Orchid phylogenomics: Diversification, evolution and systematics of the hyperdiverse   subtribe Bulbophyllinae

A project undertaken at the Australian Tropical Herbarium, CSIRO and supervised by Katharina Schulte.
Co-investigators: Mark Clements, Lars Nauheimer, and Lalita Simpson

The orchid subtribe Bulbophyllinae comprises the second largest genus of flowering plants, Bulbophyllum (ca. 2,200 species), and several satellite genera, including many threatened species. The subtribe is distributed in tropical and subtropical regions worldwide, including Asia, Australasia, Africa, Madagascar and South America, with a center of diversity in Asia and Australasia. Bulbophyllinae display a striking morphological diversity in vegetative and floral characters, which renders the recognition of evolutionary relationships difficult. Over the past, divergent taxonomic concepts have been proposed ranging from the segregation of Bulbophyllum into over 50 genera to the recognition of a single genus (Bulbophyllum). Previous molecular studies mainly relied on few molecular markers with limited phylogenetic signal. Thus evolutionary relationships within the subtribe, in particular in the Asian/Australasian clade, remain largely unclear.

Next generation sequencing approaches offer unprecedented opportunities to elucidate evolutionary relationships in challenging plant groups.

This project aims to:

  1. generate a broad scale phylogeny for Bulbophyllinae based on plastome sequencing to evaluate taxonomic concepts, examine the evolution of key morphological characters and the spatio-temporal evolution of Bulbophyllinae; and
  2. establish a highly sensitive marker system for high-throughput sequencing of hundreds of DNA markers based on target sequence capture. This DNA marker system will facilitate the assessment of finer scale evolutionary relationships in Bulbophyllinae and the conservation status of critical groups.
Figure 1. Bulbophyllum lilianae (sect. Adelopetalum) is an endemic rainforest epiphyte of the Australian Wet Tropics region. (Photo: T. Linderhaus)

Figure 2. In Bulbophyllum gracillimum (sect. Cirrhopetalum) the fly-pollinated flowers are arranged in a semicircular pattern. (Photo: T. Linderhaus)