NATURAL AND EXPERIMENTAL HYBRIDIZATION IN ARMERIA (PLUMBAGINACEAE) - ARMERIA SALMANTICA

An experimental crossing program was carried out to investigate the pr esumed hybrid origin of Armeria salmantica, a local endemic species fr om a single mountain range in western Spain. Fruit set and pollen stai nability data in artificial hybrids between the two putative parents, A. transmontana and A, bigerrensis, demonstrate that internal interspe cific barriers are weak. The F-1 hybrids exhibit an average pollen sta inability of 89.8%, which minimizes the need for a restoration of poll en viability through backcrossing. No evidence of male sterility in ar tificial hybrids was found. A morphometric analysis of 146 specimens b elonging to parental species, artificial hybrids (F-1, B-1, B-2), and wild putative hybrids showed that (1) morphological characters have a strong genetic basis and thus may be good markers to identify hybrids and to track introgression in the genus Armeria; (2) artificial backcr ossing produces variation in morphometric characters that conforms in both trend and magnitude to what is commonly attributed in the wild to introgression; and (3) the results of a multivariate morphometric stu dy are congruent with a hybrid origin of A. salmantica, although not c onclusive as to its parentage or to the degree of introgression that m ight have occurred.