Standing crop measurements indicated an important proportion of nectar intake by flower visitors. Nectar sugar composition was sucrose dominant during the night, and sucrose and hexose rich during the day. No signals of active nectar resorption were observed. Sugar concentration (23.12%) and amount (1.79 mg) remained constant during flower lifespan. Nectar was secreted during the night and early morning, with maximum accumulated volume up to 20.9 μl. Hawk moths were more frequent and responsible for most Q.
Flowers remained opened until next evening and were visited and pollinated by a wide range of nocturnal and diurnal animals. Qualea grandiflora flowers during rainy season anthesis starts at dusk, with a slightly sweet scent, pollen release and receptive stigma. We investigated pollination system of Qualea grandiflora, the most widespread woody species of Cerrado, the Neotropical savannas in Central Brazil, focusing on nectar features, their relationship with nocturnal and diurnal pollinators and how nectar affects male fitness, measured through pollen removal.
But other factors may have a role on nectar features and its efficacy as reward. Nectar production in flowers has been associated with pollination systems and seen as part of plant reproductive strategies. The high degree of metamer trait variation seems to be due to both, phenotypic plasticity and local adaptation to different environmental conditions, and may explain the success of the species in occupying all the Cerrado biome. We also found high metamer trait variation, which seemed largely influenced by precipitation, soil bulk density and wind speed during the period of metamer development. Genetic structure was more related to past climatic changes than to the current climate. Geographic distance was the main factor shaping genetic divergence in Qualea grandiflora, reflecting isolation by distance. We found high genetic diversity, which was geographically structured. We also used multiple regressions to further investigate the contributions of those environmental factors on leaf trait diversity. To evaluate the role of geography, soil, climate, and wind speed in shaping the divergence of genetic and phenotypic traits among populations, we used Generalized Dissimilarity Modelling. We analyzed genetic variation with microsatellite markers in 23 populations (418 individuals) and phenotypic variation of 10 metamer traits (internode, petiole and corresponding leaf lamina) in 36 populations (744 individuals). Here, we sampled Qualea grandiflora, the most widely distributed tree species in the Cerrado, a large Neotropical savanna. Identifying the environmental factors that shape intraspecific genetic and phenotypic diversity of species can provide insights into the processes that generate and maintain divergence in highly diverse biomes such as the savannas of the Neotropics. The genetic diversity and divergence between the studied populations indicated that the Pedregulho population should be considered an Evolutionary Significant Unit and a Management Unit.
Gene flow was high enough to counter the effects of genetic drift. Estimates of effective population size were low (<10), and the minimum viable area for conservation in the short-, medium- and long-term was estimated to be between 4 and 184 ha. The influence of the Wahlund effect on the studied populations lies between 8.5 and 53.3 %. Spatial structure was observed in the distribution of specimens in distance classes ranging from 30 to 40 km and three genetic clusters were identified, with genotypes in the Pedregulho population differing from the others by up to 90 %. All populations departed from Hardy-Weinberg equilibrium (p < 0.05). An excess of homozygotes and moderate levels of inbreeding were observed. Alleles private to particular populations and rare alleles were also detected. Results indicated a mean number of 12 alleles per locus, but only six effective alleles. Eight microsatellite loci were used to analyze samples from four populations subjected to different types of anthropic pressure, distributed throughout the state of São Paulo in the regions of Assis, Brotas, Itirapina and Pedregulho. We analyzed the genetic structure and diversity of Qualea grandiflora Mart., the most abundant woody species in the Brazilian Cerrado.
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