Diverse fish species consume fruits and seeds in the Neotropics, in particular in the lowland reaches of large rivers, such as the Amazon, Orinoco, and Parana in South America. Floodplains of the Amazon River and its lowland tributaries are characterized by marked hydrological seasonality and diverse assemblages of frugivorous fishes, including closely related and morphologically similar species of several characiform families. Here, I investigated whether or not these fishes are capable of detecting fluctuations in food availability and if they are, how they adjust their feeding strategies. I tested predictions of optimal foraging, limiting similarity and resource partitioning theories with regard to expansion or compression of niche breadth and reduction in trophic niche overlap among species in relation with fluctuations in the availability of alternative food resources. I monitored fruiting phenology patterns to assess food availability and conducted intensive fishing during the high-, falling-, and low-water seasons in an oligotrophic river and an adjacent oxbow lake in the Colombian Amazon. I combined analysis of stomach contents and stable isotope ratios to evaluate dietary patterns, niche breadth, and niche overlap. Diets of six characiform fish species (Brycon falcatus, B. melanopterus, Myloplus asterias, M. rubripinnis, and M. torquatus) changed in a manner that indicated responses to fluctuations in food availability. Feeding strategies during the peak of the flood pulse were consistent with predictions of optimal foraging theory. During times of high fruit abundance, fish preferentially consumed items to which their phenotype is best adapted, maximizing net energy gain and enhancing fitness. As the flood pulse subsided and the availability of forest food resources was reduced in aquatic habitats, there was not a consistent pattern of diet breadth expansion or compression, even though diet shifts occurred, suggesting interspecific differences in foraging efficiencies. Analyses of diets and isotopic ratios revealed a general pattern of increased dietary segregation as the water level receded. Although there never was complete niche segregation among these fishes, these dietary changes effectively reduced interspecific niche overlap. Implications of these results and contribution of allochthonous food resources to diversity maintenance of floodplain fishes are discussed.

Anthropogenic habitat disturbance is the leading cause of global biodiversity decline. Urbanization in particular is one of the most drastic forms of habitat disturbance, and it is associated with a decrease in both plant and animal diversity. Changes in biodiversity can affect the interactions between the remaining species within an ecosystem, which can, in turn, affect the provision of essential ecosystem services such as seed dispersal and pollination. Despite the wealth of studies examining the effects of urbanization on biodiversity, however, relatively few studies have investigated how urbanization impacts the interactions between species and the ecosystem services provided by them. Seed dispersal is one such ecosystem service which provides an ideal study system for investigating these effects. The goal of this study was to assess the impact of urbanization on avian seed dispersal networks in southern Appalachia. Specifically, we investigated the impact on species richness, interaction richness, and several network metrics related to ecosystem function (H2, interaction evenness, and weighted nestedness). The study was conducted across two fall – winter observation periods to coincide with the period of peak fruit production, from September – January in 2021-2022 and 2022-2023. Data was collected from 9 study sites during multiple visits via direct observation of bird-fruit interactions, with a total of 635 interactions recorded from 32 bird species on 18 fruiting plant species. Although data analysis is currently ongoing, initial results seem to indicate that there is no significant difference in species richness or interaction richness between natural and urban sites. This has interesting implications, as it suggests that plant-frugivore networks are relatively robust to disturbance caused by urbanization, which is promising for the continued provision of ecosystem services in urban areas.

Os frugívoros desempenham papel fundamental na regeneração e controle de plantas em florestas tropicais, por meio da dispersão e predação de sementes. Na floresta Atlântica, as populações dos grandes frugívoros encontram-se altamente ameaçadas pela defaunação e fragmentação do habitat o que pode comprometer as interações e consequentemente os serviços ecológicos prestados pela fauna. Meu objetivo neste estudo, foi identificar os principais mamíferos que atuam na frugivoria na Floresta Atlântica, analisar as redes de frugivoria entre mamíferos, aves e plantas em um gradiente de defaunação e também avaliar as relações entre predadores e frugívoros diante do contexto da defaunação na Floresta Atlântica. Para isso, instalei armadilhas fotográficas sob árvores que estavam frutificando em seis áreas da Floresta Atlântica no sudeste de São Paulo e averiguamos a atuação dos visitantes e frugívoros. Para atender aos objetivos, utilizei análises de regressão linear, modelos de rede de interações e modelos lineares generalizados. Encontrei que as principais plantas que tiveram seus frutos removidos pertencem a família das Myrtaceae, Arecaceae e Rubiaceae e os principais frugívoros que removeram frutos foram majoritariamente predadores de sementes, como o esquilo (Guerlinguetus brasiliensis), pequenos roedores em geral, as queixadas (Tayassu pecari) e a paca (Cuniculus paca). Identifiquei que apenas um baixo percentual do número de visitas (5,6%), culminaram em frugivoria e que mesmo em áreas com baixo grau de defaunação, a frugivoria foi realizada principalmente por pequenos roedores e aves generalistas. Por fim, encontrei que pequenos frugívoros evitam temporalmente áreas com alta frequência dos grandes frugívoros e que os grandes frugívoros evitam os potenciais predadores. Porém, em áreas com alto grau de defaunação, esse padrão de visitação nem sempre é encontrado em todos os grupos estudados. Os resultados indicam que a defaunação pode alterar as interações entre plantas, frugívoros e predadores na Floresta Atlântica e que atualmente, os principais frugívoros que atuam na remoção de frutos no chão da floresta, são os pequenos e médios mamíferos e aves generalistas. As alterações nas interações de frugivoria poderá afetar quantitativamente e qualitativamente, os processos seguintes, como a dispersão de sementes e o recrutamento de plântulas. / The frugivores play a fundamental role in the regeneration and control of plants in tropical forests, through seed dispersal and predation. In the Atlantic forest, large vertebrates are highly threatened by habitat deforestation and fragmentation, which may compromise interactions and consequently ecological services provided by wildlife. The objective of this study was to identify the main frugivores species in the Atlantic Forest, to analyze the frugivory networks between mammals, birds and plants in a defaunation gradient, as well as to evaluate the relationships between predators and frugivores in the context of Atlantic Forest defaunation. To this end, we installed cameras trap under trees that were fruiting in six areas of the Atlantic Forest in southeastern São Paulo and investigated the performance of visitors and frugivores. To meet our objectives, we used linear regression analyzes, network models of interactions and generalized linear models. We found that the main plants that had their fruits removed belong to the family Myrtaceae, Arecaceae and Rubiaceae and the main frugivores that removed fruits are mostly seed predators, such as paca, squirrel, small rodents in general and white-lipped peccary. We also suggest that only a small percentage of the number of visits was aimed at frugivory and that even in areas with low defaunation, frugivory is mainly carried out by small rodents and generalist birds. Finally, we find that small frugivores temporarily avoid areas with high frequency of large frugivores and that large frugivores avoid potential predators. However, in areas with high defaunation, this pattern of avoidance is not always found in all groups studied. Our results suggest that the defaunation is altering the interactions between plants, frugivores and predators in the Atlantic Forest, and that the main frugivores that act to remove fruits on the forest floor are small and medium mammals and generalist birds. Changes in frugivory interactions may affect quantitatively and qualitatively the following processes, such as seed dispersal and seedling recruitment.

Seed dispersal in New Zealand relies on a different guild from the one present before the arrival of humans into the islands. Post-dispersal biotic and abiotic filters have also changed due to the introduction of seed predators and herbivores. The aim of this thesis was to evaluate the actual contribution of seed dispersers to the patterns of seed fall and to understand the effects of biotic (seed density, predators, distance from conspecifics) and abiotic (pH, canopy openess, etc) factors on seed and seedling survival. I expected that tree species with different fruit sizes would be selected by different assemblages of dispersers, therefore being deposited and recruiting differentially on the forest floor. I analyzed the changes in small-scale seed diversity with the use of seed traps during two seasons in two 0.36 ha plots in a mixed broadleaf-podocarp temperate forest. The diversity of seeds was lower for in-fruit seeds (1.40 species per grid-cell) than for bird-dispersed seeds (2.62). The dominant species D. cupressinum was dispersed towards con- and heterospecific canopies (wind-dispersed trees Weinmannia racemosa and Metrosideros umbellata), giving a probable mechanism for the observed increase in finescale seed diversity. Then, using a 12-year dataset on seed fall I analyzed the changes in ground-level seed heterogeneity generated by bird-dispersed seed rain (propagule-scale) relative to the canopy composition (adult-scale) on six tree species. A Non Metric Multidimensional Scaling analysis demonstrated that the differences in species composition between sampling points (seed traps) were larger for tree canopies than for dispersed seeds. Different tree species acted as seed importers and/or exporters, although these patterns were not explained by fruit size or the richness of the disperser assemblages. I also investigated the effects of seed and seedling density on seed predation, seedling emergence and seedling survival to 12 months of five tree species. Seed predation increased with seed size, and it was higher at high density only for the largest-seeded species Beilschmiedia tawa and Prumnopitys ferruginea. Access of seed and seedling predators to the propagules was the main factor affecting seedling emergence and seedling survival. Abiotic variables were important for germination and seedling survival of the two small-seeded species, but only biotic predictors (mammalian exclosure and density) were important for medium and large-seeded species. Finally, using a split-plot experimental design I measured the effects of (a) the presence of conspecific canopy, (b) high conspecific seed densities and (c) introduced (or invasive) mammal access on seedling emergence and seedling survival (Janzen-Connell effects). Distance effects were stronger than density effects, and mediated by native and exotic predators. Final survival under conspecifics was strongly reduced in both species, with zero survival of B. tawa under conspecifics, and near zero (2/896) under D. dacrydioides. Seed dispersal service in New Zealand is still enough to produce changes in the spatial pattern of seed deposition in the forest. Post-dispersal processes such as seed predation and herbivore are having strong impacts on the survival and potential recruitment of plant species. Large-seeded trees are the most affected in terms of the impact of introduced mammals on seed predation, but seedling survival is affected independent of seed size. However, it is unknown how different these ecological processes are from the original situation without pests in New Zealand. The results of my research can contribute with valuable information for future research trying to understand the consequences of seed dispersal for recruitment, as well as inform complex models that try to predict the long-term impacts of the exotic mammals introduced in New Zealand.

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No. of bitstreams: 1 bello-lozano_lc_dr_rcla.pdf: 6995897 bytes, checksum: 3eab07c5fa5a3be2ac3b78242a7a7f8e (MD5) Previous issue date: 2018-07-27 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A extinção de animais é uma ameaça silenciosa nas florestas tropicais. As florestas tropicais estão se tornando ecossistemas defaunados, especialmente de animais de grande porte. No entanto, a defaunação vai além da perda de animais carismáticos, o que estamos perdendo são interações fundamentais que modulam a funcionalidade da floresta e, portanto, dos serviços ecossistêmicos associados. A defaunação tem efeitos sobre a dispersão de sementes, a ciclagem de nutrientes, a qualidade da água, a manipulação de matéria fecal, entre outros serviços ecossistêmicos. Nesta tese, exploramos os efeitos da defaunação de grandes animais no serviço ecosistêmico de estoque de carbono em florestas tropicais. Nós encontramos que o serviço ecossistêmico de armazenamento de carbono está sustentado pelos animais de grande porte, isso porque frugívoros grandes são os principais dispersores de árvores com sementes grandes e, as árvores com sementes grandes tendem a ser altas e com madeira densa, armazenando assim grandes quantidades de carbono. Portanto, a remoção de árvores de sementes grandes das florestas, devido à perda de dispersão induzida pela falta dos grandes frugívoros, pode reduzir o potencial do estoque de carbono da floresta. No entanto, a redução não é direta porque os frugívoros menores podem compensar parcialmente a perda dos grandes frugívoros. Além disso, a perda de grandes predadores de sementes também pode afetar o potencial estoque de carbono. Em comunidades fortemente defaunadas, pequenos roedores tendem a aumentar a sua abundância e a predação de sementes grandes, reduzindo assim o recrutamento deste tipo de árvore. Finalmente, nós exploramos o impacto da relação entre defaunação e o armazenamento potencial de carbono em programas de conservação. Nós mostramos que os projetos de restauração estão promovendo ecossistemas defaunados porque estes são dominados por árvores anemocóricas ou árvores de sementes pequenas que não irão fornecer recurso alimentar suficiente para animais grandes. Além disso, observamos que a falta de animais de grande porte pode produzir impactos econômicos nos mercados de carbono. Enfatizamos a necessidade urgente de integrar o papel dos animais em estratégias de restauração e mitigação das mudanças climáticas. O impacto econômico da defaunação no orçamento de carbono é um bom argumento para inserir os animais neste tipo de programas. Logo, devemos concentrar esforços no desenvolvimento de novas políticas nacionais e internacionais para proteger as florestas das "frentes de defaunação" assim como se tem feito com as “frentes de desmatamento." / Animal loss is a silent threat of forest ecosystem. Tropical forests are becoming defaunated ecosystems, especially defaunated of large animals. The loss of animals goes beyond than the loss of charismatic animals, what we are losing are key interactions that modulate the functionality of the forest and therefore of the associated ecosystem services. For instance, defaunation have effects over seed dispersal, nutrient cycling, water quality and dung removal among others ecosystem services. In this thesis, we explore the potential effects of defaunation of large animals in carbon stock ecosystem services of tropical forest. We found that the carbon stock ecosystem service is supported by large animals due to large frugivores are the main dispersers of large-seeded trees and, large-seeded trees tend to be tall trees with dense wood, therefore, store high quantities of carbon. Hence, the removal of large-seeded trees from the forest, because of diminished dispersal induced by the lack of large frugivores, reduce the carbon stock potential of the forest. However, the reduction is not straightforward because smaller frugivores can partially compensate for the loss of large frugivores. Moreover, strong defaunation effects in the seed predators communities can also affect the carbon stock potential of the forest. In strongly defaunated communities small rodents tend to increase their abundance and the predation pressure over large seeds, reducing their recruitment. In addition, we explore the impact of defaunation and carbon stock relation in conservation programs. We show that restoration projects are promoting defaunated ecosystems because they are dominated by abiotic trees or small-seeded trees, which will not provide enough food to large animals. Besides we observed that the lack of large animals can produce economic impacts in the carbon markets. Therefore, we argue the urgent necessity of integrating the animal role in restoration and climate mitigation strategies to. The economic impact of animal defaunation on carbon budget is a good argument to introduce animals in REED+ markets and forest restoration strategies. Within this evidence, we claim for the development of new national and international policy frames to protect forests from ‘defaunation fronts’ as well as has been done with ‘deforestation fronts’. / La extinción de animales es una amenaza silenciosa en los bosques tropicales. Los bosques tropicales se están convirtiendo en ecosistemas defaunados, especialmente despoblados de grandes animales. Esta pérdida de animales va más allá de la pérdida de animales carismáticos, lo que estamos perdiendo son interacciones clave que modulan la funcionalidad del bosque y, por lo tanto, de los servicios ecosistémicos asociados. Por ejemplo, la defaunación tiene efectos sobre la dispersión de semillas, el ciclo de nutrientes, la calidad del agua, la eliminación de excrementos, entre otros servicios de los ecosistemas. A través de esta tesis, exploramos los efectos potenciales de la defaunación de animales grandes en el servicio ecosistémico de almacenamiento de carbono de los bosques tropicales. Encontramos que el almacenamiento de carbono es soportado por animales grandes debido a que los frugívoros grandes son los principales dispersores de árboles con semillas grandes y, los árboles con semillas grandes tienden a ser árboles altos con madera densa, y consequentemente, almacenan altas cantidades de carbono. En consecuencia, la eliminación de árboles de semilla grande del bosque, debido a la dispersión disminuida inducida por la falta de grandes frugívoros, puede reducir el potencial de reserva de carbono del bosque. Sin embargo, la reducción no es directa debido a que los frugívoros más pequeños pueden compensar parcialmente la pérdida de frugívoros grandes. Además, los fuertes efectos de defaunación en las comunidades de depredadores de semillas también pueden afectar el potencial de reserva de carbono del bosque debido a que, en las comunidades fuertemente defaunadas los pequeños roedores tienden a aumentar su abundancia y la presión de depredación sobre las semillas grandes, reduciendo su reclutamiento. Finalmente, exploramos el impacto de la relación entre la defaunación y el potencial de carbono de los bosques tropicales en los programas de conservación. Mostramos que los proyectos de restauración están promoviendo ecosistemas defaunados porque están dominados por árboles abióticos o árboles de semilla pequeña, que no proporcionarán suficiente alimento a los animales grandes. Además, la falta de animales grandes puede producir impactos económicos en los mercados de carbono. Por lo tanto, recalcamos la necesidad urgente de integrar el papel de los animales en las estrategias de restauración y mitigación del cambio climático. El impacto económico de la defaunación de animales en los mercados de carbono es un buen argumento para introducir los animales en los proyectos REED+ y las estrategias de restauración forestal. A partir de estas evidencias, reivindicamos la necesidad de desarrollar nuevos marcos de políticas nacionales e internacionales para proteger los bosques de los "frentes de la defaunación", así como se ha hecho con los "frentes de deforestación". / FAPESP: 2013/22492-2 / FAPESP: 2015/23770-1

There are numerous examples of how exotic insect pests and pathogens have altered the dominance of native tree species and the ecological processes and function related to those species. While targeted species may persist in a functionally altered state via vegetative sprouting, the widespread decimation of a species can have dramatic direct and indirect consequences for organisms in multiple trophic levels. Devastation due to alien insect herbivores poses the greatest threat to native insect larvae that specialize on the impacted host species. The loss of pollinators whose larvae feed on impacted species and provide services for native plants may also be a serious but yet undocumented indirect threat of these exotic invasions. The disruption of mutualistic relationships between native species will have negative consequences for those species and could potentially benefit exotic species. In the southeastern US, laurel wilt disease (LWD) is impacting numerous species in the Lauraceae family, with the majority of cases observed on Persea borbonia, a common sub-canopy tree found in many Coastal Plain habitats. This species is also known to be the primary larval host of the palamedes swallowtail (Papilio palamedes). While infection rates and crown dieback are catastrophically high (>90%), basal resprouting is a common response in P. borbonia. The exotic Cinnamomum camphora is the only Lauraceae species that has shown resistance to LWD and could benefit from opportunities to replace P. borbonia and other Lauraceae species threatened by LWD. The primary objectives of this study were four fold: 1) to quantify P. borbonia sprouting responses in the field and greenhouse and determine the effect of P. borbonia removal on the composition and abundance of woody and herbaceous plant species in the understory layer, 2) to test the relative suitability of C. camphora as an alternative larval host for P. palamedes, 3) to determine the reliance of the Platanthera ciliaris on P. palamedes for successful pollination and the relative availability of alternative long-tongued pollinators, and 4) to forecast how disease-induced shifts in the relative abundance of native (P. borbonia) and exotic (C. camphora) fruit may alter patterns of consumption and subsequent dispersal of C. camphora by birds. The field component (Grand Bay National Estuarine Research Reserve (GBNERR), Jackson County, MS) of chapter two involved the removal of P. borbonia main stems to mimic the impacts of LWD which resulted in a significant increase (~50%) in light transmission. All treated individuals produced sprouts and the size and number of sprouts was positively related to initial tree size. Following the removal of P. borbonia from treatment plots, Ilex vomitoria showed the greatest increase in basal area after two years. Both woody seedlings and herbaceous plants showed no significant trends in composition and/or abundance over time. In the greenhouse (Southern Illinois University, Carbondale, IL), the stem and leaf biomass of vegetative sprouts was significantly greater in a high-nutrient treatment. Light treatments had no effect on sprout production. Results from chapter two suggest that the loss of P. borbonia from the canopy layer may have little direct effect on plant community dynamics. In addition, I found that sprout production is vigorous in P. borbonia and the capacity to persist and tolerate future disturbances may be enhanced on more nutrient-rich sites. In chapter three, I used laboratory experiments and field observations to compare larval performance and adult female preference of P. palamedes between C. camphora and P. borbonia foliage. My results indicate moderate survivorship on C. camphora (46%) compared to P. borbonia (87%) and there were no differences in first and fourth instar growth rates between treatments. Fourth instars consumed less C. camphora foliage than P. borbonia, but metabolic efficiency did not differ between treatments. In the field and laboratory, I found no oviposition preference for C. camphora relative to P. borbonia. While females laid eggs on C. camphora during laboratory trials, the same number of eggs was also laid on inanimate objects. I conclude that C. camphora is suitable for larval development but host-switching to this species by P. palamedes will be primarily constrained by oviposition behaviors. In chapter four, I monitored pollinator visitation and measured nectar spur lengths of P. ciliaris flowers and proboscis lengths of its floral visitors (at GBNERR). Papilio palamedes was the primary visitor (44 visits) but Phoebis sennae was also observed (4 visits). There were no significant differences among P. ciliaris nectar spurlength and the proboscis lengths of P. palamedes and P. sennae. Fruit set was 55 ± 10.8% with access to pollinators and 0% on bagged inflorescences (pollinators excluded). Although I found a positive relationship between visitation and inflorescence size, there was no such pattern in fruit set, indicating that fruit set was not limited by pollinator visitation within the range of visitation rates I observed. Phoebis sennae may provide supplemental pollination service but is likely constrained by habitat preferences that do not always overlap with those of P. cilaris. Although additional observations are needed, my results suggest that expected LWD-induced declines of P. palamedes will threaten the reproductive success and persistence of P. ciliaris populations. In chapter five, I investigated redundancy between C. camphora and P. borbonia with respect to fruit characteristics (physical and chemical) and selectivity by frugivorous birds (at GBNERR). Across two winter survey periods I observed fruit removal from artificial infructescences. I manipulated background species upon which displays were hung (Myrica cerifera and Triadica sebifera) and the accessibility of the displays. Using motion-activated cameras I confirmed foraging bouts on both P. borbonia and C. camphora fruits by three bird species (Dumetella carolinensis, Turdus migratorius, and Catharus guttatus). There was no significant difference in selectivity between fruit types during year one of my surveys but there was a significant preference for C. camphora in year two, which coincided with significantly lower mean daily temperatures. Background tree species and accessibility had no apparent effect on fruit preference. Total polyphenols and pulp:seed ratio were significantly higher in C. camphora fruit. I conclude that the fruits of C. camphora and P. borbonia represent nearly substitutable resources for native birds. However, native species may prefer C. camphora fruit in times of energetic stress. The decline of P. borbonia will likely increase the consumption and dispersal of C. camphora fruits. Additional studies are required to determine if such changes could ultimately increase the distribution and abundance of this exotic species. Combined, the chapters of this dissertation present substantial empirical evidence for the potential multi-trophic level impacts of an exotic plant disease. While it remains unclear how dramatic these impacts will be, the approach used here is vital for understanding and mitigating the long-term ecological effects of species/disease invasions.

Orientador: Marco Aurélio Pizo / Banca: Mauro Galetti / Banca: Wesley Rodrigues Silva / Resumo: A investigação das interações entre plantas e seus agentes dispersores têm implicações para a compreensão da diversidade biológica e sua conservação, e é um importante tema da ecologia evolutiva. Este estudo teve como objetivo investigar os componentes quantitativos e qualitativos na dispersão de sementes de Struthanthus flexicaulis (Loranthaceae), uma erva-de-passarinho dióica, hemiparasita generalista e de ampla distribuição no cerrado do Brasil central. O estudo foi realizado entre janeiro de 2004 e abril de 2005 em um afloramento rochoso na Serra do Cipó, Minas Gerais. Foram realizadas observações sobre a fenologia dos indivíduos femininos, observações focais para a avaliação dos parâmetros comportamentais dos dispersores, censos para avaliação da abundância relativa, sazonalidade e parâmetros comportamentais dos dispersores, observação direta e amostragem por procura ativa para avaliar a deposição das sementes de S. flexicaulis. Observou-se uma variação individual em S. flexicaulis com relação à duração do período e quantidade de produção de flores e frutos. A população estudada, no entanto, apresentou reprodução contínua ao longo do ano, porém de baixa intensidade na maioria dos indivíduos. Struthanthus flexicaulis teve seus frutos consumidos por um número bastante restrito de frugívoros: Elaenia cristata e Elaenia obscura (Tyrannidae), Mimus saturninus (Mimidae) e Schistochlamys ruficapillus (Thraupidae). No entanto, E. cristata foi o visitante mais freqüente e abundante ao longo do ano, responsável por mais de 96% das sementes dispersadas. Na área de estudo E. cristata apresentou uma dieta predominantemente frugívora, complementada pelo consumo de artrópodes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Quantity and quality components of seed dispersal in Struthanthus flexicaulis (Loranthaceae) in a rupestrian field in southeastern Brazil. The investigation of interactions between plants and their seed dispersers has implications for the understanding of the biological diversity, its conservation and is an important issue in evolutionary ecology. The goal of this study is to investigate the components of quality and quantity in the seed dispersal of Struthanthus flexicaulis (Loranthaceae), a generalist dioceous mistletoe with wide distribution in central Brazil. The study was conducted between January 2004 and April 2005 in a rocky outcrop in Serra do Cipó, Minas Gerais, southeastern Brazil. I conducted observations on female plant reproductive phenology, focal observations on fruiting plants to record behavioral parameters of seed dispersers, censuses to record the relative abundance, seasonality and behavioral parameters of seed dispersers, a direct observations and search on random established plots to evaluate seed deposition. Individual variation in the duration and quantity of flower and fruit production was detected. At the population level, reproduction was continuous, but in low intensity for most of the individuals. The fruits of S. flexicaulis were consumed by a small set of avian frugivores: Elaenia cristata and Elaenia obscura (Tyrannidae), Mimus saturninus (Mimidae) and Schistochlamys ruficapillus (Thraupidae), but E. cristata was the most frequent and abundant visitor throughout the year, responsible for more than 96% of the dispersed seeds. In the study site this bird was highly frugivorous, but also consuming a small proportion of arthropods... (Complete abstract, click electronic address below) / Mestre

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18842号 / 理博第4100号 / 新制||理||1589(附属図書館) / 31793 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 幸島 司郎, 教授 伊谷 原一, 教授 村山 美穂 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

The Amazon River drainage basin is known as the most biodiverse region in the world. Regarding freshwater fish, this region contains around 15% of the world's fish richness. The fish family Serrasalmidae have a variety of feeding preferences including Pacus (herbivores) and Piranhas (carnivores). Fruit eating fish species are evolutionarily the oldest species in the family and have a mutualistic interaction with flooded forests. Considering the diversity of feeding habits of the Serrasalmidae family, it represents an excellent model to study ecological questions related to factors that influence the spatial distribution of species and factors that contribute to the maintenance of biodiversity. I first analyzed how differences in dietary preferences influence the spatial distribution and habitat associations of species at the landscape scale using diet data and three proxies of habitat association derived from satellite products. Using Phylogenetic Generalized Least Squares models I evaluated the relationship between habitat association and feeding guilds. Differences in resource distribution (assessed through feeding guilds) can influence habitat associations. Considering the hydrological variability (i.e., floodplain extent) and landscape heterogeneity that characterize floodplains, the patterns of habitat association vary with the spatial scale considered. Second, I identified factors that aid in sustaining aquatic biodiversity in floodplain forests of the Amazon River basin, focusing on frugivorous fish. I used descriptors of the floodplain ecosystem- and landscape-level variables to assess their contribution to the maintenance of fish species richness. Using Generalized Linear Models (GLM) with negative binomial distribution I found that greater plant richness could offer a greater variety of food resources for frugivorous fishes and that a more extensive floodplain area provides larger forested habitat for fishes that depend on forest-derived food resources, as such subbasins with these characteristics support a greater frugivorous fish species richness. This work provides valuable information on species habitat associations by fish as well as food resource dynamics, floodplain dependence, and advances our understanding of the intricate relationship between forests and fish at a basin scale. This information is critical for assessing the impact of anthropogenic activities on freshwater ecosystems and can be used to inform conservation strategies in the tropics.

The decline in range and density of frugivorous birds worldwide could have consequences for the functioning of ecosystem processes such as seed dispersal. I endeavoured to determine the effects of bird declines on seed dispersal and assess the current status of dispersal in New Zealand. My first aim was to determine whether decreased bird density can reduce competitive interactions between birds, leading to birds concentrating on higher-reward fruit species. I measured fruit removal rates and fruit preferences of birds in Canterbury forest remnants with high (Hay and Prices) and low (Lords and Kaituna) bird densities. Removal rates of Melicytus ramiflorus and Coprosma spp. were lower at low-bird sites, and the size of this effect was greater for low-reward plant species. Coprosma areolata (a low-sugar fruit) had limited dispersal at Kaituna (59% fruit removed by end of 2012 season), compared with 92% removal at Hay, whereas 99-100% of M. ramiflorus and C. robusta (higher-sugar) fruits were removed at both sites. My second aim was to determine whether seed dispersal by introduced possums (Trichosurus vulpecula) can compensate for bird declines. I analysed seeds present in possum and bird faecal samples collected at Kowhai Bush, Kaikoura. Possums dispersed <3% of the total seeds, much less than bellbirds (21%), silvereyes (16%), song thrushes (33%) and blackbirds (28%). Possums also destroyed approximately 15% of seeds found in faeces, reduced the germination of gut-passed C. robusta seed to half of that from bird faeces (30% vs. 60-70%), and did not swallow fruits any larger than those moved by the much smaller birds (c. 7 mm diameter). My third aim was to determine the relationship between percentage of fruits dispersed and distance from parent tree for three large-seeded trees; Beilschmiedia tawa, Elaeocarpus dentatus, and Prumnopitys ferruginea. I fitted dispersal kernels to the observed dispersal distances out to 50 m for both undispersed whole fruits and seeds consumed by a bird, and found that dispersal quantity below the parent tree strongly underestimates total dispersal quantity. The average percentage dispersed overall was 81% for B. tawa, 75% for E. dentatus and 91% for P. ferruginea, and for all species finding only 11-18% clean seeds under the parent tree would correspond to an overall percent dispersed of at least 50% of the whole seed crop. My final aim was to determine the consequences of dispersal failure for recruitment in three plant species; Elaeocarpus hookerianus, Ripogonum scandens, and C. robusta. I compared the fate of dispersed and undispersed seeds in a manipulative field experiment. Exclusion of mammals plus removal of fruit pulp had the greatest effect on survival, while the combined effects of dispersal failure (under parent, high density, whole fruit) and inclusion of mammals decreased the number of live seedlings present at the final count by 75-92%. Overall, most native plants were receiving adequate dispersal and there was little evidence for strong risks to plant regeneration from dispersal failure, despite the reduced bird densities and ongoing negative effects of introduced mammals in New Zealand.