Floral and reproductive biology of Alcantarea nahoumii (Bromeliaceae), a vulnerable endemic species of the Atlantic Forest

Maria Josirene Souza Moreira Bastos,Daniel Vieira Morais,Lucimário Pereira Bastos,Taliane Leila Soares,Fernanda Vidigal Duarte De Souza,Maria Angélica Pereira De Carvalho Costa,Everton Hilo De Souza

doi:10.1590/0102-33062017abb0102

Abstract

Alcantarea nahoumii occurs exclusively in the state of Bahia, Brazil, and is classified as vulnerable due to deforestation and frequent fires in the region. Knowledge of floral and reproductive biology is fundamental to understanding ecological interactions, as well as the reproductive success of plant species. The objective of this study was to evaluate the floral and reproductive biology of A. nahoumii in an Atlantic Forest fragment with regard to phenology, pollen viability, stigma receptivity, pollination ecology and reproductive systems, all of which are important parameters for of the development of conservation strategies for the species. Anthesis is diurnal and heterogeneous, starting at 6:30 a.m. and lasting until 8:00 a.m. Highest germination percentages and greatest pollen tube lengths were obtained in BK culture medium. Histochemical tests revealed high pollen viability (89.71 %). Stigma receptivity occurred during anthesis and lasted for up to 24 hours after floral opening. Alcantarea nahoumii exhibited preferential allogamy and self-compatibility, and required a pollinator to production of viable seeds. Sixteen species of pollinators were observed visiting A. nahoumii, among which were five hummingbird species. Even though its reproductive system is efficient, this bromeliad remains threatened mainly due to habitat fragmentation caused by deforestation, burning and predatory extractivism.

Highlights

The Brazilian Atlantic Forest is one of the main centers of diversity and endemism of the family Bromeliaceae, with a total of 653 species recorded in the last decade (Forzza et al 2013)
The objective of this study was to investigate the floral and reproductive biology of Alcantarea nahoumii in an Atlantic Forest fragment, and acquire novel data related to reproduction forms and pollination mechanisms of this endemic and vulnerable species
Two plants bloomed in 2012, in December. This low flowering rate is related to the low rainfall that year (714 mm) and a fire in March that affected most of the experimental area (Figs. 1, 2A)

Summary

Introduction

The Brazilian Atlantic Forest is one of the main centers of diversity and endemism of the family Bromeliaceae, with a total of 653 species recorded in the last decade (Forzza et al 2013). Fifty-four of these species are classified as critically endangered, 89 as endangered, 182 as vulnerable, 17 as rare and three as extinct in nature (Forzza et al 2013); these numbers are probably underestimates due to the lack of knowledge regarding the actual status of wild populations of species of Bromeliaceae. The genus Alcantarea is native to Brazil and has approximately 40 species (Versieux & Wanderley 2015). It is estimated that in recent years the population has declined by 30 % due to deforestation and frequent fires (Versieux & Wanderley 2007; 2015; Forzza et al 2013)

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