ABSTRACT
Abstract Evolutionary analyses have been widely used for evaluation of genetic diversity of natural populations and correlate these data to the fitness of the species, especially in the case of threatened species. Calydorea crocoides occurs in a restricted area at altitudes from 800 to 1500 m in southern Brazil and is considered endangered. A study assessing genetic diversity, cytogenetic features and ecological niche was performed aiming to characterize C. crocoides by multidisciplinary approaches. Molecular data highlighted that most of the total variation (76%; p < 0.001) was found within populations and the parameters of genetic diversity were high at the species level (PPB = 98.97%; I = 0.4319; h = 0.2821). Gene flow (Nm) was estimated in 0.97 individuals per generation. Cytogenetically, C. crocoides presents a bimodal karyotype and low asymmetry. DAPI banding pattern was uniform, but the CMA-signal evidenced a pericentric inversion in the population ESC688. The species presents high pollen viability and two different morphologies of pollen grains. Our data showed high levels of polymorphism maintained in this species that could ensure conservationist practices in which the main goal is to preserve the evolutionary potential of the species through the maintenance of genetic diversity.
ABSTRACT
Sisyrinchium micranthum Cav. is a member of the family Iridaceae, which is distributed over the American continent. In Brazil, this species is found, not only in disturbed areas and coastal regions, but is also very common in urban centers, such as public parks, during the spring. Chromosome counts for North American specimens are 2n = 32 and 2n = 48, whereas in southern Brazil, there is a polyploidy series with three chromosome numbers, 2n = 16, 2n = 32, and 2n = 48. Population analyses using DNA molecular markers are inexistent for this species, in spite of its wide distribution and morphological variation. To study the genetic population structure of S. micranthum, five natural populations were accessed in a conservation park within the Atlantic Rain Forest Biome in southern Brazil. Here, the chromosome numbers 2n = 16 and 2n = 48 had already been described. Molecular analysis showed that the populations are highly structured with low gene flow among them. The population with 2n = 48 was genetically less variable than and distinct from the other populations. Population genetics in relation to cytogenetic data provided new insights regarding the genetic diversification and mating system of S. micranthum.