Cladistic analysis of the diploid and hexaploid oats (Avena, Poaceae) using numerical techniques

1975 ◽  
Vol 53 (19) ◽  
pp. 2115-2127 ◽  
Author(s):  
Bernard R. Baum
Keyword(s):  
Diploid Species ◽  
Cladistic Analysis ◽  
Evolutionary Relationships ◽  
Numerical Techniques ◽  
Avena Species ◽  
Hexaploid Species ◽  
Unit Character

Evolutionary relationships among Avena species were inferred by means of computer cladistic analysis. The method of Farris for computing Wagner networks was applied separately to the diploid and to the hexaploid species. The method of Camin and Sokal was applied to the diploid species only. A great number of networks were generated of which representatives are documented in this paper. After various roots have been chosen, a number of trees thus determined are proposed as hypotheses of cladistic relationships. Unit character consistencies were also computed to assess the degree of homoplasy of the characters in the different trees.

CHROMOSOME MORPHOLOGY IN THE GENUS AVENA

1959 ◽  
Vol 37 (3) ◽  
pp. 331-337 ◽  
Author(s):  
T. Rajhathy ◽  
J. W. Morrison
Keyword(s):  
Diploid Species ◽  
Chromosome Morphology ◽  
Polyploid Species ◽  
Avena Species ◽  
Hexaploid Species ◽  
Basic Set

The chromosomes of the Avena species were studied and their karyotypes established. The karyotype of the diploid species (excluding A. longiglumis) is designated as A. Longiglumis has a different karyotype with at least three chromosomes that have major changes. This karyotype is a modified A, designated as A′. The designation of the tetraploid karyotype is AB, including the basic set of chromosomes A and a second completely different set B. In the hexaploid species the basic set A is present but the B set is not; therefore the proposed designation is ACD. These results indicate an alloploid origin for the polyploid species.

CHROMOSOME RELATIONSHIPS BETWEEN THE CULTIVATED OAT AVENA SATIVA (6x) AND A. VENTRICOSA (2x)

1970 ◽  
Vol 12 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Hugh Thomas
Keyword(s):  
Chromosome Pairing ◽  
Avena Sativa ◽  
Diploid Species ◽  
Meiotic Behaviour ◽  
Hexaploid Species ◽  
C Genome

Chromosome pairing in the F1 hybrid between the cultivated oat Avena sativa and a diploid species A. ventricosa, and in the derived amphiploid, shows that the diploid species is related to one of the genomes of the hexaploid species. The amount of chromosome pairing observed in complex interamphiploid hybrids demonstrates further that A. ventricosa is related to the C. genome of A. sativa. However, the chromosomes of the diploid species have become differentiated from that of the C genome of A. sativa and this is readily apparent in the meiotic behaviour of both the F1 hybrid and the amphiploid.

Cladistic analysis of the Early Cambrian olenelloid trilobites

1998 ◽  
Vol 72 (1) ◽  
pp. 59-78 ◽  
Author(s):  
Bruce S. Lieberman
Keyword(s):  
Phylogenetic Analysis ◽  
Cladistic Analysis ◽  
Intraspecific Variability ◽  
Evolutionary Relationships ◽  
Early Cambrian ◽  
New Genera ◽  
Phylogenetic Structure ◽  
Major Clade ◽  
Lateral Margins

A phylogenetic analysis was used to determine evolutionary relationships within the Early Cambrian superfamily Olenelloidea Walcott, 1890. Phylogenetic patterns within the suborder Olenellina Walcott, 1890, which contains the Olenelloidea and the Fallotaspidoidea Hupé, 1953, are also discussed. The Olenelloidea are monophyletic, and synapomorphies uniting them include the condition of the ocular lobes where they intersect the frontal lobe of the glabella, and the condition of the lateral margins of the glabellar lobes. In contrast, taxa formerly assigned to the Fallotaspidoidea are shown to represent a paraphyletic grade of several genera, some more closely related to the Olenelloidea, and some more closely related to the Redlichiina Richter, 1933. Seventy-nine exoskeletal characters were coded for 26 taxa within the Olenellina. These included 22 ingroup Olenelloidea and four outgroup taxa that have traditionally been assigned to the Fallotaspidoidea. When subjected to parsimony analysis these character data yielded a single most parsimonious cladogram that provides an hypothesis of relationship for the generic clades within the superfamily. Two new genera are recognized herein, Fritzolenellus and Lochmanolenellus. It has been argued that genetic flexibility was so great and trilobite morphology was so plastic in the Early Cambrian that suprageneric classification of Early Cambrian trilobites is precluded. Although levels of intraspecific variability may have been slightly higher in the Early Cambrian relative to the mid Paleozoic, based on the extent of polymorphic character codings, it was not so high as to obviate attempts at recovering phylogenetic structure in a major clade of Early Cambrian taxa. In addition, the consistency index recovered by this analysis is not unduly low for a phylogenetic database of this size. The phylogenetic analysis also has bearing on patterns of allometric heterochrony, which have often been held to be significant in Early Cambrian trilobites. The paedomorphic retention of advanced genal spines into the adult probably evolved at least four times. Three of the episodes can be best described as neoteny, the fourth, as progenesis. Finally, based on the phylogeny, it is likely that rates of speciation in trilobites may have been two to three times higher in the Early Cambrian than in the mid Paleozoic.

A new diploid species of Leucanthemum (Asteraceae, Anthemideae) from Liguria (northwestern Italy)

Phytotaxa ◽  
2012 ◽  
Vol 66 (1) ◽  
pp. 27 ◽  
Author(s):  
MARTINA MELAI ◽  
DINO MARCHETTI ◽  
REMO BERNARDELLO ◽  
LORENZO PERUZZI
Keyword(s):  
New Species ◽  
Diploid Species ◽  
Evolutionary Relationships ◽  
Southern France ◽  
Key Species ◽  
Northwestern Spain ◽  
Western European

A new diploid (2n = 18) species, Leucanthemum ligusticum, is described from siliceous outcrops in eastern Liguria (northwestern Italy). This species differs from L. pluriflorum—endemic to northwestern Spain, Galicia and Asturias—and L. monspeliense—endemic to northeastern Spain and central and southern France—mainly by longer petioles of basal and lower cauline leaves, shorter teeth of lower cauline leaves, and narrower ligulate florets and involucral bracts. This new species has western European affinities. Because L. ligusticum is diploid, it is one of the "basic units" of Leucanthemum and therefore a key species for inferring evolutionary relationships in this genus.

Molecular diversity of the 5S rRNA gene and genomic relationships in the genus Avena (Poaceae: Aveneae)

Genome ◽  
2008 ◽  
Vol 51 (2) ◽  
pp. 137-154 ◽  
Author(s):  
Yuan-Ying Peng ◽  
Yu-Ming Wei ◽  
Bernard R. Baum ◽  
You-Liang Zheng
Keyword(s):  
Molecular Diversity ◽  
Diploid Species ◽  
5S Rdna ◽  
Rrna Gene ◽  
D Genome ◽  
Rdna Sequences ◽  
Unit Classes ◽  
Hexaploid Species ◽  
Unit Class ◽  
C Genome

The molecular diversity of the rDNA sequences (5S rDNA units) in 71 accessions from 26 taxa of Avena was evaluated. The analyses, based on 553 sequenced clones, indicated that there were 6 unit classes, named according to the haplomes (genomes) they putatively represent, namely the long A1, long B1, long M1, short C1, short D1, and short M1 unit classes. The long and short M1 unit classes were found in the tetraploid A. macrostachya , the only perennial species. The long M1 unit class was closely related to the short C1 unit class, while the short M1 unit class was closely related to the long A1 and long B1 unit classes. However, the short D1 unit class was more divergent from the other unit classes. There was only one unit class per haplome in Avena, whereas haplomes in the Triticeae often have two. Most of the sequences captured belonged to the long A1 unit class. Sequences identified as the long B1 unit class were found in the tetraploids A. abyssinica and A. vaviloviana and the diploids A. atlantica and A. longiglumis . The short C1 unit class was found in the diploid species carrying the C genome, i.e., A. clauda, A. eriantha , and A. ventricosa , and also in the diploid A. longiglumis, the tetraploids A. insularis and A. maroccana , and all the hexaploid species. The short D1 unit class was found in all the hexaploid species and two clones of A. clauda. It is noteworthy that in previous studies the B genome was found only in tetraploid species and the D genome only in hexaploid species. Unexpectedly, we found that various diploid Avena species contained the B1 and D1 units. The long B1 unit class was found in 3 accessions of the diploid A. atlantica (CN25849, CN25864, and CN25887) collected in Morocco and in 2 accessions of A. longiglumis (CIav9087 and CIav9089) collected in Algeria and Libya, respectively, whereas only 1 clone of A. clauda (CN21378) had the short D1 unit. Thus there might be a clue as to where to search for diploids carrying the B and D genomes. Avena longiglumis was found to be the most diverse species, possibly harboring the A, B, and C haplomes. The long M1 and short M1 are the unit classes typical of A. macrostachya. These results could explain the roles of A. clauda, A. longiglumis, and A. atlantica in the evolution of the genus Avena. Furthermore, one clone of the tetraploid A. murphyi was found to have sequences belonging to the short D1 unit class, which could indicate that A. murphyi might have been the progenitor of hexaploid oats and not, as postulated earlier, A. insularis. The evolution of Avena did not follow the molecular clock. The path inferred is that the C genome is more ancient than the A and B genomes and closer to the genome of A. macrostachya, the only existing perennial, which is presumed to be the most ancestral species in the genus.

scholarly journals Cytogenetic evidences on the evolutionary relationships between the tetraploids of the section Rhizomatosae and related diploid species (Arachis, Leguminosae)

2017 ◽  
Vol 130 (5) ◽  
pp. 791-807 ◽  
Author(s):  
Alejandra Marcela Ortiz ◽  
Germán Robledo ◽  
Guillermo Seijo ◽  
José Francisco Montenegro Valls ◽  
Graciela Inés Lavia
Keyword(s):  
Diploid Species ◽  
Evolutionary Relationships

scholarly journals The phylogeny of varanoid lizards and the affinities of snakes

1997 ◽  
Vol 352 (1349) ◽  
pp. 53-91 ◽  
Author(s):  
Michael S. Y. Lee
Keyword(s):  
Phylogenetic Analysis ◽  
Cervical Vertebrae ◽  
Cladistic Analysis ◽  
Axial Skeleton ◽  
Evolutionary Relationships ◽  
Aquatic Animals ◽  
Limb Reduction ◽  
Contact Free ◽  
Osteological Characters ◽  
Standing Problem

Evidence that platynotan squamates (living varanoid lizards, snakes and their fossil relatives) are monophyletic is presented. Evolutionary relationships within this group are then ascertained through a cladistic analysis of 144 osteological characters. Mosasauroids (aigialosaurs and mosasaurs), a group of large marine lizards, are identified as the nearest relatives of snakes, thus resolving the long-standing problem of snake affinities. The mosasauroid–snake clade (Pythonomorpha) is corroborated by 40 derived characters, including recumbent replacement teeth, thecodonty, four or fewer premaxillary teeth, supratemporal–prootic contact, free mandibular tips, crista circumfenestralis, straight vertical splenio-angular joint, loss of posterior ramus of the coronoid, reduced basipterygoid processes, reduced interpterygoid vacuity, zygosphene–zygantral articulations, and absence of epiphyses on the axial skeleton and skull. After mosasauroids, the next closest relatives of snakes are varanids ( Varanus , Saniwa and Saniwides ) and lanthanotids ( Lanthanotus and Cherminotus ). Derived features uniting varanids and lanthanotids include nine cervical vertebrae and three or fewer pairs of sternal ribs. The varanid–lanthanotid–pythonomorph clade, here termed Thecoglossa, is supported by features such as the anteriorly positioned basal tubera, and the loss of the second epibranchial. Successive outgroups to thecoglossans are Telmasaurus , an unresolved polytomy ( Estesia , Gobidermatidae and Helodermatidae), Paravaranus and Proplatynota . The ‘necrosaurs’ are demonstrated to be an artificial (polyphyletic) assemblage of primitive platynotans that are not particularly closely related to each other. Snakes are presumed to have evolved from small, limbless, burrowing lizards and the inability of previous analyses to resolve the affinities of snakes has been attributed to extensive convergence among the numerous lineages of such lizards. The present study contradicts this claim, demonstrating that the problem is due instead to omission of critical fossil taxa. No modern phylogenetic analysis of squamate relationships has simultaneously included both mosasauroids and snakes: previous studies have therefore failed to identify the mosasauroid–snake association and the suite of derived characters supporting it. Mosasauroids are large aquatic animals with well-developed appendages, and none of the derived characters uniting mosasauroids and snakes is obviously correlated with miniaturization, limb reduction or fossoriality. Recognition that mosasauroids, followed by varanids and lanthanotids, are the nearest relatives of snakes will also facilitate studies of relationships within snakes, which until now have been hampered by uncertainty over the most appropriate (closely–related) lizard outgroups.

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