Do plant populations on distinct inselbergs talk to each other? A case study of genetic connectivity of a bromeliad species in an Ocbil landscape.

Here, we explore the historical and contemporaneous patterns of connectivity among populations located on granitic inselbergs in an Ocbil landscape within the Brazilian Atlantic Forest, using both nuclear and chloroplast microsatellite markers. Beyond to assess the population genetic structure, we built species distribution models across four periods (current conditions, mid-Holocene, Last Glacial Maximum [LGM], and Last Interglacial) and inferred putative dispersal corridors using a least-cost path analysis to elucidate biogeographic patterns. Overall, high and significant genetic divergence was estimated among populations for both nuclear and plastid DNA (Φ = 0.463 and Φ = 0.961, respectively, < .001). For nuclear genome, almost total absence of genetic admixture among populations and very low migration rates were evident, corroborating with the very low estimates of immigration and emigration rates observed among populations. Based on the cpDNA results, putative dispersal routes in Sugar Loaf Land across cycles of climatic fluctuations in the Quaternary period revealed that the populations' connectivity changed little during those events. Genetic analyses highlighted the low genetic connectivity and long-term persistence of populations, and the founder effect and genetic drift seemed to have been very important processes that shaped the current diversity and genetic structure observed in both genomes. The genetic singularity of each population clearly shows the need for in situ conservation of all of them.