Multilocus analysis of genetic divergence between outcrossing Arabidopsis species: evidence of genome-wide admixture.
• Outcrossing Arabidopsis species that diverged from their inbreeding relative Arabidopsis thaliana 5 million yr ago and display a biogeographical pattern of interspecific sympatry vs intraspecific allopatry provides an ideal model for studying impacts of gene introgression and polyploidization on species diversification. • Flow cytometry analyses detected ploidy polymorphisms of 2× and 4× in Arabidopsis lyrata ssp. kamchatica of Taiwan. Genomic divergence between species/subspecies was estimated based on 98 randomly chosen nuclear genes. Multilocus analyses revealed a mosaic genome in diploid A. l. kamchatica composed of Arabidopsis halleri-like and A. lyrata-like alleles. • Coalescent analyses suggest that the segregation of ancestral polymorphisms alone cannot explain the high inconsistency between gene trees across loci, and that gene introgression via diploid A. l. kamchatica likely distorts the molecular phylogenies of Arabidopsis species. However, not all genes migrated across species freely. Gene ontology analyses suggested that some nonmigrating genes were constrained by natural selection. • High levels of estimated ancestral polymorphisms between A. halleri and A. lyrata suggest that gene flow between these species has not completely ceased since their initial isolation. Polymorphism data of extant populations also imply recent gene flow between the species. Our study reveals that interspecific gene flow affects the genome evolution in Arabidopsis.
Wang
Wei-Kuang
WK
Department of Life Sciences, National Cheng-Kung University, Tainan, Taiwan.
Ho
Chuan-Wen
CW
Hung
Kuo-Hsiang
KH
Wang
Kuo-Hsiung
KH
Huang
Chi-Chun
CC
Araki
Hitoshi
H
Hwang
Chi-Chuan
CC
Hsu
Tsai-Wen
TW
Osada
Naoki
N
Chiang
Tzen-Yuh
TY
D019943:Amino Acid Substitution / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics*; D003433:Crosses, Genetic; D018744:DNA, Plant / Q000032:analysis; D005434:Flow Cytometry; D051456:Gene Flow / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics; D056426:Genetic Loci / Q000235:genetics*; D014644:Genetic Variation; D018745:Genome, Plant / Q000235:genetics*; D008957:Models, Genetic; D010802:Phylogeny; D011003:Ploidies; D013045:Species Specificity
D018744:DNA, Plant