Contrasting reproductive and ecological traits affect the genetic diversity and fine-scale genetic structure of two sympatric and epiphytic tropical bromeliads

Abstract

Tropical montane forests are highly diverse ecosystems with high levels of endemism. Within these habitats, epiphytic plants are among themost diverse and understudied species groups. Despite their diverse reproductive and ecological traits, their influence on genetic diversity andfine-scale genetic structure (FSGS) has rarely been studied. We assessed how reproductive and ecological traits affect genetic diversity and FSGSwithin and among phoropytes in two epiphytic bromeliads: Aechmea mariae-reginae, a dioecious, hummingbird-pollinated, and bird-dispersedspecies, and Werauhia ampla, a hermaphroditic, self-compatible, bat-pollinated, and wind-dispersed species. We collected leaf tissue from 93 A.mariae-reginae and 94 W. ampla individuals. We used eight microsatellite loci to describe genetic diversity, structure, and FSGS in both species.Genetic diversity was higher in A. mariae-reginae than in W. ampla. Genetic diversity was not affected by multilocus identical genotypes. Bothspecies showed low genetic structure among phorophytes. Significant FSGS was found in distance classes below 25 m in A. mariae-reginae, butno FSGS was found in W. ampla. The reproductive and breeding system of these species affects genetic diversity, with the dioecious and animalpollinated species having higher diversity estimates. Limited seed dispersal by social birds in A. mariae-reginae results in significant FSGS withinphorophytes. The absence of FSGS in W. ampla is due to extensive seed dispersal by wind.