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Abstract Detail

Systematics Section/ASPT

Stefanovic, Sasa [1], Costea, Mihai [2].

Species delimitation, phylogenetic relationships,and plastome evolution in the Cuscuta chapalana species complex (horned dodders; Convolvulaceae).

Broad molecular phylogenetic analyses of parasitic genus Cuscuta identified the C. chapalana complex as one of the 15 major clades in the subgenus Grammica. This group, morphologically characterized by the presence of peculiar multicelullar appendages on the corolla and calyx lobes, includes some of the least known Cuscuta species in North America. Also, a recent Southern hybridization survey has shown that this clade exhibits a considerable loss of plastid genes compared to its close relatives. The C. chapalana aggregate is native primarily to Mexico but some members are also found in adjacent areas: C.erosa in southern Arizona, C. costaricensis reaches Central America (Costa Rica and Guatemala), and C. boldinghii expands to the Caribbean, Central and northern South America. The other species species, C. chapalana and C. mexicana, were previously known only from their type collections, and C. strobilacea was thought to be rare in Central Mexico. We have examined specimens from over 100 herbaria worldwide and have conducted extensive fieldwork in Mexico and the U.S.A. As a result, we have discovered two new species (C. carnosa and C.bonafortunae) as well as more collections and localities for all the members of this group. In turn, this allowed us to gain a more accurate view of geographical distribution, ecology, and biology of the C. chapalana species complex. Furthermore, basic morphology, scanning electron microscopy, and sequence data from both nuclear (nrITS; 26S rDNA) and plastid (trnL-F) genomes were used to determine the species boundaries and reconstruct their evolutionary relationships. Cuscuta chapalana in particular is remarkably variable, and several morphotypes have been identified around the Chapala Lake in Jalisco and MichoacÃƒÂ¡n (Mexico). Given the phylogenetically progressive distribution of the plastid gene losses across the C. chapalana species complex, this clade presents an ideal opportunity to study the reduction of the plastome of parasitic plants "in action."

Broader Impacts:

1 - UNIVERSITY OF TORONTO, Department of Botany, 3359 MISSISSAUGA RD N, MISSISSAUGA, ON, L5L 1C6, Canada
2 - Wilfrid Laurier University, Department of Biology, 75 University Avenue West, Ontario, N2L 3C5, Canada

Keywords:
Cuscuta
molecular phylogeny
nrITS
26S rDNA
trnL-F
SEM
plastome evolution.

Presentation Type: Oral Paper:Papers for Sections
Session: 49
Location: Marlborough A/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 5:00 PM
Number: 49014
Abstract ID:118
Candidate for Awards:None