Abstract Detail



The flora of Madagascar: uncovering mechanisms for diversification

Skema, Cynthia [1].

Dombeya as a case study for the diversification of the flora of Madagascar: Dombeya section Hilsenbergia (Malvaceae).

Of the roughly 206 species in the paleotropical genus Dombeya, around 173 are endemic to Madagascar and they occur throughout the island, making Dombeya an ideal case study for understanding diversification processes of the flora of Madagascar. Characterized by long staminal tubes and pendulous inflorescences, Dombeya section Hilsenbergia presents a morphologically cohesive group in which to begin this study. The five species in this section occur primarily in the (sub)humid forest along the length of Madagascar and in the Comoros. Molecular data, as of yet, provide no information about the monophyly, or lack thereof, of the section due to a lack of resolution. A nuclear ribosomal marker (ITS) presents evidence for two species pairs (D. hilsenbergii + D. hafotsy; D. baronii + D. wallichii), relationships which are supported by morphology. Plastid markers provide evidence of widespread plastid introgression, with clades reflecting gross geographic provenance of individuals rather than species designations. A series of field collections from Vohiparara (Fianarantsoa Province) suggest the possibility of hybrid zones in the section, which may account for gene flow between the overlapping species (D. baronii, D. cannabina, D. hilsenbergii). Analysis of multiple physical and biological factors (e.g., elevation, aspect, phenology, bioclimatic variables) revealed some interspecific differentiation, but also overlap among some species within the section.


1 - Morris Arboretum Of The University Of Pennsylvania, 100 E. Northwestern Ave., Philadelphia, PA, 19119, United States

Keywords:
Madagascar
diversification
Hybridization
Dombeya
Malvaceae.

Presentation Type: Colloquium Presentations
Number: 0009
Abstract ID:632
Candidate for Awards:None


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