C-banding and chromosome evolution in some related species of Australian chironominae

Genetica ◽  
1980 ◽  
Vol 54 (1) ◽  
pp. 51-68 ◽  
Author(s):  
G. Lentzios ◽  
A. J. Stocker ◽  
J. Martin
Keyword(s):  
Related Species ◽  
Chromosome Evolution ◽  
C Banding

scholarly journals Lack of underdominance in a naturally occurring pericentric inversion in Drosophila melanogaster and its implications for chromosome evolution.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 791-802
Author(s):  
J A Coyne ◽  
S Aulard ◽  
A Berry
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Genetic Drift ◽  
Related Species ◽  
Pericentric Inversion ◽  
Chromosome Evolution ◽  
Natural Populations ◽  
Crossing Over ◽  
Closely Related Species ◽  
Naturally Occurring

Abstract In(2LR)PL is a large pericentric inversion polymorphic in populations of Drosophila melanogaster on two Indian Ocean islands. This polymorphism is puzzling: because crossing over in female heterokaryotypes produces inviable zygotes, such inversions are thought to be underdominant and should be quickly eliminated from populations. The observed fixation for such inversions among related species has led to the idea that genetic drift can cause chromosome evolution in opposition to natural selection. We found, however, that In(2LR)PL is not underdominant for fertility, as heterokaryotypic females produce perfectly viable eggs. Genetic analysis shows that the lack of underdominance results from the nearly complete absence of crossing over in the inverted region. This phenomenon is probably caused by mechanical and not genetic factors, because crossing over is not suppressed in In(2LR)PL homokaryotypes. Our observations do not support the idea that the fixation of pericentric inversions among closely related species implies the action of genetic drift overcoming strong natural selection in very small populations. If chromosome arrangements vary in their underdominance, it is those with the least disadvantage as heterozygotes, like In(2LR)PL, that will be polymorphic or fixed in natural populations.

Supernumerary chromosome evolution in the Simulium vernum group (Diptera: Simuliidae)

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 516-521 ◽  
Author(s):  
Charles Brockhouse ◽  
J. A. B. Bass ◽  
R. M. Feraday ◽  
N. A. Straus
Keyword(s):  
Sibling Species ◽  
Related Species ◽  
Chromosome Evolution ◽  
Polytene Chromosomes ◽  
Nucleolar Organizer ◽  
Chromosome Analysis ◽  
B Chromosome ◽  
Supernumerary Chromosome ◽  
Closely Related Species ◽  
Black Fly

B chromosomes are present in a cluster of closely related species of black fly in the Simulium vernum group including six sibling species within the S. vernum complex, Simulium costatum, and Simulium juxtacrenobium. The S. vernum siblings all possess the same small metacentric supernumerary, while S. juxtacrenobium carries three different supernumeraries (two telocentrics and one metacentric) and S. costatum has both a metacentric and a telocentric B chromosome. Analysis of the polytene chromosomes in the larval salivary glands has revealed relationships between the supernumeraries of the different species. The metacentric B chromosome of the S. vernum siblings apparently results from a fusion of the two telocentric supernumeraries of S. juxtacrenobium. Acquisition of a nucleolar organizer then gave rise to the metacentric B chromosome in S. juxtacrenobium. The acquisition of a nucleolus by a S. juxtacrenobium telocentric gave rise to one of the S. costatum supernumeraries. Two alternate models for the origin of black fly supernumeraries are presented.Key words: supernumerary chromosome, black fly, polytene chromosome, chromosome evolution.

Heterochromatin Distribution in the Chromosome Complement of Triturus boscai (Amphibia: Caudata: Salamandridae)

1982 ◽  
Vol 3 (4) ◽  
pp. 309-315 ◽  
Author(s):  
Pilar Herrero
Keyword(s):  
Banding Pattern ◽  
Related Species ◽  
Chromosome Complement ◽  
Black Spot ◽  
Gastric Tissue ◽  
Centromere Region ◽  
Mitotic Chromosomes ◽  
C Banding ◽  
Small Black Spot

AbstractThe C-banding pattern of the I berian endemism Triturus boscai has been analyzed using mitotic chromosomes from gastric tissue and testes. The chromosome pairs are characterized for presenting a small black spot on their centromeres although a pair of pericentric bands are placed on both sides of the centromere region. Some chromosomes are characterized by the presence of terminal and subterminal bands. Present results are compared with those referred to related species within the group Triturus.

Effects of oxygen level on metabolism and development of seedlings of Trapa natans and two ecologically related species

1992 ◽  
Vol 86 (1) ◽  
pp. 168-172 ◽  
Author(s):  
Faustino Menegus ◽  
Liliana Cattaruzza ◽  
Leonardo Scaglioni ◽  
Enzio Ragg
Keyword(s):  
Related Species ◽  
Oxygen Level ◽  
Trapa Natans

Oil from Livers of Sharks and Related Species

1904 ◽  
Vol 58 (1493supp) ◽  
pp. 23927-23928
Author(s):  
Charles H. Stevenson
Keyword(s):  
Related Species

On Riccia marginata and related species (Ricciaceae, Marchantiophyta)

2012 ◽  
Vol 46 ◽  
pp. 298-305 ◽  
Author(s):  
A. D. Potemkin ◽  
T. Ahti
Keyword(s):  
Related Species ◽  
Lake Ladoga ◽  
Leningrad Region ◽  
Sem Images ◽  
North Shore ◽  
The North ◽  
Molecular Studies ◽  
The Future ◽  
The Town

Riccia marginata Lindb. was described by S. O. Lindberg (1877) from the outskirts of the town of Sortavala near the north shore of Lake Ladoga, Republic of Karelia, Russia. The species has been forgotten in most recent liverwort accounts of Europe, including Russia. Lectotypification of R. marginata is provided. R. marginata shares most characters with R. beyrichiana Hampe ex Lehm. It differs from “typical” plants of R. beyrichiana in having smaller spores, with ± distinctly finely areolate to roughly papillose proximal surfaces and a narrower and shorter thallus, as well as in scarcity or absence of marginal hairs. It may represent continental populations of the suboceanic-submediterranean R. beyrichiana, known in Russia from the Leningrad Region and Karelia only. The variability of spore surfaces in R. beyrichiana is discussed and illustrated by SEM images. A comparison with the spores of R. bifurca Hoffm. is provided. The question how distinct R. marginata is from R. beyrichiana needs to be clarified by molecular studies in the future, when adequate material is available. R. marginata is for the time being, provisionally, included in R. beyrichiana.

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