Repositório RCAAP

Many studies have revealed the ability of the endosymbiotic bacterium Wolbachia to protect its arthropod hosts against diverse pathogens. However, as Wolbachia may also increase the susceptibility of its host to infection, predicting the outcome of a particular Wolbachia-host-pathogen interaction remains elusive. Yet, understanding such interactions and their eco-evolutionary consequences is crucial for disease and pest control strategies. Moreover, how natural Wolbachia infections affect artificially introduced pathogens for biocontrol has never been studied. Tetranychus urticae spider mites are herbivorous crop pests, causing severe damage on numerous economically important crops. Due to the rapid evolution of pesticide resistance, biological control strategies using entomopathogenic fungi are being developed. However, although spider mites are infected with various Wolbachia strains worldwide, whether this endosymbiont protects them from fungi is as yet unknown. Here, we compared the survival of two populations, treated with antibiotics or naturally harboring different Wolbachia strains, after exposure to the fungal biocontrol agents Metarhizium brunneum and Beauveria bassiana. To control for potential effects of the bacterial community of spider mites, we also compared the susceptibility of two populations naturally uninfected by Wolbachia, treated with antibiotics or not. In one population, Wolbachia-infected mites had a better survival than uninfected ones in absence of fungi but not in their presence, whereas in the other population Wolbachia increased the mortality induced by B. bassiana. In one naturally Wolbachia-uninfected population, the antibiotic treatment increased the susceptibility of spider mites to M. brunneum, but it had no effect in the other treatments. These results suggest that natural Wolbachia infections may not hamper and may even improve the success of biological control using entomopathogenic fungi. However, they also draw caution on the generalization of such effects, given the complexity of within-host-pathogens interaction and the potential eco-evolutionary consequences of the use of biocontrol agents for Wolbachia-host associations.

Biological control is widely successful at controlling pests, but effective biocontrol agents are now more difficult to import from countries of origin due to more restrictive international trade laws (the Nagoya Protocol). Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genomic approaches. Although they have been underutilised in the past, application of genetic and genomic techniques is becoming more feasible from both technological and economic perspectives. We review current methods and provide a framework for using them. First, it is necessary to identify which biocontrol trait to select and in what direction. Next, the genes or markers linked to these traits need be determined, including how to implement this information into a selective breeding program. Choosing a trait can be assisted by modelling to account for the proper agro-ecological context, and by knowing which traits have sufficiently high heritability values. We provide guidelines for designing genomic strategies in biocontrol programs, which depend on the organism, budget, and desired objective. Genomic approaches start with genome sequencing and assembly. We provide a guide for deciding the most successful sequencing strategy for biocontrol agents. Gene discovery involves quantitative trait loci analyses, transcriptomic and proteomic studies, and gene editing. Improving biocontrol practices includes marker-assisted selection, genomic selection and microbiome manipulation of biocontrol agents, and monitoring for genetic variation during rearing and post-release. We conclude by identifying the most promising applications of genetic and genomic methods to improve biological control efficacy.

Few studies have tested how plant quality and the presence of competitors interact in determining how herbivores choose between different leaves within a plant. We investigated this in two herbivorous spider mites sharing tomato plants: Tetranychus urticae, which generally induces plant defenses, and Tetranychus evansi, which suppresses them, creating asymmetrical effects on coinfesting competitors. On uninfested plants, both herbivore species preferred young leaves, coinciding with increased mite performance. On plants with heterospecifics, the mites did not prefer leaves on which they had a better performance. In particular, T. urticae avoided leaves infested with T. evansi, which is in agreement with T. urticae being outcompeted by T. evansi. In contrast, T. evansi did not avoid leaves with the other species, but distributed itself evenly over plants infested with heterospecifics. We hypothesize that this behavior of T. evansi may prevent further spread of T. urticae over the shared plant. Our results indicate that leaf age determines within-plant distribution of herbivores only in absence of competitors. Moreover, they show that this distribution depends on the order of arrival of competitors and on their effects on each other, with herbivores showing differences in behavior within the plant as a possible response to the outcome of those interactions.

Nesta dissertação é abordada a equação de Schrödinger não linear no contexto de grafos métricos. Em particular, são seguidos com grande detalhe os artigos de Adami R., Serra E., Tilli P., [NLS ground states on graphs, Calc. Var. (2015) 54:743–761] e [Threshold phenomena and existence results for NLS ground states on metric graphs, J. Funct. Anal. (2016) 271(I):201-223]. O foco destes artigos é a existência ou não existência de soluções de energia mínima, com massa fixa, para o funcional de energia da equação de Schrödinger com um fator não linear do tipo potência em grafos métricos.

Speciation results from the evolution of reproductive isolation between populations. Reproductive barriers can evolve as a direct product of local adaptation, in which individuals discriminate to avoid less fit progeny, or as a by-product of such adaptation. Drosophila subobscura possesses fascinating latitudinal clines for several quantitative traits. However the neutral genetic differentiation among populations is low. Therefore, the maintenance of such clines suggests that reproductive barriers exist between populations. The main goal of the present work was to test whether reproductive barriers between populations from two extremes of the cline exist and, if so, if they decrease or increase over time when these populations invade a new common environment. For that we founded two populations of Drosophila subobscura from Adraga (Portugal) and Groningen (Netherlands). First, the initial differentiation and early adaptation in life-history traits of both populations were characterized. We found that during the first 11 generations the populations showed differences in several life-history traits. However, in general, the populations of both foundations did not exhibit temporal changes across generations. As for the reproductive barriers we found that at an early (fifth) generation, both populations demonstrated a (marginally significant) preference for assortative mating. However, hybrid breakdown was not detected among populations. Five generations later, assortative mating faded away, indicating a relaxation of the selective pressures in the new environment. This study was important as it suggests that, while pre-zygotic barriers may play a role in the maintenance of a latitudinal cline, they fade away quickly during adaptation in a novel, common environment. The study also revealed the need to add a temporal component to studies of reproductive isolation.

The mathematical theory describing small assemblages of interacting species (community modules or motifs) has significantly improved our understanding of the emergent properties of ecological communities. It is not clear whether all interactions accounted for in such models will be realized in real communities. Here, we use community modules to experimentally explore whether the number of trophic links among species scales with community complexity (i.e. by adding species known to feed on each other from pairwise trials) in a simple mite community present in avocado orchards (Persea americana). By varying the presence of each of two predators (Euseius stipulatus and Neoseiulus californicus), one herbivore as shared prey (Oligonychus perseae) and pollen of Carpobrotus edulis as an alternative food resource, we mimicked communities with simple trophic chains, intraguild predation and/or apparent competition. We then assessed predation rates and the conversion of food into offspring in those communities. We found that increasing the number of potential interactions did not result in more complex realized community modules. Instead, all species effectively fed upon a single food item, hence all community modules actually corresponded to one or two linear trophic chains. Therefore, trophic links assumed to occur when species are assembled in pairs do not necessarily occur when other components of the community are present. Consequently, food web structure may be much less complex than predicted by theory.

Aim: Understanding temporal changes in aquatic communities is essential to address the freshwater biodiversity crisis. In particular, it is important to understand the patterns and drivers of spatial variation in local community dynamics, generalizing temporal trends from discrete locations to entire landscapes that are the main focus of management. Here, we present a framework for producing spatially continuous views of community dynamics, focusing on stream fish affected by hydropower development. Location: River Sabor, NE Portugal. Methods: We sampled stream fish at thirty sites between 2012 and 2019. Community trajectory analysis was used to quantify the directionality and velocity of community change, and the geometric resemblance of community trajectories between sites. Geostatistical models for stream networks were used to relate metrics describing community dynamics to environmental variables, while controlling for Euclidean and hydrologic spatial dependencies, and to map spatial variation in community dynamics across the watershed. Results: Trajectories in multivariate space underlined strong temporal dynamics, with local communities deviating and returning to previous states, but without evidence for directional changes. Accordingly, directionality values were low and not consistently affected by environmental variables. The velocity of community change varied markedly across the watershed and it was strongly affected by stream order and elevation, with faster changes observed in lowland streams draining into hydroelectric reservoirs and with a high proportion of exotic species. Pairwise distances between community trajectories were strongly related to hydrologic and environmental distances between sites. Main conclusions: Local stream fish communities were in a loose equilibrium across the watershed, but they fluctuated at a faster rate closer to a hydroelectric reservoir. Integrating community trajectory analysis and geostatistical modelling provides a relatively simple framework to understand how, where and why temporal community dynamics vary across dendritic stream networks and to visualize spatial patterns of community change over time in relation to anthropogenic impacts.

STRUCTURE remains the most applied software aimed at recovering the true, but unknown, population structure from microsatellite or other genetic markers. About 30% of structure-based studies could not be reproduced (Molecular Ecology, 21, 2012, 4925). Here we use a large set of data from 2,323 horses from 93 domestic breeds plus the Przewalski horse, typed at 15 microsatellites, to evaluate how program settings impact the estimation of the optimal number of population clusters Kopt that best describe the observed data. Domestic horses are suited as a test case as there is extensive background knowledge on the history of many breeds and extensive phylogenetic analyses. Different methods based on different genetic assumptions and statistical procedures (dapc, flock, PCoA, and structure with different run scenarios) all revealed general, broad-scale breed relationships that largely reflect known breed histories but diverged how they characterized small-scale patterns. structure failed to consistently identify Kopt using the most widespread approach, the ΔK method, despite very large numbers of MCMC iterations (3,000,000) and replicates (100). The interpretation of breed structure over increasing numbers of K, without assuming a Kopt, was consistent with known breed histories. The over-reliance on Kopt should be replaced by a qualitative description of clustering over increasing K, which is scientifically more honest and has the advantage of being much faster and less computer intensive as lower numbers of MCMC iterations and repetitions suffice for stable results. Very large data sets are highly challenging for cluster analyses, especially when populations with complex genetic histories are investigated.

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Las últimas décadas del siglo XX fueron escenario de innumerables transformaciones a nivel epistémico (Khun, 1962; Feyerabend 1975). Lejos de la matriz axiomática reduccionista y logicista, los epistemólogos analizaron: 1) la diversidad de los modos de producción del conocimiento científico, 2) ampliaron la comprensión de lo que es el conocimiento y 3) teorizaron sobre las complejidades e interrelaciones, tanto en el interior de dominios específicos, como entre diferentes dominios. Surgieron naturalmente Filosofías de la Ciencia externalistas, interdisciplinarias y abiertas. Es en este contexto donde surgen un conjunto de investigaciones que cuestionan la posibilidad y naturaleza de la relación entre Arte y Ciencia. Desde aquellos las colocan en oposición, hasta aquellos que defienden la integración del campo tecnocientífico con el campo de las Humanidades y las Artes. En concreto, esta propuesta es una apuesta por el triángulo formado por el Arte Contemporáneo, la Física Contemporánea y la Filosofía. Esta investigación, desarrollada en el seno de un equipo interdisciplinar con sede en la Universidade de Lisboa, versa sobre el análisis del concepto de “relación” como vínculo entre la Filosofía de la Ciencia (Realismo Estructural Ontológico) y el Arte Contemporáneo. Es, igualmente, una tentativa de explorar cómo el Arte puede contribuir para la comprensión de las preocupaciones y desafíos de la Ciencia Contemporánea, próximos de la hipótesis de la obra de arte como metáfora epistemológica enunciada por U. Eco (1962). Este proyecto pretende complementar un programa de investigación que ha sido muy prolífico en los últimos años (el estudio de las relaciones entre Arte y Ciencia), contribuyendo para una mejor comprensión de este fenómeno, clarificando ambigüedades e imprecisiones. También es expectable que tanto el material publicado como el análisis crítico de la literatura contribuyan para el enriquecimiento de los programas de las disciplinas universitarias en “Ciencia y Arte” en el panorama internacional.

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This project discusses the practical and theoretical developments of the research “The Organic Screen: a visual study” initiated in the Master in Multimedia, Audiovisual Arts, Faculty of Fine Arts, University of Lisbon. It is a series of rehearsal films, which have as their subject organic matter and its possible poetics, visual narratives and reflective capacity - in a perspective focused on organic elements and their “imaginations”. From the concepts of haptic image and its tactility in contact relations between the skin of the film and the skin of the viewer, I seek logic for the image-time in a relationship of proximity and intimacy with nature, reproduced in three films presented here. Finally, the research seeks to glimpse the possibility of an image prior to language, against the logic of a cartesian view. The study of organicity as a new way of looking, building and understanding life, in images that seek to corrupt the boundaries of the screen.

Primary healthcare in Portugal is undergoing a major reform, of which family health units (FHU) are one of the more visible results. This study aimed to evaluate the FHU implementation process from 2006 onwards. Methods from a previous study of primary healthcare implementation in Brazil were used. Dimensions studied included comprehensiveness of care, organization of care, and the political-institutional perspective. The main improvements identified included better availability of care, team work, technical quality of care, innovative management practices, sustainability of the model, working conditions and infrastructure improvements. Main challenges remaining include integration with hospital care, political and institutional gray areas, need for better information systems, integration within health centers and workflow organization. These data may be useful for management decision-makers when making adjustments and corrections in the reform process. Os cuidados de saúde primários de Portugal estão em processo de reforma, sendo as Unidades de Saúde Familiar (USF) uma das principais marcas desse processo. Este estudo teve como objectivo avaliar o processo de implantação das USF a partir de 2006. Utilizou-se metodologia de análise de implantação na mesma área de atenção primária em saúde de um estudo anterior no Brasil. Na análise foram empregadas as dimensões do cuidado integral, da organização dos cuidados e político-institucional. Evidenciaram-se como avanços principais a acessibilidade, trabalho em equipe, qualidade (técnico-científica) dos cuidados, inovações nas práticas de gestão, na sustentabilidade (condições de trabalho) e infraestrutura. Principais desafios: integração com especialidades hospitalares, indefinições político-institucionais, sistemas informatizados, integração nos centros de saúde e organização do processo de trabalho. Estes dados poderão vir a informar os decisores de gestão sobre correções a efetuar no processo de reforma.

This work, in the context of the Art Sciences and focusing on a case study of the artistic practice of Alexandre Farto, also known as Vhils, has the following research objectives: a) to understand the continuous presence and role of portrait in interventions created by Vhils, by analyzing its multiple dimensions as an aesthetic, a plastic, a social and a political modality; b) to analyze the connections between traditional imagery modalities, such as portrait and the new modalities explored in street art; c) to analyze the cleavages between the mainstream art and the outsider art of Alexandre Farto's work and career; d) to identify the contributions of Vhils's work in public places so as to broaden the scope of street art. Starting from a visual imaginary of the art developed in the street, especially from the seventies onwards, in the twentieth century -, and covering issues related to space, artists and different expressions – at first, we intended to characterize the different dynamics of the graffiti and street art manifestations, and then, to contextualize and analyze the interventions of the artist Vhils, by giving a greater emphasis to the work developed in the urban space. Outside the institutionalized space, art submits to its own system of appreciation, differing from that which the works of art exhibited in museums and galleries are subjected to, which can be seen as a strategy to make reality and the public come closer, and which is characterized by the relationship between the work and the place, inevitably leading to a fusion between art and the social context, that integrates the public space and transforms the work of art. In this sense, we analyzed a set of Vhils’s artistic interventions where this relationship with the community is closer and whose dynamics involves the participation and / or collaboration of these individuals in the artistic processes. The city is seen by the artist as something ephemeral and transitory that has long since ceased to be stable, and where everything seems to happen simultaneously. Taking this reality into account, we analyze how Vhils reflects on this urban environment that influences the community in the formation of its individual and collective identity.

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It is difficult to understand plasmid maintenance in the absence of selection and theoretical models predict the conditions for plasmid persistence to be limited. Plasmid-associated fitness costs decrease bacterial competitivity, while imperfect partition allows the emergence of plasmid-free cells during cell division. Although plasmid conjugative transfer allows mobility into plasmid-free cells, the rate of such events is generally not high enough to ensure plasmid persistence. Experimental data suggest several factors that may expand the conditions favorable for plasmid maintenance, such as compensatory mutations and accessory genes that allow positive selection. Most of the previous studies focus on bacteria that carry a single plasmid. However, there is increasing evidence that multiple plasmids inhabit the same bacterial population and that interactions between them affect their transmission and persistence. Here, we adapt previous mathematical models to include multiple plasmids and perform computer simulations to study how interactions among them affect plasmid maintenance. We tested the contribution of different plasmid interaction parameters that impact three biological features: host fitness, conjugative transfer and plasmid loss - which affect plasmid persistence. The interaction affecting conjugation was studied in the contexts of intracellular and intercellular interactions, i.e., the plasmids interact when present in the same cell or when in different cells, respectively. First, we tested the effect of each type of interaction alone and concluded that only interactions affecting fitness (epistasis) prevented plasmid extinction. Although not allowing plasmid maintenance, intracellular interactions increasing conjugative efficiencies had a more determinant impact in delaying extinction than the remaining parameters. Then, we allowed multiple interactions between plasmids and concluded that, in a few cases, a combined effect of (intracellular) interactions increasing conjugation and fitness lead to plasmid maintenance. Our results show a hierarchy among these interaction parameters. Those affecting fitness favor plasmid persistence more than those affecting conjugative transfer and lastly plasmid loss. These results suggest that interactions between different plasmids can favor their persistence in bacterial communities.

Bacterial biofilms have an impact in medical and industrial environments because they often confer protection to bacteria against harmful agents, and constitute a source from which microorganisms can disperse. Conjugative plasmids can enhance bacterial ability to form biofilms because conjugative pili act as adhesion factors. However, plasmids may interact with each other, either facilitating or inhibiting plasmid transfer. Accordingly, we asked whether effects on plasmid transfer also impacts biofilm formation. We measured biofilm formation of Escherichia coli cells harboring two plasmid types, or when the two plasmids were present in the same population but carried in different cells. Using eleven natural isolated conjugative plasmids, we confirmed that some indeed promote biofilm formation and, importantly, that this ability is correlated with conjugative efficiency. Further we studied the effect of plasmid pairs on biofilm formation. We observed increased biofilm formation in approximately half of the combinations when both plasmids inhabited the same cell or when the plasmids were carried in different cells. Moreover, in approximately half of the combinations, independent of the co-inhabitation conditions, one of the plasmids alone determined the extent of biofilm formation - thus having a dominant effect over the other plasmid. The molecular mechanisms responsible for these interactions were not evaluated here and future research is required to elucidate them.

Hygienic measures imposed to control the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and contain COVID-19 have proven effective in controlling the pandemic. In this article, we argue that these measures could impact the human microbiome in two different and disparate ways, acting as a double-edged sword in human health. New lines of research have shown that the diversity of human intestinal and oropharyngeal microbiomes can shape pulmonary viral infection progression. Here, we suggest that the disruption in microbial sharing, as it is associated with dysbiosis (loss of bacterial diversity associated with an imbalance of the microbiota with deleterious consequences for the host), may worsen the prognosis of COVID-19 disease. In addition, social detachment can also decrease the rate of transmission of antibiotic-resistant bacteria. Therefore, it seems crucial to perform new studies combining the pandemic control of COVID-19 with the diversity of the human microbiome.