(2015) supported an A-chromosome origin of the B-chromosome
Presence or absence of B-chromosome
-0,23 0,00 0,68 0,38 0,48 3.
Bewildering Bs: an impression of the 1st B-chromosome
(2010) report a study of B chromosomes in a grasshopper species, Eyprepocnemis plorans: this species has become a classic model for the study of B-chromosome
evolution and of the parasitic nature of these chromosomes.
Subsequent experiments (CHIAVARINO et al., 2001) determined that a single major gene in an A chromosome controls B-chromosome
transmission rate in maize, and that ir acts in the haploid egg cell at the time of fertilization.
The effects of Secale cereale B-chromosomes
have been studied both in some B-chromosome
carrying cultivated rye varieties and in various hybrids, primarily with Triticum aestivum.
Here, we provide the first empirical evidence of the regeneration of a B-chromosome
polymorphism caused by the replacement of a nondriving B by a new B variant showing drive.
The first application of micro-dissection in the plant was to isolate B-chromosome
from rye (Sandery et al.
These species allowed a more profound understanding of B-chromosome
meiotic behavior, including mechanisms of elimination and accumulation through meiotic drive, B chromosome structure in terms of molecular composition, effects on carriers at the endo- and exophenotypic levels, distribution in natural populations, including cases of clinal variation, and the relationships of Bs with the A genome and their evolution through genomic conflict, especially in E.
Two models have been put forward to explain B-chromosome
maintenance in natural populations: the parasitic (Ostergren 1945) and the heterotic (Darlington 1958, White 1973) models.
The frequency of macro-and microspermatids showed an odd-even pattern with respect to the number of B chromosomes, with a higher frequency of abnormal spermatids associated with odd B-chromosome
numbers (Teruel et al.
where [P.sub.0] is the mean B-chromosome
frequency, [P.sub.1] represents the B-chromosome
frequency in the ith population and [N.sub.1] is the number of individuals sampled per population.