Chloroplast and ITS phylogenies to understand the evolutionary history of southern South American Azorella, Laretia and Mulinum (Azorelloideae, Apiaceae).

Azorella, Laretia and Mulinum are taxonomically complex, and good candidates to study evolutionary radiations in the Andes and the importance of hybridizations. Previous phylogenetic studies of subfamily Azorelloideae agree that Azorella and Mulinum as currently conceived are not monophyletic, and hence a revision of their circumscription is necessary. However, these phylogenies were based only on chloroplast DNA sequence data. Here, phylogenetic relationships within Azorelloideae were inferred using sequence data from five chloroplast DNA (rps16 intron, trnQ-rps16, rps16-trnKUUU 5' -exon, trnGGCC-trnSGCU and rpL32-trnLUAG), and from nuclear rDNA ITS regions to assess the monophyly of Azorella and Mulinum and discuss generic re-circumscriptions, determine hybridization and radiation events, identify and characterize important lineages, and propose hypotheses on evolution of key morphological characters. In total, 121 accessions of Azorelloideae were analyzed. Phylogenetic analyses of the different genomes were conducted separately and combined, with and without indels, using maximum parsimony, maximum likelihood, and Bayesian methods. To analyze the incongruence between plastid and nuclear-derived trees a consensus network from strongly supported nodes from cpDNA and ITS trees was constructed. Internode certainty values were calculated to evaluate the reliability of the relationships estimated from the individual cpDNA and ITS data sets and to examine the degree of conflict within the total evidence data set. Azorella and Mulinum were confirmed as not monophyletic. Except three Azorella species, the remaining azorellas, all species of Mulinum, and Laretia form a monophyletic group, designated here as Andean-Patagonian. The three species of Azorella that are not part of the Andean-Patagonian lineage are grouped together with Huanaca and Schizeilema in another lineage, designated here as Austral. Within the Andean-Patagonian clade, three major lineages can be recognized: Diversifolia, Trifurcata, and Spinosum. Each of these lineages have different leaf morpho-anatomies, Diversifolia species being more mesomorphic compared to species of Trifurcata, and species of Spinosum being the most xeromorphic. Hybridizations have been important in the evolution of the group, especially within Diversifolia, with at least six reticulation events resulting in putative homoploid and allopolyploid hybrid species. Evidence from branch lengths and low sequence divergences suggest a rapid radiation in the Spinosum group, probably associated with the acquisition of wings in the fruits.

Morphology and biogeography of Apiaceae subfamily Saniculoideae as inferred by phylogenetic analysis of molecular data.

The phylogenetic placements of several African endemic genera at the base of Apiaceae subfamilies Saniculoideae and Apioideae have revolutionized ideas of relationships that affect hypotheses of character evolution and biogeography. Using an explicit phylogeny of subfamily Saniculoideae, we reconstructed the evolutionary history of phenotypic characters traditionally important in classification, identified those characters most useful in supporting relationships, and inferred historical biogeography. The 23 characters examined include those of life history, vegetative morphology, inflorescences, and fruit morphology and anatomy. These characters were optimized over trees derived from maximum parsimony analysis of chloroplast DNA trnQ-trnK sequences from 94 accessions of Apiaceae. The results revealed that many of these characters have undergone considerable modification and that traditional assumptions regarding character-state polarity are often incorrect. Infrasubfamilial relationships inferred by molecular data are supported by one to five morphological characters. However, none of these morphological characters support the monophyly of subfamilies Saniculoideae or Apioideae, the clade of Petagnaea, Eryngium and Sanicula, or the sister-group relationship between Eryngium and Sanicula . Southern African origins of Saniculoideae and of its tribes Steganotaenieae and Saniculeae are supported based on dispersal-vicariance analysis.

The evolutionary history of Eryngium (Apiaceae, Saniculoideae): rapid radiations, long distance dispersals, and hybridizations.

Eryngium is the largest and arguably the most taxonomically complex genus in the family Apiaceae. Infrageneric relationships within Eryngium were inferred using sequence data from the chloroplast DNA trnQ-trnK 5'-exon and nuclear ribosomal DNA ITS regions to test previous hypotheses of subgeneric relationships, explain distribution patterns, reconstruct ancestral morphological features, and elucidate the evolutionary processes that gave rise to this speciose genus. In total, 157 accessions representing 118 species of Eryngium, 15 species of Sanicula (including the genus Hacquetia that was recently reduced to synonymy) and the monotypic Petagnaea were analyzed using maximum parsimony and Bayesian methods. Both separate and simultaneous analyses of plastid and nuclear data sets were carried out because of the prevalence of polyploids and hybrids within the genus. Eryngium is confirmed as monophyletic and is divided into two redefined subgenera: Eryngium subgenus Eryngium and E. subgenus Monocotyloidea. The first subgenus includes all examined species from the Old World (Africa, Europe, and Asia), except Eryngium tenue, E. viviparum, E. galioides, and E. corniculatum. Eryngium subgenus Monocotyloidea includes all examined species from the New World (North, Central and South America, and Australia; herein called the "New World sensu stricto" clade) plus the aforementioned Old World species that fall at the base of this clade. Most sectional and subgeneric divisions previously erected on the basis of morphology are not monophyletic. Within the "New World sensu stricto" group, six clades are well supported in analyses of plastid and combined plastid and nuclear data sets; the relationships among these clades, however, are unresolved. These clades are designated as "Mexican", "Eastern USA", "South American", "North American monocotyledonous", "South American monocotyledonous", and "Pacific". Members of each clade share similar geographical distributions and/or morphological or ecological traits. Evidence from branch lengths and low sequence divergence estimates suggests a rapid radiation at the base of each of these lineages. Conflict between chloroplast and nuclear data sets is weak, but the disagreements found are suggestive that hybrid speciation in Eryngium might have been a cause, but also a consequence, of the different rapid radiations observed. Dispersal-vicariance analysis indicates that Eryngium and its two subgenera originated from western Mediterranean ancestors and that the present-day distribution of the genus is explained by several dispersal events, including one trans-Atlantic dispersal. In general, these dispersals coincide with the polytomies observed, suggesting that they played key roles in the diversification of the genus. The evolution of Eryngium combines a history of long distance dispersals, rapid radiations, and hybridization, culminating in the taxonomic complexity observed today in the genus.

Circumscription and phylogeny of Apiaceae subfamily Saniculoideae based on chloroplast DNA sequences.

An estimate of phylogenetic relationships within Apiaceae subfamily Saniculoideae was inferred using data from the chloroplast DNA trnQ-trnK 5'-exon region to clarify the circumscription of the subfamily and to assess the monophyly of its constituent genera. Ninety-one accessions representing 14 genera and 82 species of Apiaceae were examined, including the genera Steganotaenia, Polemanniopsis, and Lichtensteinia which have been traditionally treated in subfamily Apioideae but determined in recent studies to be more closely related to or included within subfamily Saniculoideae. The trnQ-trnK 5'-exon region includes two intergenic spacers heretofore underutilized in molecular systematic studies and the rps16 intron. Analyses of these loci permitted an assessment of the relative utility of these noncoding regions (including the use of indel characters) for phylogenetic study at different hierarchical levels. The use of indels in phylogenetic analyses of both combined and partitioned data sets improves resolution of relationships, increases bootstrap support values, and decreases levels of overall homoplasy. Intergeneric relationships derived from maximum parsimony, Bayesian, and maximum likelihood analyses, as well as from maximum parsimony analysis of indel data alone, are fully resolved and consistent with one another and generally very well supported. We confirm the expansion of subfamily Saniculoideae to include Steganotaenia and Polemanniopsis (as the new tribe Steganotaenieae C.I. Calviño and S.R. Downie) but not Lichtensteinia. Sister group to tribe Steganotaenieae is tribe Saniculeae, redefined to include the genera Actinolema, Alepidea, Arctopus, Astrantia, Eryngium, Petagnaea, and Sanicula. With the synonymization of Hacquetia into Sanicula, all genera are monophyletic. Eryngium is divided into "Old World" and "New World" subclades and within Astrantia sections Astrantia and Astrantiella are monophyletic.

A molecular phylogenetic study of southern African Apiaceae.

It has been suggested that southern Africa is the origin of the predominantly herbaceous Apiaceae subfamily Apioideae and that the woody habit is plesiomorphic. We expand previous molecular phylogenetic analyses of the family by considering all but three of the approximately 38 genera native to southern Africa, including all genera whose members, save one, have a woody habit. Representatives of five other genera are included because they may be closely related to these southern African taxa. Chloroplast DNA rps16 intron and/or nuclear rDNA ITS sequences for 154 accessions are analyzed using maximum parsimony, Bayesian, and maximum likelihood methods. Within Apioideae, two major clades hitherto unrecognized in the subfamily are inferred. The monogeneric Lichtensteinia clade is sister group to all other members of the subfamily, whereas the Annesorhiza clade (Annesorhiza, Chamarea, and Itasina) plus Molopospermum (and Astydamia in the ITS trees) are the successive sister group to all Apioideae except Lichtensteinia. Tribe Heteromorpheae is expanded to include Pseudocarum, "Oreofraga" ined., and five genera endemic to Madagascar. The southern African origin of subfamily Apioideae is corroborated (with subsequent migration northward into Eurasia along two dispersal routes), and the positions of the herbaceous Lichtensteinia and Annesorhiza clades within the subfamily suggest, surprisingly, that its ancestor was herbaceous, not woody.

Further cytogenetical studies on diploid and polyploid species of Eryngium L. (Saniculoideae, Apiaceae) from Argentina.

Meiotic studies are carried out in 7 species of Eryngium L. (Saniculoideae, Apiaceae), belonging to both sections Foetida and Panniculata. The chromosome number of E. dorae Norm. (n=8) (Foetida) is reported for the first time, while the gametic chromosome number of E. nudicaule Lam. (n=7) (Foetida) and E. eburneum Decne. (n=8), E. horridum Malme (n=8), E. megapotamicum Malme (n=16), E. mesopotamicum Pedersen (n=24), and E. pandanifolium Cham. et Schlechtd. (n=24) (all belonging to Panniculata) is confirmed in several natural populations. Whereas in section Foetida all species are diploids and two basic chromosome numbers are present (x=8 and x=7), in section Panniculata all species are x=8 but there are three different ploidy levels (diploid, tetraploid, hexaploid). This study reveals that meiosis in all species is normal, with regular bivalent formation in all studied cells. Furthermore, the pollen stainability is above 80% in all cases. These data, together with the previous karyotype analyses, will contribute to the clarification of the relationships between members of both sections, where different mechanisms of speciation have been postulated.