https://repositorio.ufu.br/handle/123456789/5482 2026-10-07T15:27:01Z https://repositorio.ufu.br/handle/123456789/50539 Title: Fogo e parões de interação aranha-planta no cerrado: impactos em comunidades associadas a recursos florais Abstract: Understanding how environmental disturbances shape ecological interactions is fundamental for biodiversity conservation, especially in fire-adapted biomes like the Cerrado. Fire acts as a severe environmental filter, drastically altering vegetation structure and resource availability, which imposes challenges to maintaining the associated arthropod fauna. In this study, we investigated the impacts of a fire event on the abundance and richness of spiders associated with flowering plants, evaluating the mediating role of extrafloral nectaries (EFNs) and floral complexity in the maintenance of these communities. The research compared data collected in the same area during pre- and post fire periods. We observed that the occurrence of fire resulted in a sharp reduction in spider abundance and richness, in addition to modifying the plant community composition. Plants exclusive to the pre-fire period sustained the highest spider densities, indicating that post fire plant species turnover affects the associated fauna. Furthermore, the presence of EFNs proved to be a significant factor for spiders: plants bearing these structures consistently harbored greater spider abundance and richness, as well as the highest number of inflorescences per plant and flowers per inflorescence, regardless of the period. Our results suggest that, although fire causes negative impacts through habitat simplification, plant functional traits, such as the presence of EFNs, play a vital role in the resilience and structuring of arthropod communities in post-disturbance scenarios. 2026-07-27T00:00:00Z https://repositorio.ufu.br/handle/123456789/50395 Title: Aspectos do crescimento e desenvolvimento de plântulas de Cattleya walkeriana Gardner visando sua aclimatação ex vitro para reintrodução e conservação Abstract: In vitro propagation of plant species is a biotechnological tool widely used in the conservation of rare, endangered, or difficult-to-propagate species, such as Orchidaceae. Orchids produce small seeds with limited reserves, often depending on mycorrhizal fungi for germination and initial establishment. Although in vitro cultivation enables overcoming these limitations, plantlets develop under highly controlled conditions, including high humidity, low irradiance, supplementation with sugars and growth regulators, and restricted gas exchange, resulting in individuals poorly adapted to external environments. Therefore, the acclimatization phase represents one of the main bottlenecks in propagation. Many orchids are epiphytic and, in nature, establish themselves on host trees, whose bark physical and structural characteristics may influence germination and the early development of new plantlets. In addition to the substrate, light availability and dependence on atmospheric water sources are determining factors for epiphytes. Cattleya walkeriana Gardner is an epiphytic orchid endemic to Brazil, threatened with extinction and associated with environments characterized by strong seasonal water availability and high light variability. In this context, this study aimed to understand how abiotic factors influence the survival and initial performance of C. walkeriana plantlets during ex vitro acclimatization. In the first chapter, the effects of different substrates on the morphophysiological performance of micropropagated plantlets were investigated, including commercial substrates and a native-origin substrate, as well as the potential role of foliar water uptake as a compensatory mechanism. In the second chapter, the combined effects of irrigation regimes and irradiance on growth, water status, photochemical efficiency, chlorophyll indices, photoprotective mechanisms, and crassulacean acid metabolism (CAM) were evaluated 2026-07-29T00:00:00Z https://repositorio.ufu.br/handle/123456789/50199 Title: Seasonality and extrafloral nectaries shape plant–spider networks Abstract: Extrafloral nectaries (EFNs) are key plant traits mediating multitrophic interactions, yettheir role in structuring plant–spider communities at the network level remains poorlyunderstood. Here, we provide the first empirical network analysis of plant–spider interactionsin the Brazilian Cerrado, evaluating how EFNs and climatic seasonality shape interactionarchitecture and community composition. From October 2020 to September 2021, wequantified spider occurrences on flowering plants with and without EFNs across dry and rainyseasons and constructed quantitative bipartite interaction networks. We analyzed connectance,nestedness, modularity, and specialization, comparing observed values against null modelexpectations. Plant–spider networks exhibited highly non-random structures, with EFN-bearingplants promoting lower specialization and significant modularity across seasons. Contrary toexpectations, connectance was higher during the dry season, while null models revealed thatbiological constraints limited interaction realization even under high resource availability.Seasonal shifts strongly altered network topology but did not affect spider species composition,which remained stable across plant types and seasons. Our results indicate that EFNs act asstructural hubs that reorganize interaction patterns without driving species turnover,highlighting the importance of facultative interactions and behavioral flexibility in maintainingcommunity stability in seasonal savanna ecosystems. 2026-07-29T00:00:00Z https://repositorio.ufu.br/handle/123456789/50036 Title: Diversidade quimiossensorial: o papel do órgão vômero-nasal no forrageamento e adaptação evolutiva de lagartos Abstract: Chemoreception plays a fundamental role in the behavior of squamate reptiles, directly influencing prey detection and survival. This study tested the hypothesis that a relationship exists between chemosensory capacity and foraging mode, aiming to (1) investigate lipid discrimination capabilities in active-foraging versus sit-and-wait lizards; (2) record food choices among different prey types; and (3) examine the importance of vision in the foraging process for each individual. To this end, three behavioral experiments were conducted: the first evaluated individual responses to five treatments; the second observed food choices between prey items with high versus low lipid content; and the third analyzed foraging success in the absence of vision. Results from tests on 145 individuals indicated that active-foraging lizards possessed significantly superior chemosensory capabilities compared to ambush foragers, responding more intensely to the odors of insects, larvae, and saturated fat. Phylogenetic analysis revealed a phylogenetic signal of 35.7%, demonstrating that over one-third of this exploratory behavior is inherited from common ancestors. Without vision, foraging success was limited to species within the Lacertoidea clade, most notably Ameiva ameiva (80.64%). Finally, a significant number of animals did not respond to the dual-choice and foraging experiments; this was associated with behavioral inhibition caused by captivity stress and the choice of prey and substrate. 2026-07-29T00:00:00Z