Thesis (Ph. D.)--Miami University, Dept. of Botany, 2004. / Title from second page of PDF document. Includes bibliographical references (p.70-79).

Black pacu Colossoma macropomum and red pacu Piaractus brachypomus are two endemic fruit and seed-eating Amazon fishes considered to be important seed dispersing agents in flooded forests. Dwindling populations coupled with the omnivorous feeding habits, rapid growth, high meat quality and commercial acceptance of these fishes has led to them becoming prime candidates for aquaculture development. However, high aquafeed prices are the prime limiting factor for the development of pacu culture in the Peruvian Amazon. The main objectives of this dissertation were: 1) to assess the effects of fish size on seed dispersal capacity of black and red Pacu; 2) to compare seed dispersal potential of these two Amazon fishes against two other seed dispersal mechanisms (anemochory and hydrochory); 3) to determine the apparent digestibility coefficients (ADC) of three local high-carbohydrate feedstuffs (yuca or cassava, plátano or plantain, and pijuayo or peach palm) in black and red Pacu; 4) to examine the feasibility of incorporating cassava, plantain, and peach palm meal in formulated diets for black pacu; and 5) to evaluate and compare black pacu fingerling growth, feed utilization and survival when reared at three water temperatures: 27.5, 30 and 32.5 ºC. In the first study, no significant differences were found for germination rates of seeds ingested among the three different size groups of fish tested. Although germination rates varied, the findings demonstrate both fish species in different ages may play an important role as seed dispersers in the floodplain forests. In a second study, ADC for crude protein, lipid and gross energy from raw and cooked green plantain meal (GPM) and cassava root meal (CRM) were lower compared to values of other common vegetal ingredients like corn and wheat. However, ADC values for raw and cooked peach palm meal (PPM) were, in most cases, higher than those reported for raw or cooked GPM and CRM. In comparison with other traditional feedstuffs, ADC values for PPM are similar to corn and higher than those reported for soybean meal and wheat bran, which suggests this ingredient, has high potential for incorporation in low-cost pacu aquafeed formulations in the Peruvian Amazon. In a third study, weight gain, feed conversion, survival, hematocrit, hemoglobin, mean corpuscular hemoglobin concentration, alternative complement activity, and lysozyme were found to be similar among several diets tested; however, protein efficiency ratio (PER) was lower in fish fed the diet containing wheat middlings. Relative to wheat middlings, all feedstuffs tested (cassava, plantain, and peach palm meal) were effective energy sources for juvenile black pacu and can serve as carbohydrate sources in balanced aquafeeds for this species. In a fourth study, black pacu reared at 30 ºC demonstrated significantly higher final body weight, body weight gain, specific growth rate, feed conversion ratio, feeding efficiency, and PER levels than fish reared at either 27.5 or 32.5 ºC (P<0.05). No significant differences (P>0.05) were recorded for feed intake, protein intake, or condition factor. This study suggests that global temperature increase may impair the ability of pacus to efficiently utilize feed and that growth in water temperatures above 30 ºC may become limiting for this species. In summary, growing evidence suggests that over the past two decades black and red pacu populations have significantly declined as a result of human activities and over-exploitation in the Peruvian Amazon, and their substantial role as seed disperers in the flooded forests could result in serious declines of many plant and animal components of the valuable aquatic ecosystem of the Amazon basin. Therefore, aquaculture of black and red pacu in the Peruvian Amazon is an attractive option to satisfy not only the increasing demand for animal protein for human consumption, but also as a viable mitigation measure for wild fish and forestry conservation. Results from this dissertation can serve as a basis for further improvement in culture technology for these two important species.

Estudos clássicos com diversidade taxonômica, apesar de serem essenciais, não consideram as diferenças funcionais entre as espécies de uma comunidade. A abordagem considerando atributos funcionais e diversidade funcional vem preenchendo esta lacuna. A compreensão da estrutura e dinâmica de interações mutualísticas também é um elemento essencial em estudos de biodiversidade, permitindo a investigação de mecanismos ecológicos e evolutivos. Porém, a maioria dos estudos com redes de interação disponíveis na bibliografia são pequenas em número de espécies e interações, e é possível que estes dados não tenham sido suficientemente amostrados. Além disto, estudos têm mostrado que muitas métricas utilizadas em análises de rede de interação são sensíveis ao esforço amostral e ao tamanho da rede. Os objetivos desta tese foram: 1) investigar a diversidade taxonômica (DT) e funcional (DF) de aves e os padrões de organização de espécies de aves em comunidades refletindo convergência de atributos (TCAP: Trait Convergence Assembly Patterns) ao longo de transições entre floresta e campo; 2) analisar a estrutura de redes de dispersão de sementes de plantas por aves, utilizando as métricas de rede aninhamento, modularidade, conectância e distribuição do grau; 3) desenvolver um método estatístico visando avaliar suficiência amostral para métricas de redes de interação usando o método bootstrap de reamostragem com reposição. A composição de espécies de aves diferiu entre os ambientes, indicando uma substituição de espécies ao longo da transição floresta-borda-campo. DT diferiu significativamente somente entre floresta e borda de floresta, enquanto que ambas diferiram significativamente do campo em relação à DF. DT e DF podem indicar diferentes processos de organização de comunidades ao longo de mosaicos floresta-campo. A correlação significativa entre TCAP e o gradiente floresta-campo indica que provavelmente mecanismos de nicho atuam na organização da comunidade de aves, associados a mudanças na estrutura do habitat ao longo da transição floresta-borda-campo agindo como filtros ecológicos. Redes de dispersão de sementes de plantas por aves aparentemente apresentam um processo comum de organização, independentemente das diferenças na intensidade de amostragem e continentes onde as 19 redes utilizadas foram amostradas. Usando reamostragem bootstrap, encontramos que suficiência amostral pode ser alcançada com diferentes tamanhos amostrais (número de eventos de interação) para o mesmo conjunto de dados, dependendo da métrica de rede utilizada. / Classic studies on taxonomic diversity, though essential, do not consider the functional differences between species in a community. Studies using functional traits and functional diversity are filling this gap. Understanding the structure and dynamics of mutualistic interactions is also essential for biodiversity studies and allows the investigation of ecological and evolutionary mechanisms. However, most networks published are small in the number of species and interactions, and they are likely to be under-sampled. In addition, studies have demonstrated that many network metrics are sensitive to both sampling effort and network size. The aims of this thesis were: 1) to investigate bird taxonomic diversity (TD), functional diversity (FD), and patterns of trait convergence (TCAP: Trait Convergence Assembly Patterns) across forest-grassland transitions; 2) to analyse the structure of seed-dispersal networks between plants and birds using the metrics of nestedness, modularity, connectance and degree distribution; 3) to develop a statistical framework to assess sampling sufficiency for some of the most widely used metrics in network ecology, based on methods of bootstrap resampling. Bird species composition indicated species turnover between forest, forest edge and grassland. Regarding TD, only forest and edges differed. FD was significantly different between grassland and forest, and between grassland and edges. TD and FD responded differently to environmental change from forest to grassland, since they may capture different processes of community assembly along such transitions. Trait-convergence assembly patterns indicated niche mechanisms underlying assembly of bird communities, linked to changes in habitat structure across forest-edge-grassland transitions acting as ecological filters. Seed dispersal mutualistic networks apparently show a common assembly process regardless differences in sampling methodology or continents where the 19 networks were sampled. Using bootstrap resampling we found that sampling sufficiency can be reached at different sample sizes (number of interaction events) for the same dataset, depending on the metric of interest.

Estudos clássicos com diversidade taxonômica, apesar de serem essenciais, não consideram as diferenças funcionais entre as espécies de uma comunidade. A abordagem considerando atributos funcionais e diversidade funcional vem preenchendo esta lacuna. A compreensão da estrutura e dinâmica de interações mutualísticas também é um elemento essencial em estudos de biodiversidade, permitindo a investigação de mecanismos ecológicos e evolutivos. Porém, a maioria dos estudos com redes de interação disponíveis na bibliografia são pequenas em número de espécies e interações, e é possível que estes dados não tenham sido suficientemente amostrados. Além disto, estudos têm mostrado que muitas métricas utilizadas em análises de rede de interação são sensíveis ao esforço amostral e ao tamanho da rede. Os objetivos desta tese foram: 1) investigar a diversidade taxonômica (DT) e funcional (DF) de aves e os padrões de organização de espécies de aves em comunidades refletindo convergência de atributos (TCAP: Trait Convergence Assembly Patterns) ao longo de transições entre floresta e campo; 2) analisar a estrutura de redes de dispersão de sementes de plantas por aves, utilizando as métricas de rede aninhamento, modularidade, conectância e distribuição do grau; 3) desenvolver um método estatístico visando avaliar suficiência amostral para métricas de redes de interação usando o método bootstrap de reamostragem com reposição. A composição de espécies de aves diferiu entre os ambientes, indicando uma substituição de espécies ao longo da transição floresta-borda-campo. DT diferiu significativamente somente entre floresta e borda de floresta, enquanto que ambas diferiram significativamente do campo em relação à DF. DT e DF podem indicar diferentes processos de organização de comunidades ao longo de mosaicos floresta-campo. A correlação significativa entre TCAP e o gradiente floresta-campo indica que provavelmente mecanismos de nicho atuam na organização da comunidade de aves, associados a mudanças na estrutura do habitat ao longo da transição floresta-borda-campo agindo como filtros ecológicos. Redes de dispersão de sementes de plantas por aves aparentemente apresentam um processo comum de organização, independentemente das diferenças na intensidade de amostragem e continentes onde as 19 redes utilizadas foram amostradas. Usando reamostragem bootstrap, encontramos que suficiência amostral pode ser alcançada com diferentes tamanhos amostrais (número de eventos de interação) para o mesmo conjunto de dados, dependendo da métrica de rede utilizada. / Classic studies on taxonomic diversity, though essential, do not consider the functional differences between species in a community. Studies using functional traits and functional diversity are filling this gap. Understanding the structure and dynamics of mutualistic interactions is also essential for biodiversity studies and allows the investigation of ecological and evolutionary mechanisms. However, most networks published are small in the number of species and interactions, and they are likely to be under-sampled. In addition, studies have demonstrated that many network metrics are sensitive to both sampling effort and network size. The aims of this thesis were: 1) to investigate bird taxonomic diversity (TD), functional diversity (FD), and patterns of trait convergence (TCAP: Trait Convergence Assembly Patterns) across forest-grassland transitions; 2) to analyse the structure of seed-dispersal networks between plants and birds using the metrics of nestedness, modularity, connectance and degree distribution; 3) to develop a statistical framework to assess sampling sufficiency for some of the most widely used metrics in network ecology, based on methods of bootstrap resampling. Bird species composition indicated species turnover between forest, forest edge and grassland. Regarding TD, only forest and edges differed. FD was significantly different between grassland and forest, and between grassland and edges. TD and FD responded differently to environmental change from forest to grassland, since they may capture different processes of community assembly along such transitions. Trait-convergence assembly patterns indicated niche mechanisms underlying assembly of bird communities, linked to changes in habitat structure across forest-edge-grassland transitions acting as ecological filters. Seed dispersal mutualistic networks apparently show a common assembly process regardless differences in sampling methodology or continents where the 19 networks were sampled. Using bootstrap resampling we found that sampling sufficiency can be reached at different sample sizes (number of interaction events) for the same dataset, depending on the metric of interest.

Intervenções conservacionistas baseadas em receitas generalistas e uniformes têm eficácia comprometida por serem incapazes de incorporar as particularidades de cada ecossistema e as diferentes características regionais da atividade humana. Este trabalho teve como objetivo desenvolver uma metodologia que incorporasse a avaliação espacial do fluxo gênico contemporâneo de plantas ao planejamento territorial de paisagens fragmentadas. Adotou-se o Jatobá (Hymenaea courbaril), espécie zoocórica, como espécie guarda-chuva. Localizada no Pontal do Paranapanema, a área amostral utilizada possui 49km2, que abrigam sete sub-populações de Jatobá e 1,32 km2 de remanescentes florestais divididos em 4 fragmentos. Executamos o censo de árvores adultas e amostragem regular de indivíduos juvenis. Amostrou-se 359 indivíduos, dos quais 75 foram considerados como adultos, todos foram georreferenciados por GPS e genotipados por SSR. Analisando-se três locos de DNA genômico e um de c-DNA, foram realizados 21.225 testes de maternidade, nos quais 62 plantas jovens tiveram suas mães identificadas. A distribuição das distâncias de dispersão de sementes verificada indica que o isolamento para recolonização entre sub-populações ocorre em distâncias superiores a 1600m. Foram localizados 13 fragmentos que permaneceriam em condição de isolamento, mesmo após a recuperação de todas as APPs. Recomenda-se a inclusão do aumento de conectividade destas manchas, bem como do reflorestamento de todas as APPs, na lista de prioridades do planejamento da conservação da biodiversidade desta região. / Conservationist interventions, based on general and uniform protocols, lose effectiveness by being incapable to incorporate the particularities of each ecosystem and the different regional patterns of the human activity. This research meant to develop a method that incorporates the spatial evaluation of the contemporary gene flow of plants to the territorial planning of fragmented landscape. We adopted Hymenaea courbaril as an umbrella species. Located in the Pontal of the Paranapanema (São Paulo State, Brazil), the study area has 49km2, that shelters seven subpopulations of Hymenaea courbaril with 1,32km2 are covered by forest that is separated in four patches. We censused adult trees and also regular seedlings and juveniles were regularly sampled. A total of 359 individuals were identified and georreferencered by GPS and genotyped by SSR. Analyzing 3 loci of genomic DNA and one of c-DNA, we applied a maternity test. 62 young plants had them mothers identified. The distribution of distances of seed dispersal indicates that the isolation for recolonization between subpopulations occurs in distances greater than 1600m, indicating that the connectivity in the studied landscape is very low for Hymenaea courbaril. 13 habitat patches were located in isolation condition, even after the recuperation of all the law-protected riparian-corridor areas. These results emphasized the increase of connectivity of these spots, as well as the restoration in the protected riparian areas, as some of the top priorities in the planning of the biological conservation of this region.

Orientador: Wesley Rodrigues Silva / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T09:09:30Z (GMT). No. of bitstreams: 1 Guerra_TadeuJosedeAbreu_D.pdf: 2780455 bytes, checksum: a4bd5aa0f423ec7226c91f0cff7655f9 (MD5) Previous issue date: 2010 / Resumo: Neste trabalho investiguei aspectos da história natural da erva-de-passarinho lenhosa Psittacanthus robustus Mart. (Loranthaceae) em áreas de campos rupestres da Serra do Cipó, sudeste brasileiro. Essa espécie foi observada parasitando de oito espécies de hospedeiras pertencentes a cinco famílias, embora espécies arbóreas da família Vochysiaceae sejam as principais hospedeiras. O padrão de distribuição espacial é agregado nas hospedeiras e também na escala da paisagem. A prevalência aumentou em função do tamanho para as quatro espécies de hospedeiras avaliadas. A propagação se dá exclusivamente por dispersão de sementes e o período de frutificação se estendeu de maio a setembro (estação seca). Seus frutos são ornitocóricos e o principal dispersor foi a guaracava-de-topete-uniforme, Elaenia cristata (Tyrannidae), que descarta as sementes por regurgitação e depositando-as durante ato de limpar o bico nos poleiros. Esse pássaro se empoleira preferencialmente nas hospedeiras infectadas e a remoção experimental de P. robustus reduziu significativamente a deposição de sementes nas quatro espécies de hospedeiras. Esses resultados indicam que a distribuição agregada nas hospedeiras está relacionada ao comportamento do dispersor que promove uma deposição desproporcional de sementes sobre hospedeiras infectadas. Além disso, a abundância de E. cristata aumentou com disponibilidade de plantas em frutificação nos afloramentos rochosos, promovendo retro-alimentação positiva na dispersão e deposição de sementes. Esse parece ser o principal processo que levam a distribuição agregada dessa erva-de-passarinho na escala da paisagem. Hospedeiras mais altas têm maiores chances de receber sementes, indicando que a maior prevalência em hospedeiras mais altas está relacionada com seleção de poleiros pelos dispersores. Psittacanthus robustus floresceu entre novembro e março (estação chuvosa). As flores apresentam características tipicamente ornitófilas, incluindo antese diurna, corola amarela e produção copiosa de néctar diluído, que é reabsorvido caso não seja consumido pelos polinizadores. Observei oito espécies de beija-flores e duas espécies de pássaros como visitantes florais, mas os beija-flores Eupetomena macroura e Colibri serrirostris (Trochilidae) foram os principais polinizadores. Não encontrei diferenças significativas na produção de sementes entre flores polinizadas com o próprio pólen ou de forma cruzada. No entanto, esses tratamentos produziram mais sementes do que flores controle expostas aos polinizadores indicando que reprodução é limitada pela deposição de pólen. Essa planta não produziu sementes por apomixia e apresentou capacidade limitada de produzir sementes de forma autônoma por autopolinização, evidenciando a importância da polinização por beija-flores na reprodução. Por fim, apresento dados sobre a história natural do percevejo Eurystethus microlobatus (Pentatomidae), uma espécie fitófaga associada à P. robustus. Esse percevejo apresenta comportamento gregário e cuidado maternal. Os indivíduos se abrigam mais freqüentemente nas raízes e ramos onde se encontram melhor camuflados na casca de P. robustus. Além disso, esse percevejo produz exudato açucarado que é utilizado como recurso alimentar por formigas, que os protegem contra inimigos naturais ao de todo o dia. A complexa gama de interações envolvendo plantas hospedeiras, aves frugívoras e nectarívoras, além de insetos herbívoros sugerem que P. robustus desempenha importante papel na manutenção da biodiversidade nos campos rupestres da Serra do Cipó. / Abstract: In this study I investigated some aspects of the natural history of the woody mistletoe Psittacanthus robustus Mart. (Loranthaceae) in rocky outcrops in the Serra do Cipó, southeastern Brazil. This species was recorded parasitizing eight host species in Five families, although trees within Vochysiaceae comprise the main hosts. Pattern of distribution was clumped within host trees but also at landscape scale. Prevalence increased with height for the four hosts species evaluated. Dissemination occurs exclusively through seed dispersal and the fruiting period extends from April to September (dry season). The fruits are ornithochorous and the main seed disperser was the plain-crested Elaenia, Elaenia cristata (Tyrannidae), which regurgitated and deposited seeds on perch during bill wiping. This bird perched preferentially on already infected hosts and experimental removal of mistletoes decreased significantly seed deposition on four host species. These results indicate that aggregated distribution on host trees is related to behavior of seed dispersers, which promoted non-random seed deposition on already parasitized trees. In addition, abundance of E. cristata increased with availability of fruiting mistletoes on rocky outcrops, promoting a positive feedback in seed dispersal and deposition. This seems to be the main processes leading to a highly clumped distribution of woody mistletoe at landscape scale. Taller hosts have higher chances to receive seeds, what indicates that increased prevalence on taller trees is related to perch selection by seed dispersers. Psittacanthus robustus bloomed from November to March (rainy season). Flowers presented characteristics typical from ornithophilous plants, including diurnal anthesis, yellow corolla, and secretion of abundant diluted nectar, which is reabsorbed if not utilized by pollinators. I observed eight hummingbird species and two passerine species as flower visitors, but the hummingbirds Eupetomena macroura and Colibri serrirostris (Trochilidae) were the main pollinators. I found no differences in seed set between flowers hand pollinated with own pollen or with pollen from distinct genet. However, these treatments set significantly more seeds than flowers exposed to pollinators, indicating that reproduction is pollen limited. This plant did not produce seed through apomixis and presented a limited capacity to produce seeds through autonomous self-pollination, highlighting the role of hummingbirds on plant reproduction. Finally, I reported data on natural history of the stinkbug Eurystethus microlobatus (Pentatomidae), a phytophagous species associated to P. robustus. This stinkbug presents a gregarious behavior and maternal care. Individuals are likely to rest on roots and shoots where they camouflage within host bark of P. robustus. Moreover, this stinkbug produces honeydew that is utilized as food source by ants, which protect them against their natural enemies throughout the day. The intricate interactions involving hosts plants, frugivorous and nectarivorous birds and insect herbivores suggest that woody mistletoes have an important role in sustaining the biodiversity in rupestrian fields in the Serra do Cipó. / Doutorado / Ecologia / Doutor em Ecologia

Orientadores: Wesley Rodrigues Silva, Paulo Roberto Guimarães Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-13T12:23:21Z (GMT). No. of bitstreams: 1 Amatuzzi_MariaClaraOleski_M.pdf: 1407858 bytes, checksum: bb5c3ae5328b68092befea78e47ba7d7 (MD5) Previous issue date: 2009 / Resumo: O mutualismo planta-frugívoro é bem conhecido como importante processo na manutenção dos ecossistemas. O frugívoro obtém o recurso alimentar da polpa e dispersa as sementes da planta. A crescente perda e fragmentação de ambientes naturais devem afetar essas interações. Portanto, conhecer quais são os efeitos desta degradação na dispersão de sementes é um passo importante na tentativa de preservação dos ecossistemas. A abordagem de redes vem sendo usada atualmente a fim de entender melhor a estrutura, funcionamento e evolução de diversos tipos de interações. Explorei alguns padrões de extinção de espécies em uma rede de interações mutualísticas frugívoro-planta do Parque Estadual de Intervales (PEI) simulando extinções de frugívoros e plantas e observando os efeitos na sua estrutura. A rede frugívoro-planta do PEI é uma rede típica de interações mutualísticas com estrutura extremamente aninhada; baixa conectância; baixos graus médios tanto de plantas como dos animais; prevalência de interações fracas e ocorrência de interações assimétricas. As co-extinções ocorreram muito lentamente com as remoções de especialistas e geram um declínio considerável na riqueza de espécies do outro grupo, somente após remoção de 80% das espécies. Remoções aleatórias de espécies geraram um padrão quase linear de co-extinções, após a remoção de 50% das espécies observa-se um maior impacto na riqueza da rede. A remoção das espécies ameaçadas de extinção causou impacto semelhante ao observado com as remoções aleatórias. Em geral, ocorre um padrão de surgimento de pequenos componentes, a partir da remoção de 5% das espécies, porém há sempre um grande e aninhado componente. O aninhamento da rede foi pouco modificado com as simulações. A rede perde o aninhamento mais rapidamente durante a remoção de generalistas. Os resultados reforçam a idéia de robustez dessa rede que é gerada pela suas características estruturais. As espécies mais importantes para a manutenção da estrutura e riqueza de espécies da rede são as generalistas. / Abstract: The frugivore-plant mutualism has been recognized as an important process in maintaining terrestrial ecosystems. Frugivores feed on fruits and disperse their seeds. The increase of habitat fragmentation and loss may affect these interactions. Therefore, understanding the effects of these disturbances on seed dispersal process may help to predict shifts in the remaining ecosystems. In this sense, the network approach has been used to describe the structure and investigate function and evolution of different types of interactions. I explored different patterns of extinction in a network of mutualistic frugivore-plant interactions of the Parque Estadual de Intervales (PEI) by simulating the removal of frugivores and plants and observing the effects on its structure. The PEI network as a typical mutualistic network with highly nested interactions; low connectance; small average number of interactions for both plants and animals; prevalence of weak interactions and occurrence of asymmetric interactions. When removing specialists, coextinctions occurred very slowly, leading a significant decline on species richness only after the removal of 80%. Random removal of species created an almost linear co-extinction pattern, showing important cumulative loss of species after removal of 50% of species. Species diversity declined most rapidly with the removal of the generalists. The removal of endangered species caused patterns of co-extinction similar to those caused by the random removal. In general, PEI network showed a pattern of break down of small clusters after the extinction of just 5% of species, although a large and nested cluster stil observed. The nested structure of the network was slightly changed through the simulations. The network lost its nested structure more rapidly when generalists species were removed. These simulations support the notion that mutualistic networks are robust to extinction and generalists are the most important species for the maintenance of structure and species richness of these networks. / Mestrado / Mestre em Ecologia

Orientador: Ricardo Ribeiro Rodrigues / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-08T15:03:54Z (GMT). No. of bitstreams: 1 Souza_FlavianaMalufde_D.pdf: 1240667 bytes, checksum: 7ce64c73162dd8df01a650e6144d90aa (MD5) Previous issue date: 2007 / Resumo: As interações das árvores do dossel com as plantas que se estabelecem sob suas copas e suas conseqüências na organização da comunidade são pouco conhecidas para as florestas tropicais. Neste trabalho, investigamos como a deciduidade e a síndrome de dispersão das árvores do dossel podem influenciar a estrutura e riqueza da comunidade arbustivo-arbórea do subosque em um remanescente de Floresta Estacional Semidecidual, localizado na Estação Ecológica dos Caetetus, Gália - SP. Em uma parcela permanente 10,24 há amostramos todas as árvores do dossel (dossel e emergentes) e os indivíduos com diâmetro à altura do peito '> ou =' 4,8com situados sob suas copas. As espécies decíduas apresentaram maior abundância relativa e maior proporção de espécies secundárias iniciais sob suas copas do que as espécies perenifólias. Dentre os grupos de dispersão das árvores do dossel, as espécies autocóricas apresentaram maior abundância relativa de indivíduos coespecificos sob suas copas, enquanto as espécies anemocóricas e zoocóricas não diferiram entre si. A abundância relativa de indivíduos zoocóricos embaixo das copas não diferiu entre os grupos de dispersão, mas a riqueza de espécies zoocóricas foi maior sob as espécies zoocóricas do dossel. Esses resultados indicam que a deciduidade pode favorecer a sobrevivência e ao crescimento das espécies mais exigentes em relação à luz como secundárias iniciais, provavelmente em decorrência do aumento na quantidade e na qualidade da luz que chega ao subosque ...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: In tropical Forest, the consequence of interactions between canopy and understory plants to the community organization are poorly understood. We insvestigated how deciduousness and dispersal syndromes of canopy tree species could influence the community structure and species richness in a Seasonal Semideciduous Forest located at Caetetus Ecological Station Reserve, in central-western São Paulo state, Brazil. In a 10,24 ha permanent plot, we sampled all overstory trees (canopy and emergent trees) and the trees with dameter at breaster height '> ou =' 4,8 cm under their crowns (understory trees). Deciduos canopy trees showed higher relative abundance and proportion of early secondary species under their crowns than evergreen trees. Autochorous canopy trees presented higher relative abundance of cosnpecific individuals under their crowns, while there was no difference between wind and animal-dispersed canopy trees. The relative abundance of animal-dispersed trees in the understory did not differ among dispersal guilds, but estimated zoochorous species richness was higher under zoochorus canopy trees. The results suggest that the deciduousness of canopy trees may facilitate the survival and establishment of species with higher requeriments, most possibly by providing an increase in the amount and quality of the light that reaches the understory when canopy trees are leafless ...Note: The complete abstract is available with the full electronic digital thesis or dissertations / Doutorado / Doutor em Biologia Vegetal

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.

The population dynamics of small mammal populations in Punda Maria, Kruger National Park, South Africa was investigated with respect to community size and structure, seed predation and dispersal of several trees. Species populations, community structure and habitat attributes were measured at six sites comprising of 3 habitat types (2 sites per habitat); namely Acaciagrassland, North-facing and South-facing sloped sites. Seasonal variation was investigated at the Acacia sites during late summer (April) and winter months (July). Five habitat attributes were measured; percentages of total cover and herbage, plant litter depth (cm), height of dominant vegetation type measured (m) and edaphic condition were recorded at 15 randomly selected traps per site. Almonds (Prunus dulcis), baobabs (Adansonia digitata), mopane (Colophospermum mopane), and Acacia tortilis seeds were used in the predation and dispersal experiment. North- and South-facing sites were dominated by Aethomys sp. while Acacia sites were dominated by Mastomys natalensis. Seed predation was high at the North-facing slopes, with a significant difference in predation on A. tortilis seeds. Seed dispersal activity was low; no , scatter hoarding was identified; only larder hoarding was observed by Aethomys sp. and M. natalensis at North-facing sites and Acacia sites respectively. Trampling by megaherbivore activity impacted vegetation structure and has negatively affected rodent population and ground activity, particularly at the Acacia sites.