Plastid matK gene sequences for 374 genera representing all angiosperm orders and 12 genera of gymnosperms were analyzed using parsimony (MP) and Bayesian inference (BI) approaches. Traditionally, slowly evolving genomic regions have been preferred for deep-level phylogenetic inference in angiosperms. The matK gene evolves approximately three times faster than the widely used plastid genes rbcL and atpB. The MP and BI trees are highly congruent. The robustness of the strict consensus tree supercedes all individual gene analyses and is comparable only to multigene-based phylogenies. Of the 385 nodes resolved, 79% are supported by high jackknife values, averaging 88%. Amborella is sister to the remaining angiosperms, followed by a grade of Nymphaeaceae and Austrobaileyales. Bayesian inference resolves Amborella + Nymphaeaceae as sister to the rest, but with weak (0.42) posterior probability. The MP analysis shows a trichotomy sister to the Austrobaileyales representing eumagnoliids, monocots + Chloranthales, and Ceratophyllum + eudicots. The matK gene produces the highest internal support yet for basal eudicots and, within core eudicots, resolves a crown group comprising Berberidopsidaceae/Aextoxicaceae, Santalales, and Caryophyllales + asterids. Moreover, matK sequences provide good resolution within many angiosperm orders. Combined analyses of matK and other rapidly evolving DNA regions with available multigene data sets have strong potential to enhance resolution and internal support in deep level angiosperm phylogenetics and provide additional insights into angiosperm evolution.
Persea can be retained as a genus by the inclusion of Apollonias barbujana and exclusion a few species that do not fit into the established subgenera. A major revision is recommended for the delimitation between Alseodaphne, Dehaasia, and Nothaphoebe. We suggest that the Persea group originated from the Perseeae-Laureae radiation in early Eocene Laurasia. Its amphi-pacific disjunction results from the disruption of boreotropical flora by climatic cooling during the mid- to late Eocene. The American-Macaronesian disjunction may be explained by the long-distance dispersal.
The delimitation of genera within the Persea group (Lauraceae) has always been controversial. In an attempt to resolve the phylogenetic lines within this group, we analyzed ITS sequences of 61 species of the Persea group (Lauraceae) and 30 other species of Lauraceae. Several of the traditional genera or subgenera form wellsupported groups, viz., Persea subg. Eriodaphne, Machilus, Persea subg. Persea, and Alseodaphne including Dehaasia. The included species of Phoebe form two clades that are unresolved with respect to Alseodaphne. However, Persea subg. Eriodaphne (together with the Macaronesian Apollonias barbujana) forms one of the clades of an unresolved basal trichotomy within the Persea group, whereas Persea subg. Persea is well supported as member of an otherwise Asian clade including Alseodaphne and Phoebe. This indicates that Persea, as currently circumscribed, is not monophyletic. The affinities of the Macaronesian Persea indica are clearly American rather than Asian.
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