Phylogenetic Relationships and Biogeography within the Eurasian Clade of Amaryllidaceae Based on Plastid ndhF and nrDNA ITS Sequences: Lineage Sorting in a Reticulate Area?

The monophyletic Eurasian clade of Amaryllidaceae was analyzed using plastid ndhF and rDNA ITS sequences for 33 and 29 taxa, respectively; all genera were represented by at least one species. Both maximum parsimony and Bayesian analysis were used on each data set and the combined data. Both sequence matrices resolve the Central and East Asian tribe Lycorideae as sister to the Mediterranean-centered genera of the clade, and recognize two large subclades within the greater Mediterranean region: Galantheae, consisting of Acis, Galanthus and Leucojum; and Narcisseae (Narcissus and Sternbergia)/Pancratium. However, there are areas of incongruence between the ndhF and ITS trees. When three predominantly monotypic genera, Hannonia, Lapiedra, and Vagaria, centered in North Africa, are removed from the alignments, the two sequence matrices produce fully congruent topologies with increased support at many of the nodes, with ILD between partitions rising from P 5 0.07 to 0.96. We hypothesize that lineage sorting took place after the divergence of Galantheae and Narcisseae/Pancratium from a common genepool with Hannonia, Lapiedra, and Vagaria retaining a mosaic of the ancestral haplotypes. We also performed dispersal-vicariance analysis to reconstruct biogeographic scenarios on several of the generic level phylogenies found with and without these three genera included, as well as on a species-level phylogeny of Galantheae. After the vicariant divergence of the Asian Lycorideae, North Africa and the Iberian Peninsula are the most likely areas of origin for the rest of the clade. The results of the dispersal-vicariance analysis are discussed in the context of the complex biogeographic history of the Mediterranean basin. The Eurasian clade of the Amaryllidaceae contains the members of the family that have adapted to the highest latitudes in the Northern Hemisphere, and also those with the greatest economic value as spring flowering temperate zone garden plants (Narcissus L., Galanthus L., Leucojum L.). The clade has recently been recognized as a monophyletic group, resolved as sister to the endemic American genera by plastid DNA sequences (Ito et al. 1999; Meerow et al. 1999; Lledó et al. 2004) with weak bootstrap support (50–70%). The Eurasian clade encompasses four tribes that were previously recognized (Meerow and Snijman 1998): Galantheae Salisb., Lycorideae Traub, Narcisseae Endl., and Pancratieae Salisb. (Table 1), the overall relationships of which were obscured by their diversity of chromosome number and morphology (Traub 1963). Müller-Doblies and Müller-Doblies (1978a) earlier observed similarities between the internal bulb morphology of Ungernia Bunge (Lycorideae) and Sternbergia Walst. & Kit. (Narcisseae). With the exception of the Central and East Asian Lycorideae, the clade is centered within the Mediterranean region (Meerow and Snijman 1998; Lledó et al. 2004). For the purposes of our discussion in this paper, Meerow and Snijman (1998) will be followed with slight modification. References to Narcisseae refer to Narcissus and Sternbergia, Pancratieae to Pancratium and Vagaria, while references to Galantheae refer collectively to Acis, Galanthus, and Leucojum. There are 11 genera in the clade, comprising ca. 120 spp., with Lycoris (ca. 20 spp.) and Narcissus (40 spp.) the largest genera (Meerow and Snijman 1998). Lledó et al. (2004) recently presented a cladistic analysis of the clade that focused on the relationships of Leucojum and Galanthus using plastid matK, nuclear ribosomal ITS sequences, and morphology. Leucojum was revealed as paraphyletic, and the genus Acis Salisb. was resurrected to accommodate the linear-leaved Mediterranean Leucojum species with solid scapes. While their sampling within these three genera was extensive, only a single species each of the genera Pancratium, Sternbergia, Narcissus, and Vagaria Herb., along with the monotypic Lapiedra, were used as an outgroup. Hannonia was not included. Consequently, the phylogenetic relationships of the entire clade were not explicitly examined in their analyses. A similar case holds for Graham and Barrett’s (2004) study of floral evolution in Narcissus using plastid ndhF and trnL-F sequences, which included only Lapiedra and one species each of Galanthus, Leucojum, and Sternbergia as outgroups in their analyses. ITS was previously used with success to explore the phylogenetic relationships of the American clade of the Amaryllidaceae (Meerow et al. 2000), the tribes Amaryllidaeae (Meerow and Snijman 2001), Haemantheae (Meerow and Clayton 2004), Hymenocallideae (Meerow et al. 2002), and the genus Crinum (Meerow et al. 2003). 2006] 43 MEEROW ET AL.: EURASIAN AMARYLLIDACEAE TABLE 1. Treatment of the Eurasian clade of Amaryllidaceae in the four most recent intrafamilial classification of Amaryllidaceae s.s. Acis is included in Leucojum in all of these classification. aAs Dahlgren et al. (1985) did not consistently list the component genera in their tribal concepts, their exact generic composition is inferred. Most of their delimitations are presumed to have followed Traub (1963). Traub (1963) Dahlgren et al. (1985)a Müller-Doblies and Müller-Doblies (1996) Meerow (1995), Meerow and Snijman (1998) Amarylloideae Infrafamily Amarylloidinae Lycoreae Lycoris Herb. Ungernia Bunge Amaryllidaceae Lycorideae Lycoris Ungernia Amaryllidaceae Lycorideae Lycoris Ungernia Amaryllidaceae Lycorideae Lycoris Ungernia Narcisseae Narcissus L. Sternbergia Walst. & Kit. Tapeinanthus Herb. Narcisseae Narcissus (incl. Tapeinanthus Herb.) Sternbergia Narcisseae subtr. Narcissinae Narcissus Sternbergia Narcisseae Narcissus Sternbergia Galantheae Galanthus L. Leucojum L. Hannonia Braun-Blanq. & Marie Lapiedra Lag. Galantheae Galanthus Leucojum subtr. Galanthinae Galanthus Leucojum Galantheae Galanthus Leucojum Hannonia Lapiedra Infrafamily Pancratioidinae Pancratieae Pancratieae Pancratieae subtr. Pancratiinae Pancratieae