Genetic Diversity and Phylogeographic Structure of the Parasitic Plant Genus Conopholis (Orobanchaceae): Implications for Systematics and Post-glacial Colonization of North America

• Main Author: Rodrigues, Anuar
• Other Authors: Stefanovic, Sasa
• Language: en_ca
• Published: 2013
• Subjects: Phylogeography; Molecular Systematics; Morphometrics; Microsatellite marker development; North America; Parasitic Plant; Holoparasite; Last Glacial Maximum; refugia; Post-glacial colonization; 0309
• Online Access: http://hdl.handle.net/1807/43710

Parasitism in plants is often accompanied by a suite of morphological and physiological changes resulting in a condition known as the ‘parasitic reduction syndrome’. With changes including extreme vegetative reduction, frequently beyond any resemblance to its photosynthetic relatives, accompanied by significant losses of genes linked to photosynthesis, the study of parasitic plants can be challenging. Conopholis (Orobanchaceae) is a small holoparasitic genus distributed across eastern and southwestern North America and Central America. This genus has never been the subject of a molecular phylogenetic or morphometric analyses. In addition, very little is known of the relationships among populations and of their post-glacial history. To investigate the species limits and phylogenetic relationships in Conopholis, we conducted a comprehensive molecular phylogenetic study of the genus as well as a fine-scale morphometric study. Based on plastid and nuclear sequences, Conopholis was found to contain three distinct and well-supported lineages which have varying degrees of overlap with previously proposed taxa. The clustering and ordination analyses of the morphometric study corroborated the molecular data, demonstrating the morphological differentiation between the three lineages detected within Conopholis. A taxonomic re-alignment is proposed for the genus that recognizes three species, C. americana, C. panamensis, and C. alpina. To address genetic diversity and phylogeographic structure of C. americana in eastern North America, microsatellite markers were developed and characterized for the first time in this species. Using these newly generated markers along with sequences from the plastid genome, the persistence of a minimum of two glacial refugia at the last glacial maximum were inferred, one in Florida and southern Alabama and another in the Appalachian Mountains near the southern tip of Blue Ridge Mountains. The diversity seen across the southern Appalachian Mountains supports the hypothesis that populations derived from the southern and northern refugia come together in this area.