Results 161 to 170 of about 3,612 (210)

Polyploids with Different Origins and Ancestors Form a Single Sexual Polyploid Species

The American Naturalist, 2006
Polyploidization is one of the few mechanisms that can produce instantaneous speciation. Multiple origins of tetraploid lineages from the same two diploid progenitors are common, but here we report the first known instance of a single tetraploid species that originated repeatedly from at least three diploid ancestors.
Alisha K, Holloway, David C, Cannatella, H Carl, Gerhardt, David M, Hillis   +3 more
openaire   +2 more sources

Evolutionary advantage of diploidal over polyploidal sexual reproduction

Physical Review E, 2003
We modify the Penna model for biological aging, which is based on the mutation-accumulation theory, in order to verify if there would be any evolutionary advantage of triploid over diploid organisms. We show that this is not the case, and that diploidal sex is always better than that involving three individuals.
A O, Sousa, S, Moss de Oliveira, J S, Sá Martins   +2 more
openaire   +2 more sources

Sexual polyploidization and depolyploidization: some terminology and definitions

Theoretical and Applied Genetics, 1976
Sexual polyploidization (deployploidization) is the process through which a euploid zygote is formed whose chromosome number is increased above (decreased below) the level that would be expected if each parent contributed a gamete carrying one-half the parental premeiotic chromosome number. One or both gametes may contribute (lack) the extra genome (s)
A O, Mendiburu, S J, Peloquin
openaire   +2 more sources

Relevance of sexual polyploidization for crop improvement – A review

Euphytica, 2003
Colchicine induced polyploids have notdirectly contributed for crop improvementin the past. On the other hand, theso-called natural polyploids, derived fromthe functioning of numerically unreduced(2n) gametes have been shown to bemore relevant for crop improvement in manycases.
Ramanna, M.S., Jacobsen, E.
openaire   +1 more source

Polyploidy and sexual polyploidization in the genus Vaccinium

Euphytica, 2003
Genus Vaccinium,consisting of blueberries, cranberries, lingonberries and many related wild species, includes diploid, tetraploid, and hexaploid species. Most evidence indicates that the tetraploid species are autotetraploids, with non-preferential bivalent chromosome pairing.
P.M. Lyrene, N. Vorsa, J.R. Ballington
openaire   +1 more source

Minimizing inbreeding in tetraploids derived through sexual polyploidization

American Potato Journal, 1993
Diploid (2n = 2× = 24) potato (Solarium) species that produce 2n gametes are being utilized in potato breeding programs. Three breeding schemes involving these diploids are presently used by potato breeders to transfer this genetic material from diploid parents to their tetraploid offspring.
Kathleen G. Haynes, William E. Potts
openaire   +1 more source

SEXUAL POLYPLOIDIZATION OF JAPANESE PERSIMMON BY UTILIZING UNREDUCED EGG

Acta Horticulturae, 2007
We analyzed the ploidy levels of seedlings of several Japanese persimmon (Diospyros kaki) cultivars to investigate the possible occurrence of unreduced eggs in this fruit species. Among the five cultivars tested, 'Fujiwaragosho' produced seedlings whose ploidy levels were more than hexaploid, mainly nonaploid or dodecaploid, at a very high frequency ...
A. Yamada, R. Tao
openaire   +1 more source

Numerically unreduced (2n) gametes and sexual polyploidization in Actinidia

Euphytica, 1997
This is the first report on the production of numerically unreduced (2n) gametes in Actinidia species. Their occurrence was apparent from direct observations of microporogenesis in 2x, 3x, 4x and 6x plants and was inferred from ploidy analysis of progenies from 4x-2x and 2x-4x crosses. Both male and female plants were found to produce 2n gametes.
Guijun Yan, A. Ross Ferguson, Mark A. McNeilage, Brian G. Murray   +3 more
openaire   +1 more source

2n gametes in potato species and their function in sexual polyploidization

Euphytica, 1977
The extent and pattern of polyploidy in the tuber-bearing Solanums varies among the many taxanomic series that have been identified in this subsection of Solanum. While several series appear to be entirely diploid, others exhibit a range of ploidy levels from 2x to 6x, and some contain only polyploid species.
den Nijs, A.P.M., Peloquin, S.J.
openaire   +1 more source

Analysis of nrDNA polymorphism in closely related diploid sexual, tetraploid sexual and polyploid agamospermous species

Plant Systematics and Evolution, 2009
Nuclear sequences of ITS1-5.8S-ITS2 region of rDNA may be an important source of phylogenetically informative data provided that nrDNA is cloned and the character of sequence variation of clones is properly analyzed. nrDNA of selected Taraxacum sections was studied to show sequence variation differences among diploid sexual, tetraploid sexual and ...
Lenka Záveská Drábková, Jan Kirschner, Jan Štěpánek, Luděk Záveský, Čestmír Vlček   +4 more
openaire   +1 more source