title: Transcriptome-derived evidence supports recent polyploidization and a major phylogeographic division in Trithuria submersa (Hydatellaceae, Nymphaeales).
abstract: Relatively little is known about species-level genetic diversity in flowering plants outside the eudicots and monocots, and it is often unclear how to interpret genetic patterns in lineages with whole-genome duplications. We addressed these issues in a polyploid representative of Hydatellaceae, part of the water-lily order Nymphaeales. We examined a transcriptome of Trithuria submersa for evidence of recent whole-genome duplication, and applied transcriptome-derived microsatellite (expressed-sequence tag simple-sequence repeat (EST-SSR)) primers to survey genetic variation in populations across its range in mainland Australia. A transcriptome-based Ks plot revealed at least one recent polyploidization event, consistent with fixed heterozygous genotypes representing underlying sets of homeologous loci. A strong genetic division coincides with a trans-Nullarbor biogeographic boundary. Patterns of 'allelic' variation (no more than two variants per EST-SSR genotype) and recently published chromosomal evidence are consistent with the predicted polyploidization event and substantial homozygosity underlying fixed heterozygote SSR genotypes, which in turn reflect a selfing mating system. The Nullarbor Plain is a barrier to gene flow between two deep lineages of T. submersa that may represent cryptic species. The markers developed here should also be useful for further disentangling species relationships, and provide a first step towards future genomic studies in Trithuria.
authors.affiliation: Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.|UBC Botanical Garden & Centre for Plant Research, University of British Columbia, 6804 Marine Drive SW, Vancouver, BC, V6T 1Z4, Canada.|Department of Agricultural and Environmental Sciences, High Polytechnic School of Huesca, University of Zaragoza, C/Carretera de Cuarte Km 1, Huesca, E22071, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Marques
authors.affiliation: Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.|UBC Botanical Garden & Centre for Plant Research, University of British Columbia, 6804 Marine Drive SW, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Sean A
authors.initials: SA
authors.lastname: Montgomery
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Barker
authors.affiliation: Western Australian Herbarium, Science and Conservation Division, Department of Parks and Wildlife, Locked Bag 104, Bentley Delivery Centre, Bentley, WA, 6983, Australia.
authors.forename: Terry D
authors.initials: TD
authors.lastname: Macfarlane
authors.affiliation: School of Biological Sciences, Australian Centre for Evolutionary Biology and Biodiversity & Sprigg Geobiology Centre, The University of Adelaide, Benham Bldg DX 650 312, Adelaide, SA, 5005, Australia.
authors.forename: John G
authors.initials: JG
authors.lastname: Conran
authors.affiliation: Department of Agricultural and Environmental Sciences, High Polytechnic School of Huesca, University of Zaragoza, C/Carretera de Cuarte Km 1, Huesca, E22071, Spain.|Department of Botany, Institute of Biology, Tomsk State University, Lenin Av. 36, Tomsk, 634050, Russia.
authors.forename: Pilar
authors.initials: P
authors.lastname: Catalán
authors.affiliation: Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Loren H
authors.initials: LH
authors.lastname: Rieseberg
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Rudall
authors.affiliation: Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.|UBC Botanical Garden & Centre for Plant Research, University of British Columbia, 6804 Marine Drive SW, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Sean W
authors.initials: SW
authors.lastname: Graham
mesh_terms: D000483:Alleles; D001315:Australia; D020440:Gene Duplication; D005819:Genetic Markers; D014644:Genetic Variation; D006579:Heterozygote; D019684:Magnoliopsida / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics; D010802:Phylogeny; D058974:Phylogeography; D011123:Polyploidy; D017423:Sequence Analysis, RNA; D059467:Transcriptome / Q000235:genetics*
chemical_list: D005819:Genetic Markers
keywords: ANA-grade; Australia; Trithuria; microsatellite markers; population genetic diversity; trans-Nullarbor plants; transcriptome-enabled markers