Annonaceae substitution rates - a codon model perspective

The Annonaceae includes cultivated species of economic interest and represents an important source of information for better understanding the evolution of tropical rainforests. In phylogenetic analyses of DNA sequence data that are used to address evolutionary questions, it is imperative to use appropriate statistical models. Annonaceae are cases in point: Two sister clades, the subfamilies Annonoideae and Malmeoideae, contain the majority of Annonaceae species diversity. The Annonoideae generally show a greater degree of sequence divergence compared to the Malmeoideae, resulting in stark differences in branch lengths in phylogenetic trees. Uncertainty in how to interpret and analyse these differences has led to inconsistent results when estimating the ages of clades in Annonaceae using molecular dating techniques. We ask whether these differences may be attributed to inappropriate modelling assumptions in the phylogenetic analyses. Specifically, we test for (clade-specific) differences in rates of non-synonymous and synonymous substitutions. A high ratio of nonsynonymous to synonymous substitutions may lead to similarity of DNA sequences due to convergence instead of common ancestry, and as a result confound phylogenetic analyses. We use a dataset of three chloroplast genes (rbcL, matK, ndhF) for 129 species representative of the family. We find that differences in branch lengths between major clades are not attributable to different rates of non-synonymous and synonymous substitutions. The differences in evolutionary rate between the major clades of Annonaceae pose a challenge for current molecular dating techniques that should be seen as a warning for the interpretation of such results in other organisms

A plastid DNA phylogeny of Dasymaschalon (Annonaceae) and allied genera: Evidence for generic non-monophyly and the parallel evolutionary loss of inner petals

Dasymaschalon and the closely related genera Desmos, Friesodielsia and Monanthotaxis together comprise ca. 170 species of trees, shrubs and woody climbers distributed in tropical Africa and tropical Asia. These genera form the desmoid clade, which, because of the presence of diverse flower and fruit syndromes including different types of pollination chambers and moniliform monocarps, offers an opportunity to investigate potentially ecologically significant shifts in flower and fruit characters. Despite its morphological diversity, however, generic delimitation within the desmoid clade is problematic and the intergeneric relationships of the constituent genera are only poorly understood. Bayesian, maximum likelihood and maximum parsimony analyses of plastid DNA sequence data ( matK, psbA-trnH, ndhF, rbcL, trnL-F; ca. 5.4 kb; 52 taxa) were used to clarify phylogenetic relationships within the desmoid clade. The evolution and taxonomic utility of selected fruit and flower characters was investigated with likelihood and parsimony ancestral character reconstructions. The results indicate problems in the current delimitations of Dasymaschalon and Friesodielsia. Friesodielsia as currently circumscribed is polyphyletic, with African Friesodielsia species allied to the African genus Monanthotaxis, and only distantly related to Asian representatives. The majority of Dasymaschalon species form a strongly supported clade, but three species are more closely related to Asian species of Friesodielsia. Ancestral character reconstructions indicate that seed number and monocarp shape are of limited value in generic circumscriptions, and that the three-petalled corolla characteristic of Dasymaschalon evolved independently twice within the desmoid clade. Disruptions to homeotic gene expression or strong selective pressure for a partial enclosure of the mature stamens and carpels by the corolla are hypothesised to underlie the parallel evolution of pollination chambers formed by outer petal homologues subsequent to inner petal los

The Annonaceae and the Annonaceae Project: a brief overview of the state of affairs

The large tropical family Annonaceae is subject to systematic research by a group of scientists, who are collaborating within the framework of the Annonaceae Project. The significance of the Annonaceae is outlined briefly, and the achievements of the Annonaceae Project are summarize

Studies in Annonaceae XXVIII. Macromorphological variation of recent invaders in northern Central America: the case of Malmea (annonaceae)

Cluster analysis is used to reveal patterns of macromorphological variation in a species complex of Malmea (Annonaceae) distributed in eastern Mexico, Guatemala, Belize, and Honduras. Of 53 characters, 24 are important for the clustering of 238 herbarium specimens into 12 clusters. No cluster is exclusively specified by any character or combination of characters. Neither can any geographical pattern be detected, except for the clustering of specimens from Los Tuxtlas Tropical Biological Station, Veracruz. A new subspecies from this area, M. depressa subsp. abscondita, is described. Malmea gaumeri and M. leiophylla are brought into synonymy with M. depressa. Distribution patterns of Mexican and Central American taxa of Malmea are largely concordant with those of South American taxa, which spread into Cental America after the Pliocene closure of the Isthmus of Panama. A phytogeographical novelty is presented, however, as the distribution of M. depressa subsp. abscondita within the Sierra de los Tuxtlas shows an hitherto unknown pattern: the new subspecies is distributed only on the northeastern slopes of this mountain range, and is geographically separated from M. depressa subsp. depressa, which occurs only on the southwestern slope

Myristicineae, a new suborder within Magnoliales

Myristicaceae are sister group to the remaining five families of Magnoliales, which make up the suborder Magnoliineae. Both with regard to morphological and DNA sequence data, Myristicaceae have diverged substantially from Magnoliineae, whereas at the same time monophyly of Magnoliales is conclusive. This relationship between Myristicaceae and Magnoliineae is affirmed by describing the suborder Myristicineae

A nonet of novel species of Monanthotaxis (Annonaceae) from around Africa

This dataset contains the digitized treatments in Plazi based on the original journal articl

Studies in Annonaceae XXVII. Novelties in neotropical Annonaceae

In the framework of the multidisciplinary Annonaceae project, monographs of the neotropical genera Duguetia (ca. 75 species) and Malmea (ca. 30 species) are being prepared by both authors. Two new species, one of Duguetia and one of Malmea, are herewith described