Plant Systematics and Evolution

Levin, Donald

doi: 10.1007/s00606-018-1552-xpmid: N/A

In spite of their success during the past several millions of years, recent analyses indicate that polyploid species may have higher extinction rates than their diploid relatives. The idea that neopolyploid species are relatively short-lived is antithetical to the notion of polyploid exceptionalism. I propose that young, established polyploid species have unusually high extinction rates due to demographic and genetic challenges and that early demise accounts for the elevated extinction of polyploid species as a whole. Polyploid species are composed of conspecific lineages (each of an independent origin). Each origin is associated with a genetic and demographic bottleneck which reduces their abilities to cope with environment perturbations. The greater the number of independently originated lineages, the longer a polyploid species is likely to persist, given that the lineages are genetically/ecologically divergent. Autopolyploids appear to have much higher extinction rates than allopolyploids, even though the formation frequency in autopolyploids may be orders of magnitude greater. Niche differences between polyploids and their progenitors may be enhanced via the differential survival of the most divergent polyploids relative to their progenitors. It seems to be the rarely successful polyploid that flourishes during times of environmental alteration and that leaves an enduring genomic legacy.

Marinho, Cristina; Teixeira, Simone

doi: 10.1007/s00606-018-1548-6pmid: N/A

In this study, we reassessed the morphology and distribution of laticifers present in the inflorescences of nine Moraceae and three Urticaceae species and compared the substances found in their latices. Reproductive meristems and inflorescences at different developmental stages were collected, fixed and processed for light microscopy analysis. In Moraceae, laticifers occur in almost all inflorescence organs. In Urticaceae, the presence of laticifers in the inflorescence axis and sepals is a novelty, since the family is characterized by having laticifers only in the bark. The laticifers of Moraceae and Urticaceae show a thin pectocellulosic cell wall and are articulated and branched, although they are currently classified as non-articulated branched in Moraceae and non-articulated unbranched in Urticaceae. The latex contains proteins and alkaloids. Lipids are common in Moraceae latex, whereas phenolic compounds occur in the Urticaceae latex. Polysaccharides occur in the majority of the species studied, an unprecedented finding for the group. Thus, we found that the non-articulated type of laticifer may not consist of a synapomorphy for Moraceae and Urticaceae. Moreover, the laticifer branching in the inflorescences of Urticaceae indicates that its distribution and ramification as acknowledged in the literature (restricted to the bark and unbranched) should be reevaluated and may not constitute synapomorphies for this family either. The adaptive value of laticifers for Moraceae and Urticaceae is high, since they occur widely in the plant body of their representatives. The presence of proteins and alkaloids in the latex and the absence of starch grains are probably conserved traits in the urticinean rosids.

Kaveh, Akram; Kazempour-Osaloo, Shahrokh; Amirahmadi, Atefe; Maassoumi, Aliasghar; Schneeweiss, Gerald

doi: 10.1007/s00606-018-1549-5pmid: N/A

Onobrychis sect. Heliobrychis with ca. 30 species is one of the most species-rich sections of Onobrychis. It comprises predominantly perennials mainly distributed in Iran, Turkey, and Transcaucasia. In order to test the monophyly of the section and as well as its subsections and to clarify interspecific relationships, three non-coding chloroplast sequences and the nuclear ribosomal DNA internal transcribed spacer were employed. Phylogenetic analyses were performed by maximum parsimony, maximum likelihood, and Bayesian inference. Based on the combined data set, O. sect. Heliobrychis was retrieved as a well-supported monophyletic group sister to O. sect. Hymenobrychis. The annuals traditionally united in subsect. Persicae formed a paraphyletic group, whereas all perennials (the monotypic subsect. Szovitsianae nested within subsect. Boissierianae) assembled in a monophyletic group. Ancestral state reconstruction of morphological characters: life history, the absence/presence of stem, and the number of seed, indicated that annuality is plesiomorphic, whereas the absence of a stem and two-seeded pods is homoplasious in the section. Based on molecular phylogeny and morphological evidence, the taxonomy of some species of sect. Heliobrychis was re-examined. Therewith, O. aucheri subsp. aucheri was synonymized with O. heliocarpa, O. aucheri subsp. psammophila and O. aucheri subsp. teheranica were raised to species rank as O. psammophila and O. teheranica, respectively, and O. semnanensis was resurrected. Also as a complementary taxonomic treatment, a diagnostic key to the species of O. sect. Heliobrychis is supplied.

Pimenov, Michael; Degtjareva, Galina; Ostroumova, Tatiana; Samigullin, Tahir; Zakharova, Ekaterina

doi: 10.1007/s00606-018-1550-zpmid: N/A

A comprehensive study of critical South Asian species Seseli diffusum (Umbelliferae—Apioideae—Apieae) was carried out to determine the most suitable taxonomic position of the species, based on morphology (carpoanatomy, micromorphology of the fruit indumentum and some vegetative characters) and molecular data from nrDNA ITS region sequencing. Comparison with certain other species of Seseli and several provisionally related Apieae genera showed a close affinity of S. diffusum to the genus Psammogeton and more distant relationships with some species of Trachyspermum, clearly polyphyletic genus. No species of Seseli, even in broad sense, was found to be closely related to S. diffusum. It was proposed to transfer this species into Psammogeton, while separating a new section, Pseudoseseli, within the latter.

Zhang, Yu-Qu; Zhou, Yun; Hou, Xiao-Qi; Huang, Lei; Kang, Ju-Qing; Zhang, Jian-Qiang; Ren, Yi

doi: 10.1007/s00606-018-1551-ypmid: N/A

Fargesia, a temperate woody bamboo genus, is one of the largest genera and constitutes a taxonomically problematic group due to unusual life cycles and the rarity of flowering. We explored phylogenetic relationships within Fargesia and its allies based on sequence data from three cpDNA regions (matK, psbA-trnH and trnL-trnF) and one nuclear region (nrITS). A representative sample of 49 species, including 36 Fargesia and nine Yushania, were sampled, and maximum parsimony, maximum likelihood and Bayesian inference were used to reconstruct the phylogeny of Fargesia. The results suggest that Fargesia is polyphyletic, with F. crassinoda and F. damuniu in the Thamnocalamus clade, F. ampullaris, F. semiorbiculata, F. gyirongensis and F. collaris in the Drepanostachyum + Himalayacalamus clade, and the rest of species of Fargesia and all sampled species of Yushania in a Fargesia + Yushania clade, which was further divided into weakly supported Fargesia spathe and non-spathe clades. Species in the Fargesia spathe clade have the derived “spathe-like leaf sheath syndrome,” which may have evolved as a result of an adaptive advantage of compressed inflorescences in colder temperatures.

Salariato, Diego; Cueva Manchego, Marco; Cano, Asunción; Al-Shehbaz, Ihsan

doi: 10.1007/s00606-018-1553-9pmid: N/A

The genus Machaerophorus includes three perennial species (M. arequipa, M. laticarpus, and M. matthioloides) inhabiting the southern Peruvian Andes. However, based on the morphological data, this genus has been reduced for more than one hundred years to synonymy of several genera of various tribes, and its phylogenetic placement using molecular data has never been studied. Therefore, in this study we explored the phylogenetic placement of Machaerophorus to test its generic status and tribal assignment, using for this purpose ribosomal nuclear (ITS) and chloroplast (trnL-F, trnH-psbA, rps16 intron) data together with a comprehensive sampling of taxa. Results obtained here demonstrated that Machaerophorus represents a well-differentiated lineage within the South American Cremolobeae–Eudemeae–Schizopetaleae clade, and hence, the genus is reinstated and excluded from the placements in Sibara and Mathewsia. Based on molecular data and morphological affinities, we included it within the tribe Schizopetaleae. A key to Machaerophorus and the genera of Schizopetaleae is also presented.

Albarrán-Lara, Ana; Petit, Remy; Kremer, Antoine; Caron, Henry; Peñaloza-Ramírez, Juan; Gugger, Paul; Dávila-Aranda, Patricia; Oyama, Ken

doi: 10.1007/s00606-018-1554-8pmid: N/A

Quercus magnoliifolia and Q. resinosa are two Mexican white oak species that have been taxonomically reported to exhibit morphological similarities and possible hybridization. The objective of this study was to compare the variation in Q. magnoliifolia and Q. resinosa throughout their distribution range to identify the degree of species differentiation using morphological, ecological and genetic tools. Morphological analysis showed differentiation in leaf shape between the species corresponding to the taxonomical identification of Q. magnoliifolia and Q. resinosa in almost all cases, but intermediate individuals were identified in the middle of the species ranges. Comparison of ecological niche models for Q. magnoliifolia and Q. resinosa showed non-equivalent ecological niches, high climatic niche differences and low to moderate spatial and environmental niche overlap, mainly along the Trans-Mexican Volcanic Belt where morphologically intermediate individuals between species were more frequently located, suggesting recent hybridization by secondary contact. In contrast, we found low but significant genetic differentiation between Q. magnoliifolia and Q. resinosa and lower interspecific than intraspecific genetic differentiation, and Bayesian clustering analysis (K = 2) failed to assign each species to a unique genotype, suggesting shared ancestral variation as the cause of genetic similarity between species due to recent divergence. In conclusion, although neutral molecular markers do not distinguish the species Q. magnoliifolia and Q. resinosa, we found morphological and ecological differentiation between these oaks that provide preliminary evidence for divergent selection.