Impact of Intraspecific Polyploidy in Andropogon gerardii (Poaceae) Populations

Keeler, Kathleen H.

doi:10.1674/0003-0031(2004)152[0063:ioipia]2.0.co;2

Cited by 46 publications

(61 citation statements)

References 29 publications

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“…Recently, with the development of flow cytometry as a tool for assessing DNA content and ploidy in plants, large-scale assessment of cytotype distribution patterns has became possible (Kron et al 2007) revealing surprisingly widespread co-occurrence of several cytotypes (Keeler 2004;Halverson et al 2008;Stahlberg 2009) despite theoretical assumptions that without reproductive isolation, local cytotype co-occurrence is unstable and frequency-dependent selection will exclude the cytotype in minority (Levin 1975;Felber 1991).…”

Section: Discussionmentioning

confidence: 99%

Absence of pollinator-mediated premating barriers in mixed-ploidy populations of Gymnadenia conopsea s.l. (Orchidaceae)

et al. 2010

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Polyploidy has played a key role in plant evolution and diversification. Despite this, the processes governing reproductive isolation among cytotypes growing in mixedploidy populations are still largely unknown. Theoretically, coexistence of diploid and polyploid individuals in sympatric populations is unlikely unless cytotypes are prezygotically isolated through assortative pollination. Here, we investigated the pre-mating barriers involved in the maintenance of three co-occurring cytotypes from the genus Gymnadenia (Orchidaceae): tetraploid and octoploid G. conopsea and tetraploid G. densiflora. We assessed differences in flowering phenology, floral morphology, and visual and olfactory cues, which could lead to assortative mating. Gas chromatography coupled with Electronic supplementary material The online version of this article (electroantennographic detection was used to identify scent compounds with physiological activity in the two main pollinators, Deilephila porcellus and Autographa gamma. The importance of olfactory cues was also assessed in the field by analysing the moths' responses to the olfactory display of the plants, and by following the pollinator's behaviour on artificial arrays. Our complex approach demonstrated that the coexistence of Gymnadenia cytotypes in mixed-ploidy populations was only partly explained by differences in floral phenology, as cytotypes with overlapping flowering (i.e., octoploid G. conopsea and tetraploid G. densiflora) might freely exchange pollen due to only 1 mm differences in spur lengths and the lack of assortative behaviour of pollinators. While floral colour among the cytotypes was similar, floral scent differed significantly. Though both pollinator species seemed to physiologically detect these differences, and the floral scent alone was sufficient to attract them, pollinators did not use this cue to discriminate the cytotypes in the field. The absence of premating barriers among cytotypes, except partial temporal segregation, suggests the existence of other mechanisms involved in the cytotypes' coexistence. The genetic differences in ITS sequences among cytotypes were used to discuss the cytotype's origin.

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Section: Discussionmentioning

confidence: 99%

Absence of pollinator-mediated premating barriers in mixed-ploidy populations of Gymnadenia conopsea s.l. (Orchidaceae)

et al. 2010

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“…The association between clonal reproduction and polyploidy was first reported in the late 1940s [29]. Recent studies aimed at the effect of ploidy variation on genotypic diversity in clonal species [32, 33], and more specifically on clonal size [34], however, indicate that polyploids are not more clonal compared to conspecific diploids and that it is hardly possible to draw any general conclusions about the interactions between clonality and polyploidy. On the other hand, it has been shown that lateral spread is a prerequisite for polyplodization, as it can compensate for the lower efficiency of generative reproduction in some polyploids.…”

Section: Introductionmentioning

confidence: 99%

Cytotype coexistence in the field cannot be explained by inter-cytotype hybridization alone: linking experiments and computer simulations in the sexual species Pilosella echioides (Asteraceae)

et al. 2017

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BackgroundProcesses driving ploidal diversity at the population level are virtually unknown. Their identification should use a combination of large-scale screening of ploidy levels in the field, pairwise crossing experiments and mathematical modelling linking these two types of data. We applied this approach to determine the drivers of frequencies of coexisting cytotypes in mixed-ploidy field populations of the fully sexual plant species Pilosella echioides. We examined fecundity and ploidal diversity in seeds from all possible pairwise crosses among 2x, 3x and 4x plants. Using these data, we simulated the dynamics of theoretical panmictic populations of individuals whose progeny structure is identical to that determined by the hybridization experiment.ResultsThe seed set differed significantly between the crossing treatments, being highest in crosses between diploids and tetraploids and lowest in triploid-triploid crosses. The number of progeny classes (with respect to embryo and endosperm ploidy) ranged from three in the 2x-2x cross to eleven in the 3x-3x cross. Our simulations demonstrate that, provided there is no difference in clonal growth and/or survival between cytotypes, it is a clear case of minority cytotype exclusion depending on the initial conditions with two stable states, neither of which corresponds to the ploidal structure in the field: (i) with prevalent diploids and lower proportions of other ploidies, and (ii) with prevalent tetraploids and 9% of hexaploids. By contrast, if clonal growth differs between cytotypes, minority cytotype exclusion occurs only if the role of sexual reproduction is high; otherwise differences in clonal growth are sufficient to maintain triploid prevalence (as observed in the field) independently of initial conditions.ConclusionsThe projections of our model suggest that the ploidal structure observed in the field can only be reached via a relatively high capacity for clonal growth (and proportionally lower sexual reproduction) in all cytotypes combined with higher clonal growth in the prevailing cytotype (3x).

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“…However, meiosis in the enneaploids is irregular leading to defective gametes. Keeler (2004) also found that hexaploids had a higher frequency of viable seeds than enneaploids. Flow cytometric examination is needed to determine the ploidy levels within populations in the Carolinas.…”

Section: Discussionmentioning

confidence: 90%

“…Polyploidy is reported for populations of big bluestem from midwestern studies (Keeler 1992, Norrmann et al 1997, Keeler 2004. Norrmann and colleagues (1997) reported that 6x (hexaploid) and 9x (enneaploid) big bluestem cytotypes are inter-fertile in midwestern populations.…”

Section: Discussionmentioning

confidence: 99%

“…Even where nearby suitable habitat conditions occur in the Carolinas, the ability of big bluestem to either colonize or re-colonize potential sites may be negatively affected by low fecundity. Keeler (2004) estimated a low recruitment rate by seed of 1% over a 4-yr period in her study of big bluestem reproduction in study plots in Boulder, Colorado. Also, the size of her study plots (10 x 10 m) was similar, or larger in comparison, to the 3 smaller populations in this study.…”

Section: Discussionmentioning

confidence: 99%

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An Outcrossing Reciprocity Study Between Remnant Big Bluestem (Andropogon gerardii) Populations in the Carolinas

Tompkins¹,

Stringer²,

Bridges³

2011

Ecological Restoration

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During the 2007-08 growing seasons we conducted an outcrossing reciprocity study with ramets from 5 big bluestem (Andropogon gerardii) populations from North and South Carolina. We established 15 treatments each at 4 garden sites. Seed germination was low and not significantly different for outcrossed (4.6%) and selfed (2.4%) treatments. However, germination was significantly higher for both outcrossed and selfed seeds from ramets from the Suther Prairie population. The overall mean percent seed set for the outcrossed treatments was 5.9%, and 3.6% for the selfed treatments. There were no significant differences in seed set (maternal effect) for the 5 populations. In addition, there were no significant differences in parental effect in either seed germination or seed set among the 5 populations. Ramets from the BlackJacks Heritage Preserve population ( paternal) x Suther Prairie population (maternal) and its reciprocal SP x BJ had the highest combined percent seed germination (21.3% and 5.8%, respectively). Ramets from the Suther Prairie population ( paternal) x Buck Creek Serpentine Barren (maternal), and its reciprocal BC x SP, had the highest combined percentage of seed set (22.7% and 9.6%, respectively). Results from this study suggest that viable seed production is low or absent in big bluestem populations in the Carolinas, particularly in smaller populations. We recommend vegetative material or seeds from the Suther Prairie big bluestem population for potential restoration and establishment of local big bluestem populations.

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Impact of Intraspecific Polyploidy in Andropogon gerardii (Poaceae) Populations

Cited by 46 publications

References 29 publications

Absence of pollinator-mediated premating barriers in mixed-ploidy populations of Gymnadenia conopsea s.l. (Orchidaceae)

Absence of pollinator-mediated premating barriers in mixed-ploidy populations of Gymnadenia conopsea s.l. (Orchidaceae)

Cytotype coexistence in the field cannot be explained by inter-cytotype hybridization alone: linking experiments and computer simulations in the sexual species Pilosella echioides (Asteraceae)

An Outcrossing Reciprocity Study Between Remnant Big Bluestem (Andropogon gerardii) Populations in the Carolinas

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