Ecologia e Taxonomia de Collembola (Arthropoda: Hexapoda) no Pampa brasileiro

• Ano de defesa: 2023
• Autor(a) principal: Silva, Clécio Danilo Dias da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Rio Grande do Norte; Brasil; UFRN; PROGRAMA DE PÓS-GRADUAÇÃO EM SISTEMÁTICA E EVOLUÇÃO
• Palavras-chave em Português: Collembola; Campos nativos; Diversidade funcional; Diversidade taxonômica; Sul do Brasil; Taxonomia; CNPQ::CIENCIAS BIOLOGICAS
• Link de acesso: https://repositorio.ufrn.br/handle/123456789/56864

Springtails are microarthropods widely distributed in all terrestrial ecosystems, and they play a fundamental role in ecosystem functioning. However, studies focused in these animals in South America are limited and there are gaps to various phytogeographical domains, such as the Pampa. This domain is mainly composed by native grasslands, which harbor a great biodiversity of fauna and flora. The native grasslands are rapidly disappearing to make way for extensive livestock farming and Eucalyptus plantations, raising concerns about conservation in South America, especially in Brazil. In light of this, the main objective of this thesis was to assess the effects of different land uses on the taxonomic composition, functional diversity, and ecological properties of Collembola (Arthropoda: Hexapoda) communities in the Brazilian Pampa. Four municipalities in the state of Rio Grande do Sul (RS) with areas of native grasslands and Eucalyptus plantations were sampled: Pinheiro Machado, Jaguarão, Lavras do Sul, and São Gabriel. Springtails were collected using pitfall traps and Berlese funnels in 10 paired areas, each with a 250 m transect for each type of land use, divided into 5 subplots. In the laboratory, the specimens were sorted, quantified, morphotyped, mounted on slides for microscopy and identified with the help of keys and other specialized literature. The description of the new species was performed using an optical microscope with an attached camera and then drawings were vectorized using Corel Draw. Ecological analyses of taxonomic and functional diversity were performed using R software. In Chapter 1, we evaluated the taxonomic composition, alpha and beta diversity of springtails after the conversion of native grasslands into Eucalyptus plantations. We used Random Forest analysis to understand the influence of environmental factors on the structure and composition of the communities. We found significant losses in the springtail communities concerning abundance, species composition, richness, and taxonomic diversity after the conversion of the areas. Beta diversity was mainly explained by species turnover, while plant richness and dominance influenced springtail diversity. In Chapter 2, we assessed the effects of converting native grasslands into Eucalyptus plantations on the functional diversity and composition of epigeic and endogeic springtail communities. We categorized each morphospecies by their life form using an ecomorphological index. The results indicate that epigeic communities are more associated with grassland areas, while endogeic communities are more associated with Eucalyptus plantations. The conversion of grasslands to Eucalyptus plantations did not affect the functional indices of the epigeic communities, but had negative effects on the richness and functional divergence of the endogeic taxa, resulting in a reduction in body pigmentation, number of eyespots, size of the legs, and appendages of these animals. In Chapter 3, we reevaluated the identification and inventory records from the first chapter and conducted a literature review using different databases and articles. By cross-referencing these data, we provided a list of 15 families, 35 genera, and three nominal species recorded for the Pampa. We also developed diagnoses and an identification key for the suprageneric taxa present in this domain. In Chapter 4, we described and illustrated the first species of Dicranocentrus Schött for Rio Grande do Sul and the Brazilian Pampa domain. The new species belongs to the gracilis-group sensu Mari-Mutt. Dicranocentrus sp. nov. is unique within the genus by antennal segments Ib and IIb ventrally with two smooth pointed chaetae each; labium with scales, and chaeta M1 ciliated while the rest are smooth (m2, r, a1, a2, l1, and l2); tenent hair capitate; manubrial plate with 13 ciliated chaetae and nine pseudopores, and ventro-apical region of the manubrium with two ciliated chaetae. Lastly, we present a comparative table that encompasses all Dicranocentrus species from the gracilis-group worldwide. The results presented in this thesis provide unprecedented contributions to the taxonomy, ecology, and conservation knowledge of springtails in the Brazilian Pampa. They emphasize the importance of in-depth studies on the influence of land-use practices on the biodiversity of these communities. The conservation of native grasslands and the adoption of sustainable practices in Eucalyptus plantations are crucial for maintaining the diversity of these animals and, consequently, the ecological balance of the Pampa domain.