Molecular phylogeny, character evolution and historical biogeography of Cryptanthus Otto & A. Dietr. (Bromeliaceae)

Cryptanthus comprises 72 species endemic to eastern Brazil with a center of diversity in the Atlantic Forest. The majority of the species are threatened due to habitat loss. We reconstructed phylogenetic relationships in Cryptanthus based on amplified fragment length polymorphisms (AFLP) including 48 species and 109 accessions. The Bayesian phylogenetic analysis revealed four major lineages in Cryptanthus and provided further evidence for the paraphyly of subgen. Hoplocryptanthus, while subgenus Cryptanthus was resolved as monophyletic. Monophyly of previously recognized morphological species groups at sectional level could not be confirmed. Based on the phylogenetic reconstruction we inferred the evolution of the sex system in Cryptanthus via maximum likelihood (ML) ancestral character reconstruction. Homoecy, the possession of hermaphrodite flowers only, was reconstructed as the ancestral state in the genus and characterizes three of the four main lineages within Cryptanthus. Andromonoecy, the possession of male and hermaphrodite flowers on the same plant, evolved only once and represents a synapomorphy of the fourth main lineage, C. subgen. Cryptanthus. The ancestral biome analysis reconstructed Cerrado (semiarid scrublands and forests) and campos rupestres (rock fields) as the most likely ancestral biomes for the genus. A shift to the Atlantic Forest biome was reconstructed to have occurred twice, in the ancestor of the first diverging lineage within the genus and in the ancestor of the C. subgen. Cryptanthus clade. A shift to the Caatinga (tropical dryland savanna) and one reversal to Cerrado (campos rupestres - rock fields) was reconstructed to have occurred once, in C. bahianus and C. arelii, respectively. The ancestral biome reconstruction indicates a high degree of niche conservatism within Cryptanthus with rare biome shifts throughout the evolution of the genus. Further, our results imply that the current infrageneric taxonomy of Cryptanthus is problematic and requires revision.