Evolution and Systematic Significance of Polyploidy

Jackson, R. C.

doi:10.1146/annurev.es.07.110176.001233

Cited by 127 publications

(78 citation statements)

References 124 publications

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“…Polyploidy can induce a cbange in tbe ecological requirements of a taxon. Consequently, a sbift in tbe babitats of tbe cytotypes or a greater ecological amplitude of tbe polyploid cytotype relative to tbat of tbe diploid may occur, tbus facilitating tbeir coexistence (Clausen, Keck, & Hiesey, 1945;Lewis, 1967Lewis, , 1980deWet, 1971 ;Jackson, 1976;Tbompson & Lumaret, 1992).…”

Section: N T R O D L C Ti O Xmentioning

confidence: 99%

Habitat differentiation in a narrow hybrid zone between diploid and tetraploid Anthoxanthum alpinum

1996

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summary Populations of diploid and autotetraploid Anthoxanthum alpinum A. & D. Löve formed a narrow hybrid zone in a study area in the Swiss Prealps. Detailed vegetation analyses were performed along transects in several contact zones between the two cytotypes. The vegetation differed according to the position in the hybrid zone. When considering the hybrid zone as a whole, and for one transect that was analysed in detail, there was strong evidence for habitat segregation between the cytotypes. Vegetation transitions, habitat preference and segregation of the two cytotypes differed according to location in the hybrid zone. The origin and dynamics of the hybrid zone are discussed.

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Section: N T R O D L C Ti O Xmentioning

confidence: 99%

Habitat differentiation in a narrow hybrid zone between diploid and tetraploid Anthoxanthum alpinum

1996

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“…White (1973) favors the view that the prevalence of obligatory cross-fertilization is the principal barrier to bisexual polyploidy in animals. Bisexual polyploidy is unknown in amniote vertebrates, being precluded perhaps by the existence of well-developed chromosomal mechanisms of sex determination (Muller, 1925;Ohno, 1970;Jackson, 1976), but it has been a factor in the evolution of fishes and amphibians. Among amphibians, 12 bisexual polyploid species of anurans representing five families have been identified (Bogart and Tandy, 1976).…”

mentioning

confidence: 99%

EVOLUTIONARY GENETICS OF DIPLOID—TETRAPLOID SPECIES OF TREEFROGS OF THE GENUS HYLA

Ralin

Selander

1979

Evolution

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“…The absence of chiasmata in such organisms normally leads to univalents at metaphase I and their misdivision and/or lagging at anaphase I and II. Consequently, unbalanced gametes are produced and varying amounts of sterility ensue (Jackson 1976).…”

Section: Discussionmentioning

confidence: 99%

Chromosome Association and Behaviour in Autotetraploid Delphinium ajacis L.

Singh

1991

CYTOLOGIA

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Delphinium ajacis (commonly known as larkspur) of family Ranunculaceae is an extreme ly popular winter seasonal of the garden. All species of the genus Delphinium are herbaceous annuals or perennials with flowers which are habitually cross-pollinated . Colchiploidy was induced in D. ajacis which improved the size and quality of flowers (Singh and Roy 1983) . Diploid reveal n=8 chromosome at diakinesis and metaphase I of fairly large size , two of them being exceptionally too large. Delphinium was selected with a view to see how chro mosome size affect the meiotic configuration and multivalent formation in induced autote traploid. The present study deals the meiotic chromosome association , behaviour and fer tility in C1 and C2 generation of D. ajacis. Materials and methodsSeeds of Delphinium ajacis L. family Ranunculaceae used for colchiploidization were obtained from the healthy plants of the botanical garden of the university. For colchiploidiza tion, colchicine solution (0.20 to 0.50% concentration) was applied on the apical portion of the four leave old plant. Treatment was carried out for 8hr spread over 3 days.For meiotic studies, flower buds were collected and fixed in acetic-alcohol (1:3) with a few drop of ferric chloride in it to facilate staining. Squashes were made permanent in t butyl alcohol series and microphotographs were taken from temporary preparations. Pollen fertility was measured heating the pollen grains in 1% acetocarmine solution, those who suitable stained were observed as fertile and colourless, empty, shrunken ones as sterile.Meiotic studies and pollen fertility were scored in C1 and C2 generations of the autote traploid Delphinium ajacis. ObservationsObservations on induced polyploidy in D. ajacis was extended over first (C,) and second (C2) generation. Various concentrations were tried and 0.25 and 0.35% concentration were found effective in inducing polyploidy (Table 1). Some shoots arising from the treated por tion, after producing a few chimeral leaves, later gave rise to fully tetraploid normal leaves. Seeds collected from C1 generation and sown for the study of C2 generation. Cytological study of the treated plants is the only confirmatory criteria to judge the autotetraploid plants. Meiotic studies: The colchiploidy was induced in D. ajacis and changes in the chromosome associations were observed in the present plant. The diploid showed 8 bivalents in which two chromosomes were larger in size in comparison to others (Fig. 1). Regular meiosis and cy tokinesis led to the formation of normal tetrads in diploid while few pollen mother cells showed univalents at diakinesis. In the treated plants, univalents and bivalents were observed with inconsistant frequencies while few cells showed only bivalent formation in C1 generation (Fig. 2). The chromosomal association of D. ajacis in C1 generation was 1.33 univalents and 15.33

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Evolution and Systematic Significance of Polyploidy

Cited by 127 publications

References 124 publications

Habitat differentiation in a narrow hybrid zone between diploid and tetraploid Anthoxanthum alpinum

Habitat differentiation in a narrow hybrid zone between diploid and tetraploid Anthoxanthum alpinum

EVOLUTIONARY GENETICS OF DIPLOID—TETRAPLOID SPECIES OF TREEFROGS OF THE GENUS HYLA

Chromosome Association and Behaviour in Autotetraploid Delphinium ajacis L.

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