Biologia reprodutiva, polinização e barreiras reprodutivas em duas Bromeliaceae na Mata Atlântica do Rio Grande do Norte

• Ano de defesa: 2018
• Autor(a) principal: Cavalcante, Brayan Paiva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Brasil; UFRN; PROGRAMA DE PÓS-GRADUAÇÃO EM SISTEMÁTICA E EVOLUÇÃO
• Palavras-chave em Português: Barreiras pós-polinização; Bromelioideae; Fenologia da floração; Hohenbergia; Polinização por abelhas; Wittmackia; CNPQ::CIENCIAS BIOLOGICAS
• Link de acesso: https://repositorio.ufrn.br/jspui/handle/123456789/28033

Bromeliaceae is a group of neotropical monocotyledons with 3543 species in 73 genera. Recognized as one of the most notorious cases of adaptive radiation, it has a large variety of reproductive traits. However, several correlated bromeliads occur in sympatry, and to allow this, there must be strong reproductive barriers that keep these species cohesive. This dissertation aimed to describe the reproductive biology of two sympatric bromeliads in the Atlantic Forest of Rio Grande do Norte, in order to understand how reproductive dynamics occurs and the mechanisms that allow the cohesion of both, by analyzing the pollen flow and reproductive barriers. This work was carried out in the Nísia Floresta National Forest, a fragment of Atlantic Forest in the state of Rio Grande do Norte, and the species sampled were Wittmackia patentissima and Hohenbergia ridleyi. In Chapter I, the processes involving reproductive biology, pollination ecology and floral phenology of Wittmackia patentissima and Hohenbergia ridleyi, were analyzed, trying to describe their respective reproductive mechanisms, as well as possible pre-pollination barriers and the pollen flow between them. We found that both have delicate, aromatized, diurnal, flowers that are available for 1-2 days. In addition, flowering is synchronous, occurring between August and October, with several individuals overlapping and prolonging the reproductive season. The main floral visitors are bees, but other hymenoptera, lepidoptera, coleoptera and diptera can be seen, all of which use floral nectar as a resource. Basically, all the floral characteristics are shared, not being identified any type of reproductive barrier of the type pre-pollination between them. In Chapter II, the reproductive systems of this pair of species were described, in order to understand how the dynamics of pollination occurs and what mechanisms enable fruiting. In addition, hybridization tests were performed between these species, analyzing the growth of the pollen tube along the gynoecium, to observe if there are post-pollination barriers that prevent the formation of natural hybrids. As a result, it has been found that both taxa are highly self-compatible, and that there is spontaneous pollen deposition while in flower bud stage, and this can maximize their reproductive success. In the hybridization tests it was possible to observe that the pollen grains germinated and grew until the first portion of the style in all treatments in both species. There was no difference in pollen development in the self- versus cross pollination treatments for either species, however, it was possible to observe abnormalities from the second portion of the style in the hybridization tests. At this point, it was possible to observe the irregular deposition of callose along the style, as well as the stoppage of the pollen tubes in all the hybridization tests, indicating that there are strong post-pollination barriers that inhibit the formation of natural hybrids.