Genetic variation and phylogeographic analyses of two species of Carpobrotus and their hybrids in California

• Published in: Molecular ecology 2005-02, Vol.14 (2), p.539-547
• Main Authors: Schierenbeck, K.A, Symonds, V.V, Gallagher, K.G, Bell, J
• Format: Article
• Language: English
• Subjects: Aizoaceae; Aizoaceae - genetics; Base Sequence; California; Carpobrotus; Carpobrotus chilensis; Carpobrotus edulis; chloroplast DNA; cpDNA; DNA Primers; DNA, Chloroplast - genetics; Ecology; Flowers & plants; Gene Components; Gene flow; Genetic diversity; Genetic Variation; Genetics, Population; geographical variation; Geography; Haplotypes; Haplotypes - genetics; hybridization; Hybridization, Genetic; Hybrids; interspecific hybridization; Marine; Molecular Sequence Data; Phylogeny; phytogeography; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; Population differentiation; restriction fragment length polymorphism; Sequence Analysis, DNA; Species Specificity
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/j.1365-294X.2005.02417.x

Despite the commonality and study of hybridization in plants, there are few studies between invasive and noninvasive species that examine the genetic variability and gene flow of cytoplasmic DNA. We describe the phylogeographical structure of chloroplast DNA (cpDNA) variation within and among several interspecific populations of the putative native, Carpobrotus chilensis and the introduced, Carpobrotus edulis (Aizoaceae). These species co‐occur throughout much of coastal California and form several ‘geographical hybrid populations’. Two hundred and thirty‐seven individuals were analysed for variation in an approximate 7.0 kb region of the chloroplast genome using PCR‐RFLP (polymerase chain reaction – restriction fragment length polymorphism) data. Phylogenetic analyses and cpDNA population differentiation were conducted for all morphotypes. Historic geographical dispersion and the coefficient of ancestry of the haplotypes were determined using nested clade analyses. Two haplotypic groupings (I and II) were represented in C. chilensis and C. edulis, respectively. The variation in cpDNA data is in agreement with the previously reported allozyme and morphological data; this supports relatively limited variation and high population differentiation among C. chilensis and hybrids and more wide‐ranging variation in C. edulis and C. edulis populations backcrossed with C. chilensis. C. chilensis disproportionately contributes to the creation of hybrids with the direction of gene flow from C. chilensis into C. edulis. The cpDNA data support C. chilensis as the maternal contributor to the hybrid populations.