https://repositorio.ufu.br/handle/123456789/5482 Tue, 25 Aug 2026 19:01:58 GMT 2026-08-25T19:01:58Z https://repositorio.ufu.br/handle/123456789/49825 Title: Relação heterogeneidade da vegetação e diversidade de artrópodes pode ser modulada pela sazonalidade no Cerrado Abstract: Understanding the drivers of arthropod diversity in seasonal ecosystems is fundamental to advancing our knowledge of the ecological processes that structure biological communities. Two of the main mechanisms that explain this dynamic are environmental heterogeneity and climatic seasonality, which act as ecological filters directly influencing species distribution, abundance, and richness. In this context, this study evaluated how structural attributes of woody vegetation: density, biomass, and species richness, combined with seasonal variation throughout the year, affect the diversity of terrestrial arthropods in a cerrado sensu stricto area. The study was conducted at the Reserva Ecológica do Panga, where a grid of 12 plots spaced 200 meters apart was established in a typical Cerrado area. Arthropod fauna was sampled bimonthly over one year using standardized sweep net sampling in the vegetation. Simultaneously, vegetation structure was characterized through a floristic survey in each plot, recording all woody individuals taller than one meter. These data were then used to estimate the density, aboveground biomass, and species richness of woody plants in each plot. The results indicate that, overall, the abundance and richness of terrestrial arthropods showed strong temporal variation, with sharp increases during the rainy season (October to April) and pronounced declines in the dry season (May to September). In contrast, the response to structural variations in vegetation was less consistent and limited to specific periods. Plots with higher density and species richness of woody plants tended to show lower arthropod abundance in certain months, particularly during seasonal transitions, suggesting that denser and more diverse vegetation may act as a physical barrier, restricting arthropod movement, foraging, and sensory communication. On the other hand, plant biomass had occasional positive effects on diversity, particularly during the rainy season when microclimatic conditions are more favorable, and the availability of resources such as shelter and microhabitats is higher. Despite these spatial effects, seasonal patterns proved to be predominant, with temporal variation playing a dominant role in regulating arthropod abundance and richness in the Cerrado. The substantial increase in diversity during the rainy season reflects a direct response to improved environmental conditions, while the dry season imposes severe constraints, resulting in significant reductions in community activity and diversity. Therefore, this study reinforces that, in highly seasonal ecosystems such as the Cerrado, temporal dynamics function as a stronger ecological filter than vegetation structural heterogeneity, highlighting the need to jointly integrate spatial and temporal dimensions to fully understand the processes that shape biodiversity in these environments Tue, 22 Jul 2025 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49825 2025-07-22T00:00:00Z https://repositorio.ufu.br/handle/123456789/48885 Title: Influência da dieta na evolução de Iguania em ambientes florestais Abstract: Stemming from the recent phylogenetic reorganization that positions Iguania as a derived clade within Squamata, this study investigated the hypothesis that the secondary loss of the vomeronasal organ (VNO) may have favored an adaptation to low-lipid diets, thereby facilitating the colonization of forest environments. Through a macroevolutionary meta-analysis of the diets of 62 species, and using Phylogenetic Generalized Least Squares (PGLS) models with prey biomass data standardized by custom regression models, the influence of ecological factors and evolutionary history on dietary lipid content was evaluated. The results refuted the central premise: no significant differences were found in lipid content between lizards from open and forest habitats, nor as a function of foraging mode or thermoregulation. The analysis revealed that lipid content is an evolutionarily labile trait with a nearly null phylogenetic signal, being significantly lower only in species from mixed habitats (ecotones). These findings indicate that dietary lipid composition is shaped by local ecological pressures and does not represent a conserved adaptive syndrome for forest life. More broadly, the results open space for an alternative interpretation: the transition to visually oriented hunting may have acted as an ecological release, enabling Iguania to exploit chemically defended prey and turning an apparent sensory “loss” into an expansion of ecological opportunities. Mon, 20 Oct 2025 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48885 2025-10-20T00:00:00Z https://repositorio.ufu.br/handle/123456789/48870 Title: Estrutura e função dos pneumatódios em raízes de Vanda híbrida (Orchidaceae): do macro ao micro Abstract: The aerial roots present in Orchidaceae have anatomical characteristics that are efficient in optimizing the acquisition and use of water and nutrients. Among them, the formation of the velamen stands out, a simple or multiple epidermis, consisting of cells that die at maturity, which allows orchids to survive in environments with water scarcity or fluctuation. Some species have pneumatodes in the velamen. The aeration units correspond to a set of cells that include the region of the velamen above the aeration cells (the pneumatode), the aeration cells themselves, and the specialized cells of the cortex. The functioning of the aeration units is based on two non-exclusive hypotheses involving passive mechanisms. In this sense, this thesis is based on the central hypothesis that structural, chemical, and physiological variations directly influence the functional performance of the aeration units, modulating their efficiency and response to environmental conditions. It is structured in three chapters. In the first chapter, we propose that the functionality of the aeration units is anchored in the chemical composition of the walls of their different cell types and the rest of the canopy, which depends directly on the composition of their cell walls and adjacent layers, allowing dynamic adjustments in the opening and closing of the aeration channels in response to environmental variations. In the second chapter, we analyze the tolerance of the epiphytic hybrid Vanda subjected to flooding, determining whether the water saturation of the canopy leads to root oxidative stress with a systemic effect on plant metabolism, discussing the role of pneumatodes in root aeration. In the third, we present a summary of the results obtained in the form of scientific dissemination through a brochure, as well as an account of the author's academic experience, emphasizing the importance of pursuing a doctorate and valuing the educational path. Thu, 30 Oct 2025 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48870 2025-10-30T00:00:00Z https://repositorio.ufu.br/handle/123456789/48737 Title: Reversão sexual em peixes Acanthomorpha: distribuição espacial e relacional entre as comunidades Abstract: To think of sex and its associated phenotypic traits as something static, invariant, is an obsolete mentality and incoherent with the evolutionary scenarios that point to multiple origins and convergences of hermaphroditism and sexual reversal among vertebrates. Hermaphroditism is associated with genetic factors and responses to environmental and social stimuli, where phenotypic sexual expression occurs through synchronous or sequential pathways. Sex reversals are classified as protogynous, protandrous or bidirectional. Among vertebrates, the teleost fish (clade Actinopterygii) are the only group to present sex reversal as an evolutionary strategy with multiple independent origins and convergences. A more inclusive and diverse lineage within Teleostei is defined by the clade Acanthomorpha, who has the greatest diversity of sexual strategies, including the most complex sex reversal mechanisms among hermaphroditic fish. This study reviews the literature and explores the global spatial distribution of hermaphroditic bony fish allocated in the specious clade Acanthomorpha with synchronous or sequential sex reversals in marine and freshwater environments. The purpose was to compile information on hermaphroditic fish, their most frequent modes of sex reversal and their respective global geographic distributions to investigate general patterns of sexual evolution in vertebrates and the biogeographic regions that exert extraordinary influences on the structuring of hermaphrodite communities. A literature review was performated to obtain the necessary information about the hermaphroditic species in Acanthomorpha, including: the diversity of valid species, sex reversal strategies and geographic distributions in marine and freshwater biogeographic regions. All information collected was extracted from the literature by searching articles, books and museum catalogs. The geographic distributions of the species were inferred through datasets obtained from metadata repositories available online. In possession of such cleaned dataset, the spatial structuring of communities of hermaphrodite acanthomorphs was investigated using network theory with two different clustering algorithms. As a result, an extensive list was prepared with 223 hermaphroditic species, being 213 marine and 10 freshwater. Of these species, 26 are synchronous hermaphrodites and 197 are sequential hermaphrodites. Among sequential hermaphrodites, 151 are protogynous, 28 are protandrous, and 18 are serial bidirectional. Hermaphrodite acanthomorphs are widely distributed around the planet, occurring in all biogeographic realms, except Subarctic America. They are most diverse in tropic marine regions, with an extraordinary presence in shallow seas with coral reefs in the Indian Ocean (i.e., Indo-Malay and Australasian regions). There is a spatial structuring of hermaphroditic fish communities inhabiting different biogeographic realms, however the number of communities depends on the chosen algorithm. Common between the two algorithms is the existence of a community in the Americas and another distributed in the southern Eurasia, Central and Eastern Eurasia, Afrotropics, Indomalia and Oceania. The diversity of hermaphrodite acanthomorphs in Antarctica is low (e.g., 1 species), so there is no viable hypothesis on the spatial structuring in this region. Depending on the clustering algorithm, communities of hermaphroditic acanthomorphs of the Nordic seas, such as those present in the realms of Western Eurasia and Subarctic Eurasia, form independent communities or cluster with kingdoms located to the east of the planet. Wed, 30 Nov 2022 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48737 2022-11-30T00:00:00Z