Cyclamen: time, sea and speciation biogeography using a temporally calibrated phylogeny

Abstract

Aim The Mediterranean region is a species‐rich area with a complex geographical history. Geographical barriers have been removed and restored due to sea level changes and local climatic change. Such barriers have been proposed as a plausible mechanism driving the high levels of speciation and endemism in the Mediterranean basin. This raises the fundamental question: is allopatric isolation the mechanism by which speciation occurs? This study explores the potential driving influence of palaeo‐geographical events on the speciation of Cyclamen (Myrsinaceae), a group with most species endemic to the Mediterranean region. Cyclamen species have been shown experimentally to have few genetic barriers to hybridization. Location The Mediterranean region, including northern Africa, extending eastwards to the Black Sea coast. Methods A generic level molecular phylogeny of Myrsinaceae and Primulaceae is constructed, using Bayesian approximation, to produce a secondary age estimate for the stem lineage of Cyclamen. This estimate is used to calibrate temporally an infrageneric phylogeny of Cyclamen, built with nrDNA ITS, cpDNA trnL‐F and cpDNA rps16 sequences. A biogeographical analysis of Cyclamen is performed using dispersal–vicariance analysis. Results The emergence of the Cyclamen stem lineage is estimated at 30.1–29.2 Ma, and the crown divergence at 12.9–12.2 Ma. The average age of Cyclamen species is 3.7 Myr. Every pair of sister species have mutually exclusive, allopatric distributions relative to each other. This pattern appears typical of divergence events throughout the evolutionary history of the genus. Main conclusions Geographical barriers, such as the varying levels of the Mediterranean Sea, are the most plausible explanation for speciation events throughout the phylogenetic history of Cyclamen. The genus demonstrates distributional patterns congruent with the temporally reticulate palaeogeography of the Mediterranean region.

Phylogeny, Biogeography, and Evolution of Edaphic Association in the European OreophytesSempervivumandJovibarba(Crassulaceae)

“…In contrast to this general pattern, we here could demonstrate three independent dispersals from Europe into Southwest Asia for Sempervivum. This pattern has been found before in only two studies (Álvarez Fernández et al 2001;Yesson et al 2009). …”

The building of a biodiversity hotspot across a land-bridge in the Mediterranean

“…This confirms that the Mediterranean Sea has biased species migration between northern Morocco and the southern Iberian Peninsula, in such a way that better dispersers ancestors have been less likely to experience vicariance through continuous gene flows, thus favouring speciation only in certain lineages with low long-distance dispersal ability [22]. Molecular evidence further supports varying levels of the Mediterranean Sea and intermittent land-bridges as the most plausible explanation for species differentiation between southern Iberian Peninsula and northern Morocco in disparate angiosperm clades [59][60][61][62], and between other disjunct areas within the Mediterranean Basin [63][64][65]. These results illustrate how land-bridges between Europe and Africa have contributed to the emergence of this western Mediterranean biodiversity hotspot.…”

Insular Woodiness on the Canary Islands: A Remarkable Case of Convergent Evolution

“…Integrating georeferenced environmental data and evolutionary biology is an efficient way to reveal new insights into the ecological causes of evolutionary patterns (Kozak et al 2008;Evans et al 2009;Yesson et al 2009;Boucher et al 2012). On the basis of this niche-modeling approach, we hope to find environmental variables that are tightly linked to either the insular woody or the herbaceous life form on the Canary Islands.…”