Abstract Detail

Population Genetics

Sedaghatpour, Maryam [1], Oldham, Karoline [2], Weeks, Andrea [3].

Patterns in the population genetic diversity of the North American hemiparasite Melampyrum lineare (Orobanchaceae).

Melampyrum lineare Desr. (narrowleaf cowwheat) is a hemiparasitic annual flowering plant native to North America that obtains water and nutrients by penetrating the roots of its host species, which include maple trees, pine trees, and members of Ericaceae among others. Due to this physiological dependency, M. lineare is limited to the geographical range of its hosts. Within the United States, its distribution encompasses the southern Appalachian Mountains to throughout the northeastern states and westward to Minnesota, with disjunct populations in Idaho and Montana. Within Canada, it is distributed at lower latitudes from Newfoundland to Vancouver Island as well as further north along the more temperate Pacific coast. A recent morphological revision of its four taxonomic varieties showed that this highly polymorphic species cannot be partitioned into sub-specific categories reliably, yet morphological diversity seems greatest in the eastern-most part of its range. Molecular phylogeographic investigation was begun to uncover patterns of this species’ genetic diversity as a complement to our morphological work and to test Francis Pennell’s 1935 hypothesis that M. lineare found historical refuge in the southern Appalachian region and subsequently recolonized North America from this location. Under Pennell’s biogeographical scenario, we would expect greater genetic diversity of M. lineare in the southern-most part of it range. Molecular data were collected from 29 eastern U.S. populations ranging from Georgia to Maine and 20 Canadian populations in Alberta and British Columbia provinces. Four nuclear microsatellite markers (MsO66^P, MsO70^M, MsG2, and MsB58) developed for M. sylvaticum cross-amplified and showed allelic variation. A survey of 15 chloroplast gene regions found that four showed inter- and intra-population variability (trnS-trnG, psbA-trnH, trnT-trnL, and rps16-trnQ). Analysis of trnS-trnG indicated nine haplotypes are shared among 170 individuals in 49 populations. Two haplotypes are present in Canada and all nine are present in southeastern US populations, a pattern consistent with Pennell’s origin hypothesis. Further analysis of microsatellite and other chloroplast gene regions data will refine our ability to fingerprint populations, test patterns of M. lineare’s historical range expansion, and to better describe its biological diversity in areas where it must be managed as a legally rare or threatened species.

1 - George Mason University , Department of Biology , 4400 University Dr., MSN 3E1, Fairfax, VA, 22030, USA
2 - George Mason University , School of Systems Biology, 4400 University Dr., Fairfax, VA, 22030, USA
3 - George Mason University, 4400 University Drive MSN 5F2, Fairfax, VA, 22030, USA

Keywords:
Orobanchaceae
population genetics
Genetic diversity
Fingerprinting 
Phylogeography 
Biogeography
Parasitic 
hemiparasite
Microsatellite 
cpDNA
Appalachian
Refugia .

Presentation Type: Oral Paper
Session: 39, Population Genetics
Location: 201/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 9:00 AM
Number: 39005
Abstract ID:878
Candidate for Awards:Margaret Menzel Award