title: Pleistocene climate change and the origin of two desert plant species, Pugionium cornutum and Pugionium dolabratum (Brassicaceae), in northwest China.
abstract: Pleistocene climate change has had an important effect in shaping intraspecific genetic variation in many species; however, its role in driving speciation is less clear. We examined the possibility of a Pleistocene origin of the only two representatives of the genus Pugionium (Brassicaceae), Pugionium cornutum and Pugionium dolabratum, which occupy different desert habitats in northwest China. We surveyed sequence variation for internal transcribed spacer (ITS), three chloroplast (cp) DNA fragments, and eight low-copy nuclear genes among individuals sampled from 11 populations of each species across their geographic ranges. One ITS mutation distinguished the two species, whereas mutations in cpDNA and the eight low-copy nuclear gene sequences were not species-specific. Although interspecific divergence varied greatly among nuclear gene sequences, in each case divergence was estimated to have occurred within the Pleistocene when deserts expanded in northwest China. Our findings point to the importance of Pleistocene climate change, in this case an increase in aridity, as a cause of speciation in Pugionium as a result of divergence in different habitats that formed in association with the expansion of deserts in China.
authors.affiliation: Key Laboratory for Bio-resources and Eco-environment, College of Life Science, Sichuan University, Chengdu, 6100065, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: School of Biology, University of St Andrews, Mitchell Building, St Andrews, Fife, KY16 9TH, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Abbott
authors.affiliation: State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou, 730000, Gansu, China.
authors.forename: Qiu-Shi
authors.initials: QS
authors.lastname: Yu
authors.affiliation: Laboratory of Evolutionary Genomics, CAS-MPG Partner Institute for Computational Biology, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Kao
authors.initials: K
authors.lastname: Lin
authors.affiliation: Key Laboratory for Bio-resources and Eco-environment, College of Life Science, Sichuan University, Chengdu, 6100065, China.
authors.forename: Jian-Quan
authors.initials: JQ
authors.lastname: Liu
mesh_terms: D019607:Brassicaceae / Q000235:genetics* / Q000502:physiology; D002681:China; D057231:Climate Change; D018742:DNA, Chloroplast / Q000235:genetics; D021901:DNA, Intergenic; D003889:Desert Climate; D017753:Ecosystem; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D006239:Haplotypes / Q000235:genetics; D008969:Molecular Sequence Data; D058974:Phylogeography
chemical_list: D018742:DNA, Chloroplast; D021901:DNA, Intergenic
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