A CYTOLOGICAL STUDY OF THREE SPECIES AND A HYBRID TAXON OF LYCOPODIUM (SECTION COMPLANATA) IN ONTARIO

1981 ◽  
Vol 23 (3) ◽  
pp. 497-504 ◽  
Author(s):  
R. E. Hersey ◽  
D. M. Britton
Keyword(s):  
Chromosome Number ◽  
Genome Analysis ◽  
Cytological Study ◽  
Cytological Evidence ◽  
Regular Meiosis

A cytological study was carried out on three species and a hybrid taxon of Section Complanata Vict, of the genus Lycopodium L. in Ontario, Canada. The taxa studied were L. complanatum L., L. flabelliforme (Fern.) Blanchard, L. tristachyum Pursh and L. × habereri House. These taxa were examined cytologically in order to determine chromosome number and to study and compare meiosis in hybrids with meiosis in nonhybrid specimens. The chromosome number for all taxa was found to be n = 23, a number in agreement with the more recent chromosome number reports for these particular lycopods. Meiosis in L. × habereri, was found to be identical to meiosis in L. complanatum, L. flabelliforme and L. tristachyum, i.e. no irregularities were observed in the meiosis of the hybrid. Similar results were also obtained for specimens expressing morphological intermediacy between the taxa, L. complanatum and L. tristachyum and therefore possible hybrids of these two taxa. This result was completely unexpected in light of genome analysis in other pteridophytes. Due to the occurrence of regular meiosis in hybrids, cytological evidence cannot be used as a means of verifying hybridization, at least within Section Complanata of the genus Lycopodium.

CYTOGENETICS OF SOME SPECIES AND NATURAL HYBRIDS IN PROSOPIS (LEGUMINOSAE)

1975 ◽  
Vol 17 (2) ◽  
pp. 253-262 ◽  
Author(s):  
J. H. Hunziker ◽  
L. Poggio ◽  
C. A. Naranjo ◽  
R. A. Palacios ◽  
A. B. Andrada
Keyword(s):  
Chromosome Number ◽  
Interspecific Hybrids ◽  
Vegetative Reproduction ◽  
General Lack ◽  
Cytological Data ◽  
Natural Hybrids ◽  
Regular Meiosis ◽  
Putative Hybrids

Cytological results on 12 species and 4 putative hybrids of Prosopis are presented. Of these, 5 species and 4 hybrids have been hitherto unknown cytologically. The following species proved to be diploid (2n = 28) and constitute new chromosome number determinations for the genus: P. algarobilla Griseb., P. hassleri Harms, P. nigra (Griseb.) Hieron., P. patagonica Speg., P. tamarugo Phil. The diploid nature of some races of P. juliflora (Sw.) DC. is established; apparently under this taxon there are also tetraploid populations. The following putative interspecific hybrids showed regular meiosis with formation of 14 bivalents: P. vinalillo Stuck. (P. ruscifolia × P. alba?), P. alba × P. nigra? and P. hassleri × P. ruscifolia?.So far 28 taxa of the genus have been studied cytologically; 27 of these are diploid. The scarcity of polyploidy in the genus (3.5%) might be a consequence of the almost general lack of means of vegetative reproduction and of the absence of chromosome repatterning in primary speciation. Results of other authors concerning cytological data are also discussed.

scholarly journals Relations and evolution in Cheilanthes (Sinopteridaceae, Pteridophita) in Macaronesia and Mediterranean area, deduced from genome analysis of their hybrids

1983 ◽  
Vol 8 ◽  
pp. 101-126 ◽  
Author(s):  
G. Vida ◽  
A. Major ◽  
T. Reichstein
Keyword(s):  
Chromosome Number ◽  
Genome Analysis ◽  
Chromosome Doubling ◽  
Diploid Species ◽  
Mediterranean Area ◽  
Basic Chromosome Number ◽  
The Other ◽  
Experimental Conditions ◽  
Natural Group ◽  
Basic Chromosome

Nine species of "Cheilantoid ferns" are known to grow in Macaronesia and the Mediterranean basin. Two of them (lacking a pseudo-indusium and having the basic chromosome number X = 29), both aggregate species which we prefer to retain in Notholaena, are not included in this study. The other seven species (with distinct pseudo-indusium and the basic chromosome number X = 30), which we accept as members of the genus Cheilanthes Sw. sensu stricto, were subjected to detailed genome analysis of their natural and experimentally produced hybrids and shown to represent an aggregate of four very distinct ancestral diploids and three allotetraploids. The latter must have once been formed by chromosome doubling in the three diploid hybrids of C. maderensis Lowe with the other three diploid species. Theoretically three more allotetraploids would be possible but their formation has obviously been prevented by the geographical separation of the three respective diploids. The most widely distributed of the tetraploids, i.e. C. pteridioides (Reich.) C.Chr. has also been resynthesized from its ancestors (still sympatric) under experimental conditions. The intermediate morphology of the allotetraploids (as compared with their diploid ancestors) is obviously the reason why their status and existence has so long escaped recognition in Europe. These seven species form a natural group and, in our opinion, should not be divided into sections.

A chromatographic and cytological study of Dryopteris dilatata in eastern North America

1969 ◽  
Vol 47 (9) ◽  
pp. 1337-1344 ◽  
Author(s):  
Carl-Johan Widén ◽  
Donald M. Britton
Keyword(s):  
North America ◽  
Genome Analysis ◽  
Chromatographic Analysis ◽  
Cytological Study ◽  
Eastern North America ◽  
Ancestral Genome ◽  
Evolutionary Patterns ◽  
Phloroglucinol Derivatives

The phloroglucinol derivatives found in the rhizomes of Dryopteris intermedia Gray, diploid D. "dilatata", and D. campyloptera Clarkson, all from eastern North America, are compared and contrasted with those found in D. assimilis S. Walker, D. dilatata A. Gray, and D. spinulosa Watt from Europe, as well as diploid D. “dilatata” from Alaska. The presence or absence, and the morphology, of internal secreting hairs in these species was useful for comparing taxa and suggesting evolutionary patterns. Chromatographic analysis gives many more categories or finer divisions of D. dilatata s.l. than does genome analysis, which has suggested that D. assimilis, D. intermedia, and western D. “dilatata” represent the same ancestral genome.

The mitotic chromosomes of Marsupials and their bearing on taxonomy and phylogeny.

1961 ◽  
Vol 9 (1) ◽  
pp. 38 ◽  
Author(s):  
GB Sharman
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Parallel Evolution ◽  
Mitotic Chromosomes ◽  
Cytological Evidence ◽  
Separate Genus ◽  
Y Chromosomes ◽  
Related Group ◽  
Living Species ◽  
Potorous Tridactylus

Chromosome numbers of marsupials vary between 2n = 11 B 10 @ and 2n =24. Most species have 14 or 22 chromosomes. There is no evidence that polyploidy has occurred in marsupial evolution. The Dasyuridae have 12 metacentric autosomes, a small metacentric X-chromosome and a very small Y-chromosome (20% of living species have been studied) and the chromosomes of Myrmecobius fasciatus are typically like those of other Dasyuridae. The Peramelidae (30% of species have been studied) have chromosomes like the Dasyuridae except that X- and Y-chromosomes are much larger. The occurrence of similar chromosome numbers in Dasyuridae and Peramelidae is not necessarily evidence of affinity. The chromosomes of the Phascolomidae are similar in number and morphology to those of the Peramelidae and the resemblances are, almost certainly, due to parallel evolution. The chromosomes of Phascolarctos are unlike those of any of the Phalangeridae and this genus might be just as easily grouped with the Phascolomidae. The Phalangeridae have considerable chromosomal heterogeneity but less than 20% of species have been studied. Two species of Cercaertus have 12 metacentric autosomes and small sex chromosomes like all members of the Dasyuridae. This suggests that the primitive phalangers may have retained the chromosome number and morphology of possible dasyurid ancestors but the resemblances may be due to parallel evolution of similar chromosome number and morphology in separate groups. The chromosomes have been studied in more than 50% of Macropodinae. Cytological evidence suggests that Thylogale (3 species studied), Petrogale (2 species studied), and probably Lagorchestes (1 species studied), all with 22 chromosomes, are a related group. Onychogalea unguifer, with 20 chromosomes, may be derived from this group. There is no justification for the placing of Thylogale billardierii in the genus Protemnodon. Lagostrophus fasciatus has 2n = 24 and its placement in a monotypic genus is justified. Macropus major and all species of Protentnodon, except P. bicolor, are a related group with 16 chromosomes. M. robustus is possibly included in this group. M. rufus has 20 chromosomes and should perhaps be placed in the separate genus Megaleia. P. bicolor, with 11 chromosomes in the male and 10 in the female, differs from all other species of Protemnodon and this genus, as at present constituted, may be diphyletic. The relationships of P. bicolor are unknown. Setonix brachyurus has 22, mostly metacentric, chromosomes and its affinities are at present unknown. Three species of Bettongia (Potoroinae) have 22 chromosomes which are mostly metacentric. Hypsiprymnodon moschatus has 22 chromosomes which are mostly acrocentric. Both genera are very different cytologically from Potorous tridactylus.

The biosystematics of the genus Lotus (Leguminosae) in Canada. II. Numerical chemotaxonomy

1968 ◽  
Vol 46 (5) ◽  
pp. 585-589 ◽  
Author(s):  
William F. Grant ◽  
Ilse I. Zandstra
Keyword(s):  
Chromosome Number ◽  
Thin Layer ◽  
Native Species ◽  
Cytological Study ◽  
Diploid Species ◽  
Basic Chromosome Number ◽  
Chromatographic Study ◽  
Chemical Identification ◽  
Basic Chromosome ◽  
Fluorescent Compounds

A thin-layer chromatographic study of fluorescent compounds present in native (L. denticulatus, L. formosissimus, L. micranthus, L. pinnatus, L. purshianus) and introduced (L. corniculatus, L. krylovii, L.pedunculatus, L. tenuis) Canadian species of Lotus has been carried out and relationships of the species have been determined on the basis of the coefficients of association of these compounds. Chemical identification of the compounds was not attempted, but test reagents indicated a number to be phenolics. The analysis supported the general taxonomic relationships of the species based on a morphological and cytological study. Of the native species, L. pinnatus and L. formosissimus were the most closely related, with a coefficient of association of 83.33. Lotus denticulatus, the only native species with a chromosome number of n = 6, in general showed lower coefficients of association with the n = 7 species. Of the introduced species, all of which belong to the L. corniculatus group with a basic chromosome number of 6, L. krylovii and L. tenuis had the highest coefficient of association, 75.86. Based on their coefficients of association, both of these diploid species were more closely related to the tetraploid L. corniculatus than to the diploid L. pedunculatus.

A CYTOLOGICAL STUDY OF ASCOCYBE

1961 ◽  
Vol 39 (7) ◽  
pp. 1605-1607 ◽  
Author(s):  
Charles M. Wilson
Keyword(s):  
Life Cycle ◽  
Chromosome Number ◽  
Cytological Study ◽  
Nuclear Behavior

The nuclear behavior in the life cycle of Ascocybe grovesii is described. The chromosome number is given as six from counts made of chromosomes in the meiotic divisions in the asci. The ascophores are described as diploid, and as a consequence there is no fusion of nuclei in the asci.

COCCIDIOIDES IMMITIS: CYTOLOGICAL STUDY ON THE FORMATION OF THE ARTHROSPORES

1969 ◽  
Vol 11 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Kyung Joo Kwon-Ciiung
Keyword(s):  
Chromosome Number ◽  
Nuclear Division ◽  
Cytological Study ◽  
Ring Stage ◽  
Coccidioides Immitis ◽  
Active Growth ◽  
Spindle Apparatus ◽  
Relationship Of ◽  
The Relationship

Somatic nuclear division and the manner of arthrospore formation in saprophytic phase of Coccidioides immitis have been studied. Two distinct nuclear cycles, one occurring during the active growth in young hyphae and another occurring in old thin hyphae or during arthrospore formation, were observed. The first cycle consisted of several stages starting from round resting nuclei → ring stage → V stage → and filaments which divide longitudinally. The two daughter nuclear filaments reorganize into round nuclei. The second cycle is more simple than the first. The round resting nuclei become elongated and constricted at the middle, dividing vertically. The chromosome number appears to be 3. The metaphase plares or spindle apparatus were not seen.The fertile hyphae develop septa not basipetally but synchronously. Alternate cells, after being thus delimited, increase in size and in thickness of wall becoming spores while the intervening cells gradually lose cytoplasm. The nuclei remain, without cytoplasm, in the intervening cells until the adjacent spores are completely matured. The spores are released by fragmentation of the walls of the sterile segments. The relationship of C. immitis to the members of Gymnoascaceae has been discussed.

A new chromosome number in Arctostaphylos uva-ursi

1981 ◽  
Vol 59 (2) ◽  
pp. 272-273 ◽  
Author(s):  
Thomas J. Rosatti
Keyword(s):  
New York ◽  
Chromosome Number ◽  
Cytological Study ◽  
Long Island ◽  
Physiological Tolerance

Populations resembling Arctostaphylos uva-ursi (L.) Spreng. var. coactilis Fernald and MacBride growing on Long Island, New York, U.S.A., provided material for cytological study which resulted in the discovery of a new chromosome number for the species, 2n = 78. These plants differ from the most common expression of this variety in having more linear leaves, a condition that may be associated with a physiological tolerance for relatively high levels of salt in the substratum.

Chromosome elimination in a complex hybrid of the genus Hordeum

1977 ◽  
Vol 55 (24) ◽  
pp. 3023-3033 ◽  
Author(s):  
Thomas J. Orton ◽  
William Tai
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Chromosome Elimination ◽  
Progressive Increase ◽  
Basic Chromosome Number ◽  
Chromosome Loss ◽  
Cytoplasmic Organelle ◽  
Cytological Evidence ◽  
Embryonic Tissues ◽  
Hordeum Jubatum

Hybrid embryos, derived from the cross combining a Hordeum jubatum (4x) – H. compressum (2x) amphiploid and H. vulgare (4x), were observed and found to exhibit instability of chromosome numbers that resulted in an overall loss during the first 8 days of development in embryonic tissues. This instability seemed to be manifest as a progressive increase in the variability of chromosome numbers over this developmental period. The change in the overall mean chromosome number followed no discernible pattern with the exception that counts appeared to be clustered at numbers which are exact multiples of the basic chromosome number (x = 7). For each day postpollination, however, the mean chromosome numbers were significantly lower than the expected zygotic number (with one exception), indicative of net chromosome loss. Based on the data presented and cytological evidence, possible mechanisms are proposed to account for chromosome elimination in hybrid tissues. Chromosome loss may result from an incompatible interaction of the chromosomes and spindle-timing determinants originating from each genome during development or as a consequence of the malfunctioning of a proposed cytoplasmic organelle.

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