Origin and Distribution of Polyploid Achillea (Compositae) in Western North America

Tyrl, Ronald J.

doi:10.2307/2805480

Cited by 26 publications

(27 citation statements)

References 17 publications

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“…By the 1970s, plant taxonomists were sampling across large geographical areas and performing chromosome counts on 100s or 1000s of individuals-providing more rigorous sampling than previously had been done in natural species, and in some cases rivalling contemporary work that leverages flow cytometry [106][107][108]. Crossing experiments revealed reproductive barriers between ploidy levels (hybrid inviability caused by triploid block, hybrid sterility caused by production of aneuploid gametes by triploids) as expected from work by cytogeneticists in model systems [23,26,95,103,104,109].…”

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

248

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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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

248

237

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“…Here, the complex has developed an enormous secondary ecological radiation of 4x and 6x (and even 8x) populations (Clausen & al. 1948, Hiesey & Nobs 1970, Ehrendorfer 1973, Tyrl 1975. Available AFLP data (Guo & al.…”

Section: Diversification Of Achillea Sect Achillea In W Eurasiamentioning

confidence: 99%

Multidisciplinary studies onAchilleasensu lato(Compositae-Anthemideae):new data on systematics and phylogeography

Ehrendorfer

Guo²

2006

Willdenowia

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“…Unopened florets were fixed in modified Carnoy's solution (60% chloroform, 30% ethanol, 10% acetic acid), stored in 70% ethanol and stained in Snow's carmine, following Tyrl (1975). Stained anthers were mounted in Hoyer's medium and analyzed at Â 400 magnification on a compound microscope.…”

Section: Cytologymentioning

confidence: 99%

“…Tyrl (1975) found that tetraploid A. borealis produced occasional unreduced pollen grains -identifiable by their large size -and hypothesized that hexaploid A. borealis formed via unreduced pollen production in tetraploid populations. This study was conducted in two tetraploid populations occurring in grasslands on the Pacific coast of California.…”

Section: Introductionmentioning

confidence: 99%

“…Although the genus has a predominately Old World distribution, phylogenetic studies indicate that an autotetraploid lineage of the circumpolar A. millefolium aggregate colonized North America approximately 1 Mya (Guo et al, 2005;Ramsey, unpublished data). In a rapid radiation, these tetraploids evolved a diversity of ecological races (widespread across North America) as well as local occurrences of autohexaploids (restricted to the Pacific states and provinces of the United States and Canada) (Clausen et al, 1940(Clausen et al, , 1948Lawrence, 1947;Tyrl, 1975). Tetraploids (2n ¼ 4x ¼ 36) and hexaploids (2n ¼ 6x ¼ 54) are regionally sympatric along the Pacific coast and do not have distinguishing morphological characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Unreduced gametes and neopolyploids in natural populations of Achillea borealis (Asteraceae)

2006

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Polyploidy is a major mechanism of speciation and adaptation, yet little is known about the origins of polyploids in natural species. I investigated gametic nonreduction and neopolyploid formation in natural tetraploid populations of Achillea borealis (Asteraceae), an autopolyploid complex consisting of tetraploid and hexaploid cytotypes. Cytological analyses of tetraploid populations revealed the occurrence of reduced (n ¼ 2x) as well as unreduced 'big' (2n ¼ 4x) and 'jumbo' (4n ¼ 8x) pollen grains, which were clearly distinguished by size. Production of unreduced pollen was monitored in two tetraploid populations in 1997 and 1998. Mean population-level frequencies of unreduced pollen ranged from 0.030 to 0.538%, with as few as one-third and as many as one-half of sampled plants producing unreduced grains. Eight individuals were found to produce 41% unreduced pollen, with highest observed frequencies of 7.0, 13.2 and 15.8%. Experimental crosses using high unreduced pollen producers as male parents generated viable seeds. However, the frequency of neohexaploids in the progeny of experimental crosses (0.388%) was similar to that observed in progeny of randomly selected, openpollinated control parents (0.465%). These results suggest that unreduced eggs are the most likely source of new polyploids. In spite of the inefficiency of unreduced pollen in unilateral sexual polyploidization, the overall rate of neohexaploid formation (one in 233) was several orders of magnitude greater than estimates of genic mutation rates.

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Origin and Distribution of Polyploid Achillea (Compositae) in Western North America

Cited by 26 publications

References 17 publications

Ecological studies of polyploidy in the 100 years following its discovery

Ecological studies of polyploidy in the 100 years following its discovery

Multidisciplinary studies onAchilleasensu lato(Compositae-Anthemideae):new data on systematics and phylogeography

Unreduced gametes and neopolyploids in natural populations of Achillea borealis (Asteraceae)

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