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Possible causes of morphological variation in an endemic Moroccan groundsel ( Senecio leucanthemifolius var. casablancae ): evidence from chloroplast DNA and random amplified polymorphic DNA markers
Author(s) -
Coleman Max,
Abbott Richard J.
Publication year - 2003
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.2003.01729.x
Subject(s) - biology , rapd , introgression , mantel test , senecio , chloroplast dna , biological dispersal , restriction fragment length polymorphism , hybrid , botany , genetic marker , genetic divergence , genetic variation , evolutionary biology , genetics , genetic diversity , polymerase chain reaction , phylogenetics , population , gene , demography , sociology
Genetic variation was assessed in Senecio leucanthemifolius var. casablancae (Compositae), a Moroccan Atlantic coast endemic, in order to examine possible causes of atypical leaf morphology in three populations south of the known range. Evidence for introgression from S. glaucus ssp. coronopifolius and/or divergence was investigated with molecular markers. Both random amplified polymorphic DNA (RAPD) and chloroplast (cp) DNA restriction fragment length polymorphism (RFLP) differentiated the species well. Some evidence that hybridization may have occurred between the two species was provided by cpDNA markers. However, biparentally inherited RAPD markers failed to provide any support for the hypothesis that intermediate leaf morphologies in atypical populations arose through hybridization. Consequently, they are most likely to have arisen via divergence caused by drift and/or selection. Genetic distances among populations of S. leucanthemifolius were significant in all but one case. Isolation by distance was indicated by a significant positive correlation between genetic and geographical distances ( r = 0.68, P = 0.01, Mantel test). These results suggest that long‐distance achene dispersal is rare, despite the presence of a well‐developed pappus. The observed loss of pappus at achene maturity may explain this unexpected result. Due to the morphological distinction of var. casablancae from other varieties of S. leucanthemifolius , we suggest elevation to species rank and treatment of the atypical material at infraspecific rank.