Abstract Detail

Systematics

Léveillé-Bourret, Étienne [1], Starr, Julian [1], Ford, Bruce [2], Gilmour, Claire [3], Donadío, Sabina [4], Naczi, Robert [5], Nguyễn, Thị Kim Thanh [6], Vũ, Anh Tài [7], Chen, Bing-hua [8], Jin, Xiao-feng [9], Spalink, Daniel [10], Lemmon, Emily Moriarty [11], Lemmon, Alan R. [12], Sytsma, Kenneth J. [13].

Finding the sister to sedges (Carex): a new tribal and generic classification for the Cariceae-Dulichieae-Scirpeae Clade (Cyperaceae).

For over a century, the origins and mechanisms underlying the diversification of the enormous temperate genus Carex (>2000 species; Cariceae, Cyperaceae) have remained largely speculative. Characteristics such as its diverse ecology, varied biogeography, and intriguing cytology have made Carex a powerful model for studying plant evolution, but uncertain sister-group relationships hinder its use in studies that depend on accurate ancestral state estimates and biogeographic inferences. Over the past five years, we have focused our research on resolving relationships within the major clade to which Carex belongs, the Cariceae-Dulichieae-Scirpeae (CDS) clade, a lineage containing 18 genera and approximately 40% of all Cyperaceae species (~2,100). Although initial phylogenetic studies based on nuclear and plastid Sanger-sequence markers suggested that Carex was nested within a paraphyletic tribe Scirpeae, and that several Scirpeae genera could also be paraphyletic, backbone nodes were unsupported. This meant the sister-group to Carex could not be determined, and any reclassification of CDS would be problematic. Using a subset of key taxa, we generated data for 461 nuclear exons using a universal flowering plant Anchored Phylogenomics probe set. These phylogenomic analyses were fully congruent with previous Sanger-based phylogenies, but they resolved all backbone nodes with high support, corroborating the need for a new tribal and generic-level revision of CDS. Although phylogenomic trees firmly place the Trichophorum Clade (Trichophorum, Oreobolopsis, Cypringlea) as sister to Carex, long branches and considerable morphologically differences emphasized the isolated position of Carex. This highlighted the importance of sampling Sumatroscirpus, the only CDS genus never before included in molecular analyses. Although rarely collected and believed to be a monospecific Sumatran endemic, taxonomic revision revealed that Sumatroscirpus consists of four species distributed north to China, including a locality in northern Vietnam where DNA could be obtained. Molecular analyses positioned Sumatroscirpus as sister to Carex, a relationship supported by a morphological synapomorphy: sheathing spikelet prophylls (perigynia). Moreover, it supported previous hypotheses suggesting an important role for Southeast Asia in the historical biogeography of Carex. With all CDS genera now placed in a robust phylogenetic framework, it is finally possible to propose a natural tribal classification for CDS. Combined molecular, morphological, anatomical and embryological data supports the recognition of seven tribes, four of which are new (Calliscirpeae, Khaosokieae, Sumatroscirpeae, Trichophoreae). Ongoing species-level studies of Trichophoreae and Scirpus, based on plastid, nuclear, RADseq, and morphological datasets will soon resolve the only remaining problems for generic circumscription in CDS.

1 - University of Ottawa, Department of Biology, Gendron Hall, Room 160, 30 Marie-Curie, Ottawa, Ontario, K1N 6N5, Canada
2 - University Of Manitoba, Department Of Biological Sciences, 50 Sifton Road, Winnipeg, MB, R3T 2N2, Canada
3 - 301-10530 84th Ave NW, Edmonton, AB, T6E2H4, Canada
4 - CONICET - Instituto de Botánica Darwinion, Labardén 200 - Casilla de Correo 22, San Isidro, B1642HYD, Argentina
5 - The New York Botanical Garden, 2900 Southern Blvd., Bronx, NY, 10458-5126, USA
6 - Faculty of Biology, Vietnam National University - VNU University of Science, Hanoi, Vietnam
7 - Institute of Geography, Vietnam Academy of Science and Technology, Hanoi, Vietnam
8 - College of Life Sciences, Fujian Normal University, Fuzhou, Fujian, 350117, China
9 - College of Life and Environmental Sciences, Hangzhou Normal University, 16 Xuelin Street, Xiasha Higher Educational District, Hangzhou, Zhejiang, CN‐310036, China
10 - University Of Utah, Department Of Biology, 257 South 1400 East, Salt Lake City, UT, 84112, United States
11 - Florida State University, Biology, 319 Stadium Drive, P.O. Box 3064295, Tallahassee, FL, 32306-4295, USA
12 - Florida State University, Scientific Computing, 400 Dirac Science Library, Tallahassee, FL, 32306-4120, USA
13 - University of WI-Madison, Botany, 132 Birge Hall, , 430 Lincoln Drive, Madison, WI, 53706, USA

Keywords:
classification
fertile prophyll
genotyping-by-sequencing
homology
Hyb-Seq
morphology
nuclear exons
perigynium
RADseq
Taxonomy
total evidence analysis
utricle.

Presentation Type: Oral Paper
Session: 37, Systematics III--Monocots 2 to Caryophs
Location: 111/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 8:00 AM
Number: 37001
Abstract ID:767
Candidate for Awards:Cinq Mars Award