<p>Ecologists have long sought to uncover the mechanisms behind large-scale, macroecological patterns in the distribution and abundance of species. Macroecological patterns are often attributed to the dynamics of dispersal (e.g. dispersal limitation or widespread dispersal). However, few studies actually measure dispersal to determine if dispersal rates are commensurate with the observed macroecological patterns. In this dissertation, I use population genetic analyses across many species to obtain community-level estimates of dispersal rates for two different ecological systems: birds on islands and trees in tropical rainforests. These independent estimates of dispersal then allow me to determine if macroecological patterns in these two systems can be attributed to dispersal dynamics.</p><p>In chapter two, I explore the contrasting macroecological patterns of two groups of Lesser Antillean birds. The groups' differing macroecological patterns could be due to differences in dispersal, but other authors have advocated different mechanisms. Population genetic analyses show that the two groups do differ significantly in rates of inter-island dispersal, indicating that dispersal dynamics can explain their contrasting macroecological patterns. In chapter three, I turn my attention to tropical tree communities. In contrast to studies of birds on islands, studies of trees in tropical rainforests may suffer from misidentification of individuals in the field. Using a phylogenetic approach, I determine errors rates in identification, and then assess the effect of these errors on macroecological patterns and other ecological analyses of tropical tree communities. I find that error rates are substantial, but that they have little effect on macroecological patterns. In contrast, species-level ecological analyses can be dramatically affected by these errors.</p><p>In chapter four, I return to the influence of dispersal on macroecological patterns, this time in tropical tree communities. One notable macroecological pattern in Amazonian tree communities is a high correlation in the relative abundances of species shared across communities, which could indicate high rates of dispersal between communities. However, population genetic analyses show that dispersal is severely limited between communities. Thus, some factor besides dispersal, such as differences in competitive ability or susceptibility to disease, must be driving species to achieve similar relative abundances in geographically separated communities. In contrast, I show that dispersal limitation is the likely cause of another macroecological pattern frequently observed in tropical tree communities: the decline in the compositional similarity of communities with distance. However, this is not steady-state dispersal limitation in an equilibrium framework as is conventionally thought. Instead, the dispersal limitation appears to be historical in nature, which implies a heretofore unnoticed role for historical contingency in the assembly of Amazonian tree communities.</p> / Dissertation

The biological diversity on planet Earth is astounding. Understanding the origins of this diversity, and how it is maintained, are the twin goals of ecology and evolutionary biology. An early and oft-repeated insight in this investigation is that that similar organisms cannot coexist indefinitely. Theory predicts that individuals and species will compete for limited resources and whichever has even a slight advantage will drive all others extinct in a process known as ‘competitive exclusion’. By diversifying, species avoid competition, thereby ‘stabilizing’ their coexistence. Yet natural systems often display levels of diversity that are surprisingly high, given this theory and investigations of how the similarity of coexisting species is maintained have received much less attention. Using a combination of field studies and experiments I demonstrate that highly similar species of freshwater amphipods may compete for resources without resulting in competitive exclusion. These findings suggest that there exist a range of interactions among Hyalella amphipods, ranging from strong stabilizing effects due to ecological trade-offs, to weakly stabilizing effects, to a total lack of stabilizing effects among various pairs of species in this system. These findings demonstrate how the relative strength of stabilizing forces may vary among coexisting species. Although much effort has been dedicated to enumerating and classifying the ways in which ecological and evolutionary forces promote diversity among species, there has been far less attention paid to mechanisms such as convergent evolution, habitat filtering, competition for non-substitutable resources, and non-ecological speciation, among others. I surveyed current theory that may explain the high levels of similarity among species often found in natural systems. I describe how several ecological and evolutionary mechanisms may operate to promote the coexistence of similar species and present results from new theoretical combinations of mechanisms to demonstrate how they may further act in concert with one another. / text

Thesis (M.S.)--Miami University, Dept. of Botany, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], iv, 109 p. Includes bibliographical references (p. 36).

The Unified Neutral Theory of Biodiversity has been advanced as a universal theory for species coexistence in forests worldwide, but few studies have examined its relevance to high-elevation, stressful environments. I established the Utah Forest Dynamics Plot (UFDP) in a heterogeneous subalpine forest at 3,091 m elevation on the Colorado Plateau to examine three underlying assumptions of neutral theory (functional equivalence, ecological equivalence, and habitat generality) and one prediction (the species abundance distribution). The UFDP comprises 27,845 stems ≥1 cm diameter at breast height of 17 species, 10 genera, and 6 families over 13.6 ha. The neutral model was a poor fit to the observed species abundance distribution, but I did not find the alternative lognormal model to provide a better fit. Using spatial pattern analyses of tree data, topography, and soil type, I found some limited support for the neutral theory assumptions of functional and ecological equivalency, with notable exceptions. Populus tremuloides, Pinus flexilis, and Pinus longaeva were characterized by non-neutral recruitment processes, and Abies bifolia and Populus tremuloides exhibited asymmetric competitive and facilitative interactions. The assumption of habitat generality was strongly contradicted, with all ten abundant species in the UFDP having habitat preference. In this subalpine temperate forest, species diversity and community structure are influenced more by habitat heterogeneity, species differences, and niche selection, with neutral processes playing a lesser role.

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Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-07-29T17:40:22Z No. of bitstreams: 3 Dissertação - Carlos Roberto Marques Araújo - 2016.pdf: 1356967 bytes, checksum: a67bce138d3f3fc43354746e29bef2f6 (MD5) Ata de defesa-Carlos Roberto marques Araújo - 2016.jpg: 604004 bytes, checksum: b0fd3fa197d5329a4b1df03e7e2636c0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-01T13:30:23Z (GMT) No. of bitstreams: 3 Dissertação - Carlos Roberto Marques Araújo - 2016.pdf: 1356967 bytes, checksum: a67bce138d3f3fc43354746e29bef2f6 (MD5) Ata de defesa-Carlos Roberto marques Araújo - 2016.jpg: 604004 bytes, checksum: b0fd3fa197d5329a4b1df03e7e2636c0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-01T13:30:23Z (GMT). No. of bitstreams: 3 Dissertação - Carlos Roberto Marques Araújo - 2016.pdf: 1356967 bytes, checksum: a67bce138d3f3fc43354746e29bef2f6 (MD5) Ata de defesa-Carlos Roberto marques Araújo - 2016.jpg: 604004 bytes, checksum: b0fd3fa197d5329a4b1df03e7e2636c0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-04-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The biodiversity have a heterogeneous distribution along the globe. Available area, energy, evolutional and historical processes, spatial and/or temporal heterogeneity are some of the processes raised to explain those variation on species richness. On this study we tested the following hypothesis, or the combination between them to explain the richness of stream’s aquatic insects. The hypotheses were: (i) Energy, (ii) Water-energy, (iii) Temporal climatic heterogeneity, (iv) Terrestrial primary productivity and (v) Area. We used genus richness of aquatic insects from all South America, this data was retrieved from papers published on periodic with editorial board. We used Ordinary Least square models, and then choose the best model using the Akaike Information Criterion. Our results support the idea that models with multiples hypothesis are more effective when compared to single hypothesis models. The best multi-model utilized the hypotheses Water-Energy, Primary Productivity and Temporal Climatic Heterogeneity. Our models were impaired by the lack of comprehensiveness data, however we could conclude that the Water-Energy was the most robust hypothesis to explain the richness distribution of stream’s aquatic insects. / A distribuição da biodiversidade no planeta ocorre de forma heterogênea. Área disponível, energia, processos evolutivos e históricos, heterogeneidade espacial e/ou temporal são alguns dos processos organizadores propostos para explicar a variação na riqueza de espécies. Neste estudo testamos se alguma das seguintes hipóteses, ou se a combinação entre elas melhor explica a riqueza de insetos aquáticos em riachos de baixa ordem. As hipóteses foram: (i)energética, (ii) água-energia, (iii)heterogeneidade climática temporal, (iv)produtividade primária terrestre e (v)área. Usamos dados da riqueza de gêneros de insetos aquáticos para toda a América do Sul, recolhidos de artigos publicados em periódicos com corpo editorial. Nos então desenvolvemos modelos lineares de mínimos quadrados, e fizemos a seleção do melhor modelo utilizando o Critério de Informação de Akaike. Nossos resultados suportam a ideia de que modelos com múltiplas hipóteses são mais efetivos em comparação a modelos individuais. Quando analisados separadamente o modelo de água-energia foi o que melhor explicou a riqueza de gêneros. O melhor multimodelo integrou as hipóteses de Água-energia, Produtividade e Heterogeneidade Climática Temporal. A falta de abrangência nos dados prejudicou nossos modelos, porém podemos afirmar que a hipótese de água energia se mostrou como a mais robusta explicação da distribuição de insetos aquáticos em larga escala.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-09-21T11:25:10Z No. of bitstreams: 2 Dissertação - Fernanda Guimarães Fava - 2015.pdf: 1670100 bytes, checksum: 9979efb88c3552d0b60a34d9f6cf82d0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-21T13:58:05Z (GMT) No. of bitstreams: 2 Dissertação - Fernanda Guimarães Fava - 2015.pdf: 1670100 bytes, checksum: 9979efb88c3552d0b60a34d9f6cf82d0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-21T13:58:05Z (GMT). No. of bitstreams: 2 Dissertação - Fernanda Guimarães Fava - 2015.pdf: 1670100 bytes, checksum: 9979efb88c3552d0b60a34d9f6cf82d0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-03-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / To simplify and measure all the great diversity of life on Earth we use models to summarize the processes driving community patterns. The community models structured by deterministic processes are based on species niche. Those models structured by stochastic processes are based on disperson and ecological drift. The spatial scale (i.e. extent) is a very important factor to evaluate the relative importance of deterministic and stochastic processes, because it determines the spatial and environmental heterogeneity. Traditionally, we consider that local species interactions with the environment and other species are important in explaining the diversity at the local level, while in larger geographic scales the differences in species niche could be not so important and these follow a probabilistic distribution of extinction and colonization processes. However, a opposite idea has arisen, that niche could have a greater influence on large scales and stochastic events may predominate at small scales. The organism type is also important for assemblies studies due to differences in dispersal ability. Tadpoles depend on the adult form to disperse and frogs generally have low movement ability. Thus, the spatial scale and the organism type will determine the relative importance of deterministic and stochastic factors in assemblies studies. / Para simplificar e conseguir mensurar toda a diversidade biológica existente na Terra utilizamos modelos que tentam sumarizar os processos que governam as comunidades. Modelos de comunidades estruturadas por processos determinísticos são baseados no nicho das espécies, enquanto os modelos de comunidades estruturadas por processos estocásticos são baseados na dispersão e deriva ecológica. A escala (aqui referida como extensão espacial) é um fator muito importante na avaliação da importância relativa de processos determinísticos e estocásticos, pois ela influencia a variação espacial e a heterogeneidade ambiental. Tradicionalmente, consideramos que as interações locais de espécies com o ambiente e outras espécies são importantes para explicar a diversidade em nível local e que em escalas geográficas maiores as diferenças no nicho das espécies podem não ser importantes, seguindo uma distribuição probabilística de processos de extinção e colonização. Porém, uma ideia contrária tem surgido, de que o nicho pode exercer uma maior influência em grandes escalas e eventos estocásticos podem predominar em pequenas escalas. O tipo de organismo também é importante para estudos de assembleias devido às diferenças na capacidade de dispersão. Girinos dependem da forma adulta para se dispersarem e os anuros em geral possuem baixa capacidade de movimentação. Desse modo, a escala e o tipo de organismo vão influenciar a importância relativa de fatores determinísticos e estocásticos em estudos de assembleias.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-02-01T12:17:19Z No. of bitstreams: 2 Dissertação - Marco Túlio Pacheco Coelho - 2016.pdf: 2399407 bytes, checksum: bf89ac5d0151cbcfbf3b3bc2cffb2225 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-02-01T14:11:43Z (GMT) No. of bitstreams: 2 Dissertação - Marco Túlio Pacheco Coelho - 2016.pdf: 2399407 bytes, checksum: bf89ac5d0151cbcfbf3b3bc2cffb2225 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-02-01T14:11:43Z (GMT). No. of bitstreams: 2 Dissertação - Marco Túlio Pacheco Coelho - 2016.pdf: 2399407 bytes, checksum: bf89ac5d0151cbcfbf3b3bc2cffb2225 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-02-24 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / A contemporary goal in ecology is to determine the ecological and evolutionary processes that generates the recurring structural patterns in mutualistic networks. One of the greatest challenges is testing the capacity of neutral processes to replicate observed patterns in ecological networks, since original formulation of neutral theory lacks trophic interactions. Here, we developed a stochastic simulation neutral model adding trophic interactions to the neutral theory of biodiversity. We show that our model is able to reproduce accurately the evolutionary conservatism of interacting species, as well as the most common structural patterns observed in nature. Moreover, we found that evolutionary conservatism of interacting species increases with lowmigration rate.Low migration rates promote both spatial and temporal autocorrelation of phylogenetic related species, which have a higher chance of interacting randomly with the same set of partners. Random migration , in addition to speciation and probability of interaction, are also partially responsible for connectance, degree distribution, and nested structure of mutualistic networks. These findings have broad implications to the interpretation of niche-based processes as unique drives of ecological networks, as well as the integration of network structures with demographic stochasticity. / Um objetivo recente em ecologia é determinar os processos ecológicos e evolutivos capazes de gerar os padrões estruturais recorrentes de redes de interação mutualística. Um dos grandes desafios é testar a capacidade de processos neutros replicarem os padrões observados de redes de interação, já que a formulação original da teoria neutra não abrange interações tróficas. Nesse trabalho, nós desenvolvemos um modelo de simulação estocástico neutro e adicionamos interações tróficas à Teoria Neutra da Biodiversidade. Nós mostramos que o nosso modelo é capaz de reproduzir de maneira precisa a conservação de interações, assim como os mais comuns padrões estruturais de redes interação observados na natureza. Além disso, nós encontramos que a conservação de interações decresce com o aumento da taxa de migração, uma vez que, baixa taxa de migração promove autocorrelação espacial e temporal de espécies filogeneticamente relacionadas, que por sua vez tem maior chance de interagirem ao acaso com o mesmo conjunto de espécies. Os eventos aleatórios de migração, somados à probabilidade de especiação e interação, são também parcialmente responsáveis pela conectância, distribuição de grau e estrutura aninhada das redes mutualísticas. Esses resultados possuem grandes implicações para a interpretação de processos baseados em nicho como os únicos processos causais na estruturação de redes de interação, assim como a integração da estrutura de redes com estocasticidade de demográfica.

As abundâncias e identidades das espécies de qualquer comunidade biológica mudam tanto ao longo do espaço quanto do tempo. Não obstante, aspectos espaciais da biodiversidade têm sido muito mais explorados do que os temporais. Um dos motivos pelos quais padrões temporais têm recebido menos atenção é a escassez de estudos de longo prazo, especialmente na região neotropical, uma das mais biodiversas e ameaçadas do planeta. Estudar a dinâmica de populações e comunidades ao longo do tempo pode revelar processos ecológicos fundamentais, bem como descrever como pressões naturais e humanas afetam a biodiversidade. Entender a dinâmica das populações e comunidades envolve entender as histórias de vida dos organismos, como eles interagem com o ambiente, o papel de interações entre espécies, o papel de processos demográficos estocásticos, dentre outros fatores. Nesta tese investigamos a dinâmica temporal de populações e comunidades de borboletas e aves, e ao longo dos capítulos avaliamos o papel de diferentes processos na regulação dessas dinâmicas. No Capítulo 1 investigamos se um comportamento sazonal observado em borboletas Ithomiini (Nymphalidae, Danainae), supostamente adaptativo à seca - os \"bolsões de Ithomiini\"- seria uma simples resposta reativa à falta de chuvas ou se mecanismos endógenos (\"relógios biológicos\") estariam envolvidos. No Capítulo 2 realizamos um estudo de dinâmica populacional comparada de borboletas miméticas da tribo Ithomiini. Algumas evidências têm sugerido que além de convergir na morfologia, espécies co-miméticas tenderiam a convergir também no comportamento, no uso de microhabitats e possivelmente em suas dinâmicas populacionais. Testamos as hipóteses de que 1) pares de espécies co-miméticas (i.e., com a morfologia convergente) ou 2) pares de espécies mais próximas filogeneticamente teriam suas dinâmicas populacionais mais correlacionadas do que pares de espécies agrupados ao acaso. No Capítulo 3 descrevemos como a composição de espécies de assembleias de aves e borboletas de nove localidades tropicais e subtropicais na América do Sul e do Norte variou ao longo do tempo (anos a décadas), e se diferenças demográficas entre espécies (nicho) seriam importantes para explicar os padrões observados. No Capítulo 1 encontramos evidências de que a agregações seriam um comportamento endógeno sincronizado com o fotoperíodo, com plasticidade limitada para lidar com as alterações no regime de chuvas previstas para a região e para o continente. No Capítulo 2 encontramos que as dinâmicas populacionais de pares de espécies de Ithomiini de um mesmo anel mimético ou mais próximas filogeneticamente não tenderam a ser mais correlacionadas do que pares reunidos ao acaso, e que as espécies, anéis miméticos e subtribos estudadas tiveram suas dinâmicas temporais mais correlacionados do que seria esperado por acaso. Estes resultados e os do Capítulo 1 sugerem que na dinâmica desse sistema as pressões seletivas exercidas por fatores ambientais seriam mais importantes do que interações entre espécies. No Capítulo 3 mostramos que a composição de espécies de assembleias de aves na Amazônia, Cerrado, Mata Atlântica e Flórida se alterou ao longo dos anos, mesmo em assembleias de áreas bem preservadas. Sobreposta a essa rotatividade (turnover) interanual também encontramos rotatividade sazonal, previsível, na composição de espécies de assembleias de aves da Amazônia e da Mata Atlântica e na assembleia de borboletas Ithomiini. Padrões de rotatividade sazonal na composição de espécies podem ser mais comuns em comunidades neotropicais do que se imagina. As estratégias temporais dos organismos neotropicais, as quais parecem ser a base dos padrões sazonais observados nas comunidades, podem ser largamente determinadas por ritmos (\"relógios\") endógenos. Estudos sobre a regulação dos ritmos e estratégias temporais dos organismos, e dos efeitos das mudanças climáticas e do uso do solo sobre eles, são essenciais. Um importante passo nesse sentido é a disseminação de estudos de longo-prazo de populações e comunidades, contínuos, sistemáticos e com resolução para detectar padrões sazonais. Além disso, a interação das perspectivas, bases teóricas e abordagens da biologia molecular, fisiologia, cronobiologia e ecologia pode avançar nosso entendimento sobre os processos que moldam a dinâmica da biodiversidade e sobre as consequências das perturbações humanas sobre os ecossistemas / The species abundances and identities of any biological community change both over space and time. Nevertheless, Spatial biodiversity dimensions have been much more exploited than temporal ones. One of the reasons for which temporal patterns have received less attention is a scarcity of long-term studies, especially in the neotropical region, one of the most biodiverse and endangered on the planet. Studying the dynamics of populations and communities over time can reveal key ecological processes as well as describe how natural and human pressures affect biodiversity. Understanding the dynamics of populations and communities involves understanding organisms life histories, how they interact with the environment, the role of interactions among species, the role of stochastic demographic processes, and other factors. In this dissertation we investigated the temporal dynamics of butterflies and birds populations and assemblages, and throughout its chapters we evaluate the role of different processes in the regulation of dynamics. In Chapter 1 we investigated whether a seasonal behavior observed in butterflies Ithomiini (Nymphalidae, Danainae), supposedly adaptive to dissecation - the \"Ithomiini pockets \" - is a simple reactive response to drought or there is internal time-keeping mechanisms involved. In Chapter 2, we performed a comparative population dynamics study of mimetic butterflies of the Ithomiini tribe. Some evidence has suggested that besides the convergence in morphology, co-mimetic species would tend to converge also in behavior, in the use of microhabitats and possibly in their population dynamics. We hypothesized that (1) pairs of co-mimetic species or (2) pairs of species more phylogenetically related would have their population dynamics more correlated than pairs of species grouped at random. In Chapter 3 we described how species composition of bird and butterfly assemblages from nine tropical and subtropical locations in South and North America varied over time (years and decades), and if demographic differences between species (niche) are needed to explain observed patterns. In Chapter 1 we found evidence that Ithomiini pockets are regulated by internal time-keeping mechanisms synchronized to photoperiod, and that mechanism has limited plasticity to cope with rainfall regime changes predicted for the study region and for the continent as a whole. In Chapter 2 we found that the population dynamics of Ithomiini species pairs more phylogenetically related or belonging to the same mimetic ring did not tend to be more correlated than pairs assembled at random, and that the species, mimetic rings and subtribes had their temporal dynamics more correlated than would be expected By chance These results and those of Chapter 1 suggest that this system dynamics is more influenced by selective pressures exerted by environmental factors than by species interactions. In Chapter 3 we show that the composition of bird assemblages in the Amazon, Cerrado, Atlantic Rainforest, and Florida has changed over the years, even in assemblies of well-preserved areas. Superimposed to this interannual turnover we also found seasonal, predictable turnover in species composition of bird assemblages of the Amazon and Atlantic Forest and in the Ithomiini butterflies assembly. Patterns of seasonal turnover in species composition may be more common in neotropical communities than is imagined. The temporal strategies of neotropical organisms, which appear to be the basis of the seasonal patterns observed in communities, can be largely determined by endogenous rhythms (\"biological clocks\"). Studies on the regulation of organisms\' temporal rhythms and strategies, and the effects of climate change and land use on them, are essential. An important step in this direction is the dissemination of continuous, systematic, population and community long-term studies, with sampling resolution to detect seasonal patterns. In addition, the interaction of perspectives, theoretical basis, and approaches of molecular biology, physiology, chronobiology, and ecology can advance our understanding of the processes that shape biodiversity dynamics and the consequences of human disturbances on ecosystems