Chromosome Arrangements during Meiosis in Certain Oenotheras

Cleland, Ralph E.

doi:10.1086/279946

Cited by 42 publications

(10 citation statements)

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“…The meiotic behaviour of E. subarticulata causes doubts about the range of mechanisms involved in karyotype evolution in the Cyperaceae. Until now, only agmatoploidy (fission), symploidy (fusion) and polyploidy have been considered, but this case is very similar to the formation of multiple translocations found in Oenothera, involving some or all the chromosomes of the complement (Cleland, 1923). This evidence permits us to propose that chromosome reduction in these holocentrics is the result of multiple translocations that involve all the chromosomes of the complement and form a multivalent ring during meiosis, and not symploidy, because bivalents and quadrivalents were not observed.…”

Section: Resultsmentioning

confidence: 93%

Reduction of chromosome number in Eleocharis subarticulata (Cyperaceae) by multiple translocations

Silva

González‐Elizondo

Vanzela

2005

Botanical Journal of the Linnean Society

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Eleocharis subarticulata is recorded as the third species of Cyperaceae with a reduced chromosome number ( n = 3), following reports on Rhynchospora tenuis ( n = 2) and Fimbristylis umbellaris ( n = 3). For Eleocharis, the numbers recorded to date vary from 2 n = 10 to 2 n = c. 196, with x = 5 as the possible basic number. The karyotype of E. subarticulata was studied using conventional staining (mitosis and meiosis), C-CMA 3 /DAPI banding, and FISH with 45S rDNA and telomere probes. The chromosomes showed no primary constrictions, as expected in the holocentric chromosomes of Cyperaceae. The meiotic behaviour was abnormal, with a single multivalent ring of six chromosomes at metaphase I, resulting from multiple translocations. At anaphase I six chromatids migrated to each pole, evidencing the inverted meiosis, and these groups were also visible at metaphase II. The C-CMA 3 /DAPI banding technique showed only four terminal GC-rich blocks. FISH with 45S rDNA probes revealed four terminal signals, probably associated with GC-rich blocks. The telomeric probe located terminal signals in all the chromosomes, besides a hybridization site in the middle of the large pair. The occurrence of ectopic telomeric sites has not been described previously for plants with holokinetic karyotypes and with reduced chromosome numbers. These data reinforce the hypothesis of the reduction in chromosome number by multiple translocations.

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Section: Resultsmentioning

confidence: 93%

Reduction of chromosome number in Eleocharis subarticulata (Cyperaceae) by multiple translocations

Silva

González‐Elizondo

Vanzela

2005

Botanical Journal of the Linnean Society

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“…Soon after de Vries reported various mutants derived from O. lamarckiana , a number of investigators studied their chromosomal numbers and chromosomal segregation at meiosis ( Cleland 1972 ). They found many aneuploids and trisomics, but there was one elementary species ( O. gigas ), which was bigger and more vigorous than O. lamarckiana .…”

Section: Speciation By Chromosomal Mutationsmentioning

confidence: 99%

Roles of Mutation and Selection in Speciation: From Hugo de Vries to the Modern Genomic Era

Nei

Nozawa

2011

Genome Biology and Evolution

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One of the most important problems in evolutionary biology is to understand how new species are generated in nature. In the past, it was difficult to study this problem because our lifetime is too short to observe the entire process of speciation. In recent years, however, molecular and genomic techniques have been developed for identifying and studying the genes involved in speciation. Using these techniques, many investigators have already obtained new findings. At present, however, the results obtained are complex and quite confusing. We have therefore attempted to understand these findings coherently with a historical perspective and clarify the roles of mutation and natural selection in speciation. We have first indicated that the root of the currently burgeoning field of plant genomics goes back to Hugo de Vries, who proposed the mutation theory of evolution more than a century ago and that he unknowingly found the importance of polyploidy and chromosomal rearrangements in plant speciation. We have then shown that the currently popular Dobzhansky–Muller model of evolution of reproductive isolation is only one of many possible mechanisms. Some of them are Oka’s model of duplicate gene mutations, multiallelic speciation, mutation-rescue model, segregation-distorter gene model, heterochromatin-associated speciation, single-locus model, etc. The occurrence of speciation also depends on the reproductive system, population size, bottleneck effects, and environmental factors, such as temperature and day length. Some authors emphasized the importance of natural selection to speed up speciation, but mutation is crucial in speciation because reproductive barriers cannot be generated without mutations.

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“…Òàêàÿ aeå, ôàêòè÷åñêè ïîëíàÿ îñòàíîâêà ðåêîìáèíàöèè, ðàçîì èñêëþ÷àþùàÿ è êðîññèíãîâåð è ñâîáîäíóþ ñåãðåãàöèþ, íàáëþäàåòñÿ ïðè òàê íàçûâàåìîé ïåðìàíåíòíîé ãåòåðîçèãîòíîñòè ïî òðàíñëîêàöèÿì. Ýòî ÿâëåíèå âïåðâûå áûëî îïèñàíà ó îñëèííèêà Êëèëýíäîì è Ðåííåðîì (Cleland, 1923(Cleland, , 1972Renner, 1925), îíî ïîäðîáíî ðàññìàòðèâàåòñÿ Ãðàíòîì (1984). Ìíîãî÷èñëåííûå ðàñû («ìèêðîâèäû») îñëèííèêà, Oenothera (Onagraceae), øèðîêî ðàñïðîñòðàíåíû â Åâðîïå è, îñîáåííî, â Ñåâåðíîé Àìåðèêå.…”

Section: äðóãèå ìåõàíèçìû îãðàíè÷åíèÿ è îñòàíîâêè ðåêîìáèíàöèèunclassified

How many clonal species are there in the world. Part 2. Cloning in nature and its role in formation of biodiversity

Grebelnyi

2007

Invertzool

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Chromosome Arrangements during Meiosis in Certain Oenotheras

Cited by 42 publications

References 0 publications

Reduction of chromosome number in Eleocharis subarticulata (Cyperaceae) by multiple translocations

Reduction of chromosome number in Eleocharis subarticulata (Cyperaceae) by multiple translocations

Roles of Mutation and Selection in Speciation: From Hugo de Vries to the Modern Genomic Era

How many clonal species are there in the world. Part 2. Cloning in nature and its role in formation of biodiversity

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