Genetic diversity and conservation of a rare Miconia species (Melastomataceae) from the Brazilian Atlantic Forest.

Biodiversity is undergoing an unprecedented global decline, and genetic diversity plays a fundamental role in ensuring species persistence. Miconia ulei, an endemic species from the eastern Atlantic Forest in Santa Catarina, southern Brazil, is rare and has few known populations. We investigated genetic diversity and population structure using microsatellite markers and assessed its conservation status following IUCN guidelines and by incorporating genetic parameters in the evaluation. Five extant populations were sampled across the species' known distribution, and twelve species-specific microsatellite markers were developed. Populations exhibited low to moderate levels of genetic diversity. Genetic differentiation among populations was generally low, although one population showed a distinct genetic structure. No isolation by distance was detected, suggesting that factors other than geographic distance may influence patterns of gene flow. Evidence of historical reductions in population size was detected in most populations. Together, these findings indicate that M. ulei has limited genetic variation and small, fragmented populations, increasing its vulnerability to future genetic loss. Our results support the need for conservation actions, including the formal inclusion of M. ulei in official Red Lists and the maintenance of habitat connectivity to promote long-term population persistence. As the first population genetic assessment of M. ulei, this study provides an important baseline for conservation planning and highlights the need for conservation genetic studies of other rare Atlantic Forest species.