Genetic diversity of the endangered palm Butia eriospatha in grassland and forest landscapes: informing conservation and seed collection

The Atlantic Forest is a biodiversity hotspot facing severe habitat loss and fragmentation, with most of its remnants experiencing biomass and biodiversity declines. Butia eriospatha, an endangered palm species endemic to this biome, is threatened with extinction by habitat loss, poaching, and lack of regeneration. Despite its ecological and cultural importance, genetic studies have focused only on open grassland populations, leaving the rare forest populations unexplored. Here, we compared genetic diversity aspects of a forest (FOR) and a grassland (GRA) B. eriospatha population to inform seed collection guidelines and further expand our knowledge on the genetic conservation of this important species. Using nine microsatellite loci, we assessed genetic diversity, mating system, and spatial genetic structure (SGS) of both populations. We found that both FOR and GRA had moderate genetic diversity but were significantly differentiated from each other, despite the short geographic distance. Allogamy predominated in both populations, with a small proportion of mating among relatives detected in the forest population. SGS was weak but extended over longer distances in FOR (up to 60 m) compared to GRA (up to 30 m), suggesting differences in mortality dynamics. To maximize genetic diversity in long-term conservation strategies, seeds should be collected from 132 to 139 seed-trees, respecting SGS distances. Our findings highlight the need to conserve both grassland and forest populations to safeguard B. eriospatha’s genetic diversity.