Inbreeding depression in Vriesea gigantea, a perennial bromeliad from Southern Brazil

Abstract

Vriesea gigantea is a bromeliad distributed in the Atlantic Rainforest, Southeastern Brazil. It is characterized by the presence of tanks which are used as an important source of resources by populations of associated biota. Habitat destruction, fragmentation and predatory colection have decreased natural populations of V. gigantea. Inbreeding depression is a reduction in fitness in the progeny of closely related individuals. In plants species the effect of inbreeding depression is assigned to selfing or biparental inbreeding. We aim to describe the occurrence of inbreeding depression (d) in three natural populations of V. gigantea, and to correlate this phenomenon with fertility and mating system of the species. A total of 54 mother-plants were sampled and 108 flowers used for pollination treatments (selfing, outcrossing and control). In the mother-plants we analyzed plant and inflorescence height and number of flowers. In the progenies, the parameters seed set, germination and survival rate and final weight were evaluated. The results indicated no differences between treatments, but a low to moderate level of inbreeding depression was detected in V. gigantea (d = 0.02 to 0.39), according to molecular data of previous study. Based on the findings, we may infer that V. gigantea populations have a mixed mating system that tolerate some degree of inbreeding, with evolutive potential to selfing as main reproductive system.