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Abstract Detail


Bruederle, Leo P [1], Villaverde, Tamara [2], Escudero, Marcial [3], Luceño, Modesto [2], Starr, Julian [4].

Insight into the Bipolar Disjunction in Carex magellanica Lam. (Cyperaceae).

New World bipolar disjunctions have been reported for approximately 50 plant species and plant species complexes, including six carices (Cyperaceae Tribe Cariceae). While this biogeographic pattern has been well-documented, only recently have the molecular systematic tools been available to test hypotheses offered to explain this distribution. Here, phylogenetic analyses of molecular sequence data for two nuclear regions (ITS, ETS) and four chloroplast regions (atpF–atpH, matK gene, rps16, rpl32F-trnL) are used to re-examine the bipolar distribution in C. magellanica (Carex section Limosae). Although taxonomists have disagreed over the treatment of this taxon, it is recognized currently as comprising two subspecies. Carex magellanica subsp. irrigua (Wahlenb.) Hiitonen is circumboreal in the Northern Hemisphere and highly disjunct in the southern parts of its range. In contrast, C. magellanica subsp. magellanica is restricted in distribution to the Southern Hemisphere, where it occurs in the Andean alpine of South America, specifically Argentina and Chile, Tierra del Fuego, and the Falkland Islands. Sequence data were obtained from sites distributed from the Altai in southern Russia across northern North America to Finland in Western Europe, as well as from across the latitudinal range of this taxon in the Southern Hemisphere from the southern Andes to Tierra del Fuego in Argentina. The combined nuclear and plastid matrix consisted of 36 samples, 207 sequences with 4071 sites. Maximum-likelihood and Bayesian inference analyses retrieved C. magellanica as monophyletic, with C. magellanica subsp. magellanica nested within a paraphyletic C. magellanica subsp. irrigua. Genealogical relationships obtained using the cpDNA matrix and statistical parsimony revealed five haplotypes and three missing haplotypes. Two haplotypes were widely distributed in the Northern Hemisphere, while three others are Southern Hemisphere. Divergence times estimated using Beast 2 also retrieved Carex magellanica as monophyletic in a strongly supported clade with an age of 1.54 Myr (95% CI 0.75 – 2.69 Myr), indicating that diversification of C. magellanica occurred in the Northern Hemisphere from the early to middle Pleistocene. Divergence for Carex magellanica subsp. magellanica was estimated at 0.37 Myr (95% CI 0.10 – 0.82 Myr), ranging from middle-late to late Pleistocene. Collectively, our data reveal a north-south direction of dispersal approximately 0.37 million years ago during the late Pleistocene that was followed by diversification and differentiation in the Southern Hemisphere. While long-distance dispersal remains the most likely explanation for the bipolar disjunction, discriminating between stepwise and direct long-distance dispersal has proven elusive.

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1 - University of Colorado Denver, Integrative Biology, Campus Box 171, Denver, CO, 80217-3364, USA
2 - Universidad Pablo de Olavide, Molecular Biology and Biochemical Engineering, Botany Area, Ctra. de Utrera, Km1 sn, Seville, Seville, 41013, Spain
3 - Universidad de Sevilla, Plant Biology and Ecology, Botany Area, C/ S. Fernando, 4, Seville, Seville, 41004, Spain
4 - University of Ottawa, Department of Biology, Ottawa, ON, K1N 6N5, CAN

bipolar disjunction
Carex magellanica

Presentation Type: Oral Paper
Session: 37, Biogeography II
Location: 103/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 11:30 AM
Number: 37014
Abstract ID:840
Candidate for Awards:None

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