Biogeographical, ecological and ploidy variation in related asexual and sexualLimoniumtaxa (Plumbaginaceae)

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Limonium is a widespread genus of halophytes and taxa found on the Atlantic coast include sexual diploids of the L. ovalifolium complex, agamospermous tetraploids of the L. binervosum complex and the triploid L. algarvense. In this study, we investigated: (1) cytotype distribution and diversity within and among populations in an overlapping region of diploid and polyploid Limonium spp. in south-western Iberia and north-western Morocco; and (2) patterns of geographical parthenogenesis and ecological preferences across a latitudinal gradient on the Atlantic coast. We show here for the first time that L. nydeggeri and L. algarvense are found further south in Morocco than previously reported. Genome size and ploidy estimates showed that the distribution of these species is not random at the overlapping region studied: tetraploid apomicts tend to be found at higher latitudes than the sexual diploids and L. algarvense grows in sympatry at the southern boundaries of the diploids. Natural populations showed a constancy in ploidy in these complexes. However, we report for the first time the occurrence of mixed-ploidy populations of L. ovalifolium s.l., euploid triploids in L. algarvense and aneuploids in the L. binervosum complex. On the Atlantic coasts, L. algarvense followed by L. ovalifolium complexes occur significantly more frequently in thermomediterranean and dry ombrotype habitats than the L. binervosum complex. Significant differences were also observed among taxa in the frequency of occurrences on the most common lithological groups. In conclusion, this work presents the first biogeographical insights for the group based in a coarse-scale analysis of data and it provides evidence of ecological differentiation between the studied Limonium complexes.