Metacommunties are sets of interacting species embedded in landscapes and interconnected via dispersal. The development of metacommunity theory has greatly outpaced its experimental testing. This situation restricts the feedbacks between theory and natural systems, hindering the development of useful theory and limiting application of theory to natural patterns. My dissertation aims to accelerate the testing of metacommunity theory using three microcosm experiments ranging from highly to more loosely constrained. The first experiment implemented a competition-colonization tradeoff between two strains of bacteria and tested if the tradeoff produced the expected patterns of coexistence and ecosystem function. Generally, the results conformed closely to theoretical expectations, though high stochasticity limited coexistence. The second experiment utilized multi-trophic protist communities to test if assembly history followed by complete mixing can produce situations where one community replaces another. Results indicate that community replacement can occur under mixing, though it may be buffered by trophic structure. The third experiment tested the ability of variance partitioning to attribute landscape patterns to process in a one-predator two-prey system. Results indicate that both predators and dispersal can generate similar spatial patterns. Distinguishing between the two requires explicitly incorporating the predator into the partition. In summary, each of these three experiments reinforces aspects of existing theory while illuminating new paths for future theoretical and empirical exploration. / text

Environmental conditions, biotic interactions, dispersal and history have been suggested to be important processes influencing the spatial distribution of organisms and thus to affect community assembly. Understanding how these processes influence community assembly is important, particularly because community diversity and composition are suggested to be relevant for ecosystem functioning. Moreover, bacteria are strongly contributing to nutrient and carbon cycle. Bacteria are highly abundant and ubiquitous, and thus it is relevant to study how they are assembled. This thesis aims to gain insight on the role of these processes on aquatic bacterial community assembly, diversity and functioning. The studies included in this thesis involve transplant and microcosm experiments performed in the lab as well as manipulation experiments and field surveys in a natural rock pool systems. Bacterial community composition was addressed by analysis of 16S rRNA gene and community functioning by measuring bacterial production, community respiration and the ability to use different carbon substrates. This thesis highlights that species sorting is a very important assembly mechanism for bacterial communities, but also finds that other processes such as dispersal and history contribute to the patterns observed. Dispersal caused rescuing effects compensating for losses of diversity; at the same time it increased the similarity between communities. Moreover, bacteria have shown a high level of functional plasticity when colonizing a new locality. Interestingly, past environmental conditions explained the structure of bacterial communities better than present-day environmental conditions. Disturbances and biotic interactions are also important in the assembly of communities. Disturbance caused temporary shifts in bacterial function and changes in composition, the magnitude of which depended on the intensity and the frequency of the disturbance. However, natural aquatic bacterial communities showed quite high resilience capacities. Competition can shift the proportion of generalists and specialists species whereas predation or trophic interactions have been found to decrease diversity and to modify the importance of stochasticity. Both caused alterations of community functioning. Finally, this thesis shows that the diversity-functioning relationship is context dependent. Further research should be directed to understanding the intensity and direction of changes in composition and how this affects the functionality of bacterial communities

The meta-ecosystem concept is an attempt to combine metacommunity, ecosystem and landscape ecology. In meta-ecosystems, both organismal dispersal and material movement between patches can have important effects on communities. This concept provides a more realistic framework of natural systems by considering both processes jointly. My dissertation presents a case-study of natural metaecosystems by studying the role of waterfowl in structuring zooplankton communities in prairie pothole wetlands in South Dakota. I use observations of natural wetlands, microcosm and mesocosm experiments to show how dispersal of materials and organisms by waterfowl can affect zooplankton abundance and community composition. Waterfowl are conspicuous, behaviorally adaptable, highly mobile and economically important members of wetland habitats. They are thought to have possible effects on zooplankton communities either by dispersing zooplankton propagules among wetlands or by moving nutrients into (via defecation) or out of (via consumption of macrophytes and invertebrates) wetlands. In this dissertation, I show evidence that waterfowl disperse a limited subset of locally rare zooplankton species between wetlands. I also provide experimental evidence that these dispersed species may have impacts on zooplankton community assembly. I also show how input of waterfowl excreta may sometimes have strong impacts on the local community. Very large inputs of goose excreta promote abundance and diversity of zooplankton. However, inputs at more modest levels, such as those routinely found in nature, are rarely detectible. Additions of excreta at levels five-times that typically found in nature produce a possible shift in zooplankton community structure away from both no-excreta communities and communities fertilized with comparable amounts of nitrogen and phosphorus. I postulate that most excreta quickly sinks to the benthos and only a small fraction becomes available for use by zooplankton. On the time scales used in my dissertation, it is only with very large additions of excreta that shifts in the zooplankton community become apparent. My dissertation is one of the first to apply the meta-ecosystem concept to a natural system. It also shows that waterfowl impacts on the zooplankton community may be most important in small wetlands or early in community assembly. / text

Climate change can affect northern aquatic systems causing changes in the composition of resident species through either evolutionary or ecological processes. Rock pools near Churchill, Manitoba, Canada provide an ideal study system for studying the effect of environmental change in a metacommunity context, since salinity of the pools has increased significantly over the past quarter century, and dispersal between habitats is important in this landscape. I used a field experiment to study how zooplankton communities respond to increased salinity with two levels of dispersal limitation and three seasonal levels. I found that experimental zooplankton communities shifted from freshwater to more saline communities after a time lag of three weeks, and that highly connected pools became more similar to saline control communities faster than isolated pools. Moreover, freshwater communities manipulated later in the season changed faster to saline communities. This study highlights the metacommunity concept as a useful tool for studying environmental change. / This thesis has already been submitted to Graduate Program Services in hard copy and approved, however I was advised that I could upload it for electronic distribution as well.

Submitted by FABIANA DA SILVA FRANÇA (fabiana21franca@gmail.com) on 2017-12-20T15:24:12Z No. of bitstreams: 1 Arquivo Total.pdf: 8515282 bytes, checksum: 4c0688932ebc2cf358d850e2dd846f4e (MD5) / Made available in DSpace on 2017-12-20T15:24:12Z (GMT). No. of bitstreams: 1 Arquivo Total.pdf: 8515282 bytes, checksum: 4c0688932ebc2cf358d850e2dd846f4e (MD5) Previous issue date: 2015-03-27 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The Atlantic Forest is home bristle 1-8% of all the flora and fauna of the world. In particular bats this biome represent about 64% of all species of bats in Brazil. Data on the composition and abundance of species of bat communities have never been synthesized and analyzed, as well as data about the spatial distribution and structure of bat communities in this biome, especially as their dissimilarity in a meta community perspective that can be broadly defined as a set of ecological communities in different locations (potentially, but not necessarily connected by dispersion), while a community is a group of species in a given location. In view of this I sought to evaluate the spatial pattern of collections made in this biome and the structuring of bat communities along the Brazilian Atlantic Forest, as its beta diversity. Therefore gather a database of 57 articles totaling 342 locations through literature review. Realized statistics focused on spatial distribution of sampling, the sampling effort (median: 19140h.m²) and for the analysis of beta diversity and metacomunidades. The results show that there are collections across the Atlantic Forest with higher density in PR outbreaks, south of Rio de Janeiro, PB-PE, south of Bahia. Sampling gaps are reported in ES, AL, CS and RS. The bat communities along the Brazilian Atlantic Forest has a high heterogeneity (~0.9) mainly due to the turnover component and a low component of nesting. This result is valid for analysis in four spatial scales: locations, grid 2.5°, 5 and between 4 biogeographic regions of the Atlantic. The structure of arrays of occurrence of species per sample unit (as defined above) presentam a random structure (non-coherent) without latitudinal gradient. Four inventories were conducted in four biogeographical regions of the Atlantic Forest biome within the project Network Inventory: diversity patterns, biogeography and endemic species of mammals, birds, amphibians, fruit flies and parasites in the Atlantic Forest (CNPq / PPBIO) in the rainy season totaling a 99.600 h.m² effort. 935 bats were collected, and tissue samples for DNA extraction purpose and parasitological diagnosis of trypanosomes (T. cruzi et Leishmania spp.), Hantavirus and helminths. The place with the highest species richness was the APA Pratigi BA, followed by Rebio Guaribas, PB; Serra dos Orãos, RJ State Park and the Sierra Board, SC. Recorded the first occurrence of the bat Ametrida centurio Grey, 1847 for the Atlantic Forest, extending its distribution in more than 1000 km. The specimen was collected using canopy networks to 9m in REBIO Guaribas. / A Mata Atlântica abriga cerda de 1-8% de toda a flora e fauna do mundo. Em particular os morcegos deste bioma representam cerca de 64% do total de espécie de quirópteros do Brasil. Dados sobre a composição e abundância de espécies de comunidades de morcegos nunca foram sintetizados e analisados, assim como dados a cerca da distribuição espacial e estruturação das comunidades de morcegos neste bioma, sobretudo quanto a sua dissimilaridade sob uma perspectiva de metacomunidade que pode ser amplamente definida como um conjunto de comunidades ecológicas em locais diferentes (potencialmente, mas não necessariamente ligados por dispersão), enquanto que uma comunidade é um grupo de espécies em um determinado local. Em vista disto busquei avaliar o padrão espacial de coletas realizadas neste bioma e a estruturação das comunidades de morcegos ao longo da Mata Atlântica brasileira, quanto a sua beta diversidade. Para tanto reuni um banco de dados de 57 artigos somando 342 localidades através de revisão da literatura. Realizei estatísticas voltadas a distribuição espacial de coletas, do esforço amostral (mediana: 19140h.m²) e para a análise de beta diversidade e metacomunidades. Os resultados apontam que existem coletas em toda a Mata Atlântica com focos de maior densidade no PR, sul do RJ, PB-PE, sul da BA. Lacunas de amostragem publicadas se encontram no ES, AL,SC e RS. As comunidades de morcegos ao longo da Mata Atlântica brasileira tem uma heterogeneidade alta (~0.9) explicada principalmente pelo componente de Turnover e com um baixo componente de aninhamento. Este resultado é valido para analises em 4 escalas espaciais: localidades, grades de 2,5º, 5º e entre as 4 regiões biogeográficas da Mata Atlântica. A estruturação das matrizes de ocorrência de espécies por unidade amostral (como definido acima) apresentam uma estruturação aleatória (não coerente), sem gradiente latitudinal. Oito inventários foram realizados nas quatro regiões biogeográficas da Mata Atlântica dentro do projeto Rede BioMA Inventários: Padrões de diversidade, biogeografia e endemismo de espécies de mamíferos, aves, anfíbios, drosófilas e parasitos na Mata Atlântica (CNPq/PPBIO) na estação chuvosa totalizando um esforço de 99.600 m²h. Foram coletados 935 morcegos, assim como amostras de tecidos para fins de extração de A.D.N. e de diagnósticos parasitológicos de tripanossomatideos (T. cruzi et Leishmania spp.), Hantavirus e Helmintos. A localidade com maior riqueza de foi a APA do Pratigi BA, seguido da Rebio Guaribas, PB; Serra dos Orãos, RJ e Parque Estadual da Serra do Tabuleiro, SC. Registrei a primeira ocorrência do morcego Ametrida centurio Grey, 1847 para a Mata Atlântica, estendendo sua distribuição em mais de 1000 quilômetros. O espécime foi coletado utilizando redes de dossel a 9m na REBIO Guaribas.

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Metacommunity ecology explicitly incorporates processes at multiple spatial scales to explain the assembly and dynamics of a community. In a metacommunity, local communities interact with one another through the dispersal of individuals across a region. As such, metacommunities are molded by two sets of processes: local and regional. Local factors are those that directly impact a single local community, such as environmental conditions, competition, and predation. On the other hand, regional factors affect communities across a landscape and include mechanisms such as, immigration and emigration. The potential interactions between local and regional factors make metacommunity dynamics a unique body of theory when compared to classic community theory. However, while the direct influence of dispersal on metacommunity dynamics continues to be a well-researched topic, how dispersal interacts with local factors to shape metacommunity dynamics is a more open topic. In particular, one continuing gap in my knowledge is how dispersal interacts with biotic effect how it may affect metacommunities. One type of local biotic process that can directly affect communities is a strong interactive species, i.e., a species that affects community structure and diversity, and to the best of my knowledge, the interaction between dispersal and strongly interactive species has not been directly addressed experimentally. In the following study, I investigated the interaction of dispersal and a strong interactive species on metacommunity diversity and assembly. I chose Daphnia magna as my strong interacting species due to its biological and physical traits. Dispersal is known to create predictable patterns of diversity as it increases in a metacommunity. We made logical predictions based off of my knowledge of these patterns, and my inclinations regarding how dispersal would interact with a strong interacting species. The following predictions were made in relation to the control: 1) Alpha diversity would be the highest during low dispersal as new species would be introduced and maintained above the extinction threshold. I also predicted beta diversity would decrease with increased dispersal due to the homogenization of communities. 2) In the presence of D. magna, beta diversity would only increase during low dispersal due to possible rescue effects. 3) Temporal variability would decrease for the low dispersal treatment and increase for the high dispersal treatment in the absence of D. magna. 4) Temporal variability would overall increase across all treatments in the presence of D. magna. To carry out the study, I assembled outdoor mesocosms using a 2x3x3x4 factorial design (Daphnia Treatment: no addition of D. magna, addition of D. magna; Dispersal Treatment: no dispersal, low dispersal, high dispersal; three buckets were equivalent to one metacommunity; 4 replicates). There was a significant interaction between D. magna and dispersal. Over time, beta diversity decreased as communities became homogenized; however, the no dispersal treatment homogenized at a slower rate compared to the other treatments. In addition, D. magna appeared to create local selection for certain taxa resulting in the increase of Bosmina and Simocephalus while other taxa decreased, for example Streblocerus. This trend was likely due to the feeding and grazing habits of D. magna which is known to outcompete other large zooplankton for larger phytoplankton taxa. Lastly, D. magna directly influenced temporal variability of metacommunities in the experiment. In particular, the low dispersal treatment increased in temporal variability in the presence of D. magna. Again, this result could likely be attributed to D. magna effects selecting for certain taxa, or by the re-introduction of new or dying species with each dispersal through rescue effects. Overall, the results in my study supported majority of my predictions. It is clear that D. magna had an effect on communities as taxa abundances increased and beta diversity in the no dispersal treatment did not decrease as quickly. This result suggests that the introduction of D. magna as an invasive to non-local waters could pose a threat to local community dynamics. It is important to understand how a strong interactive species can affect communities across a landscape as they can greatly alter diversity and composition. Future studies should focus on expanding the dispersal gradient and incorporating a local strong interactive species and non-local strong interactive species to understand how they may change community dynamics. / Master of Science

A fundamental question of long standing in the study of life on Earth is, “Why are there so many species?” This question concerns the distribution of and relationships among species in the present day, but also requires an understanding of the history of diversity. Patterns of diversity result from multiple, interconnected ecological processes operating at different spatial scales. The goal of this research is to gain knowledge about processes that control diversity by using fossil data to provide a temporal perspective that is unavailable when studying modern ecological communities. The fossil record provides the only natural historical account of changes in the diversity of ecological communities in Earth’s past. This research examines the taxonomic composition and diversity of brachiopod paleocommunities in the Delaware Basin of west Texas (Guadalupe Mountains National Park). The study interval is the Bell Canyon Formation, a 5.4-Myr interval of upper Middle Permian (Capitanian) siliciclastic and carbonate rocks deposited on the toe-ofslope of the basin. Silicified brachiopods extracted from the carbonate rocks provide the basis to test two hypotheses: (1) the taxonomic composition of local fossil brachiopod paleocommunities remains uniform, and (2) the changes in diversity of local fossil brachiopod paleocommunities reflects the relative importance of regional processes. Multivariate analyses of clustering analysis and ordination, diversity partitioning, and rank abundance plots are used to evaluate brachiopod taxonomic composition and diversity within an ecological framework. Sequence stratigraphic analysis provides the means to place the results within an environmental context related to sea-level changes. Results indicate that the reorganization of brachiopod paleocommunity structure coincides with major basinal-scale disruptions. Large disruptions allowed rare taxa and invaders from outside the basin to become dominant within paleocommunities. The dynamics within paleocommunities do not appear to prevent the replacement of the incumbent taxa with new taxa. The importance of these findings indicate that paleocommunities are not static through this interval and can be perturbed into configurations with new dominant taxa. Therefore, ecological responses of paleocommunities are resolvable at the geological time scale.

The kingdom Fungi is taxonomically and ecologically diverse, containing an estimated 1.5 million species. Fungi include decomposers, pathogens, and plant and animal mutualists. Many fungi are microorganisms, and the processes shaping microbial diversity may be fundamentally different from those that shape plants and animals. However, ecologists do not yet fully understand how fungal species are distributed over space and time. Using fungi that inhabit the water of Sarracenia carnivorous pitchers, I describe inter and intraspecific fungal diversity and investigate the processes that shape fungal diversity. I introduce these concepts in Chapter 1. In Chapter 2, I describe changes in fungal species diversity over space and time. I enumerated fungal species in five Sarracenia populations across the United States and Canada, and show that thousands, but not hundreds of kilometers separate distinct fungal communities. I also sampled a single Sarracenia population over a Sarracenia growing season, and found that young fungal communities are significantly different from older fungal communities. Observed patterns correlate with environmental factors including temperature and pitcher pH, and with the presence or population structure of pitcher inhabiting arthropods. In Chapter 3, I describe dispersal of and competition among three common pitcher fungi. I tracked Candida glaebosa, Rhodotorula glutinis, and Pseudozyma aphidis appearances in pitchers in a single Sarracenia population, and show that different appearances reflect different dispersal times. I also describe interactions between dispersal and competition in microcosms: high numbers of propagules introduced into a microcosm give a competitive advantage to investigated fungi. In Chapter 4, I describe changes in genotype composition of a population of Candida glaebosa, which is widespread and abundant in pitchers, and disperses early in the season. I observed three C. glaebosa populations in five locations; C. glaebosa population structure does not reflect broader community structure as described in Chapter 2. Population structure instead correlates with host taxonomy, and I contrast inter and intraspecific diversity patterns and the processes that potentially cause such patterns.

In many habitats, species’ traits correspond strongly to local environmental conditions. The cause of this pattern may be in-situ evolution, where initially mal-adapted resident species evolved traits that increased their fitness. Alternatively, species with suitable traits may have colonized the focal habitat and replaced resident species. Since theories in the fields of evolutionary biology and community ecology developed independently, few guidelines tell us when to expect evolutionary adaptation or ecological species replacement as the primary driver of species and trait composition in a given habitat. The goal of my dissertation research was to explain how evolutionary adaptation and ecological species replacement together determine the composition of pond zooplankton communities. I combined theoretical models with thorough surveys of natural pond communities and manipulative experiments. I discovered that one particular zooplankton species, Daphnia pulex, evolved to have different trait values in ponds with different environments. The evolutionary divergence within D. pulex profoundly affected its ecological interactions with other zooplankton species. D. pulex populations diverged from one another so much that they differed in their ability to successfully colonize ponds full of competing zooplankton species. I also used a computer simulation model to determine when a community’s trait changes were explained by evolutionary adaptation or ecological species replacement. The dispersal rate of species among habitats and the amount of genetic variance within these species both influenced adaptive trait change in a community. The group of research studies that indicate evolutionary and ecological processes operate on a similar time scale is small but growing. My dissertation research provides another crucial demonstration that evolution within individual species, such as D. pulex, influences their community ecological interactions with other species. I also identified key parameters (dispersal rate among and genetic variance within species) that may help biologists predict whether evolution or ecological species replacement explained adaptive trait change. My projects mostly concern the community and trait distributions that result from the assembly of species in new habitats. However, this framework may inform studies of community response to environmental changes such as invasive species or habitat destruction. / text