Apparent similarity, underlying homoplasy: Morphology and molecular phylogeny of the North American clade of Manihot

Abstract

North and South American Manihot species are sister clades. Paraphyly of North American sections suggests that taxonomic revision is warranted. The position of Manihotoides pauciflora confirms that Manihotoides should remain subsumed within Manihot. Most growth forms likely evolved repeatedly in this group. The behavior of PEPC and G3pdhNA clones is probably due to incomplete lineage sorting.

Evolution of the untouchables: Phylogenetics and classification of Cnidoscolus (Euphorbiaceae)

“…2, 3), with other morphologically similar plants. Thus, the unusual clustered but non-whorled androecium and cup-like perianth are apparently not primitive as Breckon (1975) suggested.…”

“…Graminifolius due to our inability to obtain specimens of this rare taxon. Some additional Gen-Bank sequences were included from previous works (Wurdack & al., 2005;Chacón & al., 2008;Cervantes-Alcayde & al., 2015;Papadopoulou & al., 2015). For the purpose of replication, when possible we included two or three samples of the same species, especially if the material was from a different country or major region.…”

“…-Ancestral character state reconstructions of morphological traits were performed with Mesquite v.3.2 (Maddison & Maddison, 2017) using likelihood as the estimation method under the Mk1 model, assuming an equal probability of character states at the root node. We focused on the three traits having the most diagnostic and taxonomical value at both species and sectional levels (Müller, 1865(Müller, , 1866Pax, 1910;McVaugh, 1944;Breckon, 1975), i.e., primary leaf venation, arrangement of the androecium, and petiolar glands. These were mapped on both the ITS and chloroplast phylogenies, and an ancestral reconstruction was conducted.…”

“…The majority of flowers are syntepalous, at least at the base, but some can be polytepalous. As mentioned by previous authors (Baillon, 1858;Rogers & Appan, 1973;Breckon, 1975), the nature and origin of the single perianth whorl in Cnidoscolus remain unclear, and doubts persist as to whether the tepals are homologous to petals or sepals. The most important floral trait with evolutionary and taxonomic implications is the androecium, which is usually monadelphous and can have from one to six staminal whorls where the anthers are inserted.…”

“…There is no previous phylogenetic evidence to confirm that Cnidoscolus is monophyletic (Webster, 2014), and to date only a few species have been studied in a phylogenetic context, either in broad studies of Euphorbiaceae (Wurdack & al., 2005) or as outgroups in reconstructions of the closely related genus Manihot Mill. (Chacón & al., 2008;Duputié & al., 2011;Cervantes-Alcayde & al., 2015). Furthermore, a modern comprehensive infrageneric classification is lacking, and the most recent subgeneric treatment of the entire genus was done by McVaugh (1944).…”