Phylogenetic relationships of the monotypic genera Halacsya and Paramoltkia and the origins of serpentine adaptation in circum- mediterranean Lithospermeae (Boraginaceae): insights from ITS and matK DNA sequences

Publication Type:Journal Article
Year of Publication:2009
Authors:Cecchi, L., F. Selvi
Start Page:700
Keywords:Boraginaceae, edaphic habitat, Halacsya, molecular phylogeny, Paramoltkia, serpentine adaptation

Halacsya and Paramoltkia are monotypic and partially sympatric genera in the Balkans, with no clear relation-
ships among extant Lithospermeae due to striking morphological autapomorphies and scarcity of phylogenetic
analyses in this group. The two species H. sendtneri and P. doerfleri show a strict selectivity for serpentine soils,
posing the question whether this edaphic specialization reflects a common ancestry or a parallel process of adap-
tive evolution in unrelated lineages. DNA sequences from the nuclear ITS and chloroplast matK regions were
generated from multiple accessions of Halacsya and Paramoltkia, and from representatives of 16 other genera
of Mediterranean Lithospermeae. SEM analyses of pollen morphology were also conducted to test relationships
indicated by molecular phylogenies. Parsimony analyses retrieved a clade of morphologically well differentiated
monotypic Lithospermeae including Halacsya and Paramoltkia. ITS provided a better resolution of relationships
and showed the two genera to be sistergroups close to Mairetis and Moltkiopsis, and no affinity to Moltkia as sup-
posed by past authors. Pollen characters corroborated the phylogenetic link between the two Balkan genera. Five
further monophyletic clades were recognised: Onosma-Echium, Moltkia, Lithospermum s.l., Arnebia-Macrotomia,
and Alkanna-Podonosma. Mapping the edaphic preferences of Lithospermeae onto molecular cladograms showed
that serpentinophytism as an obligate condition originated separately in the clade of monotypic genera and in
that of Onosma-Echium. In Halacsya and Paramoltkia it represents an early ecological synapomorphy which
probably originated in situ from non-serpentine ancestors related to Moltkiopsis and Mairetis.


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