CHROMOSOMAL POLYMORPHISM COMMON TO SEVERAL SPECIES OF JUNCO (AVES)

1973 ◽  
Vol 15 (3) ◽  
pp. 461-471 ◽  
Author(s):  
Gerald F. Shields
Keyword(s):  
Random Sample ◽  
Pericentric Inversion ◽  
Chromosomal Polymorphism ◽  
Junco Hyemalis ◽  
Chromosome 2 ◽  
Chromosome 5 ◽  
Weinberg Equilibrium ◽  
Mating Population ◽  
Hardy Weinberg Equilibrium

Karyotypes were obtained from primary kidney cultures of nearly 250 individuals belonging to six nominate species of the avian genus Junco. Chromosome 2 was found to be dimorphic in four of the six species and chromosome 5 was dimorphic in five of the six species. The dimorphism appears to be due to the presence of a pericentric inversion in each of these autosomes. It is hypothesized that chromosomes 2 and 5 are ancestral and gave rise to chromosomes 2sm and 5m respectively. The sample of the slate-colored junco, Junco hyemalis, the largest studied, conforms to the Hardy-Weinberg equilibrium and suggests that a random sample was drawn from a randomly mating population.

Genetic variability in Muscari comosum L. (Liliaceae). II. Characterization and effects of the polymorphic variants of chromosome 2 on chiasmata formation

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 695-701
Author(s):  
C. Ruiz Rejon ◽  
R. Lozano ◽  
M. Ruiz Rejon
Keyword(s):  
Genetic Variability ◽  
Key Words ◽  
Pericentric Inversion ◽  
Chromosomal Polymorphism ◽  
Chiasma Formation ◽  
The Other ◽  
Chromosome 2 ◽  
Polymorphic Variants ◽  
Insertional Translocation ◽  
Normal Pairing

Muscari comosum L. (Liliaceae) displays a striking chromosomal polymorphism in the second largest chromosome. This polymorphism involves four cosmopolitan types. Two of these are shorter than the other two homologues. One of these is submetacentric (SSM) and the other is subtelocentric (SST). The two longer types also include a submetacentric (LSM) and a subtelocentric (LST) morph. Each of the two submetacentric chromosomes has one interstitial C-band in the short arm and each of the two subtelocentric morphs has an interstitial C-band in the long arm. The change of position of this interstitial C-band is most easily explained by a pericentric inversion. Furthermore, all four types of chromosome 2 have a centromeric C-band, while the two subtelocentrics have an additional terminal C-band in the long arm. The variability in the size of the second chromosome is most likely the consequence of an unequal interchange or an insertional translocation. The meiotic behaviour of the chromosome 2 bivalents in individuals heterozygous for the pericentric inversion is characterized by normal pairing between homologues with no inversion loops, though asynapsis was present in some meiocytes. Chiasmata are absent in two regions of chromosome 2 bivalents in these heterozygotes in which they regularly form in both classes of homozygotes. In individuals heterozygous for the long morphs of chromosome 2 the bivalents again showed normal pairing at pachytene, with chiasmata again absent in some regions in which they normally form. The net result is that homozygotes have significantly higher chiasmata frequencies than hterozygotes. Key words: genetic variability, chiasma formation, Muscari.

CHROMOSOMAL POLYMORPHISM IN CARDINALS CARDINALIS CARDINALIS

1979 ◽  
Vol 21 (4) ◽  
pp. 549-553 ◽  
Author(s):  
Rebecca A. Bass
Keyword(s):  
Pericentric Inversion ◽  
Diploid Number ◽  
Chromosomal Polymorphism ◽  
Junco Hyemalis ◽  
Zonotrichia Albicollis ◽  
Cardinalis Cardinalis

Karyotypic analyses of Cardinalis cardinalis (Linnaeus) (Passeriformes: Fringillidae) reveal a diploid number of approximately 84. Three different karyotypes were observed resulting from polymorphism of one macrochromosome pair. It is suggested that the observed polymorphism resulted from a single pericentric inversion. Similarities between karyotypes of this species and those of Zonotrichia albicollis and Junco hyemalis are discussed.

scholarly journals THE EFFECT OF LINKAGE ON THE MEAN VALUE OF INBREDS DERIVED FROM A RANDOM MATING POPULATION

Genetics ◽  
1974 ◽  
Vol 78 (4) ◽  
pp. 1245-1249
Author(s):  
I M R van Aarde
Keyword(s):  
Inbreeding Depression ◽  
Random Mating ◽  
Mean Value ◽  
Original Population ◽  
Precise Nature ◽  
Weinberg Equilibrium ◽  
Special Cases ◽  
Mating Population ◽  
Hardy Weinberg Equilibrium ◽  
The Mean

ABSTRACT An expression is derived which accounts for the effect of linkage on the mean value of diploid inbreds. The original population is taken to be in Hardy-Weinberg equilibrium. It is shown that linkage will accelerate inbreeding depression. The precise nature of the acceleration is worked out for some special cases.

Significance of Hardy-Weinberg Equilibrium in Case Control

2004 ◽  
Vol 73 (1) ◽  
pp. 95-95
Author(s):  
Hemant Kumar Bid ◽  
Rama D. Mittal
Keyword(s):  
Case Control ◽  
Weinberg Equilibrium ◽  
Hardy Weinberg Equilibrium

scholarly journals Underuse of Hardy-Weinberg equilibrium

2004 ◽  
Vol 66 (4) ◽  
pp. 1711 ◽  
Author(s):  
Gere Sunder-Plassmann ◽  
Manuela Födinger
Keyword(s):  
Weinberg Equilibrium ◽  
Hardy Weinberg Equilibrium
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