Species hybrids and spontaneous amphiploids in the Gilia laciniata group

Grant, Verne

doi:10.1038/hdy.1965.67

Cited by 17 publications

(10 citation statements)

References 17 publications

(9 reference statements)

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“…These are powerful mechanisms for generating new genome diversity by chromosome recombination or chromosome doubling, respectively. The important role of natural hybridization in the process of evolution, particularly in disturbed habitats, has been stressed by, for example, Anderson (1949, 1953), Stebbins (1959), Stebbins and Daly (1961), Grant (1965), Levin (1966), Barber (1970) and Heiser (1973). The origin and evolution of crop plants also depended strongly on hybridization ( Hancock 1992; Smartt & Simmonds 1995).…”

Section: Introductionmentioning

confidence: 99%

“…Spontaneous crossing between species belonging to the same ploidy level has been studied extensively ( see Stace 1975). The importance of polyploidization is also widely studied ( Smith 1946; Grant 1965; De Wet 1971, 1980; Stebbins 1971, 1980; Clark 1975; Simonsen 1975; Gottschalk 1976; Jackson 1976, 1982; Lewis 1976; Lewis & Suda 1976; Ehrendorfer 1980; Tal 1980; Levin 1983; Rothera & Davy 1986; Lumaret et al 1987 ). Hybridization under natural conditions between cytotypes of different ploidy levels, however, is less studied, as is the role of F 1 hybrids in the gene transfer among both parents ( Yeo 1956; Zohary & Nur 1959; Vardi 1974; Jackson 1976).…”

Section: Introductionmentioning

confidence: 99%

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Effect of ploidy level on fruit morphology, seed germination and juvenile growth in scurvy grass (Cochlearia officinalis L. s.l., Brassicaceae)

Pegtel¹

1999

Plant Species Biology

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The biennial to short‐lived wintergreen perennial Cochlearia officinalis L. s.l. (basic chromosome number x = 6) encompasses a group of closely related taxa that is difficult to delimitate morphologically. Despite a lack of distinct sets of discontinuous morphological characters, at least six numerically different cytotypes have commonly been recognized, and they have different ecologic distributions. Evolution of the wide ploidy level was likely brought about by hybridization and polyploidization. Because plants are short‐lived, seed germination was established and was likely to favor subsequent establishment. Therefore, shoot growth of juveniles was also compared. Five ecologically allopatric populations of C. officinalis s.l., each supposedly representing a different cytotype, were sampled for flowering shoots and seeds to establish shoot morphological traits, germination capabilities and chromosome number. The sampled populations differed in chromosome number: 2n = 2x = 12 (diploid); 2n = 4x = 24 (tetraploid); 2n = 33; 2n = 6x = 36 (hexaploid); and 2n = 8x = 48 (octaploid), representing the taxa C. pyrenaica DC, C. officinalis L. s.s., C. danica L. ×C. officinalis L. s.s., C. x hollandica Henrard and C. anglica L., respectively. All cytotypes produced abundant seeds and seed weight was proportional to the ploidy level. Seed weight of the diploid C. pyrenaica did not follow this correlation. Germination capacity immediately after seed collection was high over a wide temperature range. Germination was non‐photoblastic. High germination capability accentuated the short‐lived life‐cycles of the five cytotypes. Seed germination of the coastal cytotypes (C. x hollandica and C. anglica) were less negatively affected by NaCl compared to the non‐coastal cytotypes (C. pyrenaica and C. officinalis s.s.) and the very rare coastal hybrid C. danica×C. officinalis s.s. The cytotypes differed markedly in growth characteristics but there was no simple relationship between them. Increases in ploidy level were not paralleled by increased shoot growth. The hexaploid hybrid C. x hollandica indicated hybrid vigor in both shoot growth (yield) and petiole length of the strongly ascending leaves. Leaves of C. anglica were arranged in a prostratous rosette and the difference in shoot architecture between both C. x hollandica and C. anglica may be one of the reasons why this species is being replaced by the hexaploid hybrid, if sympatric, in coastal regions of The Netherlands. The 2n = 33‐hybrid C. danica×C. officinalis s.s. showed no such heterosis effects in shoot growth characteristics.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of ploidy level on fruit morphology, seed germination and juvenile growth in scurvy grass (Cochlearia officinalis L. s.l., Brassicaceae)

Pegtel¹

1999

Plant Species Biology

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“…From the initial discovery of genome duplication, much speculation was made regarding the ecology of polyploids-about competition with progenitor diploids, contributions of ploidy to environmental adaptation, intrinsic and extrinsic factors that could favour the demographic establishment of polyploid populations, and the broader significance that ploidy variation may have for species interactions and community structure [1,2,15,16,19,20,22,[64][65][66]97,121]. It is remarkable, then, that little empirical work was focused explicitly on these issues prior to the 1980s.…”

Section: The Modern Era (A) An Influx Of Population Biologists (1980smentioning

confidence: 99%

“…For example, Grant [3,22,92] viewed associations between polyploidy, life-history traits and mating systems principally in terms of polyploid formation (i.e. perennials have a longer life-cycle in which to experience somatic doubling, while selffertilizing annuals have a higher probably of uniting unreduced gametes produced by F 1 interspecific hybrids); on the other hand, associations between polyploidy and historical disturbance were viewed by Grant in terms of establishment and persistence (i.e.…”

Section: Polyploidy In Plant Taxonomy (A) the Biosystematics Era (195mentioning

confidence: 99%

Ecological studies of polyploidy in the 100 years following its discovery

Ramsey

2014

Phil. Trans. R. Soc. B

247

237

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Polyploidy is a mutation with profound phenotypic consequences and thus hypothesized to have transformative effects in plant ecology. This is most often considered in the context of geographical and environmental distributions—as achieved from divergence of physiological and life-history traits—but may also include species interactions and biological invasion. This paper presents a historical overview of hypotheses and empirical data regarding the ecology of polyploids. Early researchers of polyploidy (1910s–1930s) were geneticists by training but nonetheless savvy to its phenotypic effects, and speculated on the importance of genome duplication to adaptation and crop improvement. Cytogenetic studies in the 1930s–1950s indicated that polyploids are larger (sturdier foliage, thicker stems and taller stature) than diploids while cytogeographic surveys suggested that polyploids and diploids have allopatric or parapatric distributions. Although autopolyploidy was initially regarded as common, influential writings by North American botanists in the 1940s and 1950s argued for the principle role of allopolyploidy; according to this view, genome duplication was significant for providing a broader canvas for hybridization rather than for its phenotypic effects per se . The emphasis on allopolyploidy had a chilling effect on nascent ecological work, in part due to taxonomic challenges posed by interspecific hybridization. Nonetheless, biosystematic efforts over the next few decades (1950s–1970s) laid the foundation for ecological research by documenting cytotype distributions and identifying phenotypic correlates of polyploidy. Rigorous investigation of polyploid ecology was achieved in the 1980s and 1990s by population biologists who leveraged flow cytometry for comparative work in autopolyploid complexes. These efforts revealed multi-faceted ecological and phenotypic differences, some of which may be direct consequences of genome duplication. Several classical hypotheses about the ecology of polyploids remain untested, however, and allopolyploidy—regarded by most botanists as the primary mode of genome duplication—is largely unstudied in an ecological context.

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“…Natural hybridization is a powerful mechanism for generating new diversity by recombining the adaptive gene complexes from divergent gene pools, particularly in disturbed habitats. The classical publications by Anderson (1949Anderson ( , 1953, Heiser (1954Heiser ( ,1973, Rick (1958), Stebbins (1959), Stebbins and Daly (1961), Mangelsdorf (1961), Grant (1965), Levin (1966), Valentine (1966), Barber (1970), Chu and Oka (1970), Donald (1970), de Wet (1971 and Jackson (1976) exemplify the overwhelming role of natural hybridization in the process of evolution in general, and in the origin and evolution of crop plants in particular. Although there have been extensive studies on spontaneous crossing between species belonging to the same ploidy level {see Stace, 1973), information relating to hybridization between diploids and allotetraploids, and the role of E^ triploid hybrids in the gene transfer arnong parental genotypes, under natural conditions (Yeo, 1953;Zohary and Nur, 1959;Vardi, 1974;Jackson, 1976) is scanty.…”

Section: Introductionmentioning

confidence: 99%

CYTOGENETICS OF GALINSOGA PARVIFLORA CAV. AND G. CILIATA (RAF.) BLAKE, AND THEIR NATURAL HYBRIDS (ASTERACEAE)

Gopinathan¹,

Babu²

1982

New Phytologist

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SUMMARYThe somatic and meiotic chromosomes of four natural populations of Galinsoga Ruiz & Pav. -Population I (G. parvifiora Cav.), Population II [G. ciliata (Raf.) Blake], Population III and Population IV have been analyzed. Our studies show that G. parvifiora is a diploid (2« = 16); G. ciliata is a segmental allotetraploid (2n = 32); Population III is a triploid natural hybrid between G. parvifiora and G. ciliata (3n = 24); and population IV is a putative introgressant between G. parvifiora and the natural triploid hybrid {In = 16). The meiotic chromosomes form eight hivalents and do not reveal any irregularities in G. parvifiora which shows 100% pollen viability. During the meiosis of G. ciliata, however, 16 bivalents with occasional quadrivalents, anaphasic bridges and laggards are noticed, and pollen viability varies from 90 to 100%. In the triploid hybrids all the 24 chromosomes form univalents which are grouped into an unanalyzable chromosomal entanglement at metaphase I; consequently the per cent pollen viability is 0. The meiotic behaviour of chromosomes in introgressant is similar to that of G. parvifiora, except for the high frequency of quadrivalents and laggards, and lesser pollen viability. The presence of inversion loops in G. ciliata and in Population IV imply that the parental species differ in chromosomal rearrangements.

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Species hybrids and spontaneous amphiploids in the Gilia laciniata group

Cited by 17 publications

References 17 publications

Effect of ploidy level on fruit morphology, seed germination and juvenile growth in scurvy grass (Cochlearia officinalis L. s.l., Brassicaceae)

Effect of ploidy level on fruit morphology, seed germination and juvenile growth in scurvy grass (Cochlearia officinalis L. s.l., Brassicaceae)

Ecological studies of polyploidy in the 100 years following its discovery

CYTOGENETICS OF GALINSOGA PARVIFLORA CAV. AND G. CILIATA (RAF.) BLAKE, AND THEIR NATURAL HYBRIDS (ASTERACEAE)

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