Cytological Studies in Crepis aurea and C. rubra
| Autor: | P. Ch. Koller |
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| Rok vydání: | 1935 |
| Předmět: | |
| Zdroj: | CYTOLOGIA. 6:281-288 |
| ISSN: | 1348-7019 0011-4545 |
| DOI: | 10.1508/cytologia.6.281 |
| Popis: | 1. Crepis aurea and C. rubra have 10 chromosomes in their diploid sets. The chromosomes differ only in absolute size, the position of attachment constriction being nearly similar in both.2. In C. rubra a third strain is described, which differs from the already known strains in that it has no chromosomes with trabants.3. The behaviour of chromosomes during meiotic division in these species was compared. It was found that there is a definite difference regarding the initial chiasma frequency and the degree of terminalisation.4. The types of bivalents at meiotic metaphase are more or less alike in the two species. It is a combined result of the similar position of attachment constrictions of the chromosomes and the different terminalisation, which reduces the great deviation of chiasma frequency found at premetaphase stages.5. The importance of chromosomal changes in the process of evolution is discussed. It is concluded that the chromosome complements of two taxonomically well differentiated species of the same genus, may be similar in external structure, but dissimilar in behaviour at meiosis, thus showing the important internal differences between these species.The author is indebted to Dr. F. W. Sansome of John Innes Institution, London, for his help in the statistical treatment of the data and to Mrs. E. R. Sansome for correcting the manuscript. |
| Databáze: | OpenAIRE |
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