RESUMO
This study aimed to elucidate the breeding strategies of Varronia curassavica, an important medicinal species associated with Brazilian restinga. This was accomplished by combining phenological and genetic data. Every 2 weeks over a period of 2 years, we measured flowering and fruiting phenology to evaluate the activity and intensity of phenophases (n = 60). We evaluated the mating system, pollen ovule ratio and genotypes from progeny and mother plants using 8 nuclear microsatellite loci. We observed flowering and fruiting of V. curassavica at low intensity throughout the entire year, but with 2 distinct peaks, one of which was seasonal, corresponding to the period of gradual increase of temperature and photoperiod. Overlapping of flowering and fruiting strategies favors gene flow among different groups of individuals and between populations by attraction of fauna throughout the year. Analysis of the mating system indicates that V. curassavica is a typical outcrossed species (t^ = 0.98; pollen/ovule ratio = 7087.50). Combining phenology with genetic studies improved our understanding of the reproductive strategies of this species. The typical outcrossing system of V. curassavica reflects the existence of functional self-incompatibility mechanisms still unaffected by changes in genetic balance by polyploidy.
Assuntos
Boraginaceae/genética , Boraginaceae/fisiologia , Genética Populacional , Poliploidia , Brasil , Flores/fisiologia , Frutas/fisiologia , Fluxo Gênico , Genótipo , Repetições de Microssatélites , Estações do AnoRESUMO
Varronia curassavica is an important medicinal species associated with the restinga, one of the most threatened coastal ecosystems of the Atlantic Forest. These circumstances call for studies aimed at estimating effective population size and gene flow to improve conservation efforts. Hence, the present study aimed to characterize the genetic diversity, ploidy level, and population structure of this species in different areas of restinga using microsatellites. Varronia curassavica was characterized as an autotetraploid, with high genetic variability, low divergence, and no significant fixation indices, indicating the absence of, or reduced, inbreeding and genetic drift in the study area. About 44% of the alleles occurred at low frequency in adults of all populations and 41% in the progenies evaluated. Gene flow was high, consistent with outcrossing species with high dispersal capacity (Nm = 4.87). The results showed no tendency toward isolation by distance. The estimated effective size indicates that the populations studied have the potential to ensure conservation of the species in the long term. The genetic variability and population structure of V. curassavica, as determined in this study, could form the foundation for activities directed toward the sustainable use of this resource and its conservation. Even though the restinga ecosystem has suffered dramatic reductions in area, this study provides evidence that this species is resilient to anthropogenic threats to its genetic integrity, since it is a polyploid with self-incompatibility mechanisms that contribute to maintaining high genetic diversity in an panmictic meta-population along the coast of Santa Catarina.
Assuntos
Florestas , Variação Genética , Genética Populacional , Magnoliopsida/genética , Poliploidia , Alelos , Brasil , Fluxo Gênico , Frequência do Gene , Deriva Genética , Endogamia , Repetições de Microssatélites , Plantas Medicinais/genética , Densidade DemográficaRESUMO
Encholirium horridum is a bromeliad that occurs exclusively on inselbergs in the Atlantic Forest biome of Brazil. These rock outcrops form natural islands that isolate populations from each other. We investigated gene flow by pollen through paternity analyses of a bromeliad population in an area of approximately 2 ha in Espírito Santo State, Brazil. To that end, seed rosettes and seedlings were genotyped using nuclear microsatellite loci. A plot was also established from the same population and specimens were genotyped to evaluate their fine-scale spatial genetic structure (SGS) through analyses of spatial autocorrelation and clonal growth. Paternity analysis indicated that 80% of the attributed progenitors of the genotyped seedlings were from inside the study area. The pollen dispersal distances within the area were restricted (mean distance of 45.5 m, varying from 3 to 156 m) and fine-scale SGS was weak (F(ij) = 0.0122, P < 0.001; Sp = 0.009). Clonal growth was found to be a rare event, supporting the monocarpy of this species.
Assuntos
Bromeliaceae/genética , Demografia , Espécies em Perigo de Extinção , Fluxo Gênico/genética , Variação Genética , Dispersão de Sementes/fisiologia , Brasil , Bromeliaceae/crescimento & desenvolvimento , Florestas , Genética Populacional , Genótipo , Repetições de Microssatélites/genética , Pólen/genética , Dispersão de Sementes/genéticaRESUMO
BACKGROUND: People influence their environments through the manipulation of landscapes and species. Human influence on the landscape may lead to the development of differentiated landscape units that originate from past use and may be related to the presence of certain species. This study investigated the presence of the palm Euterpe edulis and its current and past importance in landscape units established by a community of German descendants located in southern Brazil. The objectives of this study were to characterize the use of the species, to identify the importance of E.edulis for the German immigrant community, to identify past and current uses of E.edulis, to describe the historical use of the landscape, and lastly, to identify landscape units in which E.edulis is found. METHODS: The researched community is composed of people of German descent residing in southern Brazil. A variety of research tools were used to achieve the objectives of the research. Semi-structured interviews and free-listings were conducted in all family units. The interviews focused on groups of people in the community who had current or historical connection with the species. Group workshops and guided tours were conducted to identify different landscape units. The data were analyzed using descriptive statistics, use-value index, citation frequency, salience index, and informant perception analysis. RESULTS: Over the historical period studied, the community demonstrated changes with respect to economic activities. These changes are reflected in the transformation of the landscape. The species E.edulis was and still is very important for people in the community; its importance is reflected in its high use value, citation frequency and salience. The species is found within various landscape units in the community as well as in homegardens and in secondary forests. CONCLUSIONS: The landscape heterogeneity of this community is influenced by changes in economic activities and by the relationship with the conservation unit. Landscape units resulting from this relationship may be identified. The species E.edulis is found within these landscape units and is integrated into the livelihood of the community.