Chromosome numbers and pollen types in the Epacridaceae

1955 ◽  
Vol 3 (1) ◽  
pp. 48 ◽  
Author(s):  
S Smith-White
Keyword(s):  
Chromosome Numbers ◽  
Pollen Development ◽  
Chromosome Structure ◽  
Numerical Sequence ◽  
Base Number ◽  
Evolutionary Diversification ◽  
Early Tertiary ◽  
Pollen Types ◽  
The Family ◽  
Chromosome Level

Chromosome numbers are reported for 22 genera and 116 species of the Epacridaceae.In the tribe Styphelieae, haploid numbers of 4, 6, 7, 8, 9, 10, 11, 12, and 14 occur. This numerical sequence does not represent a continuous siries either of decrease or increase, but is built up from polyploid and aneuploid changes on base numbers of x = 4 and x = 6. Polyploid series on base 4 are found in Cyathodes, Astroloma, and Leucopogon � Pleuranthus, on base 6 in Leucopogon � Perojoa, and on base 7 in Lissanthe. Aneuploidy is also found within genera, but is generally more characteristic of particular genera. In the Epacrideae, the usual haploid numbers are 13 and 12, and only one case of polyploidy is reported. Two species of Sphenotoma possess haploid numbers of n = 6 and n = 7 respectively. The base number for the Epacrideae is probably x = 6, and a relationship between the Epacrideae and the Styphelieae at the 6-chromosome level may be accepted. Any relationship between the Epacrideae and the Ericoideae at an amphidiploid level is denied. With the exception of probable autotriplolds in Lissanthe montana, meiosis is essentially regular throughout the family. Tetrad-type pollen is characteristic of the Epacrideae. In the Styphelieae, the pollen is usually monad (S-type) and never truly single. Three variants in the pattern of pollen development occur in the tribe, modified monad (S-type), full tetrad (T-type), and segregating tetrad (A-type). Variants in pollen development pattern are associated with aneuploidy. The Epacridaceae must have had an ancient origin. Features of species distribution suggest that many may be post-Miocene in origin. Most of the genera must have been established in the early Tertiary, and the differentiation of the two tribes, the origin of the monad pattern of pollen development, and some fundamental changes in chromosome structure in the Styphelieae, permitting a period of chromosomal instab~lity during their evolutionary diversification, must have been still more ancient.

scholarly journals Phylogeny and Geographic History of Annonaceae

2007 ◽  
Vol 51 (3) ◽  
pp. 353-361 ◽  
Author(s):  
James A. Doyle ◽  
Annick Le Thomas
Keyword(s):  
South America ◽  
Cladistic Analysis ◽  
Early Tertiary ◽  
Fossil Seeds ◽  
Pollen Types ◽  
The Family ◽  
History Of ◽  
Origin Of Angiosperms ◽  
North And South America ◽  
North And South

ABSTRACT Whereas Takhtajan and Smith situated the origin of angiosperms between Southeast Asia and Australia, Walker and Le Thomas emphasized the concentration of primitive pollen types of Annonaceae in South America and Africa, suggesting instead a Northern Gondwanan origin for this family of primitive angiosperms. A cladistic analysis of Annonaceae shows a basal split of the family into Anaxagorea, the only genus with an Asian and Neotropical distribution, and a basically African and Neotropical line that includes the rest of the family. Several advanced lines occur in both Africa and Asia, one of which reaches Australia. This pattern may reflect the following history: (a) disjunction of Laurasian (Anaxagorea) and Northern Gondwanan lines in the Early Cretaceous, when interchanges across the Tethys were still easy and the major lines of Magnoliidae are documented by paleobotany; (b) radiation of the Northern Gondwanan line during the Late Cretaceous, while oceanic barriers were widening; (c) dispersal of African lines into Laurasia due to northward movement of Africa and India in the Early Tertiary, attested by the presence of fossil seeds of Annonaceae in Europe, and interchanges between North and South America at the end of the Tertiary.

Chromosome numbers in the Gyrostemonaceae Endl. and the Phytolaccaceae Lindl.: a comparison

1975 ◽  
Vol 23 (2) ◽  
pp. 335 ◽  
Author(s):  
GJ Keighery
Keyword(s):  
Chromosome Numbers ◽  
New Records ◽  
Sensu Stricto ◽  
Base Number ◽  
The Family

New records for the genera Codonocarpus (n = 14), Gyrostemon (n = 14) and Tersonia (n = 14) are given. The base number for the family Gyrostemonaceae is shown to be x = 14: this is markedly different from that of the Phytolaccaceae sensu stricto (x = 9), in which it was once included.

CHROMOSOME NUMBERS OF THE FAMILY CRUCIFERAE. I

1964 ◽  
Vol 42 (11) ◽  
pp. 1509-1520 ◽  
Author(s):  
Gerald A. Mulligan
Keyword(s):  
North America ◽  
Chromosome Numbers ◽  
Base Number ◽  
Thellungiella Salsuginea ◽  
The Family ◽  
Cakile Edentula ◽  
First Time

Chromosome numbers are given for 69 collections of 24 species of Cruciferae in the genera Alyssum, Arabidopsis, Arabis, Barbarea, Cakile, Eutrema, Hali-molobos, Nasturtium, Rorippa, Thellungiella, and Turritis. The following chromosome numbers are reported for the first time: Alyssum desertorum, n = 16; Arabis canadensis, 2n = 14; A. divaricarpa, 2n = 13 + 2B, 14, 20 + 2B, 21, 28; A. drummondii, 2n = 20; A. holboellii, 2n = 13 + 2B, 20 + 2B; A. lemmonii, 2n = 14; A. lyallii, 2n = 21; A. lyrata, 2n = 32; A. pendulocarpa, 2n = 14; Barbarea orthoceras, 2n = 16; Cakile edentula, 2n = 18; Rorippa curvisiliqua, 2n = 16; Thellungiella salsuginea, 2n = 14. It is concluded that species of Arabis native to North America and western Greenland have the base number x = 7 and many of them are apomictic whereas Eurasiatic species of this genus have an x = 8 base number and are sexual.

CHROMOSOME NUMBERS OF THE FAMILY CRUCIFERAE. II

1965 ◽  
Vol 43 (6) ◽  
pp. 657-668 ◽  
Author(s):  
Gerald A. Mulligan
Keyword(s):  
North American ◽  
Chromosome Numbers ◽  
North American Species ◽  
Base Number ◽  
The Family ◽  
First Time

Chromosome numbers and taxonomic discussions are given for North American material of species in the genera Braya and Cardamine. The following chromosome numbers are reported for the first time: Braya humilis s.l., n = 14 and 2n = 28; Cardamine angulata, n = 20, and 2n = 40; C. cordifolia, 2n = 24; C. microphylla, 2n = 32; C. occidentalis, n = 32 and 2n = 64; C. oligosperma, 2n = 16; C. pensylvanica, 2n = 64; C. umbellata, n = 24 and 2n = 48. It is concluded that the base number of Braya is x = 7 not x = 8 and that North American species of Cardamine have the base numbers x = 6, 8, and 10.

scholarly journals Karyotype Characterization of Nine Periwinkle Species (Gastropoda, Littorinidae)

Genes ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 517 ◽  
Author(s):  
Daniel García-Souto ◽  
Sandra Alonso-Rubido ◽  
Diana Costa ◽  
José Eirín-López ◽  
Emilio Rolán-Álvarez ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Chromosome Numbers ◽  
Gene Clusters ◽  
Chromosomal Mapping ◽  
Closely Related Species ◽  
Submetacentric Chromosome ◽  
The Family ◽  
Littorina Arcana

Periwinkles of the family Littorinidae (Children, 1834) are common members of seashore littoral communities worldwide. Although the family is composed of more than 200 species belonging to 18 genera, chromosome numbers have been described in only eleven of them. A molecular cytogenetic analysis of nine periwinkle species, the rough periwinkles Littorina arcana, L. saxatilis, and L. compressa, the flat periwinkles L. obtusata and L. fabalis, the common periwinkle L. littorea, the mangrove periwinkle Littoraria angulifera, the beaded periwinkle Cenchritis muricatus, and the small periwinkle Melarhaphe neritoides was performed. All species showed diploid chromosome numbers of 2n = 34, and karyotypes were mostly composed of metacentric and submetacentric chromosome pairs. None of the periwinkle species showed chromosomal differences between male and female specimens. The chromosomal mapping of major and minor rDNA and H3 histone gene clusters by fluorescent in situ hybridization demonstrated that the patterns of distribution of these DNA sequences were conserved among closely related species and differed among less related ones. All signals occupied separated loci on different chromosome pairs without any evidence of co-localization in any of the species.

CYTOTAXONOMY, PHYLOGENY, AND CANADIAN DISTRIBUTION OF CIRSIUM UNDULATUM AND CIRSIUM FLODMANII

1961 ◽  
Vol 39 (1) ◽  
pp. 21-33 ◽  
Author(s):  
C. Frankton ◽  
R. J. Moore
Keyword(s):  
North American ◽  
Chromosome Numbers ◽  
World Wide ◽  
North American Species ◽  
Base Number ◽  
Total Length ◽  
The World ◽  
Cirsium Undulatum

The morphology and specific differences of Cirsium undulatum (Nutt.) Spreng. and of C. flodmanii (Rydb.) Arthur are described and their Canadian distributions are reported in detail. The chromosome numbers are C. undulatum f. undulatum and f. album Farwell, 2n = 26; C. flodmanii f. flodmanii and f. albiflorum D. Löve, 2n = 22. The origin of four North American species of Cirsium that do not follow the world-wide base number 17 is discussed; it is postulated that reduction in number has occurred by translocations. The chromosomes of species with reduced numbers are larger than those of the unreduced species but the total length of the chromosomes of both groups is approximately the same.

scholarly journals Descending Dysploidy and Bidirectional Changes in Genome Size Accompanied Crepis (Asteraceae) Evolution

Genes ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1436
Author(s):  
Magdalena Senderowicz ◽  
Teresa Nowak ◽  
Magdalena Rojek-Jelonek ◽  
Maciej Bisaga ◽  
Laszlo Papp ◽  
...  
Keyword(s):  
Genome Size ◽  
Dna Sequences ◽  
Chromosome Numbers ◽  
Karyotype Evolution ◽  
Base Number ◽  
Ancestral State ◽  
Ancestral Genome ◽  
Independent Events ◽  
Karyotype Asymmetry ◽  
Major Direction

The evolution of the karyotype and genome size was examined in species of Crepis sensu lato. The phylogenetic relationships, inferred from the plastid and nrITS DNA sequences, were used as a framework to infer the patterns of karyotype evolution. Five different base chromosome numbers (x = 3, 4, 5, 6, and 11) were observed. A phylogenetic analysis of the evolution of the chromosome numbers allowed the inference of x = 6 as the ancestral state and the descending dysploidy as the major direction of the chromosome base number evolution. The derived base chromosome numbers (x = 5, 4, and 3) were found to have originated independently and recurrently in the different lineages of the genus. A few independent events of increases in karyotype asymmetry were inferred to have accompanied the karyotype evolution in Crepis. The genome sizes of 33 Crepis species differed seven-fold and the ancestral genome size was reconstructed to be 1 C = 3.44 pg. Both decreases and increases in the genome size were inferred to have occurred within and between the lineages. The data suggest that, in addition to dysploidy, the amplification/elimination of various repetitive DNAs was likely involved in the genome and taxa differentiation in the genus.

scholarly journals Unprecedented reorganization of holocentric chromosomes provides insights into the enigma of lepidopteran chromosome evolution

2019 ◽  
Vol 5 (6) ◽  
pp. eaau3648 ◽  
Author(s):  
Jason Hill ◽  
Pasi Rastas ◽  
Emily A. Hornett ◽  
Ramprasad Neethiraj ◽  
Nathan Clark ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Chromosome Evolution ◽  
Chromosome Structure ◽  
Holocentric Chromosomes ◽  
Chromosome Counts ◽  
Pieris Napi ◽  
Haploid Chromosome Number ◽  
Genome Wide ◽  
The Face ◽  
Chromosome Level

Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.

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