Population genetic analysis reveals a homoploid hybrid origin of Stephanomeria diegensis (Asteraceae).
Homoploid hybrid speciation has generally been viewed as a rare evolutionary phenomenon, with relatively few well-documented cases in nature. Here, we investigate the origin of Stephanomeria diegensis, a diploid flowering plant species that has been proposed to have arisen as a result of hybridization between S. exigua and S. virgata. Across the range of S. diegensis, all individuals share a common chloroplast haplotype with S. virgata while showing a greater affinity for S. exigua in terms of nuclear genetic diversity. A principal coordinates analysis (PCO) based on the nuclear data revealed that S. diegensis is most similar to each parent along different axes. Moreover, a Bayesian clustering analysis as well as a hybrid index-based analysis showed evidence of mixed ancestry, with approximately two thirds of the S. diegensis nuclear genome derived from S. exigua. These results provide strong support for a homoploid hybrid origin of S. diegensis. Finally, contrary to the finding that homoploid hybrid species are typically multiply-derived, our results were most consistent with a single origin of this species.
Sherman
Natasha A
NA
Department of Plant Biology, University of Georgia, Athens, GA 30602, USA.
Burke
John M
JM
D019659:Asteraceae / Q000235:genetics*; D001499:Bayes Theorem; D002140:California; D002467:Cell Nucleus / Q000235:genetics; D016000:Cluster Analysis; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D005819:Genetic Markers; D014644:Genetic Variation; D005828:Genetics, Population; D018745:Genome, Plant; D006239:Haplotypes; D006824:Hybridization, Genetic; D025341:Principal Component Analysis; D017422:Sequence Analysis, DNA
D018742:DNA, Chloroplast; D018744:DNA, Plant; D005819:Genetic Markers