title: Genetics of cryptic speciation within an Arctic mustard, Draba nivalis.
abstract: Crossing experiments indicate that hybrid sterility barriers frequently have developed within diploid, circumpolar plant species of the genus Draba. To gain insight into the rapid evolution of postzygotic reproductive isolation in this system, we augmented the linkage map of one of these species, D. nivalis, and searched for quantitative trait loci (QTLs) associated with reproductive isolation. The map adds 63 new dominant markers to a previously published dataset of 31 co-dominant microsatellites. These markers include 52 amplified fragment length polymorphisms (AFLPs) and 11 sequence-specific amplified polymorphisms (SSAPs) based on retrotransposon sequence. 22 markers displaying transmission ratio distortion were further included in the map. We resolved eight linkage groups with a total map length of 894 cM. Significant genotype-trait associations, or quantitative trait loci (QTL), were detected for reproductive phenotypes including pollen fertility (4 QTLs), seed set (3 QTLs), flowering time (3 QTLs) and number of flowers (4 QTLs). Observed patterns of inheritance were consistent with the influence of both nuclear-nuclear interactions and chromosomal changes on these traits. All seed set QTLs and one pollen fertility QTL displayed underdominant effects suggestive of the involvement of chromosomal rearrangements in hybrid sterility. Interestingly, D. nivalis is predominantly self-fertilizing, which may facilitate the establishment of underdominant loci and contribute to reproductive isolation.
authors.affiliation: National Centre for Biosystematics, Natural History Museum, University of Oslo, Oslo, Norway.
authors.forename: A Lovisa S
authors.initials: AL
authors.lastname: Gustafsson
authors.affiliation: Microbial Evolution Research Group (MERG), Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Inger
authors.initials: I
authors.lastname: Skrede
authors.affiliation: Botany Department, University of British Columbia, Vancouver, Canada.
authors.forename: Heather C
authors.initials: HC
authors.lastname: Rowe
authors.affiliation: National Centre for Biosystematics, Natural History Museum, University of Oslo, Oslo, Norway; Botany Department, Faculty of Biology and Soil Science, St Petersburg State University, St Petersburg, Russia.
authors.forename: Galina
authors.initials: G
authors.lastname: Gussarova
authors.affiliation: National Centre for Biosystematics, Natural History Museum, University of Oslo, Oslo, Norway.
authors.forename: Liv
authors.initials: L
authors.lastname: Borgen
authors.affiliation: Botany Department, University of British Columbia, Vancouver, Canada.
authors.forename: Loren H
authors.initials: LH
authors.lastname: Rieseberg
authors.affiliation: National Centre for Biosystematics, Natural History Museum, University of Oslo, Oslo, Norway.
authors.forename: Christian
authors.initials: C
authors.lastname: Brochmann
authors.affiliation: National Centre for Biosystematics, Natural History Museum, University of Oslo, Oslo, Norway; Laboratory of Evolutionary Botany, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Parisod
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D001110:Arctic Regions; D002874:Chromosome Mapping; D005298:Fertility / Q000235:genetics; D035264:Flowers / Q000235:genetics; D049810:Genetic Speciation; D018895:Microsatellite Repeats / Q000235:genetics; D009149:Mustard Plant / Q000235:genetics* / Q000254:growth & development; D011058:Pollen / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics*; D060047:Reproductive Isolation; D012639:Seeds / Q000235:genetics