Phylogenomics confirm the monophyly of Guzmania (Bromeliaceae: Tillandsioideae) and provide evidence regarding alternative hybridization scenarios involving G. monostachia

Abstract

Premise

We present a phylogenomic framework to clarify the evolutionary origin of Guzmania within the broader Tillandsioideae. The genus represents ~15% of extant diversity in Tillandsioideae and includes the widespread G. monostachia, whose distribution spans northern South America, Central America, the Caribbean, and southern Florida. Populations of G. monostachia have been in decline recently due to habitat loss and fragmentation, with Florida populations—its northernmost limit of the species—particularly vulnerable to anthropogenic threats. Understanding the evolutionary history of these lineages is essential for assessing their genetic diversity and guiding conservation efforts.

Methods

We assembled new plastid and nuclear genome references for G. monostachia to construct novel plastome and nuclear single nucleotide polymorphism (SNP) data sets. We integrated these data sets with public sequence data to infer phylogenomic relationships and estimate divergence times across Tillandsioideae. We also performed per-site log-likelihood analyses to visualize phylogenetic signal across two discordant topologies for G. monostachia.

Results

We recovered a monophyletic Guzmania, but many relationships within Tillandsioideae remain unresolved. Notably, phylogenetic analyses revealed conflicting signals about the monophyly of G. monostachia, with some trees placing G. fuerstenbergiana and G. remyi nested within it.

Conclusions

Our findings underscore the limitations of large-scale plastid data for clarifying Tillandsioideae phylogenies. Nonetheless, they suggest a possible hybrid origin for G. monostachia and a distinct evolutionary trajectory for Florida populations. Data and insights generated by our study provide a foundation to enable forthcoming genetic diversity studies and future conservation planning for this threatened lineage.