https://repositorio.ufu.br/handle/123456789/5482 2026-09-16T08:08:47Z 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 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 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. 2025-10-20T00:00:00Z