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Abstract Detail



Systematics Section/ASPT

Les , Donald H [1], Peredo, Elena L [2], King, Ursula M [3], Tippery, Nicholas P [4].

In "guad" we trust?  Exposing the real Najas guadalupensis (Hydrocharitaceae).

Najas guadalupensis currently is subdivided into four subspecies: N. g. subsp. olivacea (Upper Great Lakes); N. g. subsp. floridana (SE USA); N. g. subsp. muenscheri (Hudson River, NY); and N. g. subsp. guadalupensis (North, Central and South America).  These infraspecific taxa have been difficult to assign satisfactorily because keys rely heavily on characters of seeds (which are absent in many field collections) and on leaf dentition, which has been quantified inaccurately.  To evaluate the taxonomic integrity of these subspecies we undertook an extensive field survey to obtain materials for genetic analysis.  Roughly 230 N. guadalupensis accessions were obtained by field collections made from 2009-2012 across the USA, Costa Rica and Honduras, from material provided by colleagues, and from sampled herbarium specimens.  DNA sequences from these accessions were obtained for four regions: nrITS, trnK/matK, pds, and rbcL and were analyzed phylogenetically among a total of approximately 750 North American Najas accessions.  DNA data revealed a pattern of infrageneric genetic subdivision, but one that was incongruent with the current taxonomic scheme.  We detected four major races within Najas guadalupensis; however, these corresponded roughly with 1) a tropical/western distribution (Honduras to California and Texas); 2) a northern distribution (Minnesota to New Hampshire); 3) a mid-central USA distribution (Texas to Iowa); and 4) a mid-to southern USA distribution (widespread).  Numerous hybrids also were found to occur between the various races.  We determined that "Najas guadalupensis  subsp. muenscheri" is an allotetraploid derivative of N. flexilis.  Furthermore, "Najas  guadalupensis subsp. floridana" represents a completely distinct lineage that is remote phylogenetically from the other races of N. guadalupensis detected.  In addition to our previous reports of interspecific N. flexilis × N. guadalupensis  hybrids, these results necessitate that a thorough taxonomic re-evaluation be made of N. guadalupensis and its former subspecific entities.


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1 - University Of Connecticut, Department Of Ecology & Evolutionary Biology, 75 N. Eagleville Road, Unit 3043, Storrs, CT, 06269-3043, USA
2 - Marine Biological Laboratory, Bay Paul Center, 7 MBL Street, Woods Hole, MA, 02543, USA
3 - University Of Connecticut, Ecology And Evolutionary Biology, Biology/Pharmacy Building, 69 North Eagleville Rd, Storrs, CT, 06269, USA
4 - University Of Wisconsin - Whitewater, Department Of Biological Sciences, 800 W Main St, 800 W Main St, Whitewater, WI, 53190, USA

Keywords:
aquatic plants
Geographical variation
North America
subspecies.

Presentation Type: Oral Paper:Papers for Sections
Session: 31
Location: Pines South/Boise Centre
Date: Tuesday, July 29th, 2014
Time: 1:30 PM
Number: 31001
Abstract ID:170
Candidate for Awards:None


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