à abertura de dossel. As riquezas de sementes quiropterocóricas, pioneiras e não pioneiras foram relacionadas negativamente à abertura de dossel e positivamente à densidade de sub-bosque. As fisionomias em estágio avançado de regeneração apresentaram maior riqueza na chuva de sementes, embora a abundância não tenha diferido entre as áreas. Tais resultados sugerem que a complexidade estrutural do ambiente um é um fator importante para a chuva de sementes, atraindo mais dispersores. Registrou-se maior abundância e riqueza de espécies ornitocóricas, o que mostra que a avifauna contribui mais para a recuperação da área. As espécies pioneiras também foram mais abundantes e mais ricas. A baixa dispersão de sementes não pioneiras é preocupante, pois indica que dispersores de médio e grande porte não frequentam a maior parte da área de estudo, atrasando o processo de regeneração natural. As espécies colonizadoras apresentaram maior riqueza, embora não tenha havido diferença entre a abundância de espécies colonizadoras e do plantio. Esse resultado mostra que, ao longo dos anos, houve um fluxo de sementes de áreas fontes para as áreas em processo de regeneração. A análise da chuva de sementes na área de estudo permite concluir que a regeneração está ocorrendo espontaneamente, pois o transporte de diásporos existe em todo o mosaico de restauração, entretanto, a maior riqueza e abundância de espécies pioneiras mostram a necessidade de ações de manejo para acelerar a colonização por frugívoros de médio e grande porte, incrementando a chuva de sementes local / Abstract: The degradation of tropical forests affects the mutualistic interaction between plants and frugivores, with reflexes in seed rain. Due to their feeding behavior and high capacity of displacement, birds and bats are important agents in restoration process, because they carry the seeds from well-preserved sources to degraded ones. This work evaluated the zoochorous seed rain in a restoration physiognomic mosaic of Atlantic Forest in São Paulo state, considering the birds and bats contribution, as well the influence of environmental factors on the seed rain. Seeds were analyzed according to their dispersal system (dispersed by birds or bats), successional group (pioneer and non-pioneer) and origin (planted and colonizing species). The seed rain between physiognomies is also compared. The abundance and richness of seeds were higher in the rainy season, which points to a high resource availability to fauna in this period. The environmental variables did not explain the overall abundance, the abundance of chiropterochorous seeds and the abundance of pioneer seeds. These results were influenced by some species largely collected in all sampling points, which made difficult a pattern. The abundance of ornitochorous seeds was explained by density of zoochorous plants, suggesting that these species are an important attraction factor for birds. The abundance of non-pioneer seeds was negatively related to canopy opening and positively related to understory density. The overall richness and the richness of ornitochorous seeds were negatively related to canopy opening. The richness of chiropterochorous, pioneer and non-pioneer seeds were negatively related to canopy opening and positively related to understory density. The physiognomies under advanced regeneration stages had higher seed richness, although the abundance did not differ between areas. These results show that the structural complexity of environment is an important factor to seed rain, by attracting more dispersers. There was a higher abundance and richness of ornitochorous seeds, which shows that birds contributed more to forest recovery. Pioneer species are also more abundant and richer. The low dispersion of non-pioneer seeds is worrying, once suggests that medium and big size dispersers don¿t occur in the most of the study area, delaying the natural restoration process. Colonizing species were richer, although the abundance between colonizing and planted seeds species did not differ. It shows that there was a seed flow from source areas to restored ones over the years. The seed rain analysis allows the conclusion that restoration is occurring spontaneously in the studied area, since transportation of seeds are occurring across all the restoration mosaic. However, the high richness and abundance of pioneer species points to the necessity of management actions in order to accelerate the colonization by medium and large size frugivorous, improving the local seed rain / Mestrado / Ecologia / Mestra em Ecologia

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22475号 / 農博第2379号 / 新制||農||1074(附属図書館) / 学位論文||R2||N5255(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 日本 典秀, 教授 田中 千尋, 准教授 刑部 正博 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Blackleg, caused by Leptosphaeria maculans, inflicts greatest canola yield losses when plants are infected before reaching the six-leaf growth stage. Studies were conducted to model pseudothecia maturation and ascospore dispersal to help growers make timely foliar fungicide applications. Pseudothecia maturation occurred mostly during the second half of June or in July in 2017 and 2018 in North Dakota and ascospores concentrations peaked during mid to late June in both years. A logistic regression model developed using temperature and relative humidity predicted the maturation of pseudothecia and ascospore dispersal with approximately 74% and 70% accuracy respectively. In addition, trials to evaluate the efficacy of five seed treatment fungicides were conducted under greenhouse and field conditions. All treatments reduced (P = 0.05) disease severity on seedlings in greenhouse trials, but not in field trials. Seed treatments, while a valuable tool, should not be used as the only means to manage blackleg.

Les invasions biologiques étant des processus raisonnablement limités dans le temps et l’espace, elles fournissent un cadre propice à l’étude de modèles complexes par simulation numérique. Nous mettons à profit la méthode de Calcul Bayésien Approché (ABC) pour étudier l’invasion du frelon asiatique (Vespa velutina), en estimant les paramètres d’un modèle probabiliste démographique et génétique spatialement explicite. La croissance des populations dans chaque unité paysagère est décrite par une fonction des conditions environnementales locales, tandis que les flux migratoires entre populations sont tirés dans des lois dont les densités sont fonctions de la distance géographique à parcourir. Certains paramètres de ces fonctions sont inconnus et doivent être estimés. Conditionnellement à la démographie, un processus de coalescence permet de simuler l’histoire génétique de l’échantillon. Une fois la simulation achevée, la procédure ABC permet de accepter/rejeter les valeurs de paramètres en fonction de la plausibilité des données génétiques qu’ils permettent de générer. La comparaison de modèles étant une étape clé de la méthodologie ABC, cela impose que différentes versions de simulateurs de coalescence puissent être rapidement développées. A cette fin, cette thèse propose Quetzal, une bibliothèque assez générale pour pouvoir aisément s’adapter à un grand nombre de modèles possibles, et qui inclue des algorithmes originaux et génériques. Les principaux concepts de programmation permettant d’utiliser et d’étendre Quetzal sont également exposés à travers les différents chapitres. Enfin, nous mettons à profit les particularités du contexte d’étude du frelon asiatique pour développer une méthodologie spécifique reposant sur le formalisme des partitions floues et qui permet, en recentrant l’analyse sur les processus démographiques très récents, de réduire le nombre d’hypothèses, le nombre de paramètres et le coût simulatoire de l’analyse. / Because biological invasions are processes well delimited in both space and time, they offer a unique framework in which complex models can be studied by numerical simulations. We use the Approximated Bayesian Computation method (ABC)to study the Vespa velutina invasion, estimating the parameters of spatially explicit demographic and genetic probabilistic model. The population growth in each landscape unit is described by a function of the local environmental features, whereas the migration flux between populations are sampled in laws which densities are functions of the geographical distance. Some of the parameters of these functions are unknown and should be estimated. Conditionally to the demography, a coalescence process allows for simulating the genetic history of the sample. Once the simulation done, the ABC method allows for accepting/rejecting the parameters values as a function of the data plausibility they generate. Models comparison is a key step in ABC methodology: this requires that various versions of coalescence-based simulators can be quickly developed. To this end, this thesis offers Quetzal, a library general enough to be easily adapted to an open-ended number of models variants. It includes original and generic algorithms. The main programming concepts required to use and extend Quetzal are presented through the various chapters. Finally, we take advantage of the biological context to develop a specific methodology built on the fuzzy partitions formalism. It allows to focus only on the very recent demographic processes, and consequently to reduce the number of hypothesis,the number of parameters, and the simulation cost of the analysis.