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Callitriche (Plantaginaceae) is a cosmopolitan plant genus in shallow lakes and river margins, wetlands, ditches and temporary pools. Its species exhibit considerable diversity in growth habit, aquatic (submerged), amphibious and terrestrial, but the polarity of growth habit evolution to or from terrestrial habitats is yet to be addressed. The origin of its cosmopolitan distribution, especially to or from Australasia, remains uncertain. We assessed evolution of growth habit and inferred biogeographic history in a phylogenetic framework using DNA sequence data from plastid DNA and the nuclear internal transcribed spacer region. These were separately analysed using maximum parsimony, maximum likelihood and Bayesian inference. The multilocus data sets, excluding two species exhibiting conflicting placement, were then used for coalescent-based species-tree analysis and the resulting species tree was used for ancestral state reconstruction and biogeographic inference. We obtained moderately resolved phylogenetic trees, showing that two terrestrial species, one from Australasia and the other from temperate and tropical Asia, are the first diverging species and the remaining terrestrial species are scattered across the trees. The ancestral state reconstruction supports a terrestrial origin of the genus and multiple reverse transitions to terrestrial conditions. The biogeographic results suggest a Northern Hemisphere origin with multiple dispersal events to Australasia or an out-of-Australasia scenario and rather recent, multiple dispersal events back to Australasia. [ABSTRACT FROM AUTHOR]

The Balkan Peninsula is considered the most important refugium for species during the Pleistocene glaciations and today harbours c. 2000 endemic species, but we know surprisingly little about the evolution of taxa in this region. Veronica saturejoides, V. thessalica and V. erinoides are a group of closely related alpine taxa endemic to the Balkan Peninsula. Here, we analyse four DNA regions [the nuclear chalcone synthase intron (CHSi) and ribosomal internal transcribed spacer (ITS) region and the plastid rpoB- trnC spacer and trnL- trnL- trnF region] and amplified fragment length polymorphism (AFLP) fingerprints to provide a phylogenetic hypothesis for the relationships among these taxa. Additionally, we analyse leaf morphological characters used to distinguish the three subspecies of V. saturejoides. The analyses support the distinction of the three subspecies based on previously intuitively suggested characters. Nuclear chalcone synthase intron data indicate that the southern taxa are genetically much more diverse than the more northern V. saturejoides subsp. saturejoides. Phylogenetic relationships inferred from this region and AFLP fingerprints support the monophyly of V. saturejoides. In contrast, plastid DNA regions suggest a closer relationship of V. saturejoides subsp. saturejoides to V. thessalica. The most likely scenario involves introgression into V. saturejoides subsp. saturejoides from V. thessalica. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159, 616–636. [ABSTRACT FROM AUTHOR]