Speciation and biogeographical history of the Campanula lusitanica complex (Campanulaceae) in the Western Mediterranean region

Abstract

A phylogenetic survey based on ITS and trnT‐L sequences was conducted in the Campanula lusitanica complex, a group of annual species of Campanula sect. Rapunculus (Campanulaceae) distributed in the western Mediterranean region. Both nuclear and plastid data unambiguously demonstrated the existence of two non‐related lineages within this complex (C. lusitanica and C. dieckii). The C. lusitanica lineage is monophyletic and comprises five species (C. broussonetiana, C. cabezudoi, C. lusitanica s.str., C. specularioides, C. transtagana) that have all been referred to C. lusitanica s.l. by various authors; the C. dieckii lineage includes only one extant species, C. dieckii. Furthermore, our data strongly indicate that the affinities of C. dieckii are outside of the Campanula sect. Rapunculus core group. Divergence times indicate that the C. lusitanica lineage most likely originated in the Betic‐Rifian area in the late Miocene (Tortonian, approx. 9.4 My). In the C. lusitanica lineage a vicariant speciation pattern is observed in the recently evolved C. transtagana/C. broussonetiana clade (ca. 5.1 My) probably as a result of continental isolation caused by the opening of the Gibraltar Strait (ca. 5.3 My). Our evolutionary study strongly supports the taxonomic recognition of these otherwise neglected microspecies.

How to Handle Speciose Clades? Mass Taxon-Sampling as a Strategy towards Illuminating the Natural History of Campanula (Campanuloideae)

“…Close relationships between C. patula (2 n = 20, 40), a species widespread in European woodlands and meadows, and the East-Mediterranean perennial geophyte C. spatulata (2 n = 20) were first revealed by Borsch et al [18], within their Campanula rotundifolia -clade. The current increased sampling of Mediterranean species, such as the annual C. lusitanica (2 n = 18, 20), C. phrygia (2 n = 16), and C. sparsa (2 n = 20), and the biennial-perennial C. olympica (2 n = 20), C. pontica (2 n = n/a), and C. rapunculus (2 n = 20), reveals sister relationships between C. lusitanica and the rest of the species, a pattern supported by a more detailed ITS-based phylogenetic study [89]. Cano-Maqueda et al [89] further included five annual, Iberian native species, which formed a well-supported clade including C. lusitanica , and sister to a C. rapunculus – C. sparsa – C. patula lineage.…”

“…The current increased sampling of Mediterranean species, such as the annual C. lusitanica (2 n = 18, 20), C. phrygia (2 n = 16), and C. sparsa (2 n = 20), and the biennial-perennial C. olympica (2 n = 20), C. pontica (2 n = n/a), and C. rapunculus (2 n = 20), reveals sister relationships between C. lusitanica and the rest of the species, a pattern supported by a more detailed ITS-based phylogenetic study [89]. Cano-Maqueda et al [89] further included five annual, Iberian native species, which formed a well-supported clade including C. lusitanica , and sister to a C. rapunculus – C. sparsa – C. patula lineage. Surprisingly, C. lusitanica was inferred as sister to a C. elatines – C. elatinoides clade by the ITS study of Park et al [22], a relationship not supported here.…”

Phylogeny and genetic structure of Erophaca (Leguminosae), a East–West Mediterranean disjunct genus from the Tertiary

“…In the West Mediterranean, for example, lowering of sea levels during Pliocene and Pleistocene glacial maxima could have permitted migrations to occur across the Strait of Gibraltar (Collina-Girard, 2001;Ortiz et al, 2007), while warmer periods allowed some species to expand and others to become restricted or extinct (Taberlet et al, 1998). Most often the Strait is considered a formidable obstacle to plant expansion (e.g., Terrab et al, 2007;Cano-Maqueda et al, 2008), but there are numerous examples of species that have successfully crossed this barrier, both from the North to the South (e.g., Caujape-Castells and Jansen, 2003;Escudero et al, 2008) and from South to North (e.g., Carranza et al, 2006;Ortiz et al, 2009).…”

Historical Isolation versus Recent Long-Distance Connections between Europe and Africa in Bifid Toadflaxes (Linaria sect. Versicolores)

“…Certainly, recurrent seed colonization over sea barriers, specifically the Strait of Gibraltar, has been shown to be more likely if favourable ecological conditions are widespread, regardless of whether plants possess special mechanisms for long-distance dispersal [9], [11]. In other cases, however, long-term isolation between Iberian and NW African populations appears to have occurred, again irrespectively of seed dispersal mechanisms [7], [12], [13], [14]. Although the role of the Strait of Gibraltar as a biogeographic bridge or barrier has been assessed in several studies (see [8] for a revision), little is still known about the impact of the Mediterranean Sea as a large barrier for floristic exchange between Europe and Africa in the last 6 Ma [9], [15], [16].…”