Extensive range persistence in peripheral and interior refugia characterizes Pleistocene range dynamics in a widespread Alpine plant species (Senecio carniolicus, Asteraceae).
Bottom Line: DNA sequences have been deposited in GenBank under accession nos.FR796701–FR797793 and nos.HE614296–HE614583.
Affiliation: Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, Vienna, Austria.Show MeSH
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Mentions: A good model system for addressing the complexity of Pleistocene range dynamics in alpine to subnival species is the diploid lineage of Senecio carniolicus (Asteraceae). Although commonly growing together, diploid and polyploid (tetraploids and hexaploids: Suda et al. 2007) cytotypes of S. carniolicus are reproductively isolated by different habitat requirements (Schönswetter et al. 2007; Hülber et al. 2009; Sonnleitner et al. 2010) as well as strong crossing barriers (Sonnleitner et al. 2010; M. Sonnleitner et al., unpublished) and apparently constitute distinct and nonintermixing lineages. Therefore, it is justified to restrict ourselves here to the diploid cytotype. Several lines of evidence suggest that both peripheral and internal refugia may have played a role in its Pleistocene history. Diploid S. carniolicus occurs in essentially all peripheral refugia identified for silicicolous species in the Eastern Alps (Schönswetter et al. 2005; Thiel-Egenter et al. 2009; the locations of these refugia are shown in Fig. 1a). Furthermore, taxonomically acknowledged (as var. or subsp. insubricus) morphological differentiation between populations from the southwestern Eastern Alps and those elsewhere suggests (under a neutral model) sufficiently long and/or repeated isolation within the prominent and geographically stable refugium in the Southern Alps. On the other hand, diploid S. carniolicus grows in exposed, rocky habitats up to more than 3100 m a.s.l. (Hülber et al. 2009; Sonnleitner et al. 2010), rendering occurrence on steep south-exposed slopes, which likely served as microclimatically favourable habitats on nunataks (Parisod & Besnard 2007), a valid hypothesis. Additionally, nunatak survival has already been suggested for S. halleri (Bettin et al. 2007), a closely related endemic of the Western Alps with similar habitat requirements.
Affiliation: Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, Vienna, Austria.