Navegando por Assunto "Anisoptera"

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Acesso aberto (Open Access)
Effects of marginal vegetation removal on Odonata communities
(Associação Brasileira de Limnologia, 2013-03) CARVALHO, Fernando Geraldo de; PINTO, Nelson Silva; OLIVEIRA JUNIOR, José Max Barbosa de; JUEN, Leandro
AIM: Here we assess the effects of habitat degradation on individuals of the two suborders of Odonata community of Borecaia river sub-basin. More specifically, we tested the hypothesis that Anisoptera richness would be positively affected by removal of vegetation; on the other hand, Zygoptera richness would be adversely affected by virtue of their ecophysiological requirements; METHODS: We selected 10 streams of similar orders, six preserved and four degraded. Streams characterized as preserved had values of Index of Habitat Integrity (HII) above 0.70 (0.77 ± 0.07, mean ± SD) and continuous forest on both sides with a minimum width of 70 meters. Each site was sampled three times on different days. The effect of vegetation removal on richness was assessed using richness estimated by first order Jackknife; RESULTS: Decreased physical integrity (measured with IIH) of streams had no significant effect on the estimated richness to Odonata in general. However, the estimated richness of Anisoptera showed an inverse relationship with the integrity (r2 = 0.485, P = 0.025), i.e., there was a reduction in their species richness with increasing integrity; DISCUSSION: As a general pattern, Anisoptera presents higher richness in an altered site; on the other hand, Zygoptera presents higher richness in a preserved one. This pattern suggests that Odonata needs to be considered at the sub-order level to access the effects of habitat degradation on these insects. Because of its restrictions ecophysiological Odonata varied widely in their composition and species richness between the two types of environments, it reinforces the potential of the order of studies and environmental monitoring also shows that Zygoptera be more affected by changes in habitat. However, further studies including more samples and different streams are need to confirm this pattern, being an interesting line of research for future works.
Acesso aberto (Open Access)
Filtros ambientais determinando caracteres funcionais de assembleias de Odonata
(Universidade Federal do Pará, 2017-03-24) PEREIRA, Diego Fernandes Gomes; JUEN, Leandro; http://lattes.cnpq.br/1369357248133029
Species distribution is affected by availability of habitas that fit within the limits of variation of their niche and by interaction with other species. Environmental modifications, especially those of anthropic origin, are increasingly common, and are considered major causes of species extinction during the Anthropocene. Aquatic ecosystems are considered among the most vulnerable on the planet because of its dependence on the surroundings and the drainage system. However, species responses to these changes are not random, and can follow patterns that are caused by the specific functionality or morphology of each taxon. This work’s goal was to evaluate if environmental factors work as ecological filters for the establishment of Odonata species through selection of their functional and morphological characters, testing the hypotheses that a) the environment works as a filter over species, by facilitating or hindering characters and b) that due to their thermoregulatory and reproductive requirements, indispensable for colonization and population maintenance, thorax width and oviposition type will be the most affected biological variables. Considering that, we sampled 97 streams in the oriental side of the Brazilian Amazon Forest, distributed over an environmental gradient which covers areas ranging from untouched primary forest to areas extremely modified by agriculture and livestock. We used six functional traits (total body length, fore wing length, fore wing width, thorax width, abdominal length and oviposition type) and seven environmental variables (habitat integrity index, dissolved oxygen, water temperature, canopy cover, macrophytes cover, pH and condutivity). To evaluate if the environmental variables affected the odonate communities, we used the combination of the RLQ and Fourth Corner analysis, with which we assessed the relation between each of the selected traits with each of the habitat descriptors. Among the studied environmental variables, habitat integrity index presented the largest effect over the community of Odonata, having a negative relation with fore wing width, thorax width and exophytic oviposition, and a positive relation with endophytic oviposition. Macrophytes cover showed a negative relation with abdominal length and a positive relation with thorax width and exophytic oviposition. No other environmental descriptor presented significant relations. The results show that poorly preserved habitats facilitate the occurrence of organisms with larger thorax and the substitution of the endophytic by the exophytic type of oviposition. Since environmental impacts usually do not change Odonata species richness, only community composition, these results point that there is favouritism towards groups of species with those characters, like the Libellulidae family, with detriment to other families or groups (specially of the Zygoptera suborder), what might result in community homogeneity and loss of functional and phylogenetic diversity. Thus, the preservation of primary forest is indispensable for the maintenance of Odonata, being the best way to conserve the different ecophysiological and behavioural groups in the order. The dragonfly communities’ responses, directed by morphological and behavioural traits, enlightens ecological response patterns, and the addition of oviposition categories to conservation policies for the Odonata is critical in making them more effective, as they are absolutely necessary for population stability and colonizing new sites.
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)
Padrões de estruturação de adultos de libélulas em uma área de proteção e seu entorno na Amazônia oriental
(Universidade Federal do Pará, 2016-09-30) MONTEIRO JÚNIOR, Cláudio da Silva; JUEN, Leandro; http://lattes.cnpq.br/1369357248133029; ESPOSITO, Maria Cristina; http://lattes.cnpq.br/2112497575917273
In Brazil is the most protected areas (PA) in the world, and mostly located in the Amazon. Currently, the Amazon biome has 73% of APs Brazil or 111 million hectares, 37% full and 63% use of sustainable use. Despite the large number, biodiversity does not have its assured conservation, since the population increases every year, as well as demands for goods and services that result in modifications of the ecosystems that are often outside or even inside the PAs. So our main objective is to study the Odonata adult structuring patterns in a protected area and its surroundings. For this, the thesis is divided into three chapters held in streams in the eastern Amazon. In the first chapter, our hypothesis was to test whether we would find a greater diversity of species of dragonflies in AP due to greater complexity of habitats. In the second chapter, we tested the hypothesis that there would be high beta diversity due to the high replacement species that is expected to find. In the third chapter, we tested the hypothesis that Odonata would be a weak to moderate substitute for other groups, because of the inherent characteristics of the group, as the great mobility. The study was carried out in 30 streams, 17 located within a protected and 13 in the surrounding area. The results of the first chapter were the largest diversity of Odonata found in the environment, compared with the AP. There were also differences in the species composition of the two environments, and differences between environmental variables between areas. Thus, the combination of the protected area and the surroundings, with a low level of disturbance retains a broad range of specialist species Odonata than just a single area. In the second chapter, there was a high beta diversity in Odonata both the AP and in the environment, possibly explained by the niche breadth combined with the spatial structure of the environment. In addition, we found that the specific requirement of the species happens associated with a natural variation in the environment, since there was large beta diversity and high turnover in both environments. Even with some environmental change, it was not big or strong enough to exclude all species and therefore they can survive in this environment. In the third chapter, we tested the correlation between adult Odonata with other aquatic groups such as fish, Ephemeroptera and Trichoptera combined (ET) and chironomids in streams of the Eastern Amazon. There was a correlation between species richness and consistency of Odonata of adults with fish and ET, though the strength of these correlations were moderate to low. So we discussed that adult Odonata are a moderate to weak group substitute for other aquatic organisms in streams of the eastern Amazon. Thus, we suggest caution in the use of a single taxon as a substitute for others and for conservation planning, the best would be to use a wide range of taxa, reflecting holistically aquatic biodiversity. Finally, both areas of protection becomes important to maintain the pool of own species of each environment, with our major challenge in the future is to find a way to identify the disturbance levels that would be acceptable to avoid over-exploitation of resources in these areas.
Acesso aberto (Open Access)
Setting boundaries: Environmental and spatial effects on Odonata larvae distribution (Insecta)
(2015-03) MENDES, Thiago Pereira; CABETTE, Helena Soares Ramos; JUEN, Leandro
Environmental characteristics and spatial distances between sites have been used to explain species distribution in the environment, through Neutral (space) and Niche theory (environment) predictions. We evaluated the effects of spatial and environmental factors on Odonata larvae distribution along the Suiá-Missú River Basin, state of Mato Grosso. We tested the hypotheses that (1) the environment is the main factor structuring the community due to its ecophysiological requirements; and (2) the pattern, if present, is clearer for Zygoptera. Samples were made in 12 sites on the Suiá-Missú River Basin in three seasons (2007/2008), with a total of 1.382 Odonata larvae, comprising 10 families, 51 genera and 100 morphospecies. The Anisoptera were more abundant than Zygoptera, comprising 81% of all specimens. The environment affected Zygoptera (R=0.291; p=0.007) and was the main factor structuring the assembly. Thus, Niche theory was confirmed. The absence of this effect on Anisoptera may be due to the ecophysiological adaptations that enable it to occupy different habitats. Zygoptera larvae are indicators of changes in habitat structure. The effects of environmental variables on larvae ecology emphasize the strong relationship between these organisms and environmental integrity.
Acesso aberto (Open Access)
Taxonomia de Dasythemis (Karsch, 1889) (Odonata: Libellulidae)
(Universidade Federal do Pará, 2024-11) MIRANDA FILHO, Jair da Costa; VILELA, Diogo Silva; http://lattes.cnpq.br/3091410701509383; NASCIMENTO, Jeane Marcelle Cavalcante do; http://lattes.cnpq.br/3880118795645876; https://orcid.org/0000-0002-5428-7495
Among the insects of the order Odonata, the suborder Anisoptera stands out for its cosmopolitan distribution and high dispersal capacity. This is made easier by their broad, non-petiolate wings, with a developed anal area on the hind wings. When perched, individuals of this suborder are recognizable by keeping their wings open. They also have a robust body and high flight capacity. Anisoptera is currently divided into five superfamilies: Aeshnoidea, Petaluroidea, Gomphoidea, Cordulegastroidea and Libelluloidea. Libelluloidea includes the most diverse and ubiquitous family, Libellulidae, which includes the target group of this study. Dasythemis is endemic to South America and has a complex taxonomic history. The lack of recent studies highlights significant gaps in understanding the diversity, taxonomy and geographical distribution of species in this group. Considering this, the present research aimed to fill these gaps through a detailed review of the literature, analysis of material collected from different regions, and a comprehensive study of morphology. To achieve this, 168 specimens from 11 institutions in three South American countries - Argentina, Brazil and Peru - were analyzed. The specimens were identified based on general identification keys and original descriptive works. For the redescriptions, the wing terminologies followed the proposal by Riek and Kukalová-Peck (1984), with modifications by Bechly (1996). The nomenclature of other morphological structures was based on Asahina (1945) and Garrison et al. (2006). Photographs were taken using a stereomicroscope equipped with a camera and illuminated by an LED dome for uniform lighting. As a result, all species and one subspecies were redescribed in a standardized manner, employing features used in more recent studies on the group. All species were illustrated with photographs; additionally, the vesica spermalis was examined using Scanning Electron Microscopy (SEM), illustrating this structure in detail for the first time.