Multiple diploid hybrid speciation of the Canary Island endemic Argyranthemum sundingii (Asteraceae)

There are several well-documented examples of multiple hybrid origins of po lyploid species. Herein we report the first, to our knowledge, explicit exa mple of a species that most probably has originated recurrently by diploid hybrid speciation. Genetic relationships and stabilization of two Argyranth emum populations of putative hybrid origin on Tenerife, the Canary Islands, were investigated using chromosomal, morphometric, and fertility analyses of cultivated progeny families and artificial Fl and Fz hybrids. These data were compared to a recently published chloroplast DNA phylogeny of the gen us, in which the same populations were included. The results suggest that t he two populations must be referred to a single species, A. sundingii, whic h is diploid, fully fertile, genetically stabilized, and occurs in an ecolo gically intermediate habitat opened by deforestation, and that this species has originated at least twice following local hybridization in two valleys . The same parental species were involved in each origin; the montane A. br oussonetii and the coastal A. frutescens. The montane species was the chlor oplast donor in one of the valleys and the coastal species in the other.