Systematics and floral evolution of Dracula orchids

The project aims to generate the first comprehensive molecular phylogeny of the orchid genus Dracula using Next Generation Sequencing data, and to use it to evaluate infrageneric classification and evolutionary transitions in floral traits. Specifically, we will test three hypotheses:

(1) Sectional divisions within Dracula represent natural (monophyletic) groups; 
(2) Evolution of floral size is associated with shifts in individual floral longevity and flower number; 
(3) Evolution of floral size requires significant shifts in resource investment in support structures (inflorescence "scaffold"). 

To this end, whole chloroplast genomes will be sequenced and morphological measurements will be obtained from cultivated plants in the Basler Botanical Garden and specimens in the Jany Renz Collection of the Herbaria Basel (Index Herbariorum: RENZ).

Scientific summary

Dracula is an enigmatic South American orchid genus in the tribe Pleurothallinidae, with about 134 species, closely related to Masdevallia with about 623 species, from which it was segregated. The species are largely restricted to New World cloud forests. Dracula orchids are popular in cultivation and have enigmatic reproductive systems: many species mimic mushrooms in morphology and floral scent, deceiving flies that normally mate on mushrooms. Although the genus is monophyletic, relations within the genus are very poorly known, because only a single, very short genomic region has been analyzed so far. Next generation sequencing techniques have never been applied to the genus. Therefore, the sectional classification is currently of limited value. The floral diversity of Dracula is a useful system for understanding the evolution of reproductive display – a central challenge in plant evolution. For instance, species differ dramatically in flower size, floral longevity, and flower number. It is poorly understood how evolutionary labile these individual aspects of floral display are, and to what extent these traits are evolutionarily coordinated. Moreover, it is very poorly known how the resource costs of floral display may constrain floral evolution among species.

Funded by
AlumniBasel Ehemaligenvereinigung der Universität Basel

Duration
01.02.2018 – 30.08.2019
 
Responsible Scientists:
Dr. Jurriaan de Vos (PI, supervisor)
Rafael Pulfer (MSc student)