Systematics and Evolution of the Spiral Gingers (Costaceae: Zingiberales)

Research with the “spiral gingers” involves utilizing a phylogenetic framework to investigate molecular evolution, floral development, and the historical biogeography of the pan-tropical family Costaceae.  This family forms an easily recognizable clade within the Zingiberales, distinguished from other families in the order by its characteristic one-sided spiral phyllotaxy and its floral design, featuring 5 infertile stamens fused to form a petaloid labellum. Costaceae presently consists of about 95 species which until recently were placed in four genera: Costus, Tapeinochilos, Dimerocostus, and Monocostus.  Recent systematic and developmental studies have led to a novel understanding of evolution within the family and have resulted in the description of three new genera (Chamaecostus, Cheilocostus and Paracostus) to accommodate the phylogenetic diversity of the Costaceae.

 The diverse floral morphology found in the family Costaceae makes this group an ideal model system for addressing a number of evolutionary questions.  Research on this group revolves around four integrated components:

(1)  developing a robust phylogeny using molecular and morphological characters and revising the taxonomy of the lineage,

(2)  investigating floral pattern formation using taxa which encompass a range of morphological and phylogenetic diversity,

(3)  conducting comparative studies of floral development characters in order to explore the association between pollination syndrome, species diversity and rates of diversification, and

(4)  comparing the age of phylogenetic diversification with the geological record to interpret the biogeographic history of this group.

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