Abstract Detail

Biogeography

Mennes, Constantijn B. [1], Lam, Vivienne K.Y. [2], Rudall, Paula J. [3], Lyon, Stephanie P. [4], Graham, Sean W. [2], Smets, Erik F. [5], Merckx, Vincent S.F.T. [6].

The “odd man out” in mycoheterotrophic angiosperms: a Gondwanan origin of Corsiaceae.

The mycoheterotrophic family Corsiaceae (Liliales) consists of three genera that show a remarkably disjunct distribution pattern across the Pacific Ocean. The genus Corsia (~30 spp.) occurs in Papua New Guinea, whereas Arachnitis (1 or 2 spp.) occurs in southern South America. The enigmatic monospecific genus Corsiopsis is known from a single specimen collected in southern China. While the family is characterized by a prominent floral synapomorphy – the outer median tepal forms a distinct labellum – the systematic affinities of Corsiaceae have long been obscure. This is the result of the family’s mycoheterotrophic lifestyle, which complicates morphological and molecular inferences of the relationships. Moreover, previous studies have questioned the monophyly of Corsiaceae, based on the putative placement of Arachnitis in Dioscoreales resulting from phylogenetic inference, as well as morphological differences between the genera. In the present study, we used nuclear and mitochondrial DNA sequence data to test the monophyly of the family and infer its phylogenetic relationships with other families. We used this phylogenetic framework to estimate divergence times of Corsiaceae and reconstruct a scenario for its biogeographic history. We found that Corsiaceae are monophyletic (although Corsiopsis was not sampled) and sister to Campynemataceae. Both families form a well-supported clade that is sister to the rest of Liliales. The split between Corsia and Arachnitis is estimated between 30 and 76 Ma, which overlaps with the plate-tectonic breakup of southern Gondwana. These results imply that the family has an origin in Gondwana, and that its current disjunct distribution is explained by ancient Gondwana vicariance. Although disjunct distributions and ancient divergence times are also observed in other mycoheterotrophic groups (e.g. Triuridaceae, Voyria (Gentianaceae)), this Gondwana vicariance scenario is unique in mycoheterotrophic angiosperms.

1 - Naturalis Biodiversity Center, Botany, Darwinweg 2, Leiden, ZH, 2333 CR, The Netherlands
2 - University of British Columbia, Department of Botany, 3529-6270 University Blvd., Vancouver, BC, V6T 1Z4, Canada
3 - Jodrell Laboratory, Royal Botanic Gardens KEW, Richmond, N/A, TW9 3DS, United Kingdom
4 - Botany, 216 E Duncan St, Columbus, OH, 43202, USA
5 - Naturalis Biodiversity Center, Department of Botany, Darwinweg 2, Leiden, ZH, 2333 CR, The Netherlands
6 - Biology, M.H. Tromplaan 152, Oegstgeest, N/A, 2341TE, Netherlands

Keywords:
BEAST
Corsiaceae
Gondwana
biogeography
Liliales
Phylogeny.

Presentation Type: Oral Paper:Papers for Topics
Session: 59
Location: Salon 3/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 8:45 AM
Number: 59004
Abstract ID:277
Candidate for Awards:None