title: Asymmetric introgression in the horticultural living fossil cycas sect. Asiorientales using a genome-wide scanning approach.
abstract: The Asian cycads are mostly allopatric, distributed in small population sizes. Hybridization between allopatric species provides clues in determining the mechanism of species divergence. Horticultural introduction provides the chance of interspecific gene flow between allopatric species. Two allopatrically eastern Asian Cycas sect. Asiorientales species, C. revoluta and C. taitungensis, which are widely distributed in Ryukyus and Fujian Province and endemic to Taiwan, respectively, were planted in eastern Taiwan for horticultural reason. Higher degrees of genetic admixture in cultivated samples than wild populations in both cycad species were detected based on multilocus scans by neutral AFLP markers. Furthermore, bidirectional but asymmetric introgression by horticultural introduction of C. revoluta is evidenced by the reanalyses of species associated loci, which are assumed to be diverged after species divergence. Partial loci introgressed from native cycad to the invaders were also detected at the loci of strong species association. Consistent results tested by all neutral loci, and the species-associated loci, specify the recent introgression from the paradox of sharing of ancestral polymorphisms. Phenomenon of introgression of cultivated cycads implies niche conservation among two geographic-isolated cycads, even though the habitats of the extant wild populations of two species are distinct.
authors.affiliation: Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan. pcliao@mail.npust.edu.tw.
authors.forename: Yu-Chung
authors.initials: YC
authors.lastname: Chiang
authors.forename: Bing-Hong
authors.initials: BH
authors.lastname: Huang
authors.forename: Chun-Wen
authors.initials: CW
authors.lastname: Chang
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Wan
authors.forename: Shih-Jie
authors.initials: SJ
authors.lastname: Lai
authors.forename: Shong
authors.initials: S
authors.lastname: Huang
authors.forename: Pei-Chun
authors.initials: PC
authors.lastname: Liao
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D001499:Bayes Theorem; D029784:Cycas / Q000145:classification / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D017753:Ecosystem; D005580:Fossils; D051456:Gene Flow; D014644:Genetic Variation; D018745:Genome, Plant; D006824:Hybridization, Genetic; D008126:Lod Score; D010802:Phylogeny; D025341:Principal Component Analysis; D013045:Species Specificity; D013624:Taiwan
chemical_list: D018744:DNA, Plant