Navegando por Orientadores "KOROIVA, Ricardo"

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Acesso aberto (Open Access)
Influência das características morfológicas e do habitat físico sobre a capacidade de dispersão de Odonata em igarapés amazônicos
(Universidade Federal do Pará, 2025-01) PEREIRA, Silvia Rafaela Alves; JUEN, Leandro; http://lattes.cnpq.br/1369357248133029; HTTPS://ORCID.ORG/0000-0002-6188-4386; KOROIVA, Ricardo; http://lattes.cnpq.br/3262687790057613; http://orcid.org/0000-0002-6658-0824
Species' dispersal capacity is directly related to their individual morphological, physiological and behavioral characteristics and to the ecological context in which they live. Species with a lower dispersal capacity tend to be more vulnerable to climate change and more intensive land use. This is due to the loss of vegetation cover and fragmentation leading to a change in habitat connectivity and thermal conditions in the environment. In this study, we investigated the factors affecting the dispersal capacity of adult Odonata in Amazonian streams, focusing on morphological traits and the effects of land use and environmental integrity. We tested the hypotheses: i) body size, thorax volume, and wing base width are positively related to dispersal capacity and wing aspect ratio is negatively related to dispersal capacity; ii) greater forest cover and habitat integrity are negatively related to dispersal capacity, as a larger canopy filters out individuals with lower flight ability. The study was conducted in 12 streams in Barcarena, Pará, Brazil. We used the mark-recapture method and analyzed the data using structural equation modeling. We considered landscape variables (forest formation and pasture), physical habitat variables (channel cover, undergrowth, channel width, habitat integrity index, and temperature), morphological variables (total body length, thoracic volume, and wing aspect ratio) and we used dispersal capacity (distance in meters) as a response variable. 541 individuals were tagged (n=466 Zygoptera e n=75 Anisoptera). The recapture rate was 29% for Zygoptera and 1.4% for Anisoptera. Most of the individuals recaptured were males belonging to the genera Mnesarete, Argia and Hetaerina. Approximately 91% of the individuals moved less than 60 meters. The results, which related only to Zygoptera, partially confirmed the first hypothesis: wing aspect ratio was negatively related to dispersal capacity, suggesting that shorter and wider wings are associated with greater flight ability. However, no direct relationship was found between habitat integrity or forest formation and dispersion, but forest formation and channel width influenced the morphology of individuals' wing aspect ratio. These patterns suggest that genera occurring in forested environments, such as Heteragrion, which have a higher wing aspect ratio, have a lower dispersal capacity, while those adapted to higher temperatures and light availability, such as Mnesarete and Hetaerina, have a lower wing aspect ratio and greater dispersal capacity. We emphasize the vulnerability of individuals with lower dispersal capacity to changes in their aquatic habitats and changes in the surrounding terrestrial landscape due to loss of vegetation cover.
Acesso aberto (Open Access)
Padrão de distribuição de larvas de EPT (Ephemeroptera, Plecoptera, Trichoptera) em riachos na Amazônia Oriental
(Universidade Federal do Pará, 2025-03) RAMOS, Thaiz Maria; JUEN, Leandro; http://lattes.cnpq.br/1369357248133029; HTTPS://ORCID.ORG/0000-0002-6188-4386; KOROIVA, Ricardo; http://lattes.cnpq.br/3262687790057613; http://orcid.org/0000-0002-6658-0824
Dispersal is the movement of organisms between habitats in the landscape. It is essential for the establishment of species in new locations and for the maintenance of genetic diversity in the region. Its efficiency depends on the dispersal capacity of individual species, environmental variables and the distance between habitats. The mechanisms of community structuring and anthropogenic impacts on aquatic invertebrates have been assessed using approaches based on species' functional traits, but the use of this method to determine species' dispersal potential is still understudied. Therefore, the dispersal potential of most species is determined indirectly based on functional traits and mainly using expert knowledge. Based on this scenario, the aim of this dissertation was to evaluate the dispersal pattern of EPT larvae (Ephemeroptera, Plecoptera and Trichoptera) and attempt to classify the dispersal potential of genera based on functional dispersal traits and relate these traits to environmental variables. The dissertation is divided into two chapters. In Chapter 1, we examine how functional dispersal traits of EPT larvae are related to environmental conditions of rivers in the eastern Amazon. Most of the traits and their categories were negatively or positively related to some of the nine physicochemical variables selected in the study. Thus, we confirm the fact that environmental conditions influence the composition of functional dispersal traits. In Chapter 2, we classify the dispersal potential of the genera of EPT larvae based on the functional dispersal traits and after consultation with experts of each order. The Ephemeroptera was the order with the most genera with high dispersal potential, while the Plecoptera genera had medium and low values for dispersal. The Trichoptera genera had very different values for dispersal potential. We also investigated whether the dispersal ability of EPT larval genera was reflected in their abundance and prevalence in the rivers of eastern Amazonia, which was not confirmed. In our study, we found that functional traits, whether related to dispersal or not, are excellent tools to be used as proxies.