0000000000178688
AUTHOR
C. Bittkau
Evolutionary processes in a continental island system: molecular phylogeography of the Aegean Nigella arvensis alliance (Ranunculaceae) inferred from chloroplast DNA
Continental shelf island systems, created by rising sea levels, provide a premier setting for studying the effects of past fragmentation, dispersal, and genetic drift on taxon diversification. We used phylogeographical (nested clade) and population genetic analyses to elucidate the relative roles of these processes in the evolutionary history of the Aegean Nigella arvensis alliance (= ‘coenospecies’). We surveyed chloroplast DNA (cpDNA) variation in 455 individuals from 47 populations (nine taxa) of the alliance throughout its core range in the Aegean Archipelago and surrounding mainland areas of Greece and Turkey. The study revealed the presence of three major lineages, with largely nonove…
Plant speciation in continental island floras as exemplified byNigellain the Aegean Archipelago
Continental shelf island systems, created by rising sea levels, provide a premier setting for studying the effects of geographical isolation on non-adaptive radiation and allopatric speciation brought about by genetic drift. The Aegean Archipelago forms a highly fragmented complex of mostly continental shelf islands that have become disconnected from each other and the mainland in relatively recent geological times (ca<5.2 Ma). These ecologically fairly homogenous islands thus provide a suitable biogeographic context for assessing the relative influences of past range fragmentation, colonization, gene flow and drift on taxon diversification. Indeed, recent molecular biogeographic studies…
Molecular inference of a Late Pleistocene diversification shift inNigellas. lat. (Ranunculaceae) resulting from increased speciation in the Aegean archipelago
Aim To infer the temporal course and geographical mode of speciation in Mediterranean/Southwest Asian Nigella s. lat. Location Mediterranean Basin, Aegean archipelago. Methods Phylogenies for Nigella L. and Garidella L. (= Nigella s. lat.) were obtained from maximum-likelihood analyses of internal transcribed spacer (ITS) sequences. Diversification through time was analysed by log lineages-through-time (LTT) plots and survival analyses. Relative node age estimates were regressed against the degree of sympatry between sister clades to infer the predominant mode of geographical speciation in Nigella s. lat. Results The Late Pleistocene radiation of the Nigella arvensis complex in the Aegean r…