Journal of Systematics and Evolution

• •    


  • 收稿日期:2021-10-28 接受日期:2023-06-02

Resolving relationships despite past hybridization in Aliciella subsection Subnuda (Polemoniaceae)

Theresa C. Saundersa,*, J. Mark Porterb, Leigh A. Johnsona   

  1. a Department of Biology, 4102 LSB, and M. L. Bean Life Science Museum, Brigham Young University, Provo, Utah 84602 USA;
    b California Botanic Garden, 1500 North College Avenue, Claremont, California 91711 USA
    *Author for correspondence e-mail: 255 NW Golden Hills Dr. Space 35 Pullman, WA 99163
  • Received:2021-10-28 Accepted:2023-06-02

Abstract: Phylogenetics is crucial in the study of evolutionary processes and events transpiring in the course of species diversification. Phylogenetic studies within kingdom Plantae often reveal hybridization and introgression. Here, we study a subsection rife with historic hybridization and discuss the impacts of such processes on evolutionary trajectories. Aliciella subsection Subnuda comprises seven species of herbaceous plants occurring in Utah, the Navajo Nation, and the Four Corners region of North America. Previous molecular and morphological work left relationships in the subsection unresolved. Here, we use comparative DNA sequencing of nuclear ITS and chloroplast DNA regions and genome-wide RAD-seq data to clarify phylogenetic relationships and examine the role of hybridization in the subsection. We construct haplotype and nucleotype networks from the chloroplast and nuclear ITS sequence matrices and compare nuclear and chloroplast phylogenies to identify multiple putative chloroplast capture events. The RAD-seq maximum likelihood phylogeny and multispecies coalescent species tree robustly resolve relationships between six species-level clades. We employ STRUCTURE and HyDe on the RAD-seq data to evaluate the influence of hybridization within the subsection. The HyDe results suggest hybridization has occurred among all species in the subsection at some point in their history. Cytonuclear discordance reveals historic chloroplast capture, and we discuss potential causes of the observed discordance. Our study robustly resolves relationships in Aliciella subsection Subnuda and provides a framework for discussing its speciation despite a history of hybridization and introgression.

Key words: Aliciella, cytonuclear discordance, introgression, phylogenomics, RAD-seq