Systematics, phylogeography and multiple origins of morphs in two species complexes belonging to Cistaceae, Helianthemum oelandicum and H. nummularium

The Helianthemum oelandicum complex shows considerable morphological variation across its geographic distribution in Europe and western Asia. By combining four primer pairs and four restriction enzymes I identified nine cpDNA haplotypes with distinct geographical distributions. Two haplotypes were most frequent over most of the range; one in western Europe and one in eastern Europe. Moreover, differences in haplotype composition were much more strongly pronounced in west-east direction than in south-north direction. There was no correlation between chloroplast haplotype and morphological variation. Parallel evolution in the regional populations produced similar morphologies without necessarily being closely related. The complex on Öland is represented by two endemic and allopatric varieties, differing in flowering phenology and indumentum. Variety oelandicum has a wide distribution, while var. canescens is restricted to small areas in the southernmost Öland. Only two, allopatrically distributed, cpDNA haplotypes are detected in the present study. The border between the distributional areas of the two haplotypes is distinct and cuts across extensive, more or less continuous populations of var. oelandicum. This border coincides with marked differences in the frequency of hairy and glabrous plants. The phylogenetic analysis of the ITS and cpDNA revealed poorly resolved trees in the Helianthemum oelandicum complex; taxa were polyphyletic. The H. nummularium complex is a morphologically variable species that has been subdivided into several subspecies, primarily based on indumentum characters. I investigated five of these subspecies for variation in chloroplast DNA and leaf and petal shape in Europe. The highest haplotype diversity was found in the Alps and the surrounding lowland areas, whereas marginal areas such as northern Europe and southeastern Balkans had low diversity. Most of the common haplotypes were shared between subspecies and showed distinct geographic structures across the species range. Leaf and petal shape descriptors could not differentiate between subspecies. It is concluded that the poor correspondence between chloroplast haplotype distribution and subspecies circumscription is due to multiple origins of morphologically similar morphs in different parts of the distribution range of the complex

Genetic and morphological differentiation across a contact zone between two postglacial immigration lineages of Helianthemum nummularium (Cistaceae) in southern Scandinavia

Helianthemum nummularium (L.) Mill. has two subspecies in southern Scandinavia, which differ in an indumentum character that is inherited as a Mendelian gene with two alleles. The dominant allele is the genetic basis for the key character of subsp. obscurum (absence of a dense felt of stellate hairs on the abaxial surface of the leaf), whereas the recessive allele is the genetic basis for the key character of subsp. nummularium (presence of a dense felt of stellate hairs). Subsp. obscurum occurs in southwest Scandinavia, whereas subsp. nummularium occurs in southeast Scandinavia. The distributions of the two subspecies overlap in a wide zone in south Sweden, where natural populations consist of a mixture of the two subspecies in various proportions. Eighty-five percent of the investigated populations in this zone are polymorphic. A significant positive correlation exists between latitude/longitude across the zone and the frequency of the recessive indumentum allele. There is no significant difference in the leaf shape between the two subspecies, but there is a geographical trend across the zone. Twenty-seven populations displayed six plastid DNA haplotypes in Scandinavia. The geographic distribution of four of these haplotypes supports an eastern postglacial immigration lineage, whereas the distribution of two others haplotypes supports a postglacial immigration lineage from southwest

Phylogeography of the European rock rose Helianthemum nummularium (Cistaceae): incongruent patterns of differentiation in plastid DNA and morphology

Helianthemum nummularium is a morphologically variable species that has been subdivided into several subspecies based on indumentum characters. We investigated four of these subspecies for variation in plastid DNA and leaf and petal shape in Europe. Three size-variable mononucleotide repeat regions were amplified by means of species-specific primers and 18 combined haplotypes were identified. The highest haplotype diversity was found in the Alps and the surrounding lowland areas, whereas marginal areas such as northern Europe and the south-eastern Balkans had a lower diversity. Most of the common haplotypes were shared between subspecies and showed a geographical structuring across the range of the species, whereas geographically restricted haplotypes were found elsewhere (e.g. in the Baltic area). Leaf and petal shape descriptors could not differentiate between subspecies. The role of hybridization and introgression between post-glacial migration lineages is discussed. As an alternative hypothesis to introgression between ancient taxa, we suggest that the poor correspondence between plastid haplotype distribution and subspecies circumscription could be a result of multiple origins of similar morphs (grouped into taxonomic subspecies) in different parts of the distribution range of the complex. (c) 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 311-331

Phylogeography of the European rock rose Helianthemum nummularium s.l. (Cistaceae) : western richness and eastern poverty

Helianthemum nummularium s.l. is a young, morphologically diverse species distributed from western Europe to the Caucasus and the Southern Urals in the east. We analysed the rps16-trnK plastid intergenic spacer sequences from 85 localities covering most of the range of H. nummularium. Thirteen haplotypes were very unevenly distributed throughout the range of the species, and exhibited a strong phylogeographic signal. The results confirm range expansions of H. nummularium from Mediterranean refugia northwards, but also show the major role of eastern European (the Caucasus and the Southern Urals) refugia in rapid postglacial colonization of east, north and central Europe. The plastid haplotypes form distinct clades, one representing an eastern European lineage with few haplotypes and the other representing a western European lineage with many haplotypes. Parallel to this split in haplotype diversity is the pronounced differentiation in morphological variation displayed by the taxa found in west and east Europe. We discuss the role of topography in generating differences in morphological and genetic diversity between these two groups. We also discuss the taxonomical status of Helianthemum arcticum, which is regarded as an endangered local endemic of the Kola Peninsula. Helianthemum arcticum appears to represent an outlying peripheral population of H. nummularium preserved since the last postglacial major range expansion of this species, and bears the same plastid haplotype as the bulk of east and north European populations