Subfamily Barnadesioideae (Asteraceae) consists of nine genera and 91 species endemic to South America. They include annual and perennial herbs, arching shrubs and trees up to 30
m tall. Presumed ...sister to all other Asteraceae, its intergeneric relationships are key to understanding the early evolution of the family. Results of the only molecular study on the subfamily conflict with relationships inferred from morphology. We investigate inter- and intrageneric relationships in Barnadesioideae with novel DNA sequence data and morphological characters using parsimony, likelihood and Bayesian inference. All results verify Barnadesioideae as monophyletic and sister to the rest of the family. A basal split within the subfamily is recognized, with
Chuquiraga,
Doniophyton and
Duseniella in one clade, and
Arnaldoa,
Barnadesia,
Dasyphyllum,
Fulcaldea,
Huarpea and possibly
Schlechtendalia in another. The largest genus,
Dasyphyllum, is revealed as biphyletic with the two clades separating along subgeneric and geographic lines.
Schlechtendalia, suggested as the earliest diverging lineage of the subfamily by morphological studies and parsimony analyses, is found in a more derived position under model-based inference methods. Competing phylogenetic hypotheses, both previous and present, are evaluated using likelihood-based tests. Evolutionary trends within Barnadesioideae are inferred: hummingbird pollination has developed convergently at least three times. An early vicariance in the subfamily’s distribution is revealed.
X
=
9 is supported as the ancestral base chromosome number for both Barnadesioideae and the family as a whole.
Abstract
We studied the epiphytic species Tillandsia capillaris and T. virescens that grow as neotenic forms with autogamous and cleistogamous flowers. They have expanded in Andean mountain ...environments, where they grow sympatrically across most of their ranges in arid regions of Peru, central-western Bolivia and north-central Argentina and Chile. We studied the relationships between the two species and populations within each of them, the morphological boundaries and the climatic characterization of distinct genetic entities. We analysed 125 and 102 individuals from 25 and 27 populations of T. virescens and T. capillaris, respectively, by means of haplotype networks, phylogenetic and genetic structure analyses, using the plastid gene ycf1 (c. 4500 bp) to define genetic groups. Morphological studies by discriminant analyses and correlation with climatic variables extracted from WorldClim were used to test differentiations among the genetic groups within each species. We confirm that T. capillaris is a distinct entity and that T. virescens consists of three groups that diverged by vicariance from widespread ancestors. The high genetic diversity found in both species is consistent with the complex geography of the Andes and the Pleistocene glaciation cycles that have driven ecological speciation in both species reflected in the timing of divergence of the clusters.
Abstract
Phylogenetic and molecular clock analyses were performed including all genera except one (Pseudomonotes) for the three subfamilies of Dipterocarpaceae. We also included representatives of ...Sarcolaenaceae and Cistaceae with Bixaceae as the ultimate outgroup. Three plastid regions (six markers), partial rbcL, trnK-matK-trnK (partial trnK intron including complete matK) and trnT-trnL-trnF (partial trnT, complete trnT-trnL intergenic spacer, complete trnL, complete trnL-trnF intergenic spacer and partial trnF), were analysed. We also investigated additional accessions for genome size and chromosome numbers. Our phylogenetic results differ in three important respects from previous interpretations of morphological characters, as reflected in recent classifications. First, our analyses strongly support assignment of Pakaraimaea (subfamily Pakaraimaeoideae) to Cistaceae. Second, the morphological concepts of Dipterocarpeae and Shoreeae in subfamily Dipterocarpoideae are not supported because Dipterocarpus is sister to Dryobalanops plus tribe Shoreeae. Our analysis revealed four clades: (1) Dipterocarpus; (2) Dryobalanops, for which tribal assignment has been contentious; (3) genera of Shoreeae; and (4) the remaining genera of Dipterocarpeae. Third, Shorea is not monophyletic. Monotoideae are weakly supported as sister to Dipterocarpoideae; Sarcolaenaceae (endemic to Madagascar) are sister to this pair. Divergence in extant Dipterocarpoideae occurred c. 55 Mya. Genome sizes for all accessions examined are small (0.3264–0.6724 pg), and the additional chromosome numbers we collected fit into the patterns previously observed for Dipterocarpaceae.
Since the first description of the genus in 1754, the taxonomy of Ananas underwent many fundamental changes and it is still the subject of a vivid debate. We present a phylogeny comprising all seven ...known Ananas taxa, Pseudananas sagenarius as well as closely related members of Bromelioideae (Aechmea subg. Chevaliera) based on three nuclear markers (agt1, ETS, phyC), five plastid markers (atpB–rbcL, trnL–trnF, matK, two segments of ycf1) and AFLP data. This study reveals a close relationship between Ananas, P. sagenarius, Aechmea tayoensis and Disteganthus basilateralis, and proposes novel relationship of the Ananas clade and Aechmea fernandae. Taxonomic implications of our analysis in particular the recognition of species versus varieties in Ananas are discussed. Furthermore, we could show that the evolution of two traits (scape bracts and the apical coma of the inflorescence) might be interlinked.
We performed a phylogenetic analysis using maximum parsimony and Bayesian inference of three plastid DNA markers and the external transcribed spacer (ETS) of nuclear ribosomal DNA to assess the ...species composition of the Tillandsia utriculata complex and their phylogenetic relationships, and to reconstruct patterns of character evolution and biogeography. The results showed that species of the T. utriculata complex are nested in a clade composed mainly of Mexican and Central American species of T. subgenus Tillandsia (Mexican Clade), and are organized in two lineages: the T. utriculata clade and the T. limbata clade. The ancestor of the core Mexican Clade was probably a T. utriculata‐like epiphyte (Group II‐type remote flowers and flexuous rachises). The T. utriculata clade is defined morphologically by the presence of acute petals. In this clade, there are two lineages: one of high‐elevation, saxicolous, grey‐leaved plants from the Mexican Plateau; and one which is more widespread and found from the Gulf of Mexico to Venezuela. The T. limbata clade probably arose in western Mesoamerica and is defined by rounded petals. These species are found mainly in tropical dry forests, but one species colonized wet environments of eastern Mesoamerica. Finally, analyses based on the ETS region allowed us to distinguish between T. utriculata and T. pringlei.
Abstract
The highly variable tufted hairgrass Deschampsia cespitosa is a tussock-forming plant especially of cool and humid environments. Although common and widespread, its phylogeographic structure ...and the significance of polyploidy for its evolution are poorly understood. Here we used a phylogenomic approach to study the genetic structure of this species in Europe and how the polyploid cytotypes/subspecies are related to the diploids. Using genomic data (RADseq and whole plastid sequencing) we found a highly divergent Iberian group, including the Spanish Deschampsia cespitosa subsp. cespitosa (diploid and tetraploid) and the Macaronesian island endemic diploid Deschampsia argentea. Moreover, we found substantial divergence of pseudoviviparous tetraploids (Deschampsia cespitosa subspp. neoalpina and rhenana) from seminiferous tetraploids (except Deschampsia cespitosa subsp. littoralis) and all diploids of the remaining European samples. The divergent pseudoviviparous tetraploids (D. cespitosa subspp. neoalpina and rhenana) and the seminiferous tetraploid D. cespitosa subsp. littoralis probably represent periglacial and relict lineages of unknown origin regarding auto- and/or allo-polyploidy, whereas other seminiferous tetraploid variants of D. cespitosa are always nested in the diploid D. cespitosa, suggesting multiple autopolyploid origins. An analysis after excluding the Iberian Group and the highly divergent tetraploids revealed five genetic groups with overlapping geographical patterns. However, the recovered geographical structure, the overall low genetic divergence and the diffuse genetic structure point to recolonization from various refugial areas and secondary contact. Effective wind dispersal of pollen and seeds in an open early post-glacial tundra landscape and, finally, increasing human impact on dispersal of this grass since the Neolithic, may have enhanced admixture and resulted in the complex patterns detected today.
Polyploidisation, agmatoploidy and symploidy have driven the diversification of
sect.
. Several morphologically very similar species with different karyotypes have evolved, but their evolutionary ...origins and relationships are unknown. In this study, we used a combination of relative genome size and karyotype estimations as well amplified fragment length polymorphism (AFLP) fingerprinting to investigate the relationships among predominately (sub)alpine
,
and
in the Eastern Alps, including also some samples of
and
as outgroup. Our study revealed common co-occurrence of two or three different ploidies (di-, tetra- and hexaploids) at the same localities, and thus also common co-occurrence of different species, of which
was morphologically, ecologically and genetically most divergent. Whereas agmatoploid
likely originated only once from the Balkan
, and hexaploid
once from tetraploid
, the AFLP data suggest multiple origins of tetraploid
, from which partly agmatoploid individuals of
likely originated recurrently by partial fragmentation of the chromosomes. In contrast to common recurrent formation of polyploids in flowering plants, populations of agmatoploids resulting by fission of complete chromosome sets appear to have single origins, whereas partial agmatoploids are formed recurrently. Whether this is a general pattern in
sect.
and whether segregation of ecological niches supports the frequent co-occurrence of closely related cytotypes in mixed populations, remains the subject of ongoing research.
On the basis of multidisciplinary studies on the tribe Rubieae, we contribute to the current discussion on paraphyly and supraspecific taxa that do not contain all descendant species of an ancestral ...clade. Rubieae belong to the large, predominantly tropical and woody family Rubiaceae and include possibly ≤ 1000 mostly temperate and herbaceous species with worldwide distribution. Our studies span distinctive groups throughout the tribe, consist of a maximum parsimony analysis of plastid atpB-rbcL and rpL32-trnL DNA sequences, and are summarized in a condensed strict consensus tree. A corresponding two-dimensional scheme illustrates alternative hypotheses for phylogenetic relationships among all major Rubieae clades identified. The small relictual genus Kelloggia Torr. in Benth. & Hook. f., formerly excluded from the Rubieae, is supported as a remnant of the ancestors of the tribe. Didymaea Hook. f. and Rubia L. represent early phylogenetic side lines. All other Rubieae form a large monophyletic crown group with the traditional genera Asperula L. being polyphyletic and Galium L. paraphyletic. Changes in the circumscription of these and other genera are thus inevitable. The necessity of accepting paraphyletic taxa as well as the positive and negative aspects of taxonomic splitting versus lumping within Rubieae are discussed. Additionally, lectotypes are designated for one section of Asperula—Asperula sect. Dioicae Airy Shaw & Turrill, typified by A. conferta Hook. f.—and for three sections of Galium—Galium sect. Leiogalium (DC.) Ledeb., typified by G. sylvaticum L.; Galium sect. Lophogalium K. Schum., typified by G. multiflorum Kellogg; and Galium sect. Depauperala Pobed., typified by G. songaricum Schrenk ex Fisch. & C. A. Mey
Heteroploid Knautia sect. Trichera constitutes a taxonomically intricate assemblage of taxa with highly complex genetic architecture, which is mirrored in high morphological variability and blurred ...boundaries among the species. Here, we aim to disentangle the relationships among the xerophytic taxa from the Dinaric Mountains on the western Balkan Peninsula, which, based on relative genome size estimations, comprise di-, tetra- and hexaploid populations. Our analyses of amplified fragment length polymorphisms (AFLP) revealed a clear genetic differentiation among the diploid members, which are also morphologically clearly divergent. On the other hand, the phylogenetic structure among tetraploid and hexaploid populations as well as the ties with their diploid progenitors are complex, conferring unclear boundaries among species. Tetraploids were intermingled among the divergent diploid lineages, suggesting recurrent polyploidisation and/or extensive gene flow across sympatric lineages, whereas hexaploids clustered in two groups, pointing to two separate origins. In line with the genetic pattern, there is a high overlap in morphological characters across and within different ploidies. Nevertheless, comparisons of environmental niches showed differentiation among the ploidy levels, with the niche of hexaploids being most divergent. It is thus obvious that dynamic polyploid evolution, virtual lack of crossing barriers among polyploid cytotypes pertaining to different species, and exceedingly variable morphology along with the uniformity of reproductive characters preclude establishing a clear-cut taxonomic structure. Still, albeit generally corroborating previous observations for K. sect. Trichera as a whole, our study restricted to a limited geographic and taxonomic assemblage yielded constructive insights towards a workable taxonomic framework in this complex system. As a result, we propose a revised taxonomic treatment, including description of a new species, Knautia ehrendorferi, but we are aware that species identifications will remain challenging also in the future.
Data will be made available on request.
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•Di-, tetra- and hexaploids exist in Dinaric populations of xerophytic Knautia.•Diploids are genetically and morphologically divergent.•Shallow genetic and morphological differentiation among polyploids.•Taxonomy is highly intricate.•A new diploid species from the central Dinaric Mountains is described.
Chromosome evolution (including polyploidy, dysploidy, and structural changes) as well as hybridization and introgression are recognized as important aspects in plant speciation. A suitable group for ...investigating the evolutionary role of chromosome number changes and reticulation is the medium-sized genus
Melampodium (Millerieae, Asteraceae), which contains several chromosome base numbers (
x
=
9, 10, 11, 12, 14) and a number of polyploid species, including putative allopolyploids. A molecular phylogenetic analysis employing both nuclear (ITS) and plastid (
matK) DNA sequences, and including all species of the genus, suggests that chromosome base numbers are predictive of evolutionary lineages within
Melampodium. Dysploidy, therefore, has clearly been important during evolution of the group. Reticulate evolution is evident with allopolyploids, which prevail over autopolyploids and several of which are confirmed here for the first time, and also (but less often) on the diploid level. Within sect.
Melampodium, the complex pattern of bifurcating phylogenetic structure among diploid taxa overlain by reticulate relationships from allopolyploids has non-trivial implications for intrasectional classification.
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